cmd/compile: restore zero-copy string->[]byte optimization

[gostls13.git] / src / cmd / compile / internal / ssagen / ssa.go

// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ssagen

import (
        "bufio"
        "bytes"
        "fmt"
        "go/constant"
        "html"
        "internal/buildcfg"
        "os"
        "path/filepath"
        "sort"
        "strings"

        "cmd/compile/internal/abi"
        "cmd/compile/internal/base"
        "cmd/compile/internal/ir"
        "cmd/compile/internal/liveness"
        "cmd/compile/internal/objw"
        "cmd/compile/internal/reflectdata"
        "cmd/compile/internal/ssa"
        "cmd/compile/internal/staticdata"
        "cmd/compile/internal/typecheck"
        "cmd/compile/internal/types"
        "cmd/internal/obj"
        "cmd/internal/src"
        "cmd/internal/sys"

        rtabi "internal/abi"
)

var ssaConfig *ssa.Config
var ssaCaches []ssa.Cache

var ssaDump string     // early copy of $GOSSAFUNC; the func name to dump output for
var ssaDir string      // optional destination for ssa dump file
var ssaDumpStdout bool // whether to dump to stdout
var ssaDumpCFG string  // generate CFGs for these phases
const ssaDumpFile = "ssa.html"

// ssaDumpInlined holds all inlined functions when ssaDump contains a function name.
var ssaDumpInlined []*ir.Func

func DumpInline(fn *ir.Func) {
        if ssaDump != "" && ssaDump == ir.FuncName(fn) {
                ssaDumpInlined = append(ssaDumpInlined, fn)
        }
}

func InitEnv() {
        ssaDump = os.Getenv("GOSSAFUNC")
        ssaDir = os.Getenv("GOSSADIR")
        if ssaDump != "" {
                if strings.HasSuffix(ssaDump, "+") {
                        ssaDump = ssaDump[:len(ssaDump)-1]
                        ssaDumpStdout = true
                }
                spl := strings.Split(ssaDump, ":")
                if len(spl) > 1 {
                        ssaDump = spl[0]
                        ssaDumpCFG = spl[1]
                }
        }
}

func InitConfig() {
        types_ := ssa.NewTypes()

        if Arch.SoftFloat {
                softfloatInit()
        }

        // Generate a few pointer types that are uncommon in the frontend but common in the backend.
        // Caching is disabled in the backend, so generating these here avoids allocations.
        _ = types.NewPtr(types.Types[types.TINTER])                             // *interface{}
        _ = types.NewPtr(types.NewPtr(types.Types[types.TSTRING]))              // **string
        _ = types.NewPtr(types.NewSlice(types.Types[types.TINTER]))             // *[]interface{}
        _ = types.NewPtr(types.NewPtr(types.ByteType))                          // **byte
        _ = types.NewPtr(types.NewSlice(types.ByteType))                        // *[]byte
        _ = types.NewPtr(types.NewSlice(types.Types[types.TSTRING]))            // *[]string
        _ = types.NewPtr(types.NewPtr(types.NewPtr(types.Types[types.TUINT8]))) // ***uint8
        _ = types.NewPtr(types.Types[types.TINT16])                             // *int16
        _ = types.NewPtr(types.Types[types.TINT64])                             // *int64
        _ = types.NewPtr(types.ErrorType)                                       // *error
        types.NewPtrCacheEnabled = false
        ssaConfig = ssa.NewConfig(base.Ctxt.Arch.Name, *types_, base.Ctxt, base.Flag.N == 0, Arch.SoftFloat)
        ssaConfig.Race = base.Flag.Race
        ssaCaches = make([]ssa.Cache, base.Flag.LowerC)

        // Set up some runtime functions we'll need to call.
        ir.Syms.AssertE2I = typecheck.LookupRuntimeFunc("assertE2I")
        ir.Syms.AssertE2I2 = typecheck.LookupRuntimeFunc("assertE2I2")
        ir.Syms.AssertI2I = typecheck.LookupRuntimeFunc("assertI2I")
        ir.Syms.AssertI2I2 = typecheck.LookupRuntimeFunc("assertI2I2")
        ir.Syms.CgoCheckMemmove = typecheck.LookupRuntimeFunc("cgoCheckMemmove")
        ir.Syms.CgoCheckPtrWrite = typecheck.LookupRuntimeFunc("cgoCheckPtrWrite")
        ir.Syms.CheckPtrAlignment = typecheck.LookupRuntimeFunc("checkptrAlignment")
        ir.Syms.Deferproc = typecheck.LookupRuntimeFunc("deferproc")
        ir.Syms.DeferprocStack = typecheck.LookupRuntimeFunc("deferprocStack")
        ir.Syms.Deferreturn = typecheck.LookupRuntimeFunc("deferreturn")
        ir.Syms.Duffcopy = typecheck.LookupRuntimeFunc("duffcopy")
        ir.Syms.Duffzero = typecheck.LookupRuntimeFunc("duffzero")
        ir.Syms.GCWriteBarrier[0] = typecheck.LookupRuntimeFunc("gcWriteBarrier1")
        ir.Syms.GCWriteBarrier[1] = typecheck.LookupRuntimeFunc("gcWriteBarrier2")
        ir.Syms.GCWriteBarrier[2] = typecheck.LookupRuntimeFunc("gcWriteBarrier3")
        ir.Syms.GCWriteBarrier[3] = typecheck.LookupRuntimeFunc("gcWriteBarrier4")
        ir.Syms.GCWriteBarrier[4] = typecheck.LookupRuntimeFunc("gcWriteBarrier5")
        ir.Syms.GCWriteBarrier[5] = typecheck.LookupRuntimeFunc("gcWriteBarrier6")
        ir.Syms.GCWriteBarrier[6] = typecheck.LookupRuntimeFunc("gcWriteBarrier7")
        ir.Syms.GCWriteBarrier[7] = typecheck.LookupRuntimeFunc("gcWriteBarrier8")
        ir.Syms.Goschedguarded = typecheck.LookupRuntimeFunc("goschedguarded")
        ir.Syms.Growslice = typecheck.LookupRuntimeFunc("growslice")
        ir.Syms.Memmove = typecheck.LookupRuntimeFunc("memmove")
        ir.Syms.Msanread = typecheck.LookupRuntimeFunc("msanread")
        ir.Syms.Msanwrite = typecheck.LookupRuntimeFunc("msanwrite")
        ir.Syms.Msanmove = typecheck.LookupRuntimeFunc("msanmove")
        ir.Syms.Asanread = typecheck.LookupRuntimeFunc("asanread")
        ir.Syms.Asanwrite = typecheck.LookupRuntimeFunc("asanwrite")
        ir.Syms.Newobject = typecheck.LookupRuntimeFunc("newobject")
        ir.Syms.Newproc = typecheck.LookupRuntimeFunc("newproc")
        ir.Syms.Panicdivide = typecheck.LookupRuntimeFunc("panicdivide")
        ir.Syms.PanicdottypeE = typecheck.LookupRuntimeFunc("panicdottypeE")
        ir.Syms.PanicdottypeI = typecheck.LookupRuntimeFunc("panicdottypeI")
        ir.Syms.Panicnildottype = typecheck.LookupRuntimeFunc("panicnildottype")
        ir.Syms.Panicoverflow = typecheck.LookupRuntimeFunc("panicoverflow")
        ir.Syms.Panicshift = typecheck.LookupRuntimeFunc("panicshift")
        ir.Syms.Raceread = typecheck.LookupRuntimeFunc("raceread")
        ir.Syms.Racereadrange = typecheck.LookupRuntimeFunc("racereadrange")
        ir.Syms.Racewrite = typecheck.LookupRuntimeFunc("racewrite")
        ir.Syms.Racewriterange = typecheck.LookupRuntimeFunc("racewriterange")
        ir.Syms.WBZero = typecheck.LookupRuntimeFunc("wbZero")
        ir.Syms.WBMove = typecheck.LookupRuntimeFunc("wbMove")
        ir.Syms.X86HasPOPCNT = typecheck.LookupRuntimeVar("x86HasPOPCNT")       // bool
        ir.Syms.X86HasSSE41 = typecheck.LookupRuntimeVar("x86HasSSE41")         // bool
        ir.Syms.X86HasFMA = typecheck.LookupRuntimeVar("x86HasFMA")             // bool
        ir.Syms.ARMHasVFPv4 = typecheck.LookupRuntimeVar("armHasVFPv4")         // bool
        ir.Syms.ARM64HasATOMICS = typecheck.LookupRuntimeVar("arm64HasATOMICS") // bool
        ir.Syms.Staticuint64s = typecheck.LookupRuntimeVar("staticuint64s")
        ir.Syms.Typedmemmove = typecheck.LookupRuntimeFunc("typedmemmove")
        ir.Syms.Udiv = typecheck.LookupRuntimeVar("udiv")                 // asm func with special ABI
        ir.Syms.WriteBarrier = typecheck.LookupRuntimeVar("writeBarrier") // struct { bool; ... }
        ir.Syms.Zerobase = typecheck.LookupRuntimeVar("zerobase")

        if Arch.LinkArch.Family == sys.Wasm {
                BoundsCheckFunc[ssa.BoundsIndex] = typecheck.LookupRuntimeFunc("goPanicIndex")
                BoundsCheckFunc[ssa.BoundsIndexU] = typecheck.LookupRuntimeFunc("goPanicIndexU")
                BoundsCheckFunc[ssa.BoundsSliceAlen] = typecheck.LookupRuntimeFunc("goPanicSliceAlen")
                BoundsCheckFunc[ssa.BoundsSliceAlenU] = typecheck.LookupRuntimeFunc("goPanicSliceAlenU")
                BoundsCheckFunc[ssa.BoundsSliceAcap] = typecheck.LookupRuntimeFunc("goPanicSliceAcap")
                BoundsCheckFunc[ssa.BoundsSliceAcapU] = typecheck.LookupRuntimeFunc("goPanicSliceAcapU")
                BoundsCheckFunc[ssa.BoundsSliceB] = typecheck.LookupRuntimeFunc("goPanicSliceB")
                BoundsCheckFunc[ssa.BoundsSliceBU] = typecheck.LookupRuntimeFunc("goPanicSliceBU")
                BoundsCheckFunc[ssa.BoundsSlice3Alen] = typecheck.LookupRuntimeFunc("goPanicSlice3Alen")
                BoundsCheckFunc[ssa.BoundsSlice3AlenU] = typecheck.LookupRuntimeFunc("goPanicSlice3AlenU")
                BoundsCheckFunc[ssa.BoundsSlice3Acap] = typecheck.LookupRuntimeFunc("goPanicSlice3Acap")
                BoundsCheckFunc[ssa.BoundsSlice3AcapU] = typecheck.LookupRuntimeFunc("goPanicSlice3AcapU")
                BoundsCheckFunc[ssa.BoundsSlice3B] = typecheck.LookupRuntimeFunc("goPanicSlice3B")
                BoundsCheckFunc[ssa.BoundsSlice3BU] = typecheck.LookupRuntimeFunc("goPanicSlice3BU")
                BoundsCheckFunc[ssa.BoundsSlice3C] = typecheck.LookupRuntimeFunc("goPanicSlice3C")
                BoundsCheckFunc[ssa.BoundsSlice3CU] = typecheck.LookupRuntimeFunc("goPanicSlice3CU")
                BoundsCheckFunc[ssa.BoundsConvert] = typecheck.LookupRuntimeFunc("goPanicSliceConvert")
        } else {
                BoundsCheckFunc[ssa.BoundsIndex] = typecheck.LookupRuntimeFunc("panicIndex")
                BoundsCheckFunc[ssa.BoundsIndexU] = typecheck.LookupRuntimeFunc("panicIndexU")
                BoundsCheckFunc[ssa.BoundsSliceAlen] = typecheck.LookupRuntimeFunc("panicSliceAlen")
                BoundsCheckFunc[ssa.BoundsSliceAlenU] = typecheck.LookupRuntimeFunc("panicSliceAlenU")
                BoundsCheckFunc[ssa.BoundsSliceAcap] = typecheck.LookupRuntimeFunc("panicSliceAcap")
                BoundsCheckFunc[ssa.BoundsSliceAcapU] = typecheck.LookupRuntimeFunc("panicSliceAcapU")
                BoundsCheckFunc[ssa.BoundsSliceB] = typecheck.LookupRuntimeFunc("panicSliceB")
                BoundsCheckFunc[ssa.BoundsSliceBU] = typecheck.LookupRuntimeFunc("panicSliceBU")
                BoundsCheckFunc[ssa.BoundsSlice3Alen] = typecheck.LookupRuntimeFunc("panicSlice3Alen")
                BoundsCheckFunc[ssa.BoundsSlice3AlenU] = typecheck.LookupRuntimeFunc("panicSlice3AlenU")
                BoundsCheckFunc[ssa.BoundsSlice3Acap] = typecheck.LookupRuntimeFunc("panicSlice3Acap")
                BoundsCheckFunc[ssa.BoundsSlice3AcapU] = typecheck.LookupRuntimeFunc("panicSlice3AcapU")
                BoundsCheckFunc[ssa.BoundsSlice3B] = typecheck.LookupRuntimeFunc("panicSlice3B")
                BoundsCheckFunc[ssa.BoundsSlice3BU] = typecheck.LookupRuntimeFunc("panicSlice3BU")
                BoundsCheckFunc[ssa.BoundsSlice3C] = typecheck.LookupRuntimeFunc("panicSlice3C")
                BoundsCheckFunc[ssa.BoundsSlice3CU] = typecheck.LookupRuntimeFunc("panicSlice3CU")
                BoundsCheckFunc[ssa.BoundsConvert] = typecheck.LookupRuntimeFunc("panicSliceConvert")
        }
        if Arch.LinkArch.PtrSize == 4 {
                ExtendCheckFunc[ssa.BoundsIndex] = typecheck.LookupRuntimeVar("panicExtendIndex")
                ExtendCheckFunc[ssa.BoundsIndexU] = typecheck.LookupRuntimeVar("panicExtendIndexU")
                ExtendCheckFunc[ssa.BoundsSliceAlen] = typecheck.LookupRuntimeVar("panicExtendSliceAlen")
                ExtendCheckFunc[ssa.BoundsSliceAlenU] = typecheck.LookupRuntimeVar("panicExtendSliceAlenU")
                ExtendCheckFunc[ssa.BoundsSliceAcap] = typecheck.LookupRuntimeVar("panicExtendSliceAcap")
                ExtendCheckFunc[ssa.BoundsSliceAcapU] = typecheck.LookupRuntimeVar("panicExtendSliceAcapU")
                ExtendCheckFunc[ssa.BoundsSliceB] = typecheck.LookupRuntimeVar("panicExtendSliceB")
                ExtendCheckFunc[ssa.BoundsSliceBU] = typecheck.LookupRuntimeVar("panicExtendSliceBU")
                ExtendCheckFunc[ssa.BoundsSlice3Alen] = typecheck.LookupRuntimeVar("panicExtendSlice3Alen")
                ExtendCheckFunc[ssa.BoundsSlice3AlenU] = typecheck.LookupRuntimeVar("panicExtendSlice3AlenU")
                ExtendCheckFunc[ssa.BoundsSlice3Acap] = typecheck.LookupRuntimeVar("panicExtendSlice3Acap")
                ExtendCheckFunc[ssa.BoundsSlice3AcapU] = typecheck.LookupRuntimeVar("panicExtendSlice3AcapU")
                ExtendCheckFunc[ssa.BoundsSlice3B] = typecheck.LookupRuntimeVar("panicExtendSlice3B")
                ExtendCheckFunc[ssa.BoundsSlice3BU] = typecheck.LookupRuntimeVar("panicExtendSlice3BU")
                ExtendCheckFunc[ssa.BoundsSlice3C] = typecheck.LookupRuntimeVar("panicExtendSlice3C")
                ExtendCheckFunc[ssa.BoundsSlice3CU] = typecheck.LookupRuntimeVar("panicExtendSlice3CU")
        }

        // Wasm (all asm funcs with special ABIs)
        ir.Syms.WasmDiv = typecheck.LookupRuntimeVar("wasmDiv")
        ir.Syms.WasmTruncS = typecheck.LookupRuntimeVar("wasmTruncS")
        ir.Syms.WasmTruncU = typecheck.LookupRuntimeVar("wasmTruncU")
        ir.Syms.SigPanic = typecheck.LookupRuntimeFunc("sigpanic")
}

// AbiForBodylessFuncStackMap returns the ABI for a bodyless function's stack map.
// This is not necessarily the ABI used to call it.
// Currently (1.17 dev) such a stack map is always ABI0;
// any ABI wrapper that is present is nosplit, hence a precise
// stack map is not needed there (the parameters survive only long
// enough to call the wrapped assembly function).
// This always returns a freshly copied ABI.
func AbiForBodylessFuncStackMap(fn *ir.Func) *abi.ABIConfig {
        return ssaConfig.ABI0.Copy() // No idea what races will result, be safe
}

// abiForFunc implements ABI policy for a function, but does not return a copy of the ABI.
// Passing a nil function returns the default ABI based on experiment configuration.
func abiForFunc(fn *ir.Func, abi0, abi1 *abi.ABIConfig) *abi.ABIConfig {
        if buildcfg.Experiment.RegabiArgs {
                // Select the ABI based on the function's defining ABI.
                if fn == nil {
                        return abi1
                }
                switch fn.ABI {
                case obj.ABI0:
                        return abi0
                case obj.ABIInternal:
                        // TODO(austin): Clean up the nomenclature here.
                        // It's not clear that "abi1" is ABIInternal.
                        return abi1
                }
                base.Fatalf("function %v has unknown ABI %v", fn, fn.ABI)
                panic("not reachable")
        }

        a := abi0
        if fn != nil {
                if fn.Pragma&ir.RegisterParams != 0 { // TODO(register args) remove after register abi is working
                        a = abi1
                }
        }
        return a
}

// dvarint writes a varint v to the funcdata in symbol x and returns the new offset.
func dvarint(x *obj.LSym, off int, v int64) int {
        if v < 0 || v > 1e9 {
                panic(fmt.Sprintf("dvarint: bad offset for funcdata - %v", v))
        }
        if v < 1<<7 {
                return objw.Uint8(x, off, uint8(v))
        }
        off = objw.Uint8(x, off, uint8((v&127)|128))
        if v < 1<<14 {
                return objw.Uint8(x, off, uint8(v>>7))
        }
        off = objw.Uint8(x, off, uint8(((v>>7)&127)|128))
        if v < 1<<21 {
                return objw.Uint8(x, off, uint8(v>>14))
        }
        off = objw.Uint8(x, off, uint8(((v>>14)&127)|128))
        if v < 1<<28 {
                return objw.Uint8(x, off, uint8(v>>21))
        }
        off = objw.Uint8(x, off, uint8(((v>>21)&127)|128))
        return objw.Uint8(x, off, uint8(v>>28))
}

// emitOpenDeferInfo emits FUNCDATA information about the defers in a function
// that is using open-coded defers.  This funcdata is used to determine the active
// defers in a function and execute those defers during panic processing.
//
// The funcdata is all encoded in varints (since values will almost always be less than
// 128, but stack offsets could potentially be up to 2Gbyte). All "locations" (offsets)
// for stack variables are specified as the number of bytes below varp (pointer to the
// top of the local variables) for their starting address. The format is:
//
//   - Offset of the deferBits variable
//   - Offset of the first closure slot (the rest are laid out consecutively).
func (s *state) emitOpenDeferInfo() {
        firstOffset := s.openDefers[0].closureNode.FrameOffset()

        // Verify that cmpstackvarlt laid out the slots in order.
        for i, r := range s.openDefers {
                have := r.closureNode.FrameOffset()
                want := firstOffset + int64(i)*int64(types.PtrSize)
                if have != want {
                        base.FatalfAt(s.curfn.Pos(), "unexpected frame offset for open-coded defer slot #%v: have %v, want %v", i, have, want)
                }
        }

        x := base.Ctxt.Lookup(s.curfn.LSym.Name + ".opendefer")
        x.Set(obj.AttrContentAddressable, true)
        s.curfn.LSym.Func().OpenCodedDeferInfo = x

        off := 0
        off = dvarint(x, off, -s.deferBitsTemp.FrameOffset())
        off = dvarint(x, off, -firstOffset)
}

func okOffset(offset int64) int64 {
        if offset == types.BOGUS_FUNARG_OFFSET {
                panic(fmt.Errorf("Bogus offset %d", offset))
        }
        return offset
}

// buildssa builds an SSA function for fn.
// worker indicates which of the backend workers is doing the processing.
func buildssa(fn *ir.Func, worker int) *ssa.Func {
        name := ir.FuncName(fn)
        printssa := false
        if ssaDump != "" { // match either a simple name e.g. "(*Reader).Reset", package.name e.g. "compress/gzip.(*Reader).Reset", or subpackage name "gzip.(*Reader).Reset"
                pkgDotName := base.Ctxt.Pkgpath + "." + name
                printssa = name == ssaDump ||
                        strings.HasSuffix(pkgDotName, ssaDump) && (pkgDotName == ssaDump || strings.HasSuffix(pkgDotName, "/"+ssaDump))
        }
        var astBuf *bytes.Buffer
        if printssa {
                astBuf = &bytes.Buffer{}
                ir.FDumpList(astBuf, "buildssa-enter", fn.Enter)
                ir.FDumpList(astBuf, "buildssa-body", fn.Body)
                ir.FDumpList(astBuf, "buildssa-exit", fn.Exit)
                if ssaDumpStdout {
                        fmt.Println("generating SSA for", name)
                        fmt.Print(astBuf.String())
                }
        }

        var s state
        s.pushLine(fn.Pos())
        defer s.popLine()

        s.hasdefer = fn.HasDefer()
        if fn.Pragma&ir.CgoUnsafeArgs != 0 {
                s.cgoUnsafeArgs = true
        }
        s.checkPtrEnabled = ir.ShouldCheckPtr(fn, 1)

        fe := ssafn{
                curfn: fn,
                log:   printssa && ssaDumpStdout,
        }
        s.curfn = fn

        s.f = ssa.NewFunc(&fe)
        s.config = ssaConfig
        s.f.Type = fn.Type()
        s.f.Config = ssaConfig
        s.f.Cache = &ssaCaches[worker]
        s.f.Cache.Reset()
        s.f.Name = name
        s.f.PrintOrHtmlSSA = printssa
        if fn.Pragma&ir.Nosplit != 0 {
                s.f.NoSplit = true
        }
        s.f.ABI0 = ssaConfig.ABI0.Copy() // Make a copy to avoid racy map operations in type-register-width cache.
        s.f.ABI1 = ssaConfig.ABI1.Copy()
        s.f.ABIDefault = abiForFunc(nil, s.f.ABI0, s.f.ABI1)
        s.f.ABISelf = abiForFunc(fn, s.f.ABI0, s.f.ABI1)

        s.panics = map[funcLine]*ssa.Block{}
        s.softFloat = s.config.SoftFloat

        // Allocate starting block
        s.f.Entry = s.f.NewBlock(ssa.BlockPlain)
        s.f.Entry.Pos = fn.Pos()

        if printssa {
                ssaDF := ssaDumpFile
                if ssaDir != "" {
                        ssaDF = filepath.Join(ssaDir, base.Ctxt.Pkgpath+"."+name+".html")
                        ssaD := filepath.Dir(ssaDF)
                        os.MkdirAll(ssaD, 0755)
                }
                s.f.HTMLWriter = ssa.NewHTMLWriter(ssaDF, s.f, ssaDumpCFG)
                // TODO: generate and print a mapping from nodes to values and blocks
                dumpSourcesColumn(s.f.HTMLWriter, fn)
                s.f.HTMLWriter.WriteAST("AST", astBuf)
        }

        // Allocate starting values
        s.labels = map[string]*ssaLabel{}
        s.fwdVars = map[ir.Node]*ssa.Value{}
        s.startmem = s.entryNewValue0(ssa.OpInitMem, types.TypeMem)

        s.hasOpenDefers = base.Flag.N == 0 && s.hasdefer && !s.curfn.OpenCodedDeferDisallowed()
        switch {
        case base.Debug.NoOpenDefer != 0:
                s.hasOpenDefers = false
        case s.hasOpenDefers && (base.Ctxt.Flag_shared || base.Ctxt.Flag_dynlink) && base.Ctxt.Arch.Name == "386":
                // Don't support open-coded defers for 386 ONLY when using shared
                // libraries, because there is extra code (added by rewriteToUseGot())
                // preceding the deferreturn/ret code that we don't track correctly.
                s.hasOpenDefers = false
        }
        if s.hasOpenDefers && len(s.curfn.Exit) > 0 {
                // Skip doing open defers if there is any extra exit code (likely
                // race detection), since we will not generate that code in the
                // case of the extra deferreturn/ret segment.
                s.hasOpenDefers = false
        }
        if s.hasOpenDefers {
                // Similarly, skip if there are any heap-allocated result
                // parameters that need to be copied back to their stack slots.
                for _, f := range s.curfn.Type().Results().FieldSlice() {
                        if !f.Nname.(*ir.Name).OnStack() {
                                s.hasOpenDefers = false
                                break
                        }
                }
        }
        if s.hasOpenDefers &&
                s.curfn.NumReturns*s.curfn.NumDefers > 15 {
                // Since we are generating defer calls at every exit for
                // open-coded defers, skip doing open-coded defers if there are
                // too many returns (especially if there are multiple defers).
                // Open-coded defers are most important for improving performance
                // for smaller functions (which don't have many returns).
                s.hasOpenDefers = false
        }

        s.sp = s.entryNewValue0(ssa.OpSP, types.Types[types.TUINTPTR]) // TODO: use generic pointer type (unsafe.Pointer?) instead
        s.sb = s.entryNewValue0(ssa.OpSB, types.Types[types.TUINTPTR])

        s.startBlock(s.f.Entry)
        s.vars[memVar] = s.startmem
        if s.hasOpenDefers {
                // Create the deferBits variable and stack slot.  deferBits is a
                // bitmask showing which of the open-coded defers in this function
                // have been activated.
                deferBitsTemp := typecheck.TempAt(src.NoXPos, s.curfn, types.Types[types.TUINT8])
                deferBitsTemp.SetAddrtaken(true)
                s.deferBitsTemp = deferBitsTemp
                // For this value, AuxInt is initialized to zero by default
                startDeferBits := s.entryNewValue0(ssa.OpConst8, types.Types[types.TUINT8])
                s.vars[deferBitsVar] = startDeferBits
                s.deferBitsAddr = s.addr(deferBitsTemp)
                s.store(types.Types[types.TUINT8], s.deferBitsAddr, startDeferBits)
                // Make sure that the deferBits stack slot is kept alive (for use
                // by panics) and stores to deferBits are not eliminated, even if
                // all checking code on deferBits in the function exit can be
                // eliminated, because the defer statements were all
                // unconditional.
                s.vars[memVar] = s.newValue1Apos(ssa.OpVarLive, types.TypeMem, deferBitsTemp, s.mem(), false)
        }

        var params *abi.ABIParamResultInfo
        params = s.f.ABISelf.ABIAnalyze(fn.Type(), true)

        // The backend's stackframe pass prunes away entries from the fn's
        // Dcl list, including PARAMOUT nodes that correspond to output
        // params passed in registers. Walk the Dcl list and capture these
        // nodes to a side list, so that we'll have them available during
        // DWARF-gen later on. See issue 48573 for more details.
        var debugInfo ssa.FuncDebug
        for _, n := range fn.Dcl {
                if n.Class == ir.PPARAMOUT && n.IsOutputParamInRegisters() {
                        debugInfo.RegOutputParams = append(debugInfo.RegOutputParams, n)
                }
        }
        fn.DebugInfo = &debugInfo

        // Generate addresses of local declarations
        s.decladdrs = map[*ir.Name]*ssa.Value{}
        for _, n := range fn.Dcl {
                switch n.Class {
                case ir.PPARAM:
                        // Be aware that blank and unnamed input parameters will not appear here, but do appear in the type
                        s.decladdrs[n] = s.entryNewValue2A(ssa.OpLocalAddr, types.NewPtr(n.Type()), n, s.sp, s.startmem)
                case ir.PPARAMOUT:
                        s.decladdrs[n] = s.entryNewValue2A(ssa.OpLocalAddr, types.NewPtr(n.Type()), n, s.sp, s.startmem)
                case ir.PAUTO:
                        // processed at each use, to prevent Addr coming
                        // before the decl.
                default:
                        s.Fatalf("local variable with class %v unimplemented", n.Class)
                }
        }

        s.f.OwnAux = ssa.OwnAuxCall(fn.LSym, params)

        // Populate SSAable arguments.
        for _, n := range fn.Dcl {
                if n.Class == ir.PPARAM {
                        if s.canSSA(n) {
                                v := s.newValue0A(ssa.OpArg, n.Type(), n)
                                s.vars[n] = v
                                s.addNamedValue(n, v) // This helps with debugging information, not needed for compilation itself.
                        } else { // address was taken AND/OR too large for SSA
                                paramAssignment := ssa.ParamAssignmentForArgName(s.f, n)
                                if len(paramAssignment.Registers) > 0 {
                                        if TypeOK(n.Type()) { // SSA-able type, so address was taken -- receive value in OpArg, DO NOT bind to var, store immediately to memory.
                                                v := s.newValue0A(ssa.OpArg, n.Type(), n)
                                                s.store(n.Type(), s.decladdrs[n], v)
                                        } else { // Too big for SSA.
                                                // Brute force, and early, do a bunch of stores from registers
                                                // TODO fix the nasty storeArgOrLoad recursion in ssa/expand_calls.go so this Just Works with store of a big Arg.
                                                s.storeParameterRegsToStack(s.f.ABISelf, paramAssignment, n, s.decladdrs[n], false)
                                        }
                                }
                        }
                }
        }

        // Populate closure variables.
        if fn.Needctxt() {
                clo := s.entryNewValue0(ssa.OpGetClosurePtr, s.f.Config.Types.BytePtr)
                offset := int64(types.PtrSize) // PtrSize to skip past function entry PC field
                for _, n := range fn.ClosureVars {
                        typ := n.Type()
                        if !n.Byval() {
                                typ = types.NewPtr(typ)
                        }

                        offset = types.RoundUp(offset, typ.Alignment())
                        ptr := s.newValue1I(ssa.OpOffPtr, types.NewPtr(typ), offset, clo)
                        offset += typ.Size()

                        // If n is a small variable captured by value, promote
                        // it to PAUTO so it can be converted to SSA.
                        //
                        // Note: While we never capture a variable by value if
                        // the user took its address, we may have generated
                        // runtime calls that did (#43701). Since we don't
                        // convert Addrtaken variables to SSA anyway, no point
                        // in promoting them either.
                        if n.Byval() && !n.Addrtaken() && TypeOK(n.Type()) {
                                n.Class = ir.PAUTO
                                fn.Dcl = append(fn.Dcl, n)
                                s.assign(n, s.load(n.Type(), ptr), false, 0)
                                continue
                        }

                        if !n.Byval() {
                                ptr = s.load(typ, ptr)
                        }
                        s.setHeapaddr(fn.Pos(), n, ptr)
                }
        }

        // Convert the AST-based IR to the SSA-based IR
        s.stmtList(fn.Enter)
        s.zeroResults()
        s.paramsToHeap()
        s.stmtList(fn.Body)

        // fallthrough to exit
        if s.curBlock != nil {
                s.pushLine(fn.Endlineno)
                s.exit()
                s.popLine()
        }

        for _, b := range s.f.Blocks {
                if b.Pos != src.NoXPos {
                        s.updateUnsetPredPos(b)
                }
        }

        s.f.HTMLWriter.WritePhase("before insert phis", "before insert phis")

        s.insertPhis()

        // Main call to ssa package to compile function
        ssa.Compile(s.f)

        if len(s.openDefers) != 0 {
                s.emitOpenDeferInfo()
        }

        // Record incoming parameter spill information for morestack calls emitted in the assembler.
        // This is done here, using all the parameters (used, partially used, and unused) because
        // it mimics the behavior of the former ABI (everything stored) and because it's not 100%
        // clear if naming conventions are respected in autogenerated code.
        // TODO figure out exactly what's unused, don't spill it. Make liveness fine-grained, also.
        for _, p := range params.InParams() {
                typs, offs := p.RegisterTypesAndOffsets()
                for i, t := range typs {
                        o := offs[i]                // offset within parameter
                        fo := p.FrameOffset(params) // offset of parameter in frame
                        reg := ssa.ObjRegForAbiReg(p.Registers[i], s.f.Config)
                        s.f.RegArgs = append(s.f.RegArgs, ssa.Spill{Reg: reg, Offset: fo + o, Type: t})
                }
        }

        return s.f
}

func (s *state) storeParameterRegsToStack(abi *abi.ABIConfig, paramAssignment *abi.ABIParamAssignment, n *ir.Name, addr *ssa.Value, pointersOnly bool) {
        typs, offs := paramAssignment.RegisterTypesAndOffsets()
        for i, t := range typs {
                if pointersOnly && !t.IsPtrShaped() {
                        continue
                }
                r := paramAssignment.Registers[i]
                o := offs[i]
                op, reg := ssa.ArgOpAndRegisterFor(r, abi)
                aux := &ssa.AuxNameOffset{Name: n, Offset: o}
                v := s.newValue0I(op, t, reg)
                v.Aux = aux
                p := s.newValue1I(ssa.OpOffPtr, types.NewPtr(t), o, addr)
                s.store(t, p, v)
        }
}

// zeroResults zeros the return values at the start of the function.
// We need to do this very early in the function.  Defer might stop a
// panic and show the return values as they exist at the time of
// panic.  For precise stacks, the garbage collector assumes results
// are always live, so we need to zero them before any allocations,
// even allocations to move params/results to the heap.
func (s *state) zeroResults() {
        for _, f := range s.curfn.Type().Results().FieldSlice() {
                n := f.Nname.(*ir.Name)
                if !n.OnStack() {
                        // The local which points to the return value is the
                        // thing that needs zeroing. This is already handled
                        // by a Needzero annotation in plive.go:(*liveness).epilogue.
                        continue
                }
                // Zero the stack location containing f.
                if typ := n.Type(); TypeOK(typ) {
                        s.assign(n, s.zeroVal(typ), false, 0)
                } else {
                        if typ.HasPointers() {
                                s.vars[memVar] = s.newValue1A(ssa.OpVarDef, types.TypeMem, n, s.mem())
                        }
                        s.zero(n.Type(), s.decladdrs[n])
                }
        }
}

// paramsToHeap produces code to allocate memory for heap-escaped parameters
// and to copy non-result parameters' values from the stack.
func (s *state) paramsToHeap() {
        do := func(params *types.Type) {
                for _, f := range params.FieldSlice() {
                        if f.Nname == nil {
                                continue // anonymous or blank parameter
                        }
                        n := f.Nname.(*ir.Name)
                        if ir.IsBlank(n) || n.OnStack() {
                                continue
                        }
                        s.newHeapaddr(n)
                        if n.Class == ir.PPARAM {
                                s.move(n.Type(), s.expr(n.Heapaddr), s.decladdrs[n])
                        }
                }
        }

        typ := s.curfn.Type()
        do(typ.Recvs())
        do(typ.Params())
        do(typ.Results())
}

// newHeapaddr allocates heap memory for n and sets its heap address.
func (s *state) newHeapaddr(n *ir.Name) {
        s.setHeapaddr(n.Pos(), n, s.newObject(n.Type(), nil))
}

// setHeapaddr allocates a new PAUTO variable to store ptr (which must be non-nil)
// and then sets it as n's heap address.
func (s *state) setHeapaddr(pos src.XPos, n *ir.Name, ptr *ssa.Value) {
        if !ptr.Type.IsPtr() || !types.Identical(n.Type(), ptr.Type.Elem()) {
                base.FatalfAt(n.Pos(), "setHeapaddr %L with type %v", n, ptr.Type)
        }

        // Declare variable to hold address.
        sym := &types.Sym{Name: "&" + n.Sym().Name, Pkg: types.LocalPkg}
        addr := s.curfn.NewLocal(pos, sym, ir.PAUTO, types.NewPtr(n.Type()))
        addr.SetUsed(true)
        types.CalcSize(addr.Type())

        if n.Class == ir.PPARAMOUT {
                addr.SetIsOutputParamHeapAddr(true)
        }

        n.Heapaddr = addr
        s.assign(addr, ptr, false, 0)
}

// newObject returns an SSA value denoting new(typ).
func (s *state) newObject(typ *types.Type, rtype *ssa.Value) *ssa.Value {
        if typ.Size() == 0 {
                return s.newValue1A(ssa.OpAddr, types.NewPtr(typ), ir.Syms.Zerobase, s.sb)
        }
        if rtype == nil {
                rtype = s.reflectType(typ)
        }
        return s.rtcall(ir.Syms.Newobject, true, []*types.Type{types.NewPtr(typ)}, rtype)[0]
}

func (s *state) checkPtrAlignment(n *ir.ConvExpr, v *ssa.Value, count *ssa.Value) {
        if !n.Type().IsPtr() {
                s.Fatalf("expected pointer type: %v", n.Type())
        }
        elem, rtypeExpr := n.Type().Elem(), n.ElemRType
        if count != nil {
                if !elem.IsArray() {
                        s.Fatalf("expected array type: %v", elem)
                }
                elem, rtypeExpr = elem.Elem(), n.ElemElemRType
        }
        size := elem.Size()
        // Casting from larger type to smaller one is ok, so for smallest type, do nothing.
        if elem.Alignment() == 1 && (size == 0 || size == 1 || count == nil) {
                return
        }
        if count == nil {
                count = s.constInt(types.Types[types.TUINTPTR], 1)
        }
        if count.Type.Size() != s.config.PtrSize {
                s.Fatalf("expected count fit to a uintptr size, have: %d, want: %d", count.Type.Size(), s.config.PtrSize)
        }
        var rtype *ssa.Value
        if rtypeExpr != nil {
                rtype = s.expr(rtypeExpr)
        } else {
                rtype = s.reflectType(elem)
        }
        s.rtcall(ir.Syms.CheckPtrAlignment, true, nil, v, rtype, count)
}

// reflectType returns an SSA value representing a pointer to typ's
// reflection type descriptor.
func (s *state) reflectType(typ *types.Type) *ssa.Value {
        // TODO(mdempsky): Make this Fatalf under Unified IR; frontend needs
        // to supply RType expressions.
        lsym := reflectdata.TypeLinksym(typ)
        return s.entryNewValue1A(ssa.OpAddr, types.NewPtr(types.Types[types.TUINT8]), lsym, s.sb)
}

func dumpSourcesColumn(writer *ssa.HTMLWriter, fn *ir.Func) {
        // Read sources of target function fn.
        fname := base.Ctxt.PosTable.Pos(fn.Pos()).Filename()
        targetFn, err := readFuncLines(fname, fn.Pos().Line(), fn.Endlineno.Line())
        if err != nil {
                writer.Logf("cannot read sources for function %v: %v", fn, err)
        }

        // Read sources of inlined functions.
        var inlFns []*ssa.FuncLines
        for _, fi := range ssaDumpInlined {
                elno := fi.Endlineno
                fname := base.Ctxt.PosTable.Pos(fi.Pos()).Filename()
                fnLines, err := readFuncLines(fname, fi.Pos().Line(), elno.Line())
                if err != nil {
                        writer.Logf("cannot read sources for inlined function %v: %v", fi, err)
                        continue
                }
                inlFns = append(inlFns, fnLines)
        }

        sort.Sort(ssa.ByTopo(inlFns))
        if targetFn != nil {
                inlFns = append([]*ssa.FuncLines{targetFn}, inlFns...)
        }

        writer.WriteSources("sources", inlFns)
}

func readFuncLines(file string, start, end uint) (*ssa.FuncLines, error) {
        f, err := os.Open(os.ExpandEnv(file))
        if err != nil {
                return nil, err
        }
        defer f.Close()
        var lines []string
        ln := uint(1)
        scanner := bufio.NewScanner(f)
        for scanner.Scan() && ln <= end {
                if ln >= start {
                        lines = append(lines, scanner.Text())
                }
                ln++
        }
        return &ssa.FuncLines{Filename: file, StartLineno: start, Lines: lines}, nil
}

// updateUnsetPredPos propagates the earliest-value position information for b
// towards all of b's predecessors that need a position, and recurs on that
// predecessor if its position is updated. B should have a non-empty position.
func (s *state) updateUnsetPredPos(b *ssa.Block) {
        if b.Pos == src.NoXPos {
                s.Fatalf("Block %s should have a position", b)
        }
        bestPos := src.NoXPos
        for _, e := range b.Preds {
                p := e.Block()
                if !p.LackingPos() {
                        continue
                }
                if bestPos == src.NoXPos {
                        bestPos = b.Pos
                        for _, v := range b.Values {
                                if v.LackingPos() {
                                        continue
                                }
                                if v.Pos != src.NoXPos {
                                        // Assume values are still in roughly textual order;
                                        // TODO: could also seek minimum position?
                                        bestPos = v.Pos
                                        break
                                }
                        }
                }
                p.Pos = bestPos
                s.updateUnsetPredPos(p) // We do not expect long chains of these, thus recursion is okay.
        }
}

// Information about each open-coded defer.
type openDeferInfo struct {
        // The node representing the call of the defer
        n *ir.CallExpr
        // If defer call is closure call, the address of the argtmp where the
        // closure is stored.
        closure *ssa.Value
        // The node representing the argtmp where the closure is stored - used for
        // function, method, or interface call, to store a closure that panic
        // processing can use for this defer.
        closureNode *ir.Name
}

type state struct {
        // configuration (arch) information
        config *ssa.Config

        // function we're building
        f *ssa.Func

        // Node for function
        curfn *ir.Func

        // labels in f
        labels map[string]*ssaLabel

        // unlabeled break and continue statement tracking
        breakTo    *ssa.Block // current target for plain break statement
        continueTo *ssa.Block // current target for plain continue statement

        // current location where we're interpreting the AST
        curBlock *ssa.Block

        // variable assignments in the current block (map from variable symbol to ssa value)
        // *Node is the unique identifier (an ONAME Node) for the variable.
        // TODO: keep a single varnum map, then make all of these maps slices instead?
        vars map[ir.Node]*ssa.Value

        // fwdVars are variables that are used before they are defined in the current block.
        // This map exists just to coalesce multiple references into a single FwdRef op.
        // *Node is the unique identifier (an ONAME Node) for the variable.
        fwdVars map[ir.Node]*ssa.Value

        // all defined variables at the end of each block. Indexed by block ID.
        defvars []map[ir.Node]*ssa.Value

        // addresses of PPARAM and PPARAMOUT variables on the stack.
        decladdrs map[*ir.Name]*ssa.Value

        // starting values. Memory, stack pointer, and globals pointer
        startmem *ssa.Value
        sp       *ssa.Value
        sb       *ssa.Value
        // value representing address of where deferBits autotmp is stored
        deferBitsAddr *ssa.Value
        deferBitsTemp *ir.Name

        // line number stack. The current line number is top of stack
        line []src.XPos
        // the last line number processed; it may have been popped
        lastPos src.XPos

        // list of panic calls by function name and line number.
        // Used to deduplicate panic calls.
        panics map[funcLine]*ssa.Block

        cgoUnsafeArgs   bool
        hasdefer        bool // whether the function contains a defer statement
        softFloat       bool
        hasOpenDefers   bool // whether we are doing open-coded defers
        checkPtrEnabled bool // whether to insert checkptr instrumentation

        // If doing open-coded defers, list of info about the defer calls in
        // scanning order. Hence, at exit we should run these defers in reverse
        // order of this list
        openDefers []*openDeferInfo
        // For open-coded defers, this is the beginning and end blocks of the last
        // defer exit code that we have generated so far. We use these to share
        // code between exits if the shareDeferExits option (disabled by default)
        // is on.
        lastDeferExit       *ssa.Block // Entry block of last defer exit code we generated
        lastDeferFinalBlock *ssa.Block // Final block of last defer exit code we generated
        lastDeferCount      int        // Number of defers encountered at that point

        prevCall *ssa.Value // the previous call; use this to tie results to the call op.
}

type funcLine struct {
        f    *obj.LSym
        base *src.PosBase
        line uint
}

type ssaLabel struct {
        target         *ssa.Block // block identified by this label
        breakTarget    *ssa.Block // block to break to in control flow node identified by this label
        continueTarget *ssa.Block // block to continue to in control flow node identified by this label
}

// label returns the label associated with sym, creating it if necessary.
func (s *state) label(sym *types.Sym) *ssaLabel {
        lab := s.labels[sym.Name]
        if lab == nil {
                lab = new(ssaLabel)
                s.labels[sym.Name] = lab
        }
        return lab
}

func (s *state) Logf(msg string, args ...interface{}) { s.f.Logf(msg, args...) }
func (s *state) Log() bool                            { return s.f.Log() }
func (s *state) Fatalf(msg string, args ...interface{}) {
        s.f.Frontend().Fatalf(s.peekPos(), msg, args...)
}
func (s *state) Warnl(pos src.XPos, msg string, args ...interface{}) { s.f.Warnl(pos, msg, args...) }
func (s *state) Debug_checknil() bool                                { return s.f.Frontend().Debug_checknil() }

func ssaMarker(name string) *ir.Name {
        return ir.NewNameAt(base.Pos, &types.Sym{Name: name}, nil)
}

var (
        // marker node for the memory variable
        memVar = ssaMarker("mem")

        // marker nodes for temporary variables
        ptrVar       = ssaMarker("ptr")
        lenVar       = ssaMarker("len")
        capVar       = ssaMarker("cap")
        typVar       = ssaMarker("typ")
        okVar        = ssaMarker("ok")
        deferBitsVar = ssaMarker("deferBits")
)

// startBlock sets the current block we're generating code in to b.
func (s *state) startBlock(b *ssa.Block) {
        if s.curBlock != nil {
                s.Fatalf("starting block %v when block %v has not ended", b, s.curBlock)
        }
        s.curBlock = b
        s.vars = map[ir.Node]*ssa.Value{}
        for n := range s.fwdVars {
                delete(s.fwdVars, n)
        }
}

// endBlock marks the end of generating code for the current block.
// Returns the (former) current block. Returns nil if there is no current
// block, i.e. if no code flows to the current execution point.
func (s *state) endBlock() *ssa.Block {
        b := s.curBlock
        if b == nil {
                return nil
        }
        for len(s.defvars) <= int(b.ID) {
                s.defvars = append(s.defvars, nil)
        }
        s.defvars[b.ID] = s.vars
        s.curBlock = nil
        s.vars = nil
        if b.LackingPos() {
                // Empty plain blocks get the line of their successor (handled after all blocks created),
                // except for increment blocks in For statements (handled in ssa conversion of OFOR),
                // and for blocks ending in GOTO/BREAK/CONTINUE.
                b.Pos = src.NoXPos
        } else {
                b.Pos = s.lastPos
        }
        return b
}

// pushLine pushes a line number on the line number stack.
func (s *state) pushLine(line src.XPos) {
        if !line.IsKnown() {
                // the frontend may emit node with line number missing,
                // use the parent line number in this case.
                line = s.peekPos()
                if base.Flag.K != 0 {
                        base.Warn("buildssa: unknown position (line 0)")
                }
        } else {
                s.lastPos = line
        }

        s.line = append(s.line, line)
}

// popLine pops the top of the line number stack.
func (s *state) popLine() {
        s.line = s.line[:len(s.line)-1]
}

// peekPos peeks the top of the line number stack.
func (s *state) peekPos() src.XPos {
        return s.line[len(s.line)-1]
}

// newValue0 adds a new value with no arguments to the current block.
func (s *state) newValue0(op ssa.Op, t *types.Type) *ssa.Value {
        return s.curBlock.NewValue0(s.peekPos(), op, t)
}

// newValue0A adds a new value with no arguments and an aux value to the current block.
func (s *state) newValue0A(op ssa.Op, t *types.Type, aux ssa.Aux) *ssa.Value {
        return s.curBlock.NewValue0A(s.peekPos(), op, t, aux)
}

// newValue0I adds a new value with no arguments and an auxint value to the current block.
func (s *state) newValue0I(op ssa.Op, t *types.Type, auxint int64) *ssa.Value {
        return s.curBlock.NewValue0I(s.peekPos(), op, t, auxint)
}

// newValue1 adds a new value with one argument to the current block.
func (s *state) newValue1(op ssa.Op, t *types.Type, arg *ssa.Value) *ssa.Value {
        return s.curBlock.NewValue1(s.peekPos(), op, t, arg)
}

// newValue1A adds a new value with one argument and an aux value to the current block.
func (s *state) newValue1A(op ssa.Op, t *types.Type, aux ssa.Aux, arg *ssa.Value) *ssa.Value {
        return s.curBlock.NewValue1A(s.peekPos(), op, t, aux, arg)
}

// newValue1Apos adds a new value with one argument and an aux value to the current block.
// isStmt determines whether the created values may be a statement or not
// (i.e., false means never, yes means maybe).
func (s *state) newValue1Apos(op ssa.Op, t *types.Type, aux ssa.Aux, arg *ssa.Value, isStmt bool) *ssa.Value {
        if isStmt {
                return s.curBlock.NewValue1A(s.peekPos(), op, t, aux, arg)
        }
        return s.curBlock.NewValue1A(s.peekPos().WithNotStmt(), op, t, aux, arg)
}

// newValue1I adds a new value with one argument and an auxint value to the current block.
func (s *state) newValue1I(op ssa.Op, t *types.Type, aux int64, arg *ssa.Value) *ssa.Value {
        return s.curBlock.NewValue1I(s.peekPos(), op, t, aux, arg)
}

// newValue2 adds a new value with two arguments to the current block.
func (s *state) newValue2(op ssa.Op, t *types.Type, arg0, arg1 *ssa.Value) *ssa.Value {
        return s.curBlock.NewValue2(s.peekPos(), op, t, arg0, arg1)
}

// newValue2A adds a new value with two arguments and an aux value to the current block.
func (s *state) newValue2A(op ssa.Op, t *types.Type, aux ssa.Aux, arg0, arg1 *ssa.Value) *ssa.Value {
        return s.curBlock.NewValue2A(s.peekPos(), op, t, aux, arg0, arg1)
}

// newValue2Apos adds a new value with two arguments and an aux value to the current block.
// isStmt determines whether the created values may be a statement or not
// (i.e., false means never, yes means maybe).
func (s *state) newValue2Apos(op ssa.Op, t *types.Type, aux ssa.Aux, arg0, arg1 *ssa.Value, isStmt bool) *ssa.Value {
        if isStmt {
                return s.curBlock.NewValue2A(s.peekPos(), op, t, aux, arg0, arg1)
        }
        return s.curBlock.NewValue2A(s.peekPos().WithNotStmt(), op, t, aux, arg0, arg1)
}

// newValue2I adds a new value with two arguments and an auxint value to the current block.
func (s *state) newValue2I(op ssa.Op, t *types.Type, aux int64, arg0, arg1 *ssa.Value) *ssa.Value {
        return s.curBlock.NewValue2I(s.peekPos(), op, t, aux, arg0, arg1)
}

// newValue3 adds a new value with three arguments to the current block.
func (s *state) newValue3(op ssa.Op, t *types.Type, arg0, arg1, arg2 *ssa.Value) *ssa.Value {
        return s.curBlock.NewValue3(s.peekPos(), op, t, arg0, arg1, arg2)
}

// newValue3I adds a new value with three arguments and an auxint value to the current block.
func (s *state) newValue3I(op ssa.Op, t *types.Type, aux int64, arg0, arg1, arg2 *ssa.Value) *ssa.Value {
        return s.curBlock.NewValue3I(s.peekPos(), op, t, aux, arg0, arg1, arg2)
}

// newValue3A adds a new value with three arguments and an aux value to the current block.
func (s *state) newValue3A(op ssa.Op, t *types.Type, aux ssa.Aux, arg0, arg1, arg2 *ssa.Value) *ssa.Value {
        return s.curBlock.NewValue3A(s.peekPos(), op, t, aux, arg0, arg1, arg2)
}

// newValue3Apos adds a new value with three arguments and an aux value to the current block.
// isStmt determines whether the created values may be a statement or not
// (i.e., false means never, yes means maybe).
func (s *state) newValue3Apos(op ssa.Op, t *types.Type, aux ssa.Aux, arg0, arg1, arg2 *ssa.Value, isStmt bool) *ssa.Value {
        if isStmt {
                return s.curBlock.NewValue3A(s.peekPos(), op, t, aux, arg0, arg1, arg2)
        }
        return s.curBlock.NewValue3A(s.peekPos().WithNotStmt(), op, t, aux, arg0, arg1, arg2)
}

// newValue4 adds a new value with four arguments to the current block.
func (s *state) newValue4(op ssa.Op, t *types.Type, arg0, arg1, arg2, arg3 *ssa.Value) *ssa.Value {
        return s.curBlock.NewValue4(s.peekPos(), op, t, arg0, arg1, arg2, arg3)
}

// newValue4I adds a new value with four arguments and an auxint value to the current block.
func (s *state) newValue4I(op ssa.Op, t *types.Type, aux int64, arg0, arg1, arg2, arg3 *ssa.Value) *ssa.Value {
        return s.curBlock.NewValue4I(s.peekPos(), op, t, aux, arg0, arg1, arg2, arg3)
}

func (s *state) entryBlock() *ssa.Block {
        b := s.f.Entry
        if base.Flag.N > 0 && s.curBlock != nil {
                // If optimizations are off, allocate in current block instead. Since with -N
                // we're not doing the CSE or tighten passes, putting lots of stuff in the
                // entry block leads to O(n^2) entries in the live value map during regalloc.
                // See issue 45897.
                b = s.curBlock
        }
        return b
}

// entryNewValue0 adds a new value with no arguments to the entry block.
func (s *state) entryNewValue0(op ssa.Op, t *types.Type) *ssa.Value {
        return s.entryBlock().NewValue0(src.NoXPos, op, t)
}

// entryNewValue0A adds a new value with no arguments and an aux value to the entry block.
func (s *state) entryNewValue0A(op ssa.Op, t *types.Type, aux ssa.Aux) *ssa.Value {
        return s.entryBlock().NewValue0A(src.NoXPos, op, t, aux)
}

// entryNewValue1 adds a new value with one argument to the entry block.
func (s *state) entryNewValue1(op ssa.Op, t *types.Type, arg *ssa.Value) *ssa.Value {
        return s.entryBlock().NewValue1(src.NoXPos, op, t, arg)
}

// entryNewValue1I adds a new value with one argument and an auxint value to the entry block.
func (s *state) entryNewValue1I(op ssa.Op, t *types.Type, auxint int64, arg *ssa.Value) *ssa.Value {
        return s.entryBlock().NewValue1I(src.NoXPos, op, t, auxint, arg)
}

// entryNewValue1A adds a new value with one argument and an aux value to the entry block.
func (s *state) entryNewValue1A(op ssa.Op, t *types.Type, aux ssa.Aux, arg *ssa.Value) *ssa.Value {
        return s.entryBlock().NewValue1A(src.NoXPos, op, t, aux, arg)
}

// entryNewValue2 adds a new value with two arguments to the entry block.
func (s *state) entryNewValue2(op ssa.Op, t *types.Type, arg0, arg1 *ssa.Value) *ssa.Value {
        return s.entryBlock().NewValue2(src.NoXPos, op, t, arg0, arg1)
}

// entryNewValue2A adds a new value with two arguments and an aux value to the entry block.
func (s *state) entryNewValue2A(op ssa.Op, t *types.Type, aux ssa.Aux, arg0, arg1 *ssa.Value) *ssa.Value {
        return s.entryBlock().NewValue2A(src.NoXPos, op, t, aux, arg0, arg1)
}

// const* routines add a new const value to the entry block.
func (s *state) constSlice(t *types.Type) *ssa.Value {
        return s.f.ConstSlice(t)
}
func (s *state) constInterface(t *types.Type) *ssa.Value {
        return s.f.ConstInterface(t)
}
func (s *state) constNil(t *types.Type) *ssa.Value { return s.f.ConstNil(t) }
func (s *state) constEmptyString(t *types.Type) *ssa.Value {
        return s.f.ConstEmptyString(t)
}
func (s *state) constBool(c bool) *ssa.Value {
        return s.f.ConstBool(types.Types[types.TBOOL], c)
}
func (s *state) constInt8(t *types.Type, c int8) *ssa.Value {
        return s.f.ConstInt8(t, c)
}
func (s *state) constInt16(t *types.Type, c int16) *ssa.Value {
        return s.f.ConstInt16(t, c)
}
func (s *state) constInt32(t *types.Type, c int32) *ssa.Value {
        return s.f.ConstInt32(t, c)
}
func (s *state) constInt64(t *types.Type, c int64) *ssa.Value {
        return s.f.ConstInt64(t, c)
}
func (s *state) constFloat32(t *types.Type, c float64) *ssa.Value {
        return s.f.ConstFloat32(t, c)
}
func (s *state) constFloat64(t *types.Type, c float64) *ssa.Value {
        return s.f.ConstFloat64(t, c)
}
func (s *state) constInt(t *types.Type, c int64) *ssa.Value {
        if s.config.PtrSize == 8 {
                return s.constInt64(t, c)
        }
        if int64(int32(c)) != c {
                s.Fatalf("integer constant too big %d", c)
        }
        return s.constInt32(t, int32(c))
}
func (s *state) constOffPtrSP(t *types.Type, c int64) *ssa.Value {
        return s.f.ConstOffPtrSP(t, c, s.sp)
}

// newValueOrSfCall* are wrappers around newValue*, which may create a call to a
// soft-float runtime function instead (when emitting soft-float code).
func (s *state) newValueOrSfCall1(op ssa.Op, t *types.Type, arg *ssa.Value) *ssa.Value {
        if s.softFloat {
                if c, ok := s.sfcall(op, arg); ok {
                        return c
                }
        }
        return s.newValue1(op, t, arg)
}
func (s *state) newValueOrSfCall2(op ssa.Op, t *types.Type, arg0, arg1 *ssa.Value) *ssa.Value {
        if s.softFloat {
                if c, ok := s.sfcall(op, arg0, arg1); ok {
                        return c
                }
        }
        return s.newValue2(op, t, arg0, arg1)
}

type instrumentKind uint8

const (
        instrumentRead = iota
        instrumentWrite
        instrumentMove
)

func (s *state) instrument(t *types.Type, addr *ssa.Value, kind instrumentKind) {
        s.instrument2(t, addr, nil, kind)
}

// instrumentFields instruments a read/write operation on addr.
// If it is instrumenting for MSAN or ASAN and t is a struct type, it instruments
// operation for each field, instead of for the whole struct.
func (s *state) instrumentFields(t *types.Type, addr *ssa.Value, kind instrumentKind) {
        if !(base.Flag.MSan || base.Flag.ASan) || !t.IsStruct() {
                s.instrument(t, addr, kind)
                return
        }
        for _, f := range t.Fields().Slice() {
                if f.Sym.IsBlank() {
                        continue
                }
                offptr := s.newValue1I(ssa.OpOffPtr, types.NewPtr(f.Type), f.Offset, addr)
                s.instrumentFields(f.Type, offptr, kind)
        }
}

func (s *state) instrumentMove(t *types.Type, dst, src *ssa.Value) {
        if base.Flag.MSan {
                s.instrument2(t, dst, src, instrumentMove)
        } else {
                s.instrument(t, src, instrumentRead)
                s.instrument(t, dst, instrumentWrite)
        }
}

func (s *state) instrument2(t *types.Type, addr, addr2 *ssa.Value, kind instrumentKind) {
        if !s.curfn.InstrumentBody() {
                return
        }

        w := t.Size()
        if w == 0 {
                return // can't race on zero-sized things
        }

        if ssa.IsSanitizerSafeAddr(addr) {
                return
        }

        var fn *obj.LSym
        needWidth := false

        if addr2 != nil && kind != instrumentMove {
                panic("instrument2: non-nil addr2 for non-move instrumentation")
        }

        if base.Flag.MSan {
                switch kind {
                case instrumentRead:
                        fn = ir.Syms.Msanread
                case instrumentWrite:
                        fn = ir.Syms.Msanwrite
                case instrumentMove:
                        fn = ir.Syms.Msanmove
                default:
                        panic("unreachable")
                }
                needWidth = true
        } else if base.Flag.Race && t.NumComponents(types.CountBlankFields) > 1 {
                // for composite objects we have to write every address
                // because a write might happen to any subobject.
                // composites with only one element don't have subobjects, though.
                switch kind {
                case instrumentRead:
                        fn = ir.Syms.Racereadrange
                case instrumentWrite:
                        fn = ir.Syms.Racewriterange
                default:
                        panic("unreachable")
                }
                needWidth = true
        } else if base.Flag.Race {
                // for non-composite objects we can write just the start
                // address, as any write must write the first byte.
                switch kind {
                case instrumentRead:
                        fn = ir.Syms.Raceread
                case instrumentWrite:
                        fn = ir.Syms.Racewrite
                default:
                        panic("unreachable")
                }
        } else if base.Flag.ASan {
                switch kind {
                case instrumentRead:
                        fn = ir.Syms.Asanread
                case instrumentWrite:
                        fn = ir.Syms.Asanwrite
                default:
                        panic("unreachable")
                }
                needWidth = true
        } else {
                panic("unreachable")
        }

        args := []*ssa.Value{addr}
        if addr2 != nil {
                args = append(args, addr2)
        }
        if needWidth {
                args = append(args, s.constInt(types.Types[types.TUINTPTR], w))
        }
        s.rtcall(fn, true, nil, args...)
}

func (s *state) load(t *types.Type, src *ssa.Value) *ssa.Value {
        s.instrumentFields(t, src, instrumentRead)
        return s.rawLoad(t, src)
}

func (s *state) rawLoad(t *types.Type, src *ssa.Value) *ssa.Value {
        return s.newValue2(ssa.OpLoad, t, src, s.mem())
}

func (s *state) store(t *types.Type, dst, val *ssa.Value) {
        s.vars[memVar] = s.newValue3A(ssa.OpStore, types.TypeMem, t, dst, val, s.mem())
}

func (s *state) zero(t *types.Type, dst *ssa.Value) {
        s.instrument(t, dst, instrumentWrite)
        store := s.newValue2I(ssa.OpZero, types.TypeMem, t.Size(), dst, s.mem())
        store.Aux = t
        s.vars[memVar] = store
}

func (s *state) move(t *types.Type, dst, src *ssa.Value) {
        s.moveWhichMayOverlap(t, dst, src, false)
}
func (s *state) moveWhichMayOverlap(t *types.Type, dst, src *ssa.Value, mayOverlap bool) {
        s.instrumentMove(t, dst, src)
        if mayOverlap && t.IsArray() && t.NumElem() > 1 && !ssa.IsInlinableMemmove(dst, src, t.Size(), s.f.Config) {
                // Normally, when moving Go values of type T from one location to another,
                // we don't need to worry about partial overlaps. The two Ts must either be
                // in disjoint (nonoverlapping) memory or in exactly the same location.
                // There are 2 cases where this isn't true:
                //  1) Using unsafe you can arrange partial overlaps.
                //  2) Since Go 1.17, you can use a cast from a slice to a ptr-to-array.
                //     https://go.dev/ref/spec#Conversions_from_slice_to_array_pointer
                //     This feature can be used to construct partial overlaps of array types.
                //       var a [3]int
                //       p := (*[2]int)(a[:])
                //       q := (*[2]int)(a[1:])
                //       *p = *q
                // We don't care about solving 1. Or at least, we haven't historically
                // and no one has complained.
                // For 2, we need to ensure that if there might be partial overlap,
                // then we can't use OpMove; we must use memmove instead.
                // (memmove handles partial overlap by copying in the correct
                // direction. OpMove does not.)
                //
                // Note that we have to be careful here not to introduce a call when
                // we're marshaling arguments to a call or unmarshaling results from a call.
                // Cases where this is happening must pass mayOverlap to false.
                // (Currently this only happens when unmarshaling results of a call.)
                if t.HasPointers() {
                        s.rtcall(ir.Syms.Typedmemmove, true, nil, s.reflectType(t), dst, src)
                        // We would have otherwise implemented this move with straightline code,
                        // including a write barrier. Pretend we issue a write barrier here,
                        // so that the write barrier tests work. (Otherwise they'd need to know
                        // the details of IsInlineableMemmove.)
                        s.curfn.SetWBPos(s.peekPos())
                } else {
                        s.rtcall(ir.Syms.Memmove, true, nil, dst, src, s.constInt(types.Types[types.TUINTPTR], t.Size()))
                }
                ssa.LogLargeCopy(s.f.Name, s.peekPos(), t.Size())
                return
        }
        store := s.newValue3I(ssa.OpMove, types.TypeMem, t.Size(), dst, src, s.mem())
        store.Aux = t
        s.vars[memVar] = store
}

// stmtList converts the statement list n to SSA and adds it to s.
func (s *state) stmtList(l ir.Nodes) {
        for _, n := range l {
                s.stmt(n)
        }
}

// stmt converts the statement n to SSA and adds it to s.
func (s *state) stmt(n ir.Node) {
        s.pushLine(n.Pos())
        defer s.popLine()

        // If s.curBlock is nil, and n isn't a label (which might have an associated goto somewhere),
        // then this code is dead. Stop here.
        if s.curBlock == nil && n.Op() != ir.OLABEL {
                return
        }

        s.stmtList(n.Init())
        switch n.Op() {

        case ir.OBLOCK:
                n := n.(*ir.BlockStmt)
                s.stmtList(n.List)

        case ir.OFALL: // no-op

        // Expression statements
        case ir.OCALLFUNC:
                n := n.(*ir.CallExpr)
                if ir.IsIntrinsicCall(n) {
                        s.intrinsicCall(n)
                        return
                }
                fallthrough

        case ir.OCALLINTER:
                n := n.(*ir.CallExpr)
                s.callResult(n, callNormal)
                if n.Op() == ir.OCALLFUNC && n.X.Op() == ir.ONAME && n.X.(*ir.Name).Class == ir.PFUNC {
                        if fn := n.X.Sym().Name; base.Flag.CompilingRuntime && fn == "throw" ||
                                n.X.Sym().Pkg == ir.Pkgs.Runtime && (fn == "throwinit" || fn == "gopanic" || fn == "panicwrap" || fn == "block" || fn == "panicmakeslicelen" || fn == "panicmakeslicecap" || fn == "panicunsafeslicelen" || fn == "panicunsafeslicenilptr" || fn == "panicunsafestringlen" || fn == "panicunsafestringnilptr") {
                                m := s.mem()
                                b := s.endBlock()
                                b.Kind = ssa.BlockExit
                                b.SetControl(m)
                                // TODO: never rewrite OPANIC to OCALLFUNC in the
                                // first place. Need to wait until all backends
                                // go through SSA.
                        }
                }
        case ir.ODEFER:
                n := n.(*ir.GoDeferStmt)
                if base.Debug.Defer > 0 {
                        var defertype string
                        if s.hasOpenDefers {
                                defertype = "open-coded"
                        } else if n.Esc() == ir.EscNever {
                                defertype = "stack-allocated"
                        } else {
                                defertype = "heap-allocated"
                        }
                        base.WarnfAt(n.Pos(), "%s defer", defertype)
                }
                if s.hasOpenDefers {
                        s.openDeferRecord(n.Call.(*ir.CallExpr))
                } else {
                        d := callDefer
                        if n.Esc() == ir.EscNever {
                                d = callDeferStack
                        }
                        s.callResult(n.Call.(*ir.CallExpr), d)
                }
        case ir.OGO:
                n := n.(*ir.GoDeferStmt)
                s.callResult(n.Call.(*ir.CallExpr), callGo)

        case ir.OAS2DOTTYPE:
                n := n.(*ir.AssignListStmt)
                var res, resok *ssa.Value
                if n.Rhs[0].Op() == ir.ODOTTYPE2 {
                        res, resok = s.dottype(n.Rhs[0].(*ir.TypeAssertExpr), true)
                } else {
                        res, resok = s.dynamicDottype(n.Rhs[0].(*ir.DynamicTypeAssertExpr), true)
                }
                deref := false
                if !TypeOK(n.Rhs[0].Type()) {
                        if res.Op != ssa.OpLoad {
                                s.Fatalf("dottype of non-load")
                        }
                        mem := s.mem()
                        if res.Args[1] != mem {
                                s.Fatalf("memory no longer live from 2-result dottype load")
                        }
                        deref = true
                        res = res.Args[0]
                }
                s.assign(n.Lhs[0], res, deref, 0)
                s.assign(n.Lhs[1], resok, false, 0)
                return

        case ir.OAS2FUNC:
                // We come here only when it is an intrinsic call returning two values.
                n := n.(*ir.AssignListStmt)
                call := n.Rhs[0].(*ir.CallExpr)
                if !ir.IsIntrinsicCall(call) {
                        s.Fatalf("non-intrinsic AS2FUNC not expanded %v", call)
                }
                v := s.intrinsicCall(call)
                v1 := s.newValue1(ssa.OpSelect0, n.Lhs[0].Type(), v)
                v2 := s.newValue1(ssa.OpSelect1, n.Lhs[1].Type(), v)
                s.assign(n.Lhs[0], v1, false, 0)
                s.assign(n.Lhs[1], v2, false, 0)
                return

        case ir.ODCL:
                n := n.(*ir.Decl)
                if v := n.X; v.Esc() == ir.EscHeap {
                        s.newHeapaddr(v)
                }

        case ir.OLABEL:
                n := n.(*ir.LabelStmt)
                sym := n.Label
                if sym.IsBlank() {
                        // Nothing to do because the label isn't targetable. See issue 52278.
                        break
                }
                lab := s.label(sym)

                // The label might already have a target block via a goto.
                if lab.target == nil {
                        lab.target = s.f.NewBlock(ssa.BlockPlain)
                }

                // Go to that label.
                // (We pretend "label:" is preceded by "goto label", unless the predecessor is unreachable.)
                if s.curBlock != nil {
                        b := s.endBlock()
                        b.AddEdgeTo(lab.target)
                }
                s.startBlock(lab.target)

        case ir.OGOTO:
                n := n.(*ir.BranchStmt)
                sym := n.Label

                lab := s.label(sym)
                if lab.target == nil {
                        lab.target = s.f.NewBlock(ssa.BlockPlain)
                }

                b := s.endBlock()
                b.Pos = s.lastPos.WithIsStmt() // Do this even if b is an empty block.
                b.AddEdgeTo(lab.target)

        case ir.OAS:
                n := n.(*ir.AssignStmt)
                if n.X == n.Y && n.X.Op() == ir.ONAME {
                        // An x=x assignment. No point in doing anything
                        // here. In addition, skipping this assignment
                        // prevents generating:
                        //   VARDEF x
                        //   COPY x -> x
                        // which is bad because x is incorrectly considered
                        // dead before the vardef. See issue #14904.
                        return
                }

                // mayOverlap keeps track of whether the LHS and RHS might
                // refer to partially overlapping memory. Partial overlapping can
                // only happen for arrays, see the comment in moveWhichMayOverlap.
                //
                // If both sides of the assignment are not dereferences, then partial
                // overlap can't happen. Partial overlap can only occur only when the
                // arrays referenced are strictly smaller parts of the same base array.
                // If one side of the assignment is a full array, then partial overlap
                // can't happen. (The arrays are either disjoint or identical.)
                mayOverlap := n.X.Op() == ir.ODEREF && (n.Y != nil && n.Y.Op() == ir.ODEREF)
                if n.Y != nil && n.Y.Op() == ir.ODEREF {
                        p := n.Y.(*ir.StarExpr).X
                        for p.Op() == ir.OCONVNOP {
                                p = p.(*ir.ConvExpr).X
                        }
                        if p.Op() == ir.OSPTR && p.(*ir.UnaryExpr).X.Type().IsString() {
                                // Pointer fields of strings point to unmodifiable memory.
                                // That memory can't overlap with the memory being written.
                                mayOverlap = false
                        }
                }

                // Evaluate RHS.
                rhs := n.Y
                if rhs != nil {
                        switch rhs.Op() {
                        case ir.OSTRUCTLIT, ir.OARRAYLIT, ir.OSLICELIT:
                                // All literals with nonzero fields have already been
                                // rewritten during walk. Any that remain are just T{}
                                // or equivalents. Use the zero value.
                                if !ir.IsZero(rhs) {
                                        s.Fatalf("literal with nonzero value in SSA: %v", rhs)
                                }
                                rhs = nil
                        case ir.OAPPEND:
                                rhs := rhs.(*ir.CallExpr)
                                // Check whether we're writing the result of an append back to the same slice.
                                // If so, we handle it specially to avoid write barriers on the fast
                                // (non-growth) path.
                                if !ir.SameSafeExpr(n.X, rhs.Args[0]) || base.Flag.N != 0 {
                                        break
                                }
                                // If the slice can be SSA'd, it'll be on the stack,
                                // so there will be no write barriers,
                                // so there's no need to attempt to prevent them.
                                if s.canSSA(n.X) {
                                        if base.Debug.Append > 0 { // replicating old diagnostic message
                                                base.WarnfAt(n.Pos(), "append: len-only update (in local slice)")
                                        }
                                        break
                                }
                                if base.Debug.Append > 0 {
                                        base.WarnfAt(n.Pos(), "append: len-only update")
                                }
                                s.append(rhs, true)
                                return
                        }
                }

                if ir.IsBlank(n.X) {
                        // _ = rhs
                        // Just evaluate rhs for side-effects.
                        if rhs != nil {
                                s.expr(rhs)
                        }
                        return
                }

                var t *types.Type
                if n.Y != nil {
                        t = n.Y.Type()
                } else {
                        t = n.X.Type()
                }

                var r *ssa.Value
                deref := !TypeOK(t)
                if deref {
                        if rhs == nil {
                                r = nil // Signal assign to use OpZero.
                        } else {
                                r = s.addr(rhs)
                        }
                } else {
                        if rhs == nil {
                                r = s.zeroVal(t)
                        } else {
                                r = s.expr(rhs)
                        }
                }

                var skip skipMask
                if rhs != nil && (rhs.Op() == ir.OSLICE || rhs.Op() == ir.OSLICE3 || rhs.Op() == ir.OSLICESTR) && ir.SameSafeExpr(rhs.(*ir.SliceExpr).X, n.X) {
                        // We're assigning a slicing operation back to its source.
                        // Don't write back fields we aren't changing. See issue #14855.
                        rhs := rhs.(*ir.SliceExpr)
                        i, j, k := rhs.Low, rhs.High, rhs.Max
                        if i != nil && (i.Op() == ir.OLITERAL && i.Val().Kind() == constant.Int && ir.Int64Val(i) == 0) {
                                // [0:...] is the same as [:...]
                                i = nil
                        }
                        // TODO: detect defaults for len/cap also.
                        // Currently doesn't really work because (*p)[:len(*p)] appears here as:
                        //    tmp = len(*p)
                        //    (*p)[:tmp]
                        // if j != nil && (j.Op == OLEN && SameSafeExpr(j.Left, n.Left)) {
                        //      j = nil
                        // }
                        // if k != nil && (k.Op == OCAP && SameSafeExpr(k.Left, n.Left)) {
                        //      k = nil
                        // }
                        if i == nil {
                                skip |= skipPtr
                                if j == nil {
                                        skip |= skipLen
                                }
                                if k == nil {
                                        skip |= skipCap
                                }
                        }
                }

                s.assignWhichMayOverlap(n.X, r, deref, skip, mayOverlap)

        case ir.OIF:
                n := n.(*ir.IfStmt)
                if ir.IsConst(n.Cond, constant.Bool) {
                        s.stmtList(n.Cond.Init())
                        if ir.BoolVal(n.Cond) {
                                s.stmtList(n.Body)
                        } else {
                                s.stmtList(n.Else)
                        }
                        break
                }

                bEnd := s.f.NewBlock(ssa.BlockPlain)
                var likely int8
                if n.Likely {
                        likely = 1
                }
                var bThen *ssa.Block
                if len(n.Body) != 0 {
                        bThen = s.f.NewBlock(ssa.BlockPlain)
                } else {
                        bThen = bEnd
                }
                var bElse *ssa.Block
                if len(n.Else) != 0 {
                        bElse = s.f.NewBlock(ssa.BlockPlain)
                } else {
                        bElse = bEnd
                }
                s.condBranch(n.Cond, bThen, bElse, likely)

                if len(n.Body) != 0 {
                        s.startBlock(bThen)
                        s.stmtList(n.Body)
                        if b := s.endBlock(); b != nil {
                                b.AddEdgeTo(bEnd)
                        }
                }
                if len(n.Else) != 0 {
                        s.startBlock(bElse)
                        s.stmtList(n.Else)
                        if b := s.endBlock(); b != nil {
                                b.AddEdgeTo(bEnd)
                        }
                }
                s.startBlock(bEnd)

        case ir.ORETURN:
                n := n.(*ir.ReturnStmt)
                s.stmtList(n.Results)
                b := s.exit()
                b.Pos = s.lastPos.WithIsStmt()

        case ir.OTAILCALL:
                n := n.(*ir.TailCallStmt)
                s.callResult(n.Call, callTail)
                call := s.mem()
                b := s.endBlock()
                b.Kind = ssa.BlockRetJmp // could use BlockExit. BlockRetJmp is mostly for clarity.
                b.SetControl(call)

        case ir.OCONTINUE, ir.OBREAK:
                n := n.(*ir.BranchStmt)
                var to *ssa.Block
                if n.Label == nil {
                        // plain break/continue
                        switch n.Op() {
                        case ir.OCONTINUE:
                                to = s.continueTo
                        case ir.OBREAK:
                                to = s.breakTo
                        }
                } else {
                        // labeled break/continue; look up the target
                        sym := n.Label
                        lab := s.label(sym)
                        switch n.Op() {
                        case ir.OCONTINUE:
                                to = lab.continueTarget
                        case ir.OBREAK:
                                to = lab.breakTarget
                        }
                }

                b := s.endBlock()
                b.Pos = s.lastPos.WithIsStmt() // Do this even if b is an empty block.
                b.AddEdgeTo(to)

        case ir.OFOR:
                // OFOR: for Ninit; Left; Right { Nbody }
                // cond (Left); body (Nbody); incr (Right)
                n := n.(*ir.ForStmt)
                base.Assert(!n.DistinctVars) // Should all be rewritten before escape analysis
                bCond := s.f.NewBlock(ssa.BlockPlain)
                bBody := s.f.NewBlock(ssa.BlockPlain)
                bIncr := s.f.NewBlock(ssa.BlockPlain)
                bEnd := s.f.NewBlock(ssa.BlockPlain)

                // ensure empty for loops have correct position; issue #30167
                bBody.Pos = n.Pos()

                // first, jump to condition test
                b := s.endBlock()
                b.AddEdgeTo(bCond)

                // generate code to test condition
                s.startBlock(bCond)
                if n.Cond != nil {
                        s.condBranch(n.Cond, bBody, bEnd, 1)
                } else {
                        b := s.endBlock()
                        b.Kind = ssa.BlockPlain
                        b.AddEdgeTo(bBody)
                }

                // set up for continue/break in body
                prevContinue := s.continueTo
                prevBreak := s.breakTo
                s.continueTo = bIncr
                s.breakTo = bEnd
                var lab *ssaLabel
                if sym := n.Label; sym != nil {
                        // labeled for loop
                        lab = s.label(sym)
                        lab.continueTarget = bIncr
                        lab.breakTarget = bEnd
                }

                // generate body
                s.startBlock(bBody)
                s.stmtList(n.Body)

                // tear down continue/break
                s.continueTo = prevContinue
                s.breakTo = prevBreak
                if lab != nil {
                        lab.continueTarget = nil
                        lab.breakTarget = nil
                }

                // done with body, goto incr
                if b := s.endBlock(); b != nil {
                        b.AddEdgeTo(bIncr)
                }

                // generate incr
                s.startBlock(bIncr)
                if n.Post != nil {
                        s.stmt(n.Post)
                }
                if b := s.endBlock(); b != nil {
                        b.AddEdgeTo(bCond)
                        // It can happen that bIncr ends in a block containing only VARKILL,
                        // and that muddles the debugging experience.
                        if b.Pos == src.NoXPos {
                                b.Pos = bCond.Pos
                        }
                }

                s.startBlock(bEnd)

        case ir.OSWITCH, ir.OSELECT:
                // These have been mostly rewritten by the front end into their Nbody fields.
                // Our main task is to correctly hook up any break statements.
                bEnd := s.f.NewBlock(ssa.BlockPlain)

                prevBreak := s.breakTo
                s.breakTo = bEnd
                var sym *types.Sym
                var body ir.Nodes
                if n.Op() == ir.OSWITCH {
                        n := n.(*ir.SwitchStmt)
                        sym = n.Label
                        body = n.Compiled
                } else {
                        n := n.(*ir.SelectStmt)
                        sym = n.Label
                        body = n.Compiled
                }

                var lab *ssaLabel
                if sym != nil {
                        // labeled
                        lab = s.label(sym)
                        lab.breakTarget = bEnd
                }

                // generate body code
                s.stmtList(body)

                s.breakTo = prevBreak
                if lab != nil {
                        lab.breakTarget = nil
                }

                // walk adds explicit OBREAK nodes to the end of all reachable code paths.
                // If we still have a current block here, then mark it unreachable.
                if s.curBlock != nil {
                        m := s.mem()
                        b := s.endBlock()
                        b.Kind = ssa.BlockExit
                        b.SetControl(m)
                }
                s.startBlock(bEnd)

        case ir.OJUMPTABLE:
                n := n.(*ir.JumpTableStmt)

                // Make blocks we'll need.
                jt := s.f.NewBlock(ssa.BlockJumpTable)
                bEnd := s.f.NewBlock(ssa.BlockPlain)

                // The only thing that needs evaluating is the index we're looking up.
                idx := s.expr(n.Idx)
                unsigned := idx.Type.IsUnsigned()

                // Extend so we can do everything in uintptr arithmetic.
                t := types.Types[types.TUINTPTR]
                idx = s.conv(nil, idx, idx.Type, t)

                // The ending condition for the current block decides whether we'll use
                // the jump table at all.
                // We check that min <= idx <= max and jump around the jump table
                // if that test fails.
                // We implement min <= idx <= max with 0 <= idx-min <= max-min, because
                // we'll need idx-min anyway as the control value for the jump table.
                var min, max uint64
                if unsigned {
                        min, _ = constant.Uint64Val(n.Cases[0])
                        max, _ = constant.Uint64Val(n.Cases[len(n.Cases)-1])
                } else {
                        mn, _ := constant.Int64Val(n.Cases[0])
                        mx, _ := constant.Int64Val(n.Cases[len(n.Cases)-1])
                        min = uint64(mn)
                        max = uint64(mx)
                }
                // Compare idx-min with max-min, to see if we can use the jump table.
                idx = s.newValue2(s.ssaOp(ir.OSUB, t), t, idx, s.uintptrConstant(min))
                width := s.uintptrConstant(max - min)
                cmp := s.newValue2(s.ssaOp(ir.OLE, t), types.Types[types.TBOOL], idx, width)
                b := s.endBlock()
                b.Kind = ssa.BlockIf
                b.SetControl(cmp)
                b.AddEdgeTo(jt)             // in range - use jump table
                b.AddEdgeTo(bEnd)           // out of range - no case in the jump table will trigger
                b.Likely = ssa.BranchLikely // TODO: assumes missing the table entirely is unlikely. True?

                // Build jump table block.
                s.startBlock(jt)
                jt.Pos = n.Pos()
                if base.Flag.Cfg.SpectreIndex {
                        idx = s.newValue2(ssa.OpSpectreSliceIndex, t, idx, width)
                }
                jt.SetControl(idx)

                // Figure out where we should go for each index in the table.
                table := make([]*ssa.Block, max-min+1)
                for i := range table {
                        table[i] = bEnd // default target
                }
                for i := range n.Targets {
                        c := n.Cases[i]
                        lab := s.label(n.Targets[i])
                        if lab.target == nil {
                                lab.target = s.f.NewBlock(ssa.BlockPlain)
                        }
                        var val uint64
                        if unsigned {
                                val, _ = constant.Uint64Val(c)
                        } else {
                                vl, _ := constant.Int64Val(c)
                                val = uint64(vl)
                        }
                        // Overwrite the default target.
                        table[val-min] = lab.target
                }
                for _, t := range table {
                        jt.AddEdgeTo(t)
                }
                s.endBlock()

                s.startBlock(bEnd)

        case ir.OCHECKNIL:
                n := n.(*ir.UnaryExpr)
                p := s.expr(n.X)
                s.nilCheck(p)

        case ir.OINLMARK:
                n := n.(*ir.InlineMarkStmt)
                s.newValue1I(ssa.OpInlMark, types.TypeVoid, n.Index, s.mem())

        default:
                s.Fatalf("unhandled stmt %v", n.Op())
        }
}

// If true, share as many open-coded defer exits as possible (with the downside of
// worse line-number information)
const shareDeferExits = false

// exit processes any code that needs to be generated just before returning.
// It returns a BlockRet block that ends the control flow. Its control value
// will be set to the final memory state.
func (s *state) exit() *ssa.Block {
        if s.hasdefer {
                if s.hasOpenDefers {
                        if shareDeferExits && s.lastDeferExit != nil && len(s.openDefers) == s.lastDeferCount {
                                if s.curBlock.Kind != ssa.BlockPlain {
                                        panic("Block for an exit should be BlockPlain")
                                }
                                s.curBlock.AddEdgeTo(s.lastDeferExit)
                                s.endBlock()
                                return s.lastDeferFinalBlock
                        }
                        s.openDeferExit()
                } else {
                        s.rtcall(ir.Syms.Deferreturn, true, nil)
                }
        }

        var b *ssa.Block
        var m *ssa.Value
        // Do actual return.
        // These currently turn into self-copies (in many cases).
        resultFields := s.curfn.Type().Results().FieldSlice()
        results := make([]*ssa.Value, len(resultFields)+1, len(resultFields)+1)
        m = s.newValue0(ssa.OpMakeResult, s.f.OwnAux.LateExpansionResultType())
        // Store SSAable and heap-escaped PPARAMOUT variables back to stack locations.
        for i, f := range resultFields {
                n := f.Nname.(*ir.Name)
                if s.canSSA(n) { // result is in some SSA variable
                        if !n.IsOutputParamInRegisters() && n.Type().HasPointers() {
                                // We are about to store to the result slot.
                                s.vars[memVar] = s.newValue1A(ssa.OpVarDef, types.TypeMem, n, s.mem())
                        }
                        results[i] = s.variable(n, n.Type())
                } else if !n.OnStack() { // result is actually heap allocated
                        // We are about to copy the in-heap result to the result slot.
                        if n.Type().HasPointers() {
                                s.vars[memVar] = s.newValue1A(ssa.OpVarDef, types.TypeMem, n, s.mem())
                        }
                        ha := s.expr(n.Heapaddr)
                        s.instrumentFields(n.Type(), ha, instrumentRead)
                        results[i] = s.newValue2(ssa.OpDereference, n.Type(), ha, s.mem())
                } else { // result is not SSA-able; not escaped, so not on heap, but too large for SSA.
                        // Before register ABI this ought to be a self-move, home=dest,
                        // With register ABI, it's still a self-move if parameter is on stack (i.e., too big or overflowed)
                        // No VarDef, as the result slot is already holding live value.
                        results[i] = s.newValue2(ssa.OpDereference, n.Type(), s.addr(n), s.mem())
                }
        }

        // Run exit code. Today, this is just racefuncexit, in -race mode.
        // TODO(register args) this seems risky here with a register-ABI, but not clear it is right to do it earlier either.
        // Spills in register allocation might just fix it.
        s.stmtList(s.curfn.Exit)

        results[len(results)-1] = s.mem()
        m.AddArgs(results...)

        b = s.endBlock()
        b.Kind = ssa.BlockRet
        b.SetControl(m)
        if s.hasdefer && s.hasOpenDefers {
                s.lastDeferFinalBlock = b
        }
        return b
}

type opAndType struct {
        op    ir.Op
        etype types.Kind
}

var opToSSA = map[opAndType]ssa.Op{
        {ir.OADD, types.TINT8}:    ssa.OpAdd8,
        {ir.OADD, types.TUINT8}:   ssa.OpAdd8,
        {ir.OADD, types.TINT16}:   ssa.OpAdd16,
        {ir.OADD, types.TUINT16}:  ssa.OpAdd16,
        {ir.OADD, types.TINT32}:   ssa.OpAdd32,
        {ir.OADD, types.TUINT32}:  ssa.OpAdd32,
        {ir.OADD, types.TINT64}:   ssa.OpAdd64,
        {ir.OADD, types.TUINT64}:  ssa.OpAdd64,
        {ir.OADD, types.TFLOAT32}: ssa.OpAdd32F,
        {ir.OADD, types.TFLOAT64}: ssa.OpAdd64F,

        {ir.OSUB, types.TINT8}:    ssa.OpSub8,
        {ir.OSUB, types.TUINT8}:   ssa.OpSub8,
        {ir.OSUB, types.TINT16}:   ssa.OpSub16,
        {ir.OSUB, types.TUINT16}:  ssa.OpSub16,
        {ir.OSUB, types.TINT32}:   ssa.OpSub32,
        {ir.OSUB, types.TUINT32}:  ssa.OpSub32,
        {ir.OSUB, types.TINT64}:   ssa.OpSub64,
        {ir.OSUB, types.TUINT64}:  ssa.OpSub64,
        {ir.OSUB, types.TFLOAT32}: ssa.OpSub32F,
        {ir.OSUB, types.TFLOAT64}: ssa.OpSub64F,

        {ir.ONOT, types.TBOOL}: ssa.OpNot,

        {ir.ONEG, types.TINT8}:    ssa.OpNeg8,
        {ir.ONEG, types.TUINT8}:   ssa.OpNeg8,
        {ir.ONEG, types.TINT16}:   ssa.OpNeg16,
        {ir.ONEG, types.TUINT16}:  ssa.OpNeg16,
        {ir.ONEG, types.TINT32}:   ssa.OpNeg32,
        {ir.ONEG, types.TUINT32}:  ssa.OpNeg32,
        {ir.ONEG, types.TINT64}:   ssa.OpNeg64,
        {ir.ONEG, types.TUINT64}:  ssa.OpNeg64,
        {ir.ONEG, types.TFLOAT32}: ssa.OpNeg32F,
        {ir.ONEG, types.TFLOAT64}: ssa.OpNeg64F,

        {ir.OBITNOT, types.TINT8}:   ssa.OpCom8,
        {ir.OBITNOT, types.TUINT8}:  ssa.OpCom8,
        {ir.OBITNOT, types.TINT16}:  ssa.OpCom16,
        {ir.OBITNOT, types.TUINT16}: ssa.OpCom16,
        {ir.OBITNOT, types.TINT32}:  ssa.OpCom32,
        {ir.OBITNOT, types.TUINT32}: ssa.OpCom32,
        {ir.OBITNOT, types.TINT64}:  ssa.OpCom64,
        {ir.OBITNOT, types.TUINT64}: ssa.OpCom64,

        {ir.OIMAG, types.TCOMPLEX64}:  ssa.OpComplexImag,
        {ir.OIMAG, types.TCOMPLEX128}: ssa.OpComplexImag,
        {ir.OREAL, types.TCOMPLEX64}:  ssa.OpComplexReal,
        {ir.OREAL, types.TCOMPLEX128}: ssa.OpComplexReal,

        {ir.OMUL, types.TINT8}:    ssa.OpMul8,
        {ir.OMUL, types.TUINT8}:   ssa.OpMul8,
        {ir.OMUL, types.TINT16}:   ssa.OpMul16,
        {ir.OMUL, types.TUINT16}:  ssa.OpMul16,
        {ir.OMUL, types.TINT32}:   ssa.OpMul32,
        {ir.OMUL, types.TUINT32}:  ssa.OpMul32,
        {ir.OMUL, types.TINT64}:   ssa.OpMul64,
        {ir.OMUL, types.TUINT64}:  ssa.OpMul64,
        {ir.OMUL, types.TFLOAT32}: ssa.OpMul32F,
        {ir.OMUL, types.TFLOAT64}: ssa.OpMul64F,

        {ir.ODIV, types.TFLOAT32}: ssa.OpDiv32F,
        {ir.ODIV, types.TFLOAT64}: ssa.OpDiv64F,

        {ir.ODIV, types.TINT8}:   ssa.OpDiv8,
        {ir.ODIV, types.TUINT8}:  ssa.OpDiv8u,
        {ir.ODIV, types.TINT16}:  ssa.OpDiv16,
        {ir.ODIV, types.TUINT16}: ssa.OpDiv16u,
        {ir.ODIV, types.TINT32}:  ssa.OpDiv32,
        {ir.ODIV, types.TUINT32}: ssa.OpDiv32u,
        {ir.ODIV, types.TINT64}:  ssa.OpDiv64,
        {ir.ODIV, types.TUINT64}: ssa.OpDiv64u,

        {ir.OMOD, types.TINT8}:   ssa.OpMod8,
        {ir.OMOD, types.TUINT8}:  ssa.OpMod8u,
        {ir.OMOD, types.TINT16}:  ssa.OpMod16,
        {ir.OMOD, types.TUINT16}: ssa.OpMod16u,
        {ir.OMOD, types.TINT32}:  ssa.OpMod32,
        {ir.OMOD, types.TUINT32}: ssa.OpMod32u,
        {ir.OMOD, types.TINT64}:  ssa.OpMod64,
        {ir.OMOD, types.TUINT64}: ssa.OpMod64u,

        {ir.OAND, types.TINT8}:   ssa.OpAnd8,
        {ir.OAND, types.TUINT8}:  ssa.OpAnd8,
        {ir.OAND, types.TINT16}:  ssa.OpAnd16,
        {ir.OAND, types.TUINT16}: ssa.OpAnd16,
        {ir.OAND, types.TINT32}:  ssa.OpAnd32,
        {ir.OAND, types.TUINT32}: ssa.OpAnd32,
        {ir.OAND, types.TINT64}:  ssa.OpAnd64,
        {ir.OAND, types.TUINT64}: ssa.OpAnd64,

        {ir.OOR, types.TINT8}:   ssa.OpOr8,
        {ir.OOR, types.TUINT8}:  ssa.OpOr8,
        {ir.OOR, types.TINT16}:  ssa.OpOr16,
        {ir.OOR, types.TUINT16}: ssa.OpOr16,
        {ir.OOR, types.TINT32}:  ssa.OpOr32,
        {ir.OOR, types.TUINT32}: ssa.OpOr32,
        {ir.OOR, types.TINT64}:  ssa.OpOr64,
        {ir.OOR, types.TUINT64}: ssa.OpOr64,

        {ir.OXOR, types.TINT8}:   ssa.OpXor8,
        {ir.OXOR, types.TUINT8}:  ssa.OpXor8,
        {ir.OXOR, types.TINT16}:  ssa.OpXor16,
        {ir.OXOR, types.TUINT16}: ssa.OpXor16,
        {ir.OXOR, types.TINT32}:  ssa.OpXor32,
        {ir.OXOR, types.TUINT32}: ssa.OpXor32,
        {ir.OXOR, types.TINT64}:  ssa.OpXor64,
        {ir.OXOR, types.TUINT64}: ssa.OpXor64,

        {ir.OEQ, types.TBOOL}:      ssa.OpEqB,
        {ir.OEQ, types.TINT8}:      ssa.OpEq8,
        {ir.OEQ, types.TUINT8}:     ssa.OpEq8,
        {ir.OEQ, types.TINT16}:     ssa.OpEq16,
        {ir.OEQ, types.TUINT16}:    ssa.OpEq16,
        {ir.OEQ, types.TINT32}:     ssa.OpEq32,
        {ir.OEQ, types.TUINT32}:    ssa.OpEq32,
        {ir.OEQ, types.TINT64}:     ssa.OpEq64,
        {ir.OEQ, types.TUINT64}:    ssa.OpEq64,
        {ir.OEQ, types.TINTER}:     ssa.OpEqInter,
        {ir.OEQ, types.TSLICE}:     ssa.OpEqSlice,
        {ir.OEQ, types.TFUNC}:      ssa.OpEqPtr,
        {ir.OEQ, types.TMAP}:       ssa.OpEqPtr,
        {ir.OEQ, types.TCHAN}:      ssa.OpEqPtr,
        {ir.OEQ, types.TPTR}:       ssa.OpEqPtr,
        {ir.OEQ, types.TUINTPTR}:   ssa.OpEqPtr,
        {ir.OEQ, types.TUNSAFEPTR}: ssa.OpEqPtr,
        {ir.OEQ, types.TFLOAT64}:   ssa.OpEq64F,
        {ir.OEQ, types.TFLOAT32}:   ssa.OpEq32F,

        {ir.ONE, types.TBOOL}:      ssa.OpNeqB,
        {ir.ONE, types.TINT8}:      ssa.OpNeq8,
        {ir.ONE, types.TUINT8}:     ssa.OpNeq8,
        {ir.ONE, types.TINT16}:     ssa.OpNeq16,
        {ir.ONE, types.TUINT16}:    ssa.OpNeq16,
        {ir.ONE, types.TINT32}:     ssa.OpNeq32,
        {ir.ONE, types.TUINT32}:    ssa.OpNeq32,
        {ir.ONE, types.TINT64}:     ssa.OpNeq64,
        {ir.ONE, types.TUINT64}:    ssa.OpNeq64,
        {ir.ONE, types.TINTER}:     ssa.OpNeqInter,
        {ir.ONE, types.TSLICE}:     ssa.OpNeqSlice,
        {ir.ONE, types.TFUNC}:      ssa.OpNeqPtr,
        {ir.ONE, types.TMAP}:       ssa.OpNeqPtr,
        {ir.ONE, types.TCHAN}:      ssa.OpNeqPtr,
        {ir.ONE, types.TPTR}:       ssa.OpNeqPtr,
        {ir.ONE, types.TUINTPTR}:   ssa.OpNeqPtr,
        {ir.ONE, types.TUNSAFEPTR}: ssa.OpNeqPtr,
        {ir.ONE, types.TFLOAT64}:   ssa.OpNeq64F,
        {ir.ONE, types.TFLOAT32}:   ssa.OpNeq32F,

        {ir.OLT, types.TINT8}:    ssa.OpLess8,
        {ir.OLT, types.TUINT8}:   ssa.OpLess8U,
        {ir.OLT, types.TINT16}:   ssa.OpLess16,
        {ir.OLT, types.TUINT16}:  ssa.OpLess16U,
        {ir.OLT, types.TINT32}:   ssa.OpLess32,
        {ir.OLT, types.TUINT32}:  ssa.OpLess32U,
        {ir.OLT, types.TINT64}:   ssa.OpLess64,
        {ir.OLT, types.TUINT64}:  ssa.OpLess64U,
        {ir.OLT, types.TFLOAT64}: ssa.OpLess64F,
        {ir.OLT, types.TFLOAT32}: ssa.OpLess32F,

        {ir.OLE, types.TINT8}:    ssa.OpLeq8,
        {ir.OLE, types.TUINT8}:   ssa.OpLeq8U,
        {ir.OLE, types.TINT16}:   ssa.OpLeq16,
        {ir.OLE, types.TUINT16}:  ssa.OpLeq16U,
        {ir.OLE, types.TINT32}:   ssa.OpLeq32,
        {ir.OLE, types.TUINT32}:  ssa.OpLeq32U,
        {ir.OLE, types.TINT64}:   ssa.OpLeq64,
        {ir.OLE, types.TUINT64}:  ssa.OpLeq64U,
        {ir.OLE, types.TFLOAT64}: ssa.OpLeq64F,
        {ir.OLE, types.TFLOAT32}: ssa.OpLeq32F,
}

func (s *state) concreteEtype(t *types.Type) types.Kind {
        e := t.Kind()
        switch e {
        default:
                return e
        case types.TINT:
                if s.config.PtrSize == 8 {
                        return types.TINT64
                }
                return types.TINT32
        case types.TUINT:
                if s.config.PtrSize == 8 {
                        return types.TUINT64
                }
                return types.TUINT32
        case types.TUINTPTR:
                if s.config.PtrSize == 8 {
                        return types.TUINT64
                }
                return types.TUINT32
        }
}

func (s *state) ssaOp(op ir.Op, t *types.Type) ssa.Op {
        etype := s.concreteEtype(t)
        x, ok := opToSSA[opAndType{op, etype}]
        if !ok {
                s.Fatalf("unhandled binary op %v %s", op, etype)
        }
        return x
}

type opAndTwoTypes struct {
        op     ir.Op
        etype1 types.Kind
        etype2 types.Kind
}

type twoTypes struct {
        etype1 types.Kind
        etype2 types.Kind
}

type twoOpsAndType struct {
        op1              ssa.Op
        op2              ssa.Op
        intermediateType types.Kind
}

var fpConvOpToSSA = map[twoTypes]twoOpsAndType{

        {types.TINT8, types.TFLOAT32}:  {ssa.OpSignExt8to32, ssa.OpCvt32to32F, types.TINT32},
        {types.TINT16, types.TFLOAT32}: {ssa.OpSignExt16to32, ssa.OpCvt32to32F, types.TINT32},
        {types.TINT32, types.TFLOAT32}: {ssa.OpCopy, ssa.OpCvt32to32F, types.TINT32},
        {types.TINT64, types.TFLOAT32}: {ssa.OpCopy, ssa.OpCvt64to32F, types.TINT64},

        {types.TINT8, types.TFLOAT64}:  {ssa.OpSignExt8to32, ssa.OpCvt32to64F, types.TINT32},
        {types.TINT16, types.TFLOAT64}: {ssa.OpSignExt16to32, ssa.OpCvt32to64F, types.TINT32},
        {types.TINT32, types.TFLOAT64}: {ssa.OpCopy, ssa.OpCvt32to64F, types.TINT32},
        {types.TINT64, types.TFLOAT64}: {ssa.OpCopy, ssa.OpCvt64to64F, types.TINT64},

        {types.TFLOAT32, types.TINT8}:  {ssa.OpCvt32Fto32, ssa.OpTrunc32to8, types.TINT32},
        {types.TFLOAT32, types.TINT16}: {ssa.OpCvt32Fto32, ssa.OpTrunc32to16, types.TINT32},
        {types.TFLOAT32, types.TINT32}: {ssa.OpCvt32Fto32, ssa.OpCopy, types.TINT32},
        {types.TFLOAT32, types.TINT64}: {ssa.OpCvt32Fto64, ssa.OpCopy, types.TINT64},

        {types.TFLOAT64, types.TINT8}:  {ssa.OpCvt64Fto32, ssa.OpTrunc32to8, types.TINT32},
        {types.TFLOAT64, types.TINT16}: {ssa.OpCvt64Fto32, ssa.OpTrunc32to16, types.TINT32},
        {types.TFLOAT64, types.TINT32}: {ssa.OpCvt64Fto32, ssa.OpCopy, types.TINT32},
        {types.TFLOAT64, types.TINT64}: {ssa.OpCvt64Fto64, ssa.OpCopy, types.TINT64},
        // unsigned
        {types.TUINT8, types.TFLOAT32}:  {ssa.OpZeroExt8to32, ssa.OpCvt32to32F, types.TINT32},
        {types.TUINT16, types.TFLOAT32}: {ssa.OpZeroExt16to32, ssa.OpCvt32to32F, types.TINT32},
        {types.TUINT32, types.TFLOAT32}: {ssa.OpZeroExt32to64, ssa.OpCvt64to32F, types.TINT64}, // go wide to dodge unsigned
        {types.TUINT64, types.TFLOAT32}: {ssa.OpCopy, ssa.OpInvalid, types.TUINT64},            // Cvt64Uto32F, branchy code expansion instead

        {types.TUINT8, types.TFLOAT64}:  {ssa.OpZeroExt8to32, ssa.OpCvt32to64F, types.TINT32},
        {types.TUINT16, types.TFLOAT64}: {ssa.OpZeroExt16to32, ssa.OpCvt32to64F, types.TINT32},
        {types.TUINT32, types.TFLOAT64}: {ssa.OpZeroExt32to64, ssa.OpCvt64to64F, types.TINT64}, // go wide to dodge unsigned
        {types.TUINT64, types.TFLOAT64}: {ssa.OpCopy, ssa.OpInvalid, types.TUINT64},            // Cvt64Uto64F, branchy code expansion instead

        {types.TFLOAT32, types.TUINT8}:  {ssa.OpCvt32Fto32, ssa.OpTrunc32to8, types.TINT32},
        {types.TFLOAT32, types.TUINT16}: {ssa.OpCvt32Fto32, ssa.OpTrunc32to16, types.TINT32},
        {types.TFLOAT32, types.TUINT32}: {ssa.OpCvt32Fto64, ssa.OpTrunc64to32, types.TINT64}, // go wide to dodge unsigned
        {types.TFLOAT32, types.TUINT64}: {ssa.OpInvalid, ssa.OpCopy, types.TUINT64},          // Cvt32Fto64U, branchy code expansion instead

        {types.TFLOAT64, types.TUINT8}:  {ssa.OpCvt64Fto32, ssa.OpTrunc32to8, types.TINT32},
        {types.TFLOAT64, types.TUINT16}: {ssa.OpCvt64Fto32, ssa.OpTrunc32to16, types.TINT32},
        {types.TFLOAT64, types.TUINT32}: {ssa.OpCvt64Fto64, ssa.OpTrunc64to32, types.TINT64}, // go wide to dodge unsigned
        {types.TFLOAT64, types.TUINT64}: {ssa.OpInvalid, ssa.OpCopy, types.TUINT64},          // Cvt64Fto64U, branchy code expansion instead

        // float
        {types.TFLOAT64, types.TFLOAT32}: {ssa.OpCvt64Fto32F, ssa.OpCopy, types.TFLOAT32},
        {types.TFLOAT64, types.TFLOAT64}: {ssa.OpRound64F, ssa.OpCopy, types.TFLOAT64},
        {types.TFLOAT32, types.TFLOAT32}: {ssa.OpRound32F, ssa.OpCopy, types.TFLOAT32},
        {types.TFLOAT32, types.TFLOAT64}: {ssa.OpCvt32Fto64F, ssa.OpCopy, types.TFLOAT64},
}

// this map is used only for 32-bit arch, and only includes the difference
// on 32-bit arch, don't use int64<->float conversion for uint32
var fpConvOpToSSA32 = map[twoTypes]twoOpsAndType{
        {types.TUINT32, types.TFLOAT32}: {ssa.OpCopy, ssa.OpCvt32Uto32F, types.TUINT32},
        {types.TUINT32, types.TFLOAT64}: {ssa.OpCopy, ssa.OpCvt32Uto64F, types.TUINT32},
        {types.TFLOAT32, types.TUINT32}: {ssa.OpCvt32Fto32U, ssa.OpCopy, types.TUINT32},
        {types.TFLOAT64, types.TUINT32}: {ssa.OpCvt64Fto32U, ssa.OpCopy, types.TUINT32},
}

// uint64<->float conversions, only on machines that have instructions for that
var uint64fpConvOpToSSA = map[twoTypes]twoOpsAndType{
        {types.TUINT64, types.TFLOAT32}: {ssa.OpCopy, ssa.OpCvt64Uto32F, types.TUINT64},
        {types.TUINT64, types.TFLOAT64}: {ssa.OpCopy, ssa.OpCvt64Uto64F, types.TUINT64},
        {types.TFLOAT32, types.TUINT64}: {ssa.OpCvt32Fto64U, ssa.OpCopy, types.TUINT64},
        {types.TFLOAT64, types.TUINT64}: {ssa.OpCvt64Fto64U, ssa.OpCopy, types.TUINT64},
}

var shiftOpToSSA = map[opAndTwoTypes]ssa.Op{
        {ir.OLSH, types.TINT8, types.TUINT8}:   ssa.OpLsh8x8,
        {ir.OLSH, types.TUINT8, types.TUINT8}:  ssa.OpLsh8x8,
        {ir.OLSH, types.TINT8, types.TUINT16}:  ssa.OpLsh8x16,
        {ir.OLSH, types.TUINT8, types.TUINT16}: ssa.OpLsh8x16,
        {ir.OLSH, types.TINT8, types.TUINT32}:  ssa.OpLsh8x32,
        {ir.OLSH, types.TUINT8, types.TUINT32}: ssa.OpLsh8x32,
        {ir.OLSH, types.TINT8, types.TUINT64}:  ssa.OpLsh8x64,
        {ir.OLSH, types.TUINT8, types.TUINT64}: ssa.OpLsh8x64,

        {ir.OLSH, types.TINT16, types.TUINT8}:   ssa.OpLsh16x8,
        {ir.OLSH, types.TUINT16, types.TUINT8}:  ssa.OpLsh16x8,
        {ir.OLSH, types.TINT16, types.TUINT16}:  ssa.OpLsh16x16,
        {ir.OLSH, types.TUINT16, types.TUINT16}: ssa.OpLsh16x16,
        {ir.OLSH, types.TINT16, types.TUINT32}:  ssa.OpLsh16x32,
        {ir.OLSH, types.TUINT16, types.TUINT32}: ssa.OpLsh16x32,
        {ir.OLSH, types.TINT16, types.TUINT64}:  ssa.OpLsh16x64,
        {ir.OLSH, types.TUINT16, types.TUINT64}: ssa.OpLsh16x64,

        {ir.OLSH, types.TINT32, types.TUINT8}:   ssa.OpLsh32x8,
        {ir.OLSH, types.TUINT32, types.TUINT8}:  ssa.OpLsh32x8,
        {ir.OLSH, types.TINT32, types.TUINT16}:  ssa.OpLsh32x16,
        {ir.OLSH, types.TUINT32, types.TUINT16}: ssa.OpLsh32x16,
        {ir.OLSH, types.TINT32, types.TUINT32}:  ssa.OpLsh32x32,
        {ir.OLSH, types.TUINT32, types.TUINT32}: ssa.OpLsh32x32,
        {ir.OLSH, types.TINT32, types.TUINT64}:  ssa.OpLsh32x64,
        {ir.OLSH, types.TUINT32, types.TUINT64}: ssa.OpLsh32x64,

        {ir.OLSH, types.TINT64, types.TUINT8}:   ssa.OpLsh64x8,
        {ir.OLSH, types.TUINT64, types.TUINT8}:  ssa.OpLsh64x8,
        {ir.OLSH, types.TINT64, types.TUINT16}:  ssa.OpLsh64x16,
        {ir.OLSH, types.TUINT64, types.TUINT16}: ssa.OpLsh64x16,
        {ir.OLSH, types.TINT64, types.TUINT32}:  ssa.OpLsh64x32,
        {ir.OLSH, types.TUINT64, types.TUINT32}: ssa.OpLsh64x32,
        {ir.OLSH, types.TINT64, types.TUINT64}:  ssa.OpLsh64x64,
        {ir.OLSH, types.TUINT64, types.TUINT64}: ssa.OpLsh64x64,

        {ir.ORSH, types.TINT8, types.TUINT8}:   ssa.OpRsh8x8,
        {ir.ORSH, types.TUINT8, types.TUINT8}:  ssa.OpRsh8Ux8,
        {ir.ORSH, types.TINT8, types.TUINT16}:  ssa.OpRsh8x16,
        {ir.ORSH, types.TUINT8, types.TUINT16}: ssa.OpRsh8Ux16,
        {ir.ORSH, types.TINT8, types.TUINT32}:  ssa.OpRsh8x32,
        {ir.ORSH, types.TUINT8, types.TUINT32}: ssa.OpRsh8Ux32,
        {ir.ORSH, types.TINT8, types.TUINT64}:  ssa.OpRsh8x64,
        {ir.ORSH, types.TUINT8, types.TUINT64}: ssa.OpRsh8Ux64,

        {ir.ORSH, types.TINT16, types.TUINT8}:   ssa.OpRsh16x8,
        {ir.ORSH, types.TUINT16, types.TUINT8}:  ssa.OpRsh16Ux8,
        {ir.ORSH, types.TINT16, types.TUINT16}:  ssa.OpRsh16x16,
        {ir.ORSH, types.TUINT16, types.TUINT16}: ssa.OpRsh16Ux16,
        {ir.ORSH, types.TINT16, types.TUINT32}:  ssa.OpRsh16x32,
        {ir.ORSH, types.TUINT16, types.TUINT32}: ssa.OpRsh16Ux32,
        {ir.ORSH, types.TINT16, types.TUINT64}:  ssa.OpRsh16x64,
        {ir.ORSH, types.TUINT16, types.TUINT64}: ssa.OpRsh16Ux64,

        {ir.ORSH, types.TINT32, types.TUINT8}:   ssa.OpRsh32x8,
        {ir.ORSH, types.TUINT32, types.TUINT8}:  ssa.OpRsh32Ux8,
        {ir.ORSH, types.TINT32, types.TUINT16}:  ssa.OpRsh32x16,
        {ir.ORSH, types.TUINT32, types.TUINT16}: ssa.OpRsh32Ux16,
        {ir.ORSH, types.TINT32, types.TUINT32}:  ssa.OpRsh32x32,
        {ir.ORSH, types.TUINT32, types.TUINT32}: ssa.OpRsh32Ux32,
        {ir.ORSH, types.TINT32, types.TUINT64}:  ssa.OpRsh32x64,
        {ir.ORSH, types.TUINT32, types.TUINT64}: ssa.OpRsh32Ux64,

        {ir.ORSH, types.TINT64, types.TUINT8}:   ssa.OpRsh64x8,
        {ir.ORSH, types.TUINT64, types.TUINT8}:  ssa.OpRsh64Ux8,
        {ir.ORSH, types.TINT64, types.TUINT16}:  ssa.OpRsh64x16,
        {ir.ORSH, types.TUINT64, types.TUINT16}: ssa.OpRsh64Ux16,
        {ir.ORSH, types.TINT64, types.TUINT32}:  ssa.OpRsh64x32,
        {ir.ORSH, types.TUINT64, types.TUINT32}: ssa.OpRsh64Ux32,
        {ir.ORSH, types.TINT64, types.TUINT64}:  ssa.OpRsh64x64,
        {ir.ORSH, types.TUINT64, types.TUINT64}: ssa.OpRsh64Ux64,
}

func (s *state) ssaShiftOp(op ir.Op, t *types.Type, u *types.Type) ssa.Op {
        etype1 := s.concreteEtype(t)
        etype2 := s.concreteEtype(u)
        x, ok := shiftOpToSSA[opAndTwoTypes{op, etype1, etype2}]
        if !ok {
                s.Fatalf("unhandled shift op %v etype=%s/%s", op, etype1, etype2)
        }
        return x
}

func (s *state) uintptrConstant(v uint64) *ssa.Value {
        if s.config.PtrSize == 4 {
                return s.newValue0I(ssa.OpConst32, types.Types[types.TUINTPTR], int64(v))
        }
        return s.newValue0I(ssa.OpConst64, types.Types[types.TUINTPTR], int64(v))
}

func (s *state) conv(n ir.Node, v *ssa.Value, ft, tt *types.Type) *ssa.Value {
        if ft.IsBoolean() && tt.IsKind(types.TUINT8) {
                // Bool -> uint8 is generated internally when indexing into runtime.staticbyte.
                return s.newValue1(ssa.OpCvtBoolToUint8, tt, v)
        }
        if ft.IsInteger() && tt.IsInteger() {
                var op ssa.Op
                if tt.Size() == ft.Size() {
                        op = ssa.OpCopy
                } else if tt.Size() < ft.Size() {
                        // truncation
                        switch 10*ft.Size() + tt.Size() {
                        case 21:
                                op = ssa.OpTrunc16to8
                        case 41:
                                op = ssa.OpTrunc32to8
                        case 42:
                                op = ssa.OpTrunc32to16
                        case 81:
                                op = ssa.OpTrunc64to8
                        case 82:
                                op = ssa.OpTrunc64to16
                        case 84:
                                op = ssa.OpTrunc64to32
                        default:
                                s.Fatalf("weird integer truncation %v -> %v", ft, tt)
                        }
                } else if ft.IsSigned() {
                        // sign extension
                        switch 10*ft.Size() + tt.Size() {
                        case 12:
                                op = ssa.OpSignExt8to16
                        case 14:
                                op = ssa.OpSignExt8to32
                        case 18:
                                op = ssa.OpSignExt8to64
                        case 24:
                                op = ssa.OpSignExt16to32
                        case 28:
                                op = ssa.OpSignExt16to64
                        case 48:
                                op = ssa.OpSignExt32to64
                        default:
                                s.Fatalf("bad integer sign extension %v -> %v", ft, tt)
                        }
                } else {
                        // zero extension
                        switch 10*ft.Size() + tt.Size() {
                        case 12:
                                op = ssa.OpZeroExt8to16
                        case 14:
                                op = ssa.OpZeroExt8to32
                        case 18:
                                op = ssa.OpZeroExt8to64
                        case 24:
                                op = ssa.OpZeroExt16to32
                        case 28:
                                op = ssa.OpZeroExt16to64
                        case 48:
                                op = ssa.OpZeroExt32to64
                        default:
                                s.Fatalf("weird integer sign extension %v -> %v", ft, tt)
                        }
                }
                return s.newValue1(op, tt, v)
        }

        if ft.IsComplex() && tt.IsComplex() {
                var op ssa.Op
                if ft.Size() == tt.Size() {
                        switch ft.Size() {
                        case 8:
                                op = ssa.OpRound32F
                        case 16:
                                op = ssa.OpRound64F
                        default:
                                s.Fatalf("weird complex conversion %v -> %v", ft, tt)
                        }
                } else if ft.Size() == 8 && tt.Size() == 16 {
                        op = ssa.OpCvt32Fto64F
                } else if ft.Size() == 16 && tt.Size() == 8 {
                        op = ssa.OpCvt64Fto32F
                } else {
                        s.Fatalf("weird complex conversion %v -> %v", ft, tt)
                }
                ftp := types.FloatForComplex(ft)
                ttp := types.FloatForComplex(tt)
                return s.newValue2(ssa.OpComplexMake, tt,
                        s.newValueOrSfCall1(op, ttp, s.newValue1(ssa.OpComplexReal, ftp, v)),
                        s.newValueOrSfCall1(op, ttp, s.newValue1(ssa.OpComplexImag, ftp, v)))
        }

        if tt.IsComplex() { // and ft is not complex
                // Needed for generics support - can't happen in normal Go code.
                et := types.FloatForComplex(tt)
                v = s.conv(n, v, ft, et)
                return s.newValue2(ssa.OpComplexMake, tt, v, s.zeroVal(et))
        }

        if ft.IsFloat() || tt.IsFloat() {
                conv, ok := fpConvOpToSSA[twoTypes{s.concreteEtype(ft), s.concreteEtype(tt)}]
                if s.config.RegSize == 4 && Arch.LinkArch.Family != sys.MIPS && !s.softFloat {
                        if conv1, ok1 := fpConvOpToSSA32[twoTypes{s.concreteEtype(ft), s.concreteEtype(tt)}]; ok1 {
                                conv = conv1
                        }
                }
                if Arch.LinkArch.Family == sys.ARM64 || Arch.LinkArch.Family == sys.Wasm || Arch.LinkArch.Family == sys.S390X || s.softFloat {
                        if conv1, ok1 := uint64fpConvOpToSSA[twoTypes{s.concreteEtype(ft), s.concreteEtype(tt)}]; ok1 {
                                conv = conv1
                        }
                }

                if Arch.LinkArch.Family == sys.MIPS && !s.softFloat {
                        if ft.Size() == 4 && ft.IsInteger() && !ft.IsSigned() {
                                // tt is float32 or float64, and ft is also unsigned
                                if tt.Size() == 4 {
                                        return s.uint32Tofloat32(n, v, ft, tt)
                                }
                                if tt.Size() == 8 {
                                        return s.uint32Tofloat64(n, v, ft, tt)
                                }
                        } else if tt.Size() == 4 && tt.IsInteger() && !tt.IsSigned() {
                                // ft is float32 or float64, and tt is unsigned integer
                                if ft.Size() == 4 {
                                        return s.float32ToUint32(n, v, ft, tt)
                                }
                                if ft.Size() == 8 {
                                        return s.float64ToUint32(n, v, ft, tt)
                                }
                        }
                }

                if !ok {
                        s.Fatalf("weird float conversion %v -> %v", ft, tt)
                }
                op1, op2, it := conv.op1, conv.op2, conv.intermediateType

                if op1 != ssa.OpInvalid && op2 != ssa.OpInvalid {
                        // normal case, not tripping over unsigned 64
                        if op1 == ssa.OpCopy {
                                if op2 == ssa.OpCopy {
                                        return v
                                }
                                return s.newValueOrSfCall1(op2, tt, v)
                        }
                        if op2 == ssa.OpCopy {
                                return s.newValueOrSfCall1(op1, tt, v)
                        }
                        return s.newValueOrSfCall1(op2, tt, s.newValueOrSfCall1(op1, types.Types[it], v))
                }
                // Tricky 64-bit unsigned cases.
                if ft.IsInteger() {
                        // tt is float32 or float64, and ft is also unsigned
                        if tt.Size() == 4 {
                                return s.uint64Tofloat32(n, v, ft, tt)
                        }
                        if tt.Size() == 8 {
                                return s.uint64Tofloat64(n, v, ft, tt)
                        }
                        s.Fatalf("weird unsigned integer to float conversion %v -> %v", ft, tt)
                }
                // ft is float32 or float64, and tt is unsigned integer
                if ft.Size() == 4 {
                        return s.float32ToUint64(n, v, ft, tt)
                }
                if ft.Size() == 8 {
                        return s.float64ToUint64(n, v, ft, tt)
                }
                s.Fatalf("weird float to unsigned integer conversion %v -> %v", ft, tt)
                return nil
        }

        s.Fatalf("unhandled OCONV %s -> %s", ft.Kind(), tt.Kind())
        return nil
}

// expr converts the expression n to ssa, adds it to s and returns the ssa result.
func (s *state) expr(n ir.Node) *ssa.Value {
        return s.exprCheckPtr(n, true)
}

func (s *state) exprCheckPtr(n ir.Node, checkPtrOK bool) *ssa.Value {
        if ir.HasUniquePos(n) {
                // ONAMEs and named OLITERALs have the line number
                // of the decl, not the use. See issue 14742.
                s.pushLine(n.Pos())
                defer s.popLine()
        }

        s.stmtList(n.Init())
        switch n.Op() {
        case ir.OBYTES2STRTMP:
                n := n.(*ir.ConvExpr)
                slice := s.expr(n.X)
                ptr := s.newValue1(ssa.OpSlicePtr, s.f.Config.Types.BytePtr, slice)
                len := s.newValue1(ssa.OpSliceLen, types.Types[types.TINT], slice)
                return s.newValue2(ssa.OpStringMake, n.Type(), ptr, len)
        case ir.OSTR2BYTESTMP:
                n := n.(*ir.ConvExpr)
                str := s.expr(n.X)
                ptr := s.newValue1(ssa.OpStringPtr, s.f.Config.Types.BytePtr, str)
                if !n.NonNil() {
                        // We need to ensure []byte("") evaluates to []byte{}, and not []byte(nil).
                        //
                        // TODO(mdempsky): Investigate using "len != 0" instead of "ptr != nil".
                        cond := s.newValue2(ssa.OpNeqPtr, types.Types[types.TBOOL], ptr, s.constNil(ptr.Type))
                        zerobase := s.newValue1A(ssa.OpAddr, ptr.Type, ir.Syms.Zerobase, s.sb)
                        ptr = s.ternary(cond, ptr, zerobase)
                }
                len := s.newValue1(ssa.OpStringLen, types.Types[types.TINT], str)
                return s.newValue3(ssa.OpSliceMake, n.Type(), ptr, len, len)
        case ir.OCFUNC:
                n := n.(*ir.UnaryExpr)
                aux := n.X.(*ir.Name).Linksym()
                // OCFUNC is used to build function values, which must
                // always reference ABIInternal entry points.
                if aux.ABI() != obj.ABIInternal {
                        s.Fatalf("expected ABIInternal: %v", aux.ABI())
                }
                return s.entryNewValue1A(ssa.OpAddr, n.Type(), aux, s.sb)
        case ir.ONAME:
                n := n.(*ir.Name)
                if n.Class == ir.PFUNC {
                        // "value" of a function is the address of the function's closure
                        sym := staticdata.FuncLinksym(n)
                        return s.entryNewValue1A(ssa.OpAddr, types.NewPtr(n.Type()), sym, s.sb)
                }
                if s.canSSA(n) {
                        return s.variable(n, n.Type())
                }
                return s.load(n.Type(), s.addr(n))
        case ir.OLINKSYMOFFSET:
                n := n.(*ir.LinksymOffsetExpr)
                return s.load(n.Type(), s.addr(n))
        case ir.ONIL:
                n := n.(*ir.NilExpr)
                t := n.Type()
                switch {
                case t.IsSlice():
                        return s.constSlice(t)
                case t.IsInterface():
                        return s.constInterface(t)
                default:
                        return s.constNil(t)
                }
        case ir.OLITERAL:
                switch u := n.Val(); u.Kind() {
                case constant.Int:
                        i := ir.IntVal(n.Type(), u)
                        switch n.Type().Size() {
                        case 1:
                                return s.constInt8(n.Type(), int8(i))
                        case 2:
                                return s.constInt16(n.Type(), int16(i))
                        case 4:
                                return s.constInt32(n.Type(), int32(i))
                        case 8:
                                return s.constInt64(n.Type(), i)
                        default:
                                s.Fatalf("bad integer size %d", n.Type().Size())
                                return nil
                        }
                case constant.String:
                        i := constant.StringVal(u)
                        if i == "" {
                                return s.constEmptyString(n.Type())
                        }
                        return s.entryNewValue0A(ssa.OpConstString, n.Type(), ssa.StringToAux(i))
                case constant.Bool:
                        return s.constBool(constant.BoolVal(u))
                case constant.Float:
                        f, _ := constant.Float64Val(u)
                        switch n.Type().Size() {
                        case 4:
                                return s.constFloat32(n.Type(), f)
                        case 8:
                                return s.constFloat64(n.Type(), f)
                        default:
                                s.Fatalf("bad float size %d", n.Type().Size())
                                return nil
                        }
                case constant.Complex:
                        re, _ := constant.Float64Val(constant.Real(u))
                        im, _ := constant.Float64Val(constant.Imag(u))
                        switch n.Type().Size() {
                        case 8:
                                pt := types.Types[types.TFLOAT32]
                                return s.newValue2(ssa.OpComplexMake, n.Type(),
                                        s.constFloat32(pt, re),
                                        s.constFloat32(pt, im))
                        case 16:
                                pt := types.Types[types.TFLOAT64]
                                return s.newValue2(ssa.OpComplexMake, n.Type(),
                                        s.constFloat64(pt, re),
                                        s.constFloat64(pt, im))
                        default:
                                s.Fatalf("bad complex size %d", n.Type().Size())
                                return nil
                        }
                default:
                        s.Fatalf("unhandled OLITERAL %v", u.Kind())
                        return nil
                }
        case ir.OCONVNOP:
                n := n.(*ir.ConvExpr)
                to := n.Type()
                from := n.X.Type()

                // Assume everything will work out, so set up our return value.
                // Anything interesting that happens from here is a fatal.
                x := s.expr(n.X)
                if to == from {
                        return x
                }

                // Special case for not confusing GC and liveness.
                // We don't want pointers accidentally classified
                // as not-pointers or vice-versa because of copy
                // elision.
                if to.IsPtrShaped() != from.IsPtrShaped() {
                        return s.newValue2(ssa.OpConvert, to, x, s.mem())
                }

                v := s.newValue1(ssa.OpCopy, to, x) // ensure that v has the right type

                // CONVNOP closure
                if to.Kind() == types.TFUNC && from.IsPtrShaped() {
                        return v
                }

                // named <--> unnamed type or typed <--> untyped const
                if from.Kind() == to.Kind() {
                        return v
                }

                // unsafe.Pointer <--> *T
                if to.IsUnsafePtr() && from.IsPtrShaped() || from.IsUnsafePtr() && to.IsPtrShaped() {
                        if s.checkPtrEnabled && checkPtrOK && to.IsPtr() && from.IsUnsafePtr() {
                                s.checkPtrAlignment(n, v, nil)
                        }
                        return v
                }

                // map <--> *hmap
                if to.Kind() == types.TMAP && from.IsPtr() &&
                        to.MapType().Hmap == from.Elem() {
                        return v
                }

                types.CalcSize(from)
                types.CalcSize(to)
                if from.Size() != to.Size() {
                        s.Fatalf("CONVNOP width mismatch %v (%d) -> %v (%d)\n", from, from.Size(), to, to.Size())
                        return nil
                }
                if etypesign(from.Kind()) != etypesign(to.Kind()) {
                        s.Fatalf("CONVNOP sign mismatch %v (%s) -> %v (%s)\n", from, from.Kind(), to, to.Kind())
                        return nil
                }

                if base.Flag.Cfg.Instrumenting {
                        // These appear to be fine, but they fail the
                        // integer constraint below, so okay them here.
                        // Sample non-integer conversion: map[string]string -> *uint8
                        return v
                }

                if etypesign(from.Kind()) == 0 {
                        s.Fatalf("CONVNOP unrecognized non-integer %v -> %v\n", from, to)
                        return nil
                }

                // integer, same width, same sign
                return v

        case ir.OCONV:
                n := n.(*ir.ConvExpr)
                x := s.expr(n.X)
                return s.conv(n, x, n.X.Type(), n.Type())

        case ir.ODOTTYPE:
                n := n.(*ir.TypeAssertExpr)
                res, _ := s.dottype(n, false)
                return res

        case ir.ODYNAMICDOTTYPE:
                n := n.(*ir.DynamicTypeAssertExpr)
                res, _ := s.dynamicDottype(n, false)
                return res

        // binary ops
        case ir.OLT, ir.OEQ, ir.ONE, ir.OLE, ir.OGE, ir.OGT:
                n := n.(*ir.BinaryExpr)
                a := s.expr(n.X)
                b := s.expr(n.Y)
                if n.X.Type().IsComplex() {
                        pt := types.FloatForComplex(n.X.Type())
                        op := s.ssaOp(ir.OEQ, pt)
                        r := s.newValueOrSfCall2(op, types.Types[types.TBOOL], s.newValue1(ssa.OpComplexReal, pt, a), s.newValue1(ssa.OpComplexReal, pt, b))
                        i := s.newValueOrSfCall2(op, types.Types[types.TBOOL], s.newValue1(ssa.OpComplexImag, pt, a), s.newValue1(ssa.OpComplexImag, pt, b))
                        c := s.newValue2(ssa.OpAndB, types.Types[types.TBOOL], r, i)
                        switch n.Op() {
                        case ir.OEQ:
                                return c
                        case ir.ONE:
                                return s.newValue1(ssa.OpNot, types.Types[types.TBOOL], c)
                        default:
                                s.Fatalf("ordered complex compare %v", n.Op())
                        }
                }

                // Convert OGE and OGT into OLE and OLT.
                op := n.Op()
                switch op {
                case ir.OGE:
                        op, a, b = ir.OLE, b, a
                case ir.OGT:
                        op, a, b = ir.OLT, b, a
                }
                if n.X.Type().IsFloat() {
                        // float comparison
                        return s.newValueOrSfCall2(s.ssaOp(op, n.X.Type()), types.Types[types.TBOOL], a, b)
                }
                // integer comparison
                return s.newValue2(s.ssaOp(op, n.X.Type()), types.Types[types.TBOOL], a, b)
        case ir.OMUL:
                n := n.(*ir.BinaryExpr)
                a := s.expr(n.X)
                b := s.expr(n.Y)
                if n.Type().IsComplex() {
                        mulop := ssa.OpMul64F
                        addop := ssa.OpAdd64F
                        subop := ssa.OpSub64F
                        pt := types.FloatForComplex(n.Type()) // Could be Float32 or Float64
                        wt := types.Types[types.TFLOAT64]     // Compute in Float64 to minimize cancellation error

                        areal := s.newValue1(ssa.OpComplexReal, pt, a)
                        breal := s.newValue1(ssa.OpComplexReal, pt, b)
                        aimag := s.newValue1(ssa.OpComplexImag, pt, a)
                        bimag := s.newValue1(ssa.OpComplexImag, pt, b)

                        if pt != wt { // Widen for calculation
                                areal = s.newValueOrSfCall1(ssa.OpCvt32Fto64F, wt, areal)
                                breal = s.newValueOrSfCall1(ssa.OpCvt32Fto64F, wt, breal)
                                aimag = s.newValueOrSfCall1(ssa.OpCvt32Fto64F, wt, aimag)
                                bimag = s.newValueOrSfCall1(ssa.OpCvt32Fto64F, wt, bimag)
                        }

                        xreal := s.newValueOrSfCall2(subop, wt, s.newValueOrSfCall2(mulop, wt, areal, breal), s.newValueOrSfCall2(mulop, wt, aimag, bimag))
                        ximag := s.newValueOrSfCall2(addop, wt, s.newValueOrSfCall2(mulop, wt, areal, bimag), s.newValueOrSfCall2(mulop, wt, aimag, breal))

                        if pt != wt { // Narrow to store back
                                xreal = s.newValueOrSfCall1(ssa.OpCvt64Fto32F, pt, xreal)
                                ximag = s.newValueOrSfCall1(ssa.OpCvt64Fto32F, pt, ximag)
                        }

                        return s.newValue2(ssa.OpComplexMake, n.Type(), xreal, ximag)
                }

                if n.Type().IsFloat() {
                        return s.newValueOrSfCall2(s.ssaOp(n.Op(), n.Type()), a.Type, a, b)
                }

                return s.newValue2(s.ssaOp(n.Op(), n.Type()), a.Type, a, b)

        case ir.ODIV:
                n := n.(*ir.BinaryExpr)
                a := s.expr(n.X)
                b := s.expr(n.Y)
                if n.Type().IsComplex() {
                        // TODO this is not executed because the front-end substitutes a runtime call.
                        // That probably ought to change; with modest optimization the widen/narrow
                        // conversions could all be elided in larger expression trees.
                        mulop := ssa.OpMul64F
                        addop := ssa.OpAdd64F
                        subop := ssa.OpSub64F
                        divop := ssa.OpDiv64F
                        pt := types.FloatForComplex(n.Type()) // Could be Float32 or Float64
                        wt := types.Types[types.TFLOAT64]     // Compute in Float64 to minimize cancellation error

                        areal := s.newValue1(ssa.OpComplexReal, pt, a)
                        breal := s.newValue1(ssa.OpComplexReal, pt, b)
                        aimag := s.newValue1(ssa.OpComplexImag, pt, a)
                        bimag := s.newValue1(ssa.OpComplexImag, pt, b)

                        if pt != wt { // Widen for calculation
                                areal = s.newValueOrSfCall1(ssa.OpCvt32Fto64F, wt, areal)
                                breal = s.newValueOrSfCall1(ssa.OpCvt32Fto64F, wt, breal)
                                aimag = s.newValueOrSfCall1(ssa.OpCvt32Fto64F, wt, aimag)
                                bimag = s.newValueOrSfCall1(ssa.OpCvt32Fto64F, wt, bimag)
                        }

                        denom := s.newValueOrSfCall2(addop, wt, s.newValueOrSfCall2(mulop, wt, breal, breal), s.newValueOrSfCall2(mulop, wt, bimag, bimag))
                        xreal := s.newValueOrSfCall2(addop, wt, s.newValueOrSfCall2(mulop, wt, areal, breal), s.newValueOrSfCall2(mulop, wt, aimag, bimag))
                        ximag := s.newValueOrSfCall2(subop, wt, s.newValueOrSfCall2(mulop, wt, aimag, breal), s.newValueOrSfCall2(mulop, wt, areal, bimag))

                        // TODO not sure if this is best done in wide precision or narrow
                        // Double-rounding might be an issue.
                        // Note that the pre-SSA implementation does the entire calculation
                        // in wide format, so wide is compatible.
                        xreal = s.newValueOrSfCall2(divop, wt, xreal, denom)
                        ximag = s.newValueOrSfCall2(divop, wt, ximag, denom)

                        if pt != wt { // Narrow to store back
                                xreal = s.newValueOrSfCall1(ssa.OpCvt64Fto32F, pt, xreal)
                                ximag = s.newValueOrSfCall1(ssa.OpCvt64Fto32F, pt, ximag)
                        }
                        return s.newValue2(ssa.OpComplexMake, n.Type(), xreal, ximag)
                }
                if n.Type().IsFloat() {
                        return s.newValueOrSfCall2(s.ssaOp(n.Op(), n.Type()), a.Type, a, b)
                }
                return s.intDivide(n, a, b)
        case ir.OMOD:
                n := n.(*ir.BinaryExpr)
                a := s.expr(n.X)
                b := s.expr(n.Y)
                return s.intDivide(n, a, b)
        case ir.OADD, ir.OSUB:
                n := n.(*ir.BinaryExpr)
                a := s.expr(n.X)
                b := s.expr(n.Y)
                if n.Type().IsComplex() {
                        pt := types.FloatForComplex(n.Type())
                        op := s.ssaOp(n.Op(), pt)
                        return s.newValue2(ssa.OpComplexMake, n.Type(),
                                s.newValueOrSfCall2(op, pt, s.newValue1(ssa.OpComplexReal, pt, a), s.newValue1(ssa.OpComplexReal, pt, b)),
                                s.newValueOrSfCall2(op, pt, s.newValue1(ssa.OpComplexImag, pt, a), s.newValue1(ssa.OpComplexImag, pt, b)))
                }
                if n.Type().IsFloat() {
                        return s.newValueOrSfCall2(s.ssaOp(n.Op(), n.Type()), a.Type, a, b)
                }
                return s.newValue2(s.ssaOp(n.Op(), n.Type()), a.Type, a, b)
        case ir.OAND, ir.OOR, ir.OXOR:
                n := n.(*ir.BinaryExpr)
                a := s.expr(n.X)
                b := s.expr(n.Y)
                return s.newValue2(s.ssaOp(n.Op(), n.Type()), a.Type, a, b)
        case ir.OANDNOT:
                n := n.(*ir.BinaryExpr)
                a := s.expr(n.X)
                b := s.expr(n.Y)
                b = s.newValue1(s.ssaOp(ir.OBITNOT, b.Type), b.Type, b)
                return s.newValue2(s.ssaOp(ir.OAND, n.Type()), a.Type, a, b)
        case ir.OLSH, ir.ORSH:
                n := n.(*ir.BinaryExpr)
                a := s.expr(n.X)
                b := s.expr(n.Y)
                bt := b.Type
                if bt.IsSigned() {
                        cmp := s.newValue2(s.ssaOp(ir.OLE, bt), types.Types[types.TBOOL], s.zeroVal(bt), b)
                        s.check(cmp, ir.Syms.Panicshift)
                        bt = bt.ToUnsigned()
                }
                return s.newValue2(s.ssaShiftOp(n.Op(), n.Type(), bt), a.Type, a, b)
        case ir.OANDAND, ir.OOROR:
                // To implement OANDAND (and OOROR), we introduce a
                // new temporary variable to hold the result. The
                // variable is associated with the OANDAND node in the
                // s.vars table (normally variables are only
                // associated with ONAME nodes). We convert
                //     A && B
                // to
                //     var = A
                //     if var {
                //         var = B
                //     }
                // Using var in the subsequent block introduces the
                // necessary phi variable.
                n := n.(*ir.LogicalExpr)
                el := s.expr(n.X)
                s.vars[n] = el

                b := s.endBlock()
                b.Kind = ssa.BlockIf
                b.SetControl(el)
                // In theory, we should set b.Likely here based on context.
                // However, gc only gives us likeliness hints
                // in a single place, for plain OIF statements,
                // and passing around context is finnicky, so don't bother for now.

                bRight := s.f.NewBlock(ssa.BlockPlain)
                bResult := s.f.NewBlock(ssa.BlockPlain)
                if n.Op() == ir.OANDAND {
                        b.AddEdgeTo(bRight)
                        b.AddEdgeTo(bResult)
                } else if n.Op() == ir.OOROR {
                        b.AddEdgeTo(bResult)
                        b.AddEdgeTo(bRight)
                }

                s.startBlock(bRight)
                er := s.expr(n.Y)
                s.vars[n] = er

                b = s.endBlock()
                b.AddEdgeTo(bResult)

                s.startBlock(bResult)
                return s.variable(n, types.Types[types.TBOOL])
        case ir.OCOMPLEX:
                n := n.(*ir.BinaryExpr)
                r := s.expr(n.X)
                i := s.expr(n.Y)
                return s.newValue2(ssa.OpComplexMake, n.Type(), r, i)

        // unary ops
        case ir.ONEG:
                n := n.(*ir.UnaryExpr)
                a := s.expr(n.X)
                if n.Type().IsComplex() {
                        tp := types.FloatForComplex(n.Type())
                        negop := s.ssaOp(n.Op(), tp)
                        return s.newValue2(ssa.OpComplexMake, n.Type(),
                                s.newValue1(negop, tp, s.newValue1(ssa.OpComplexReal, tp, a)),
                                s.newValue1(negop, tp, s.newValue1(ssa.OpComplexImag, tp, a)))
                }
                return s.newValue1(s.ssaOp(n.Op(), n.Type()), a.Type, a)
        case ir.ONOT, ir.OBITNOT:
                n := n.(*ir.UnaryExpr)
                a := s.expr(n.X)
                return s.newValue1(s.ssaOp(n.Op(), n.Type()), a.Type, a)
        case ir.OIMAG, ir.OREAL:
                n := n.(*ir.UnaryExpr)
                a := s.expr(n.X)
                return s.newValue1(s.ssaOp(n.Op(), n.X.Type()), n.Type(), a)
        case ir.OPLUS:
                n := n.(*ir.UnaryExpr)
                return s.expr(n.X)

        case ir.OADDR:
                n := n.(*ir.AddrExpr)
                return s.addr(n.X)

        case ir.ORESULT:
                n := n.(*ir.ResultExpr)
                if s.prevCall == nil || s.prevCall.Op != ssa.OpStaticLECall && s.prevCall.Op != ssa.OpInterLECall && s.prevCall.Op != ssa.OpClosureLECall {
                        panic("Expected to see a previous call")
                }
                which := n.Index
                if which == -1 {
                        panic(fmt.Errorf("ORESULT %v does not match call %s", n, s.prevCall))
                }
                return s.resultOfCall(s.prevCall, which, n.Type())

        case ir.ODEREF:
                n := n.(*ir.StarExpr)
                p := s.exprPtr(n.X, n.Bounded(), n.Pos())
                return s.load(n.Type(), p)

        case ir.ODOT:
                n := n.(*ir.SelectorExpr)
                if n.X.Op() == ir.OSTRUCTLIT {
                        // All literals with nonzero fields have already been
                        // rewritten during walk. Any that remain are just T{}
                        // or equivalents. Use the zero value.
                        if !ir.IsZero(n.X) {
                                s.Fatalf("literal with nonzero value in SSA: %v", n.X)
                        }
                        return s.zeroVal(n.Type())
                }
                // If n is addressable and can't be represented in
                // SSA, then load just the selected field. This
                // prevents false memory dependencies in race/msan/asan
                // instrumentation.
                if ir.IsAddressable(n) && !s.canSSA(n) {
                        p := s.addr(n)
                        return s.load(n.Type(), p)
                }
                v := s.expr(n.X)
                return s.newValue1I(ssa.OpStructSelect, n.Type(), int64(fieldIdx(n)), v)

        case ir.ODOTPTR:
                n := n.(*ir.SelectorExpr)
                p := s.exprPtr(n.X, n.Bounded(), n.Pos())
                p = s.newValue1I(ssa.OpOffPtr, types.NewPtr(n.Type()), n.Offset(), p)
                return s.load(n.Type(), p)

        case ir.OINDEX:
                n := n.(*ir.IndexExpr)
                switch {
                case n.X.Type().IsString():
                        if n.Bounded() && ir.IsConst(n.X, constant.String) && ir.IsConst(n.Index, constant.Int) {
                                // Replace "abc"[1] with 'b'.
                                // Delayed until now because "abc"[1] is not an ideal constant.
                                // See test/fixedbugs/issue11370.go.
                                return s.newValue0I(ssa.OpConst8, types.Types[types.TUINT8], int64(int8(ir.StringVal(n.X)[ir.Int64Val(n.Index)])))
                        }
                        a := s.expr(n.X)
                        i := s.expr(n.Index)
                        len := s.newValue1(ssa.OpStringLen, types.Types[types.TINT], a)
                        i = s.boundsCheck(i, len, ssa.BoundsIndex, n.Bounded())
                        ptrtyp := s.f.Config.Types.BytePtr
                        ptr := s.newValue1(ssa.OpStringPtr, ptrtyp, a)
                        if ir.IsConst(n.Index, constant.Int) {
                                ptr = s.newValue1I(ssa.OpOffPtr, ptrtyp, ir.Int64Val(n.Index), ptr)
                        } else {
                                ptr = s.newValue2(ssa.OpAddPtr, ptrtyp, ptr, i)
                        }
                        return s.load(types.Types[types.TUINT8], ptr)
                case n.X.Type().IsSlice():
                        p := s.addr(n)
                        return s.load(n.X.Type().Elem(), p)
                case n.X.Type().IsArray():
                        if TypeOK(n.X.Type()) {
                                // SSA can handle arrays of length at most 1.
                                bound := n.X.Type().NumElem()
                                a := s.expr(n.X)
                                i := s.expr(n.Index)
                                if bound == 0 {
                                        // Bounds check will never succeed.  Might as well
                                        // use constants for the bounds check.
                                        z := s.constInt(types.Types[types.TINT], 0)
                                        s.boundsCheck(z, z, ssa.BoundsIndex, false)
                                        // The return value won't be live, return junk.
                                        // But not quite junk, in case bounds checks are turned off. See issue 48092.
                                        return s.zeroVal(n.Type())
                                }
                                len := s.constInt(types.Types[types.TINT], bound)
                                s.boundsCheck(i, len, ssa.BoundsIndex, n.Bounded()) // checks i == 0
                                return s.newValue1I(ssa.OpArraySelect, n.Type(), 0, a)
                        }
                        p := s.addr(n)
                        return s.load(n.X.Type().Elem(), p)
                default:
                        s.Fatalf("bad type for index %v", n.X.Type())
                        return nil
                }

        case ir.OLEN, ir.OCAP:
                n := n.(*ir.UnaryExpr)
                switch {
                case n.X.Type().IsSlice():
                        op := ssa.OpSliceLen
                        if n.Op() == ir.OCAP {
                                op = ssa.OpSliceCap
                        }
                        return s.newValue1(op, types.Types[types.TINT], s.expr(n.X))
                case n.X.Type().IsString(): // string; not reachable for OCAP
                        return s.newValue1(ssa.OpStringLen, types.Types[types.TINT], s.expr(n.X))
                case n.X.Type().IsMap(), n.X.Type().IsChan():
                        return s.referenceTypeBuiltin(n, s.expr(n.X))
                default: // array
                        return s.constInt(types.Types[types.TINT], n.X.Type().NumElem())
                }

        case ir.OSPTR:
                n := n.(*ir.UnaryExpr)
                a := s.expr(n.X)
                if n.X.Type().IsSlice() {
                        if n.Bounded() {
                                return s.newValue1(ssa.OpSlicePtr, n.Type(), a)
                        }
                        return s.newValue1(ssa.OpSlicePtrUnchecked, n.Type(), a)
                } else {
                        return s.newValue1(ssa.OpStringPtr, n.Type(), a)
                }

        case ir.OITAB:
                n := n.(*ir.UnaryExpr)
                a := s.expr(n.X)
                return s.newValue1(ssa.OpITab, n.Type(), a)

        case ir.OIDATA:
                n := n.(*ir.UnaryExpr)
                a := s.expr(n.X)
                return s.newValue1(ssa.OpIData, n.Type(), a)

        case ir.OEFACE:
                n := n.(*ir.BinaryExpr)
                tab := s.expr(n.X)
                data := s.expr(n.Y)
                return s.newValue2(ssa.OpIMake, n.Type(), tab, data)

        case ir.OSLICEHEADER:
                n := n.(*ir.SliceHeaderExpr)
                p := s.expr(n.Ptr)
                l := s.expr(n.Len)
                c := s.expr(n.Cap)
                return s.newValue3(ssa.OpSliceMake, n.Type(), p, l, c)

        case ir.OSTRINGHEADER:
                n := n.(*ir.StringHeaderExpr)
                p := s.expr(n.Ptr)
                l := s.expr(n.Len)
                return s.newValue2(ssa.OpStringMake, n.Type(), p, l)

        case ir.OSLICE, ir.OSLICEARR, ir.OSLICE3, ir.OSLICE3ARR:
                n := n.(*ir.SliceExpr)
                check := s.checkPtrEnabled && n.Op() == ir.OSLICE3ARR && n.X.Op() == ir.OCONVNOP && n.X.(*ir.ConvExpr).X.Type().IsUnsafePtr()
                v := s.exprCheckPtr(n.X, !check)
                var i, j, k *ssa.Value
                if n.Low != nil {
                        i = s.expr(n.Low)
                }
                if n.High != nil {
                        j = s.expr(n.High)
                }
                if n.Max != nil {
                        k = s.expr(n.Max)
                }
                p, l, c := s.slice(v, i, j, k, n.Bounded())
                if check {
                        // Emit checkptr instrumentation after bound check to prevent false positive, see #46938.
                        s.checkPtrAlignment(n.X.(*ir.ConvExpr), v, s.conv(n.Max, k, k.Type, types.Types[types.TUINTPTR]))
                }
                return s.newValue3(ssa.OpSliceMake, n.Type(), p, l, c)

        case ir.OSLICESTR:
                n := n.(*ir.SliceExpr)
                v := s.expr(n.X)
                var i, j *ssa.Value
                if n.Low != nil {
                        i = s.expr(n.Low)
                }
                if n.High != nil {
                        j = s.expr(n.High)
                }
                p, l, _ := s.slice(v, i, j, nil, n.Bounded())
                return s.newValue2(ssa.OpStringMake, n.Type(), p, l)

        case ir.OSLICE2ARRPTR:
                // if arrlen > slice.len {
                //   panic(...)
                // }
                // slice.ptr
                n := n.(*ir.ConvExpr)
                v := s.expr(n.X)
                nelem := n.Type().Elem().NumElem()
                arrlen := s.constInt(types.Types[types.TINT], nelem)
                cap := s.newValue1(ssa.OpSliceLen, types.Types[types.TINT], v)
                s.boundsCheck(arrlen, cap, ssa.BoundsConvert, false)
                op := ssa.OpSlicePtr
                if nelem == 0 {
                        op = ssa.OpSlicePtrUnchecked
                }
                return s.newValue1(op, n.Type(), v)

        case ir.OCALLFUNC:
                n := n.(*ir.CallExpr)
                if ir.IsIntrinsicCall(n) {
                        return s.intrinsicCall(n)
                }
                fallthrough

        case ir.OCALLINTER:
                n := n.(*ir.CallExpr)
                return s.callResult(n, callNormal)

        case ir.OGETG:
                n := n.(*ir.CallExpr)
                return s.newValue1(ssa.OpGetG, n.Type(), s.mem())

        case ir.OGETCALLERPC:
                n := n.(*ir.CallExpr)
                return s.newValue0(ssa.OpGetCallerPC, n.Type())

        case ir.OGETCALLERSP:
                n := n.(*ir.CallExpr)
                return s.newValue1(ssa.OpGetCallerSP, n.Type(), s.mem())

        case ir.OAPPEND:
                return s.append(n.(*ir.CallExpr), false)

        case ir.OMIN, ir.OMAX:
                return s.minMax(n.(*ir.CallExpr))

        case ir.OSTRUCTLIT, ir.OARRAYLIT:
                // All literals with nonzero fields have already been
                // rewritten during walk. Any that remain are just T{}
                // or equivalents. Use the zero value.
                n := n.(*ir.CompLitExpr)
                if !ir.IsZero(n) {
                        s.Fatalf("literal with nonzero value in SSA: %v", n)
                }
                return s.zeroVal(n.Type())

        case ir.ONEW:
                n := n.(*ir.UnaryExpr)
                var rtype *ssa.Value
                if x, ok := n.X.(*ir.DynamicType); ok && x.Op() == ir.ODYNAMICTYPE {
                        rtype = s.expr(x.RType)
                }
                return s.newObject(n.Type().Elem(), rtype)

        case ir.OUNSAFEADD:
                n := n.(*ir.BinaryExpr)
                ptr := s.expr(n.X)
                len := s.expr(n.Y)

                // Force len to uintptr to prevent misuse of garbage bits in the
                // upper part of the register (#48536).
                len = s.conv(n, len, len.Type, types.Types[types.TUINTPTR])

                return s.newValue2(ssa.OpAddPtr, n.Type(), ptr, len)

        default:
                s.Fatalf("unhandled expr %v", n.Op())
                return nil
        }
}

func (s *state) resultOfCall(c *ssa.Value, which int64, t *types.Type) *ssa.Value {
        aux := c.Aux.(*ssa.AuxCall)
        pa := aux.ParamAssignmentForResult(which)
        // TODO(register args) determine if in-memory TypeOK is better loaded early from SelectNAddr or later when SelectN is expanded.
        // SelectN is better for pattern-matching and possible call-aware analysis we might want to do in the future.
        if len(pa.Registers) == 0 && !TypeOK(t) {
                addr := s.newValue1I(ssa.OpSelectNAddr, types.NewPtr(t), which, c)
                return s.rawLoad(t, addr)
        }
        return s.newValue1I(ssa.OpSelectN, t, which, c)
}

func (s *state) resultAddrOfCall(c *ssa.Value, which int64, t *types.Type) *ssa.Value {
        aux := c.Aux.(*ssa.AuxCall)
        pa := aux.ParamAssignmentForResult(which)
        if len(pa.Registers) == 0 {
                return s.newValue1I(ssa.OpSelectNAddr, types.NewPtr(t), which, c)
        }
        _, addr := s.temp(c.Pos, t)
        rval := s.newValue1I(ssa.OpSelectN, t, which, c)
        s.vars[memVar] = s.newValue3Apos(ssa.OpStore, types.TypeMem, t, addr, rval, s.mem(), false)
        return addr
}

// append converts an OAPPEND node to SSA.
// If inplace is false, it converts the OAPPEND expression n to an ssa.Value,
// adds it to s, and returns the Value.
// If inplace is true, it writes the result of the OAPPEND expression n
// back to the slice being appended to, and returns nil.
// inplace MUST be set to false if the slice can be SSA'd.
// Note: this code only handles fixed-count appends. Dotdotdot appends
// have already been rewritten at this point (by walk).
func (s *state) append(n *ir.CallExpr, inplace bool) *ssa.Value {
        // If inplace is false, process as expression "append(s, e1, e2, e3)":
        //
        // ptr, len, cap := s
        // len += 3
        // if uint(len) > uint(cap) {
        //     ptr, len, cap = growslice(ptr, len, cap, 3, typ)
        //     Note that len is unmodified by growslice.
        // }
        // // with write barriers, if needed:
        // *(ptr+(len-3)) = e1
        // *(ptr+(len-2)) = e2
        // *(ptr+(len-1)) = e3
        // return makeslice(ptr, len, cap)
        //
        //
        // If inplace is true, process as statement "s = append(s, e1, e2, e3)":
        //
        // a := &s
        // ptr, len, cap := s
        // len += 3
        // if uint(len) > uint(cap) {
        //    ptr, len, cap = growslice(ptr, len, cap, 3, typ)
        //    vardef(a)    // if necessary, advise liveness we are writing a new a
        //    *a.cap = cap // write before ptr to avoid a spill
        //    *a.ptr = ptr // with write barrier
        // }
        // *a.len = len
        // // with write barriers, if needed:
        // *(ptr+(len-3)) = e1
        // *(ptr+(len-2)) = e2
        // *(ptr+(len-1)) = e3

        et := n.Type().Elem()
        pt := types.NewPtr(et)

        // Evaluate slice
        sn := n.Args[0] // the slice node is the first in the list
        var slice, addr *ssa.Value
        if inplace {
                addr = s.addr(sn)
                slice = s.load(n.Type(), addr)
        } else {
                slice = s.expr(sn)
        }

        // Allocate new blocks
        grow := s.f.NewBlock(ssa.BlockPlain)
        assign := s.f.NewBlock(ssa.BlockPlain)

        // Decomposse input slice.
        p := s.newValue1(ssa.OpSlicePtr, pt, slice)
        l := s.newValue1(ssa.OpSliceLen, types.Types[types.TINT], slice)
        c := s.newValue1(ssa.OpSliceCap, types.Types[types.TINT], slice)

        // Add number of new elements to length.
        nargs := s.constInt(types.Types[types.TINT], int64(len(n.Args)-1))
        l = s.newValue2(s.ssaOp(ir.OADD, types.Types[types.TINT]), types.Types[types.TINT], l, nargs)

        // Decide if we need to grow
        cmp := s.newValue2(s.ssaOp(ir.OLT, types.Types[types.TUINT]), types.Types[types.TBOOL], c, l)

        // Record values of ptr/len/cap before branch.
        s.vars[ptrVar] = p
        s.vars[lenVar] = l
        if !inplace {
                s.vars[capVar] = c
        }

        b := s.endBlock()
        b.Kind = ssa.BlockIf
        b.Likely = ssa.BranchUnlikely
        b.SetControl(cmp)
        b.AddEdgeTo(grow)
        b.AddEdgeTo(assign)

        // Call growslice
        s.startBlock(grow)
        taddr := s.expr(n.X)
        r := s.rtcall(ir.Syms.Growslice, true, []*types.Type{n.Type()}, p, l, c, nargs, taddr)

        // Decompose output slice
        p = s.newValue1(ssa.OpSlicePtr, pt, r[0])
        l = s.newValue1(ssa.OpSliceLen, types.Types[types.TINT], r[0])
        c = s.newValue1(ssa.OpSliceCap, types.Types[types.TINT], r[0])

        s.vars[ptrVar] = p
        s.vars[lenVar] = l
        s.vars[capVar] = c
        if inplace {
                if sn.Op() == ir.ONAME {
                        sn := sn.(*ir.Name)
                        if sn.Class != ir.PEXTERN {
                                // Tell liveness we're about to build a new slice
                                s.vars[memVar] = s.newValue1A(ssa.OpVarDef, types.TypeMem, sn, s.mem())
                        }
                }
                capaddr := s.newValue1I(ssa.OpOffPtr, s.f.Config.Types.IntPtr, types.SliceCapOffset, addr)
                s.store(types.Types[types.TINT], capaddr, c)
                s.store(pt, addr, p)
        }

        b = s.endBlock()
        b.AddEdgeTo(assign)

        // assign new elements to slots
        s.startBlock(assign)
        p = s.variable(ptrVar, pt)                      // generates phi for ptr
        l = s.variable(lenVar, types.Types[types.TINT]) // generates phi for len
        if !inplace {
                c = s.variable(capVar, types.Types[types.TINT]) // generates phi for cap
        }

        if inplace {
                // Update length in place.
                // We have to wait until here to make sure growslice succeeded.
                lenaddr := s.newValue1I(ssa.OpOffPtr, s.f.Config.Types.IntPtr, types.SliceLenOffset, addr)
                s.store(types.Types[types.TINT], lenaddr, l)
        }

        // Evaluate args
        type argRec struct {
                // if store is true, we're appending the value v.  If false, we're appending the
                // value at *v.
                v     *ssa.Value
                store bool
        }
        args := make([]argRec, 0, len(n.Args[1:]))
        for _, n := range n.Args[1:] {
                if TypeOK(n.Type()) {
                        args = append(args, argRec{v: s.expr(n), store: true})
                } else {
                        v := s.addr(n)
                        args = append(args, argRec{v: v})
                }
        }

        // Write args into slice.
        oldLen := s.newValue2(s.ssaOp(ir.OSUB, types.Types[types.TINT]), types.Types[types.TINT], l, nargs)
        p2 := s.newValue2(ssa.OpPtrIndex, pt, p, oldLen)
        for i, arg := range args {
                addr := s.newValue2(ssa.OpPtrIndex, pt, p2, s.constInt(types.Types[types.TINT], int64(i)))
                if arg.store {
                        s.storeType(et, addr, arg.v, 0, true)
                } else {
                        s.move(et, addr, arg.v)
                }
        }

        // The following deletions have no practical effect at this time
        // because state.vars has been reset by the preceding state.startBlock.
        // They only enforce the fact that these variables are no longer need in
        // the current scope.
        delete(s.vars, ptrVar)
        delete(s.vars, lenVar)
        if !inplace {
                delete(s.vars, capVar)
        }

        // make result
        if inplace {
                return nil
        }
        return s.newValue3(ssa.OpSliceMake, n.Type(), p, l, c)
}

// minMax converts an OMIN/OMAX builtin call into SSA.
func (s *state) minMax(n *ir.CallExpr) *ssa.Value {
        // The OMIN/OMAX builtin is variadic, but its semantics are
        // equivalent to left-folding a binary min/max operation across the
        // arguments list.
        fold := func(op func(x, a *ssa.Value) *ssa.Value) *ssa.Value {
                x := s.expr(n.Args[0])
                for _, arg := range n.Args[1:] {
                        x = op(x, s.expr(arg))
                }
                return x
        }

        typ := n.Type()

        if typ.IsFloat() || typ.IsString() {
                // min/max semantics for floats are tricky because of NaNs and
                // negative zero. Some architectures have instructions which
                // we can use to generate the right result. For others we must
                // call into the runtime instead.
                //
                // Strings are conceptually simpler, but we currently desugar
                // string comparisons during walk, not ssagen.

                if typ.IsFloat() {
                        switch Arch.LinkArch.Family {
                        case sys.AMD64, sys.ARM64:
                                var op ssa.Op
                                switch {
                                case typ.Kind() == types.TFLOAT64 && n.Op() == ir.OMIN:
                                        op = ssa.OpMin64F
                                case typ.Kind() == types.TFLOAT64 && n.Op() == ir.OMAX:
                                        op = ssa.OpMax64F
                                case typ.Kind() == types.TFLOAT32 && n.Op() == ir.OMIN:
                                        op = ssa.OpMin32F
                                case typ.Kind() == types.TFLOAT32 && n.Op() == ir.OMAX:
                                        op = ssa.OpMax32F
                                }
                                return fold(func(x, a *ssa.Value) *ssa.Value {
                                        return s.newValue2(op, typ, x, a)
                                })
                        }
                }
                var name string
                switch typ.Kind() {
                case types.TFLOAT32:
                        switch n.Op() {
                        case ir.OMIN:
                                name = "fmin32"
                        case ir.OMAX:
                                name = "fmax32"
                        }
                case types.TFLOAT64:
                        switch n.Op() {
                        case ir.OMIN:
                                name = "fmin64"
                        case ir.OMAX:
                                name = "fmax64"
                        }
                case types.TSTRING:
                        switch n.Op() {
                        case ir.OMIN:
                                name = "strmin"
                        case ir.OMAX:
                                name = "strmax"
                        }
                }
                fn := typecheck.LookupRuntimeFunc(name)

                return fold(func(x, a *ssa.Value) *ssa.Value {
                        return s.rtcall(fn, true, []*types.Type{typ}, x, a)[0]
                })
        }

        lt := s.ssaOp(ir.OLT, typ)

        return fold(func(x, a *ssa.Value) *ssa.Value {
                switch n.Op() {
                case ir.OMIN:
                        // a < x ? a : x
                        return s.ternary(s.newValue2(lt, types.Types[types.TBOOL], a, x), a, x)
                case ir.OMAX:
                        // x < a ? a : x
                        return s.ternary(s.newValue2(lt, types.Types[types.TBOOL], x, a), a, x)
                }
                panic("unreachable")
        })
}

// ternary emits code to evaluate cond ? x : y.
func (s *state) ternary(cond, x, y *ssa.Value) *ssa.Value {
        // Note that we need a new ternaryVar each time (unlike okVar where we can
        // reuse the variable) because it might have a different type every time.
        ternaryVar := ssaMarker("ternary")

        bThen := s.f.NewBlock(ssa.BlockPlain)
        bElse := s.f.NewBlock(ssa.BlockPlain)
        bEnd := s.f.NewBlock(ssa.BlockPlain)

        b := s.endBlock()
        b.Kind = ssa.BlockIf
        b.SetControl(cond)
        b.AddEdgeTo(bThen)
        b.AddEdgeTo(bElse)

        s.startBlock(bThen)
        s.vars[ternaryVar] = x
        s.endBlock().AddEdgeTo(bEnd)

        s.startBlock(bElse)
        s.vars[ternaryVar] = y
        s.endBlock().AddEdgeTo(bEnd)

        s.startBlock(bEnd)
        r := s.variable(ternaryVar, x.Type)
        delete(s.vars, ternaryVar)
        return r
}

// condBranch evaluates the boolean expression cond and branches to yes
// if cond is true and no if cond is false.
// This function is intended to handle && and || better than just calling
// s.expr(cond) and branching on the result.
func (s *state) condBranch(cond ir.Node, yes, no *ssa.Block, likely int8) {
        switch cond.Op() {
        case ir.OANDAND:
                cond := cond.(*ir.LogicalExpr)
                mid := s.f.NewBlock(ssa.BlockPlain)
                s.stmtList(cond.Init())
                s.condBranch(cond.X, mid, no, max8(likely, 0))
                s.startBlock(mid)
                s.condBranch(cond.Y, yes, no, likely)
                return
                // Note: if likely==1, then both recursive calls pass 1.
                // If likely==-1, then we don't have enough information to decide
                // whether the first branch is likely or not. So we pass 0 for
                // the likeliness of the first branch.
                // TODO: have the frontend give us branch prediction hints for
                // OANDAND and OOROR nodes (if it ever has such info).
        case ir.OOROR:
                cond := cond.(*ir.LogicalExpr)
                mid := s.f.NewBlock(ssa.BlockPlain)
                s.stmtList(cond.Init())
                s.condBranch(cond.X, yes, mid, min8(likely, 0))
                s.startBlock(mid)
                s.condBranch(cond.Y, yes, no, likely)
                return
                // Note: if likely==-1, then both recursive calls pass -1.
                // If likely==1, then we don't have enough info to decide
                // the likelihood of the first branch.
        case ir.ONOT:
                cond := cond.(*ir.UnaryExpr)
                s.stmtList(cond.Init())
                s.condBranch(cond.X, no, yes, -likely)
                return
        case ir.OCONVNOP:
                cond := cond.(*ir.ConvExpr)
                s.stmtList(cond.Init())
                s.condBranch(cond.X, yes, no, likely)
                return
        }
        c := s.expr(cond)
        b := s.endBlock()
        b.Kind = ssa.BlockIf
        b.SetControl(c)
        b.Likely = ssa.BranchPrediction(likely) // gc and ssa both use -1/0/+1 for likeliness
        b.AddEdgeTo(yes)
        b.AddEdgeTo(no)
}

type skipMask uint8

const (
        skipPtr skipMask = 1 << iota
        skipLen
        skipCap
)

// assign does left = right.
// Right has already been evaluated to ssa, left has not.
// If deref is true, then we do left = *right instead (and right has already been nil-checked).
// If deref is true and right == nil, just do left = 0.
// skip indicates assignments (at the top level) that can be avoided.
// mayOverlap indicates whether left&right might partially overlap in memory. Default is false.
func (s *state) assign(left ir.Node, right *ssa.Value, deref bool, skip skipMask) {
        s.assignWhichMayOverlap(left, right, deref, skip, false)
}
func (s *state) assignWhichMayOverlap(left ir.Node, right *ssa.Value, deref bool, skip skipMask, mayOverlap bool) {
        if left.Op() == ir.ONAME && ir.IsBlank(left) {
                return
        }
        t := left.Type()
        types.CalcSize(t)
        if s.canSSA(left) {
                if deref {
                        s.Fatalf("can SSA LHS %v but not RHS %s", left, right)
                }
                if left.Op() == ir.ODOT {
                        // We're assigning to a field of an ssa-able value.
                        // We need to build a new structure with the new value for the
                        // field we're assigning and the old values for the other fields.
                        // For instance:
                        //   type T struct {a, b, c int}
                        //   var T x
                        //   x.b = 5
                        // For the x.b = 5 assignment we want to generate x = T{x.a, 5, x.c}

                        // Grab information about the structure type.
                        left := left.(*ir.SelectorExpr)
                        t := left.X.Type()
                        nf := t.NumFields()
                        idx := fieldIdx(left)

                        // Grab old value of structure.
                        old := s.expr(left.X)

                        // Make new structure.
                        new := s.newValue0(ssa.StructMakeOp(t.NumFields()), t)

                        // Add fields as args.
                        for i := 0; i < nf; i++ {
                                if i == idx {
                                        new.AddArg(right)
                                } else {
                                        new.AddArg(s.newValue1I(ssa.OpStructSelect, t.FieldType(i), int64(i), old))
                                }
                        }

                        // Recursively assign the new value we've made to the base of the dot op.
                        s.assign(left.X, new, false, 0)
                        // TODO: do we need to update named values here?
                        return
                }
                if left.Op() == ir.OINDEX && left.(*ir.IndexExpr).X.Type().IsArray() {
                        left := left.(*ir.IndexExpr)
                        s.pushLine(left.Pos())
                        defer s.popLine()
                        // We're assigning to an element of an ssa-able array.
                        // a[i] = v
                        t := left.X.Type()
                        n := t.NumElem()

                        i := s.expr(left.Index) // index
                        if n == 0 {
                                // The bounds check must fail.  Might as well
                                // ignore the actual index and just use zeros.
                                z := s.constInt(types.Types[types.TINT], 0)
                                s.boundsCheck(z, z, ssa.BoundsIndex, false)
                                return
                        }
                        if n != 1 {
                                s.Fatalf("assigning to non-1-length array")
                        }
                        // Rewrite to a = [1]{v}
                        len := s.constInt(types.Types[types.TINT], 1)
                        s.boundsCheck(i, len, ssa.BoundsIndex, false) // checks i == 0
                        v := s.newValue1(ssa.OpArrayMake1, t, right)
                        s.assign(left.X, v, false, 0)
                        return
                }
                left := left.(*ir.Name)
                // Update variable assignment.
                s.vars[left] = right
                s.addNamedValue(left, right)
                return
        }

        // If this assignment clobbers an entire local variable, then emit
        // OpVarDef so liveness analysis knows the variable is redefined.
        if base, ok := clobberBase(left).(*ir.Name); ok && base.OnStack() && skip == 0 && t.HasPointers() {
                s.vars[memVar] = s.newValue1Apos(ssa.OpVarDef, types.TypeMem, base, s.mem(), !ir.IsAutoTmp(base))
        }

        // Left is not ssa-able. Compute its address.
        addr := s.addr(left)
        if ir.IsReflectHeaderDataField(left) {
                // Package unsafe's documentation says storing pointers into
                // reflect.SliceHeader and reflect.StringHeader's Data fields
                // is valid, even though they have type uintptr (#19168).
                // Mark it pointer type to signal the writebarrier pass to
                // insert a write barrier.
                t = types.Types[types.TUNSAFEPTR]
        }
        if deref {
                // Treat as a mem->mem move.
                if right == nil {
                        s.zero(t, addr)
                } else {
                        s.moveWhichMayOverlap(t, addr, right, mayOverlap)
                }
                return
        }
        // Treat as a store.
        s.storeType(t, addr, right, skip, !ir.IsAutoTmp(left))
}

// zeroVal returns the zero value for type t.
func (s *state) zeroVal(t *types.Type) *ssa.Value {
        switch {
        case t.IsInteger():
                switch t.Size() {
                case 1:
                        return s.constInt8(t, 0)
                case 2:
                        return s.constInt16(t, 0)
                case 4:
                        return s.constInt32(t, 0)
                case 8:
                        return s.constInt64(t, 0)
                default:
                        s.Fatalf("bad sized integer type %v", t)
                }
        case t.IsFloat():
                switch t.Size() {
                case 4:
                        return s.constFloat32(t, 0)
                case 8:
                        return s.constFloat64(t, 0)
                default:
                        s.Fatalf("bad sized float type %v", t)
                }
        case t.IsComplex():
                switch t.Size() {
                case 8:
                        z := s.constFloat32(types.Types[types.TFLOAT32], 0)
                        return s.entryNewValue2(ssa.OpComplexMake, t, z, z)
                case 16:
                        z := s.constFloat64(types.Types[types.TFLOAT64], 0)
                        return s.entryNewValue2(ssa.OpComplexMake, t, z, z)
                default:
                        s.Fatalf("bad sized complex type %v", t)
                }

        case t.IsString():
                return s.constEmptyString(t)
        case t.IsPtrShaped():
                return s.constNil(t)
        case t.IsBoolean():
                return s.constBool(false)
        case t.IsInterface():
                return s.constInterface(t)
        case t.IsSlice():
                return s.constSlice(t)
        case t.IsStruct():
                n := t.NumFields()
                v := s.entryNewValue0(ssa.StructMakeOp(t.NumFields()), t)
                for i := 0; i < n; i++ {
                        v.AddArg(s.zeroVal(t.FieldType(i)))
                }
                return v
        case t.IsArray():
                switch t.NumElem() {
                case 0:
                        return s.entryNewValue0(ssa.OpArrayMake0, t)
                case 1:
                        return s.entryNewValue1(ssa.OpArrayMake1, t, s.zeroVal(t.Elem()))
                }
        }
        s.Fatalf("zero for type %v not implemented", t)
        return nil
}

type callKind int8

const (
        callNormal callKind = iota
        callDefer
        callDeferStack
        callGo
        callTail
)

type sfRtCallDef struct {
        rtfn  *obj.LSym
        rtype types.Kind
}

var softFloatOps map[ssa.Op]sfRtCallDef

func softfloatInit() {
        // Some of these operations get transformed by sfcall.
        softFloatOps = map[ssa.Op]sfRtCallDef{
                ssa.OpAdd32F: {typecheck.LookupRuntimeFunc("fadd32"), types.TFLOAT32},
                ssa.OpAdd64F: {typecheck.LookupRuntimeFunc("fadd64"), types.TFLOAT64},
                ssa.OpSub32F: {typecheck.LookupRuntimeFunc("fadd32"), types.TFLOAT32},
                ssa.OpSub64F: {typecheck.LookupRuntimeFunc("fadd64"), types.TFLOAT64},
                ssa.OpMul32F: {typecheck.LookupRuntimeFunc("fmul32"), types.TFLOAT32},
                ssa.OpMul64F: {typecheck.LookupRuntimeFunc("fmul64"), types.TFLOAT64},
                ssa.OpDiv32F: {typecheck.LookupRuntimeFunc("fdiv32"), types.TFLOAT32},
                ssa.OpDiv64F: {typecheck.LookupRuntimeFunc("fdiv64"), types.TFLOAT64},

                ssa.OpEq64F:   {typecheck.LookupRuntimeFunc("feq64"), types.TBOOL},
                ssa.OpEq32F:   {typecheck.LookupRuntimeFunc("feq32"), types.TBOOL},
                ssa.OpNeq64F:  {typecheck.LookupRuntimeFunc("feq64"), types.TBOOL},
                ssa.OpNeq32F:  {typecheck.LookupRuntimeFunc("feq32"), types.TBOOL},
                ssa.OpLess64F: {typecheck.LookupRuntimeFunc("fgt64"), types.TBOOL},
                ssa.OpLess32F: {typecheck.LookupRuntimeFunc("fgt32"), types.TBOOL},
                ssa.OpLeq64F:  {typecheck.LookupRuntimeFunc("fge64"), types.TBOOL},
                ssa.OpLeq32F:  {typecheck.LookupRuntimeFunc("fge32"), types.TBOOL},

                ssa.OpCvt32to32F:  {typecheck.LookupRuntimeFunc("fint32to32"), types.TFLOAT32},
                ssa.OpCvt32Fto32:  {typecheck.LookupRuntimeFunc("f32toint32"), types.TINT32},
                ssa.OpCvt64to32F:  {typecheck.LookupRuntimeFunc("fint64to32"), types.TFLOAT32},
                ssa.OpCvt32Fto64:  {typecheck.LookupRuntimeFunc("f32toint64"), types.TINT64},
                ssa.OpCvt64Uto32F: {typecheck.LookupRuntimeFunc("fuint64to32"), types.TFLOAT32},
                ssa.OpCvt32Fto64U: {typecheck.LookupRuntimeFunc("f32touint64"), types.TUINT64},
                ssa.OpCvt32to64F:  {typecheck.LookupRuntimeFunc("fint32to64"), types.TFLOAT64},
                ssa.OpCvt64Fto32:  {typecheck.LookupRuntimeFunc("f64toint32"), types.TINT32},
                ssa.OpCvt64to64F:  {typecheck.LookupRuntimeFunc("fint64to64"), types.TFLOAT64},
                ssa.OpCvt64Fto64:  {typecheck.LookupRuntimeFunc("f64toint64"), types.TINT64},
                ssa.OpCvt64Uto64F: {typecheck.LookupRuntimeFunc("fuint64to64"), types.TFLOAT64},
                ssa.OpCvt64Fto64U: {typecheck.LookupRuntimeFunc("f64touint64"), types.TUINT64},
                ssa.OpCvt32Fto64F: {typecheck.LookupRuntimeFunc("f32to64"), types.TFLOAT64},
                ssa.OpCvt64Fto32F: {typecheck.LookupRuntimeFunc("f64to32"), types.TFLOAT32},
        }
}

// TODO: do not emit sfcall if operation can be optimized to constant in later
// opt phase
func (s *state) sfcall(op ssa.Op, args ...*ssa.Value) (*ssa.Value, bool) {
        f2i := func(t *types.Type) *types.Type {
                switch t.Kind() {
                case types.TFLOAT32:
                        return types.Types[types.TUINT32]
                case types.TFLOAT64:
                        return types.Types[types.TUINT64]
                }
                return t
        }

        if callDef, ok := softFloatOps[op]; ok {
                switch op {
                case ssa.OpLess32F,
                        ssa.OpLess64F,
                        ssa.OpLeq32F,
                        ssa.OpLeq64F:
                        args[0], args[1] = args[1], args[0]
                case ssa.OpSub32F,
                        ssa.OpSub64F:
                        args[1] = s.newValue1(s.ssaOp(ir.ONEG, types.Types[callDef.rtype]), args[1].Type, args[1])
                }

                // runtime functions take uints for floats and returns uints.
                // Convert to uints so we use the right calling convention.
                for i, a := range args {
                        if a.Type.IsFloat() {
                                args[i] = s.newValue1(ssa.OpCopy, f2i(a.Type), a)
                        }
                }

                rt := types.Types[callDef.rtype]
                result := s.rtcall(callDef.rtfn, true, []*types.Type{f2i(rt)}, args...)[0]
                if rt.IsFloat() {
                        result = s.newValue1(ssa.OpCopy, rt, result)
                }
                if op == ssa.OpNeq32F || op == ssa.OpNeq64F {
                        result = s.newValue1(ssa.OpNot, result.Type, result)
                }
                return result, true
        }
        return nil, false
}

var intrinsics map[intrinsicKey]intrinsicBuilder

// An intrinsicBuilder converts a call node n into an ssa value that
// implements that call as an intrinsic. args is a list of arguments to the func.
type intrinsicBuilder func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value

type intrinsicKey struct {
        arch *sys.Arch
        pkg  string
        fn   string
}

func InitTables() {
        intrinsics = map[intrinsicKey]intrinsicBuilder{}

        var all []*sys.Arch
        var p4 []*sys.Arch
        var p8 []*sys.Arch
        var lwatomics []*sys.Arch
        for _, a := range &sys.Archs {
                all = append(all, a)
                if a.PtrSize == 4 {
                        p4 = append(p4, a)
                } else {
                        p8 = append(p8, a)
                }
                if a.Family != sys.PPC64 {
                        lwatomics = append(lwatomics, a)
                }
        }

        // add adds the intrinsic b for pkg.fn for the given list of architectures.
        add := func(pkg, fn string, b intrinsicBuilder, archs ...*sys.Arch) {
                for _, a := range archs {
                        intrinsics[intrinsicKey{a, pkg, fn}] = b
                }
        }
        // addF does the same as add but operates on architecture families.
        addF := func(pkg, fn string, b intrinsicBuilder, archFamilies ...sys.ArchFamily) {
                m := 0
                for _, f := range archFamilies {
                        if f >= 32 {
                                panic("too many architecture families")
                        }
                        m |= 1 << uint(f)
                }
                for _, a := range all {
                        if m>>uint(a.Family)&1 != 0 {
                                intrinsics[intrinsicKey{a, pkg, fn}] = b
                        }
                }
        }
        // alias defines pkg.fn = pkg2.fn2 for all architectures in archs for which pkg2.fn2 exists.
        alias := func(pkg, fn, pkg2, fn2 string, archs ...*sys.Arch) {
                aliased := false
                for _, a := range archs {
                        if b, ok := intrinsics[intrinsicKey{a, pkg2, fn2}]; ok {
                                intrinsics[intrinsicKey{a, pkg, fn}] = b
                                aliased = true
                        }
                }
                if !aliased {
                        panic(fmt.Sprintf("attempted to alias undefined intrinsic: %s.%s", pkg, fn))
                }
        }

        /******** runtime ********/
        if !base.Flag.Cfg.Instrumenting {
                add("runtime", "slicebytetostringtmp",
                        func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                                // Compiler frontend optimizations emit OBYTES2STRTMP nodes
                                // for the backend instead of slicebytetostringtmp calls
                                // when not instrumenting.
                                return s.newValue2(ssa.OpStringMake, n.Type(), args[0], args[1])
                        },
                        all...)
        }
        addF("runtime/internal/math", "MulUintptr",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        if s.config.PtrSize == 4 {
                                return s.newValue2(ssa.OpMul32uover, types.NewTuple(types.Types[types.TUINT], types.Types[types.TUINT]), args[0], args[1])
                        }
                        return s.newValue2(ssa.OpMul64uover, types.NewTuple(types.Types[types.TUINT], types.Types[types.TUINT]), args[0], args[1])
                },
                sys.AMD64, sys.I386, sys.Loong64, sys.MIPS64, sys.RISCV64, sys.ARM64)
        alias("runtime", "mulUintptr", "runtime/internal/math", "MulUintptr", all...)
        add("runtime", "KeepAlive",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        data := s.newValue1(ssa.OpIData, s.f.Config.Types.BytePtr, args[0])
                        s.vars[memVar] = s.newValue2(ssa.OpKeepAlive, types.TypeMem, data, s.mem())
                        return nil
                },
                all...)
        add("runtime", "getclosureptr",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        return s.newValue0(ssa.OpGetClosurePtr, s.f.Config.Types.Uintptr)
                },
                all...)

        add("runtime", "getcallerpc",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        return s.newValue0(ssa.OpGetCallerPC, s.f.Config.Types.Uintptr)
                },
                all...)

        add("runtime", "getcallersp",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        return s.newValue1(ssa.OpGetCallerSP, s.f.Config.Types.Uintptr, s.mem())
                },
                all...)

        addF("runtime", "publicationBarrier",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        s.vars[memVar] = s.newValue1(ssa.OpPubBarrier, types.TypeMem, s.mem())
                        return nil
                },
                sys.ARM64, sys.PPC64)

        brev_arch := []sys.ArchFamily{sys.AMD64, sys.I386, sys.ARM64, sys.ARM, sys.S390X}
        if buildcfg.GOPPC64 >= 10 {
                // Use only on Power10 as the new byte reverse instructions that Power10 provide
                // make it worthwhile as an intrinsic
                brev_arch = append(brev_arch, sys.PPC64)
        }
        /******** runtime/internal/sys ********/
        addF("runtime/internal/sys", "Bswap32",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        return s.newValue1(ssa.OpBswap32, types.Types[types.TUINT32], args[0])
                },
                brev_arch...)
        addF("runtime/internal/sys", "Bswap64",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        return s.newValue1(ssa.OpBswap64, types.Types[types.TUINT64], args[0])
                },
                brev_arch...)

        /****** Prefetch ******/
        makePrefetchFunc := func(op ssa.Op) func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                return func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        s.vars[memVar] = s.newValue2(op, types.TypeMem, args[0], s.mem())
                        return nil
                }
        }

        // Make Prefetch intrinsics for supported platforms
        // On the unsupported platforms stub function will be eliminated
        addF("runtime/internal/sys", "Prefetch", makePrefetchFunc(ssa.OpPrefetchCache),
                sys.AMD64, sys.ARM64, sys.PPC64)
        addF("runtime/internal/sys", "PrefetchStreamed", makePrefetchFunc(ssa.OpPrefetchCacheStreamed),
                sys.AMD64, sys.ARM64, sys.PPC64)

        /******** runtime/internal/atomic ********/
        addF("runtime/internal/atomic", "Load",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        v := s.newValue2(ssa.OpAtomicLoad32, types.NewTuple(types.Types[types.TUINT32], types.TypeMem), args[0], s.mem())
                        s.vars[memVar] = s.newValue1(ssa.OpSelect1, types.TypeMem, v)
                        return s.newValue1(ssa.OpSelect0, types.Types[types.TUINT32], v)
                },
                sys.AMD64, sys.ARM64, sys.Loong64, sys.MIPS, sys.MIPS64, sys.PPC64, sys.RISCV64, sys.S390X)
        addF("runtime/internal/atomic", "Load8",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        v := s.newValue2(ssa.OpAtomicLoad8, types.NewTuple(types.Types[types.TUINT8], types.TypeMem), args[0], s.mem())
                        s.vars[memVar] = s.newValue1(ssa.OpSelect1, types.TypeMem, v)
                        return s.newValue1(ssa.OpSelect0, types.Types[types.TUINT8], v)
                },
                sys.AMD64, sys.ARM64, sys.Loong64, sys.MIPS, sys.MIPS64, sys.PPC64, sys.RISCV64, sys.S390X)
        addF("runtime/internal/atomic", "Load64",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        v := s.newValue2(ssa.OpAtomicLoad64, types.NewTuple(types.Types[types.TUINT64], types.TypeMem), args[0], s.mem())
                        s.vars[memVar] = s.newValue1(ssa.OpSelect1, types.TypeMem, v)
                        return s.newValue1(ssa.OpSelect0, types.Types[types.TUINT64], v)
                },
                sys.AMD64, sys.ARM64, sys.Loong64, sys.MIPS64, sys.PPC64, sys.RISCV64, sys.S390X)
        addF("runtime/internal/atomic", "LoadAcq",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        v := s.newValue2(ssa.OpAtomicLoadAcq32, types.NewTuple(types.Types[types.TUINT32], types.TypeMem), args[0], s.mem())
                        s.vars[memVar] = s.newValue1(ssa.OpSelect1, types.TypeMem, v)
                        return s.newValue1(ssa.OpSelect0, types.Types[types.TUINT32], v)
                },
                sys.PPC64, sys.S390X)
        addF("runtime/internal/atomic", "LoadAcq64",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        v := s.newValue2(ssa.OpAtomicLoadAcq64, types.NewTuple(types.Types[types.TUINT64], types.TypeMem), args[0], s.mem())
                        s.vars[memVar] = s.newValue1(ssa.OpSelect1, types.TypeMem, v)
                        return s.newValue1(ssa.OpSelect0, types.Types[types.TUINT64], v)
                },
                sys.PPC64)
        addF("runtime/internal/atomic", "Loadp",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        v := s.newValue2(ssa.OpAtomicLoadPtr, types.NewTuple(s.f.Config.Types.BytePtr, types.TypeMem), args[0], s.mem())
                        s.vars[memVar] = s.newValue1(ssa.OpSelect1, types.TypeMem, v)
                        return s.newValue1(ssa.OpSelect0, s.f.Config.Types.BytePtr, v)
                },
                sys.AMD64, sys.ARM64, sys.Loong64, sys.MIPS, sys.MIPS64, sys.PPC64, sys.RISCV64, sys.S390X)

        addF("runtime/internal/atomic", "Store",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        s.vars[memVar] = s.newValue3(ssa.OpAtomicStore32, types.TypeMem, args[0], args[1], s.mem())
                        return nil
                },
                sys.AMD64, sys.ARM64, sys.Loong64, sys.MIPS, sys.MIPS64, sys.PPC64, sys.RISCV64, sys.S390X)
        addF("runtime/internal/atomic", "Store8",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        s.vars[memVar] = s.newValue3(ssa.OpAtomicStore8, types.TypeMem, args[0], args[1], s.mem())
                        return nil
                },
                sys.AMD64, sys.ARM64, sys.Loong64, sys.MIPS, sys.MIPS64, sys.PPC64, sys.RISCV64, sys.S390X)
        addF("runtime/internal/atomic", "Store64",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        s.vars[memVar] = s.newValue3(ssa.OpAtomicStore64, types.TypeMem, args[0], args[1], s.mem())
                        return nil
                },
                sys.AMD64, sys.ARM64, sys.Loong64, sys.MIPS64, sys.PPC64, sys.RISCV64, sys.S390X)
        addF("runtime/internal/atomic", "StorepNoWB",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        s.vars[memVar] = s.newValue3(ssa.OpAtomicStorePtrNoWB, types.TypeMem, args[0], args[1], s.mem())
                        return nil
                },
                sys.AMD64, sys.ARM64, sys.Loong64, sys.MIPS, sys.MIPS64, sys.RISCV64, sys.S390X)
        addF("runtime/internal/atomic", "StoreRel",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        s.vars[memVar] = s.newValue3(ssa.OpAtomicStoreRel32, types.TypeMem, args[0], args[1], s.mem())
                        return nil
                },
                sys.PPC64, sys.S390X)
        addF("runtime/internal/atomic", "StoreRel64",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        s.vars[memVar] = s.newValue3(ssa.OpAtomicStoreRel64, types.TypeMem, args[0], args[1], s.mem())
                        return nil
                },
                sys.PPC64)

        addF("runtime/internal/atomic", "Xchg",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        v := s.newValue3(ssa.OpAtomicExchange32, types.NewTuple(types.Types[types.TUINT32], types.TypeMem), args[0], args[1], s.mem())
                        s.vars[memVar] = s.newValue1(ssa.OpSelect1, types.TypeMem, v)
                        return s.newValue1(ssa.OpSelect0, types.Types[types.TUINT32], v)
                },
                sys.AMD64, sys.Loong64, sys.MIPS, sys.MIPS64, sys.PPC64, sys.RISCV64, sys.S390X)
        addF("runtime/internal/atomic", "Xchg64",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        v := s.newValue3(ssa.OpAtomicExchange64, types.NewTuple(types.Types[types.TUINT64], types.TypeMem), args[0], args[1], s.mem())
                        s.vars[memVar] = s.newValue1(ssa.OpSelect1, types.TypeMem, v)
                        return s.newValue1(ssa.OpSelect0, types.Types[types.TUINT64], v)
                },
                sys.AMD64, sys.Loong64, sys.MIPS64, sys.PPC64, sys.RISCV64, sys.S390X)

        type atomicOpEmitter func(s *state, n *ir.CallExpr, args []*ssa.Value, op ssa.Op, typ types.Kind)

        makeAtomicGuardedIntrinsicARM64 := func(op0, op1 ssa.Op, typ, rtyp types.Kind, emit atomicOpEmitter) intrinsicBuilder {

                return func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        // Target Atomic feature is identified by dynamic detection
                        addr := s.entryNewValue1A(ssa.OpAddr, types.Types[types.TBOOL].PtrTo(), ir.Syms.ARM64HasATOMICS, s.sb)
                        v := s.load(types.Types[types.TBOOL], addr)
                        b := s.endBlock()
                        b.Kind = ssa.BlockIf
                        b.SetControl(v)
                        bTrue := s.f.NewBlock(ssa.BlockPlain)
                        bFalse := s.f.NewBlock(ssa.BlockPlain)
                        bEnd := s.f.NewBlock(ssa.BlockPlain)
                        b.AddEdgeTo(bTrue)
                        b.AddEdgeTo(bFalse)
                        b.Likely = ssa.BranchLikely

                        // We have atomic instructions - use it directly.
                        s.startBlock(bTrue)
                        emit(s, n, args, op1, typ)
                        s.endBlock().AddEdgeTo(bEnd)

                        // Use original instruction sequence.
                        s.startBlock(bFalse)
                        emit(s, n, args, op0, typ)
                        s.endBlock().AddEdgeTo(bEnd)

                        // Merge results.
                        s.startBlock(bEnd)
                        if rtyp == types.TNIL {
                                return nil
                        } else {
                                return s.variable(n, types.Types[rtyp])
                        }
                }
        }

        atomicXchgXaddEmitterARM64 := func(s *state, n *ir.CallExpr, args []*ssa.Value, op ssa.Op, typ types.Kind) {
                v := s.newValue3(op, types.NewTuple(types.Types[typ], types.TypeMem), args[0], args[1], s.mem())
                s.vars[memVar] = s.newValue1(ssa.OpSelect1, types.TypeMem, v)
                s.vars[n] = s.newValue1(ssa.OpSelect0, types.Types[typ], v)
        }
        addF("runtime/internal/atomic", "Xchg",
                makeAtomicGuardedIntrinsicARM64(ssa.OpAtomicExchange32, ssa.OpAtomicExchange32Variant, types.TUINT32, types.TUINT32, atomicXchgXaddEmitterARM64),
                sys.ARM64)
        addF("runtime/internal/atomic", "Xchg64",
                makeAtomicGuardedIntrinsicARM64(ssa.OpAtomicExchange64, ssa.OpAtomicExchange64Variant, types.TUINT64, types.TUINT64, atomicXchgXaddEmitterARM64),
                sys.ARM64)

        addF("runtime/internal/atomic", "Xadd",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        v := s.newValue3(ssa.OpAtomicAdd32, types.NewTuple(types.Types[types.TUINT32], types.TypeMem), args[0], args[1], s.mem())
                        s.vars[memVar] = s.newValue1(ssa.OpSelect1, types.TypeMem, v)
                        return s.newValue1(ssa.OpSelect0, types.Types[types.TUINT32], v)
                },
                sys.AMD64, sys.Loong64, sys.MIPS, sys.MIPS64, sys.PPC64, sys.RISCV64, sys.S390X)
        addF("runtime/internal/atomic", "Xadd64",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        v := s.newValue3(ssa.OpAtomicAdd64, types.NewTuple(types.Types[types.TUINT64], types.TypeMem), args[0], args[1], s.mem())
                        s.vars[memVar] = s.newValue1(ssa.OpSelect1, types.TypeMem, v)
                        return s.newValue1(ssa.OpSelect0, types.Types[types.TUINT64], v)
                },
                sys.AMD64, sys.Loong64, sys.MIPS64, sys.PPC64, sys.RISCV64, sys.S390X)

        addF("runtime/internal/atomic", "Xadd",
                makeAtomicGuardedIntrinsicARM64(ssa.OpAtomicAdd32, ssa.OpAtomicAdd32Variant, types.TUINT32, types.TUINT32, atomicXchgXaddEmitterARM64),
                sys.ARM64)
        addF("runtime/internal/atomic", "Xadd64",
                makeAtomicGuardedIntrinsicARM64(ssa.OpAtomicAdd64, ssa.OpAtomicAdd64Variant, types.TUINT64, types.TUINT64, atomicXchgXaddEmitterARM64),
                sys.ARM64)

        addF("runtime/internal/atomic", "Cas",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        v := s.newValue4(ssa.OpAtomicCompareAndSwap32, types.NewTuple(types.Types[types.TBOOL], types.TypeMem), args[0], args[1], args[2], s.mem())
                        s.vars[memVar] = s.newValue1(ssa.OpSelect1, types.TypeMem, v)
                        return s.newValue1(ssa.OpSelect0, types.Types[types.TBOOL], v)
                },
                sys.AMD64, sys.Loong64, sys.MIPS, sys.MIPS64, sys.PPC64, sys.RISCV64, sys.S390X)
        addF("runtime/internal/atomic", "Cas64",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        v := s.newValue4(ssa.OpAtomicCompareAndSwap64, types.NewTuple(types.Types[types.TBOOL], types.TypeMem), args[0], args[1], args[2], s.mem())
                        s.vars[memVar] = s.newValue1(ssa.OpSelect1, types.TypeMem, v)
                        return s.newValue1(ssa.OpSelect0, types.Types[types.TBOOL], v)
                },
                sys.AMD64, sys.Loong64, sys.MIPS64, sys.PPC64, sys.RISCV64, sys.S390X)
        addF("runtime/internal/atomic", "CasRel",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        v := s.newValue4(ssa.OpAtomicCompareAndSwap32, types.NewTuple(types.Types[types.TBOOL], types.TypeMem), args[0], args[1], args[2], s.mem())
                        s.vars[memVar] = s.newValue1(ssa.OpSelect1, types.TypeMem, v)
                        return s.newValue1(ssa.OpSelect0, types.Types[types.TBOOL], v)
                },
                sys.PPC64)

        atomicCasEmitterARM64 := func(s *state, n *ir.CallExpr, args []*ssa.Value, op ssa.Op, typ types.Kind) {
                v := s.newValue4(op, types.NewTuple(types.Types[types.TBOOL], types.TypeMem), args[0], args[1], args[2], s.mem())
                s.vars[memVar] = s.newValue1(ssa.OpSelect1, types.TypeMem, v)
                s.vars[n] = s.newValue1(ssa.OpSelect0, types.Types[typ], v)
        }

        addF("runtime/internal/atomic", "Cas",
                makeAtomicGuardedIntrinsicARM64(ssa.OpAtomicCompareAndSwap32, ssa.OpAtomicCompareAndSwap32Variant, types.TUINT32, types.TBOOL, atomicCasEmitterARM64),
                sys.ARM64)
        addF("runtime/internal/atomic", "Cas64",
                makeAtomicGuardedIntrinsicARM64(ssa.OpAtomicCompareAndSwap64, ssa.OpAtomicCompareAndSwap64Variant, types.TUINT64, types.TBOOL, atomicCasEmitterARM64),
                sys.ARM64)

        addF("runtime/internal/atomic", "And8",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        s.vars[memVar] = s.newValue3(ssa.OpAtomicAnd8, types.TypeMem, args[0], args[1], s.mem())
                        return nil
                },
                sys.AMD64, sys.MIPS, sys.MIPS64, sys.PPC64, sys.RISCV64, sys.S390X)
        addF("runtime/internal/atomic", "And",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        s.vars[memVar] = s.newValue3(ssa.OpAtomicAnd32, types.TypeMem, args[0], args[1], s.mem())
                        return nil
                },
                sys.AMD64, sys.MIPS, sys.MIPS64, sys.PPC64, sys.RISCV64, sys.S390X)
        addF("runtime/internal/atomic", "Or8",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        s.vars[memVar] = s.newValue3(ssa.OpAtomicOr8, types.TypeMem, args[0], args[1], s.mem())
                        return nil
                },
                sys.AMD64, sys.ARM64, sys.MIPS, sys.MIPS64, sys.PPC64, sys.RISCV64, sys.S390X)
        addF("runtime/internal/atomic", "Or",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        s.vars[memVar] = s.newValue3(ssa.OpAtomicOr32, types.TypeMem, args[0], args[1], s.mem())
                        return nil
                },
                sys.AMD64, sys.MIPS, sys.MIPS64, sys.PPC64, sys.RISCV64, sys.S390X)

        atomicAndOrEmitterARM64 := func(s *state, n *ir.CallExpr, args []*ssa.Value, op ssa.Op, typ types.Kind) {
                s.vars[memVar] = s.newValue3(op, types.TypeMem, args[0], args[1], s.mem())
        }

        addF("runtime/internal/atomic", "And8",
                makeAtomicGuardedIntrinsicARM64(ssa.OpAtomicAnd8, ssa.OpAtomicAnd8Variant, types.TNIL, types.TNIL, atomicAndOrEmitterARM64),
                sys.ARM64)
        addF("runtime/internal/atomic", "And",
                makeAtomicGuardedIntrinsicARM64(ssa.OpAtomicAnd32, ssa.OpAtomicAnd32Variant, types.TNIL, types.TNIL, atomicAndOrEmitterARM64),
                sys.ARM64)
        addF("runtime/internal/atomic", "Or8",
                makeAtomicGuardedIntrinsicARM64(ssa.OpAtomicOr8, ssa.OpAtomicOr8Variant, types.TNIL, types.TNIL, atomicAndOrEmitterARM64),
                sys.ARM64)
        addF("runtime/internal/atomic", "Or",
                makeAtomicGuardedIntrinsicARM64(ssa.OpAtomicOr32, ssa.OpAtomicOr32Variant, types.TNIL, types.TNIL, atomicAndOrEmitterARM64),
                sys.ARM64)

        // Aliases for atomic load operations
        alias("runtime/internal/atomic", "Loadint32", "runtime/internal/atomic", "Load", all...)
        alias("runtime/internal/atomic", "Loadint64", "runtime/internal/atomic", "Load64", all...)
        alias("runtime/internal/atomic", "Loaduintptr", "runtime/internal/atomic", "Load", p4...)
        alias("runtime/internal/atomic", "Loaduintptr", "runtime/internal/atomic", "Load64", p8...)
        alias("runtime/internal/atomic", "Loaduint", "runtime/internal/atomic", "Load", p4...)
        alias("runtime/internal/atomic", "Loaduint", "runtime/internal/atomic", "Load64", p8...)
        alias("runtime/internal/atomic", "LoadAcq", "runtime/internal/atomic", "Load", lwatomics...)
        alias("runtime/internal/atomic", "LoadAcq64", "runtime/internal/atomic", "Load64", lwatomics...)
        alias("runtime/internal/atomic", "LoadAcquintptr", "runtime/internal/atomic", "LoadAcq", p4...)
        alias("sync", "runtime_LoadAcquintptr", "runtime/internal/atomic", "LoadAcq", p4...) // linknamed
        alias("runtime/internal/atomic", "LoadAcquintptr", "runtime/internal/atomic", "LoadAcq64", p8...)
        alias("sync", "runtime_LoadAcquintptr", "runtime/internal/atomic", "LoadAcq64", p8...) // linknamed

        // Aliases for atomic store operations
        alias("runtime/internal/atomic", "Storeint32", "runtime/internal/atomic", "Store", all...)
        alias("runtime/internal/atomic", "Storeint64", "runtime/internal/atomic", "Store64", all...)
        alias("runtime/internal/atomic", "Storeuintptr", "runtime/internal/atomic", "Store", p4...)
        alias("runtime/internal/atomic", "Storeuintptr", "runtime/internal/atomic", "Store64", p8...)
        alias("runtime/internal/atomic", "StoreRel", "runtime/internal/atomic", "Store", lwatomics...)
        alias("runtime/internal/atomic", "StoreRel64", "runtime/internal/atomic", "Store64", lwatomics...)
        alias("runtime/internal/atomic", "StoreReluintptr", "runtime/internal/atomic", "StoreRel", p4...)
        alias("sync", "runtime_StoreReluintptr", "runtime/internal/atomic", "StoreRel", p4...) // linknamed
        alias("runtime/internal/atomic", "StoreReluintptr", "runtime/internal/atomic", "StoreRel64", p8...)
        alias("sync", "runtime_StoreReluintptr", "runtime/internal/atomic", "StoreRel64", p8...) // linknamed

        // Aliases for atomic swap operations
        alias("runtime/internal/atomic", "Xchgint32", "runtime/internal/atomic", "Xchg", all...)
        alias("runtime/internal/atomic", "Xchgint64", "runtime/internal/atomic", "Xchg64", all...)
        alias("runtime/internal/atomic", "Xchguintptr", "runtime/internal/atomic", "Xchg", p4...)
        alias("runtime/internal/atomic", "Xchguintptr", "runtime/internal/atomic", "Xchg64", p8...)

        // Aliases for atomic add operations
        alias("runtime/internal/atomic", "Xaddint32", "runtime/internal/atomic", "Xadd", all...)
        alias("runtime/internal/atomic", "Xaddint64", "runtime/internal/atomic", "Xadd64", all...)
        alias("runtime/internal/atomic", "Xadduintptr", "runtime/internal/atomic", "Xadd", p4...)
        alias("runtime/internal/atomic", "Xadduintptr", "runtime/internal/atomic", "Xadd64", p8...)

        // Aliases for atomic CAS operations
        alias("runtime/internal/atomic", "Casint32", "runtime/internal/atomic", "Cas", all...)
        alias("runtime/internal/atomic", "Casint64", "runtime/internal/atomic", "Cas64", all...)
        alias("runtime/internal/atomic", "Casuintptr", "runtime/internal/atomic", "Cas", p4...)
        alias("runtime/internal/atomic", "Casuintptr", "runtime/internal/atomic", "Cas64", p8...)
        alias("runtime/internal/atomic", "Casp1", "runtime/internal/atomic", "Cas", p4...)
        alias("runtime/internal/atomic", "Casp1", "runtime/internal/atomic", "Cas64", p8...)
        alias("runtime/internal/atomic", "CasRel", "runtime/internal/atomic", "Cas", lwatomics...)

        /******** math ********/
        addF("math", "sqrt",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        return s.newValue1(ssa.OpSqrt, types.Types[types.TFLOAT64], args[0])
                },
                sys.I386, sys.AMD64, sys.ARM, sys.ARM64, sys.Loong64, sys.MIPS, sys.MIPS64, sys.PPC64, sys.RISCV64, sys.S390X, sys.Wasm)
        addF("math", "Trunc",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        return s.newValue1(ssa.OpTrunc, types.Types[types.TFLOAT64], args[0])
                },
                sys.ARM64, sys.PPC64, sys.S390X, sys.Wasm)
        addF("math", "Ceil",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        return s.newValue1(ssa.OpCeil, types.Types[types.TFLOAT64], args[0])
                },
                sys.ARM64, sys.PPC64, sys.S390X, sys.Wasm)
        addF("math", "Floor",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        return s.newValue1(ssa.OpFloor, types.Types[types.TFLOAT64], args[0])
                },
                sys.ARM64, sys.PPC64, sys.S390X, sys.Wasm)
        addF("math", "Round",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        return s.newValue1(ssa.OpRound, types.Types[types.TFLOAT64], args[0])
                },
                sys.ARM64, sys.PPC64, sys.S390X)
        addF("math", "RoundToEven",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        return s.newValue1(ssa.OpRoundToEven, types.Types[types.TFLOAT64], args[0])
                },
                sys.ARM64, sys.S390X, sys.Wasm)
        addF("math", "Abs",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        return s.newValue1(ssa.OpAbs, types.Types[types.TFLOAT64], args[0])
                },
                sys.ARM64, sys.ARM, sys.PPC64, sys.RISCV64, sys.Wasm, sys.MIPS, sys.MIPS64)
        addF("math", "Copysign",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        return s.newValue2(ssa.OpCopysign, types.Types[types.TFLOAT64], args[0], args[1])
                },
                sys.PPC64, sys.RISCV64, sys.Wasm)
        addF("math", "FMA",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        return s.newValue3(ssa.OpFMA, types.Types[types.TFLOAT64], args[0], args[1], args[2])
                },
                sys.ARM64, sys.PPC64, sys.RISCV64, sys.S390X)
        addF("math", "FMA",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        if !s.config.UseFMA {
                                s.vars[n] = s.callResult(n, callNormal) // types.Types[TFLOAT64]
                                return s.variable(n, types.Types[types.TFLOAT64])
                        }

                        if buildcfg.GOAMD64 >= 3 {
                                return s.newValue3(ssa.OpFMA, types.Types[types.TFLOAT64], args[0], args[1], args[2])
                        }

                        v := s.entryNewValue0A(ssa.OpHasCPUFeature, types.Types[types.TBOOL], ir.Syms.X86HasFMA)
                        b := s.endBlock()
                        b.Kind = ssa.BlockIf
                        b.SetControl(v)
                        bTrue := s.f.NewBlock(ssa.BlockPlain)
                        bFalse := s.f.NewBlock(ssa.BlockPlain)
                        bEnd := s.f.NewBlock(ssa.BlockPlain)
                        b.AddEdgeTo(bTrue)
                        b.AddEdgeTo(bFalse)
                        b.Likely = ssa.BranchLikely // >= haswell cpus are common

                        // We have the intrinsic - use it directly.
                        s.startBlock(bTrue)
                        s.vars[n] = s.newValue3(ssa.OpFMA, types.Types[types.TFLOAT64], args[0], args[1], args[2])
                        s.endBlock().AddEdgeTo(bEnd)

                        // Call the pure Go version.
                        s.startBlock(bFalse)
                        s.vars[n] = s.callResult(n, callNormal) // types.Types[TFLOAT64]
                        s.endBlock().AddEdgeTo(bEnd)

                        // Merge results.
                        s.startBlock(bEnd)
                        return s.variable(n, types.Types[types.TFLOAT64])
                },
                sys.AMD64)
        addF("math", "FMA",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        if !s.config.UseFMA {
                                s.vars[n] = s.callResult(n, callNormal) // types.Types[TFLOAT64]
                                return s.variable(n, types.Types[types.TFLOAT64])
                        }
                        addr := s.entryNewValue1A(ssa.OpAddr, types.Types[types.TBOOL].PtrTo(), ir.Syms.ARMHasVFPv4, s.sb)
                        v := s.load(types.Types[types.TBOOL], addr)
                        b := s.endBlock()
                        b.Kind = ssa.BlockIf
                        b.SetControl(v)
                        bTrue := s.f.NewBlock(ssa.BlockPlain)
                        bFalse := s.f.NewBlock(ssa.BlockPlain)
                        bEnd := s.f.NewBlock(ssa.BlockPlain)
                        b.AddEdgeTo(bTrue)
                        b.AddEdgeTo(bFalse)
                        b.Likely = ssa.BranchLikely

                        // We have the intrinsic - use it directly.
                        s.startBlock(bTrue)
                        s.vars[n] = s.newValue3(ssa.OpFMA, types.Types[types.TFLOAT64], args[0], args[1], args[2])
                        s.endBlock().AddEdgeTo(bEnd)

                        // Call the pure Go version.
                        s.startBlock(bFalse)
                        s.vars[n] = s.callResult(n, callNormal) // types.Types[TFLOAT64]
                        s.endBlock().AddEdgeTo(bEnd)

                        // Merge results.
                        s.startBlock(bEnd)
                        return s.variable(n, types.Types[types.TFLOAT64])
                },
                sys.ARM)

        makeRoundAMD64 := func(op ssa.Op) func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                return func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        if buildcfg.GOAMD64 >= 2 {
                                return s.newValue1(op, types.Types[types.TFLOAT64], args[0])
                        }

                        v := s.entryNewValue0A(ssa.OpHasCPUFeature, types.Types[types.TBOOL], ir.Syms.X86HasSSE41)
                        b := s.endBlock()
                        b.Kind = ssa.BlockIf
                        b.SetControl(v)
                        bTrue := s.f.NewBlock(ssa.BlockPlain)
                        bFalse := s.f.NewBlock(ssa.BlockPlain)
                        bEnd := s.f.NewBlock(ssa.BlockPlain)
                        b.AddEdgeTo(bTrue)
                        b.AddEdgeTo(bFalse)
                        b.Likely = ssa.BranchLikely // most machines have sse4.1 nowadays

                        // We have the intrinsic - use it directly.
                        s.startBlock(bTrue)
                        s.vars[n] = s.newValue1(op, types.Types[types.TFLOAT64], args[0])
                        s.endBlock().AddEdgeTo(bEnd)

                        // Call the pure Go version.
                        s.startBlock(bFalse)
                        s.vars[n] = s.callResult(n, callNormal) // types.Types[TFLOAT64]
                        s.endBlock().AddEdgeTo(bEnd)

                        // Merge results.
                        s.startBlock(bEnd)
                        return s.variable(n, types.Types[types.TFLOAT64])
                }
        }
        addF("math", "RoundToEven",
                makeRoundAMD64(ssa.OpRoundToEven),
                sys.AMD64)
        addF("math", "Floor",
                makeRoundAMD64(ssa.OpFloor),
                sys.AMD64)
        addF("math", "Ceil",
                makeRoundAMD64(ssa.OpCeil),
                sys.AMD64)
        addF("math", "Trunc",
                makeRoundAMD64(ssa.OpTrunc),
                sys.AMD64)

        /******** math/bits ********/
        addF("math/bits", "TrailingZeros64",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        return s.newValue1(ssa.OpCtz64, types.Types[types.TINT], args[0])
                },
                sys.AMD64, sys.I386, sys.ARM64, sys.ARM, sys.S390X, sys.MIPS, sys.PPC64, sys.Wasm)
        addF("math/bits", "TrailingZeros32",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        return s.newValue1(ssa.OpCtz32, types.Types[types.TINT], args[0])
                },
                sys.AMD64, sys.I386, sys.ARM64, sys.ARM, sys.S390X, sys.MIPS, sys.PPC64, sys.Wasm)
        addF("math/bits", "TrailingZeros16",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        x := s.newValue1(ssa.OpZeroExt16to32, types.Types[types.TUINT32], args[0])
                        c := s.constInt32(types.Types[types.TUINT32], 1<<16)
                        y := s.newValue2(ssa.OpOr32, types.Types[types.TUINT32], x, c)
                        return s.newValue1(ssa.OpCtz32, types.Types[types.TINT], y)
                },
                sys.MIPS)
        addF("math/bits", "TrailingZeros16",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        return s.newValue1(ssa.OpCtz16, types.Types[types.TINT], args[0])
                },
                sys.AMD64, sys.I386, sys.ARM, sys.ARM64, sys.Wasm)
        addF("math/bits", "TrailingZeros16",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        x := s.newValue1(ssa.OpZeroExt16to64, types.Types[types.TUINT64], args[0])
                        c := s.constInt64(types.Types[types.TUINT64], 1<<16)
                        y := s.newValue2(ssa.OpOr64, types.Types[types.TUINT64], x, c)
                        return s.newValue1(ssa.OpCtz64, types.Types[types.TINT], y)
                },
                sys.S390X, sys.PPC64)
        addF("math/bits", "TrailingZeros8",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        x := s.newValue1(ssa.OpZeroExt8to32, types.Types[types.TUINT32], args[0])
                        c := s.constInt32(types.Types[types.TUINT32], 1<<8)
                        y := s.newValue2(ssa.OpOr32, types.Types[types.TUINT32], x, c)
                        return s.newValue1(ssa.OpCtz32, types.Types[types.TINT], y)
                },
                sys.MIPS)
        addF("math/bits", "TrailingZeros8",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        return s.newValue1(ssa.OpCtz8, types.Types[types.TINT], args[0])
                },
                sys.AMD64, sys.I386, sys.ARM, sys.ARM64, sys.Wasm)
        addF("math/bits", "TrailingZeros8",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        x := s.newValue1(ssa.OpZeroExt8to64, types.Types[types.TUINT64], args[0])
                        c := s.constInt64(types.Types[types.TUINT64], 1<<8)
                        y := s.newValue2(ssa.OpOr64, types.Types[types.TUINT64], x, c)
                        return s.newValue1(ssa.OpCtz64, types.Types[types.TINT], y)
                },
                sys.S390X)
        alias("math/bits", "ReverseBytes64", "runtime/internal/sys", "Bswap64", all...)
        alias("math/bits", "ReverseBytes32", "runtime/internal/sys", "Bswap32", all...)
        // ReverseBytes inlines correctly, no need to intrinsify it.
        // Nothing special is needed for targets where ReverseBytes16 lowers to a rotate
        // On Power10, 16-bit rotate is not available so use BRH instruction
        if buildcfg.GOPPC64 >= 10 {
                addF("math/bits", "ReverseBytes16",
                        func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                                return s.newValue1(ssa.OpBswap16, types.Types[types.TUINT], args[0])
                        },
                        sys.PPC64)
        }

        addF("math/bits", "Len64",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        return s.newValue1(ssa.OpBitLen64, types.Types[types.TINT], args[0])
                },
                sys.AMD64, sys.ARM64, sys.ARM, sys.S390X, sys.MIPS, sys.PPC64, sys.Wasm)
        addF("math/bits", "Len32",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        return s.newValue1(ssa.OpBitLen32, types.Types[types.TINT], args[0])
                },
                sys.AMD64, sys.ARM64, sys.PPC64)
        addF("math/bits", "Len32",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        if s.config.PtrSize == 4 {
                                return s.newValue1(ssa.OpBitLen32, types.Types[types.TINT], args[0])
                        }
                        x := s.newValue1(ssa.OpZeroExt32to64, types.Types[types.TUINT64], args[0])
                        return s.newValue1(ssa.OpBitLen64, types.Types[types.TINT], x)
                },
                sys.ARM, sys.S390X, sys.MIPS, sys.Wasm)
        addF("math/bits", "Len16",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        if s.config.PtrSize == 4 {
                                x := s.newValue1(ssa.OpZeroExt16to32, types.Types[types.TUINT32], args[0])
                                return s.newValue1(ssa.OpBitLen32, types.Types[types.TINT], x)
                        }
                        x := s.newValue1(ssa.OpZeroExt16to64, types.Types[types.TUINT64], args[0])
                        return s.newValue1(ssa.OpBitLen64, types.Types[types.TINT], x)
                },
                sys.ARM64, sys.ARM, sys.S390X, sys.MIPS, sys.PPC64, sys.Wasm)
        addF("math/bits", "Len16",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        return s.newValue1(ssa.OpBitLen16, types.Types[types.TINT], args[0])
                },
                sys.AMD64)
        addF("math/bits", "Len8",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        if s.config.PtrSize == 4 {
                                x := s.newValue1(ssa.OpZeroExt8to32, types.Types[types.TUINT32], args[0])
                                return s.newValue1(ssa.OpBitLen32, types.Types[types.TINT], x)
                        }
                        x := s.newValue1(ssa.OpZeroExt8to64, types.Types[types.TUINT64], args[0])
                        return s.newValue1(ssa.OpBitLen64, types.Types[types.TINT], x)
                },
                sys.ARM64, sys.ARM, sys.S390X, sys.MIPS, sys.PPC64, sys.Wasm)
        addF("math/bits", "Len8",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        return s.newValue1(ssa.OpBitLen8, types.Types[types.TINT], args[0])
                },
                sys.AMD64)
        addF("math/bits", "Len",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        if s.config.PtrSize == 4 {
                                return s.newValue1(ssa.OpBitLen32, types.Types[types.TINT], args[0])
                        }
                        return s.newValue1(ssa.OpBitLen64, types.Types[types.TINT], args[0])
                },
                sys.AMD64, sys.ARM64, sys.ARM, sys.S390X, sys.MIPS, sys.PPC64, sys.Wasm)
        // LeadingZeros is handled because it trivially calls Len.
        addF("math/bits", "Reverse64",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        return s.newValue1(ssa.OpBitRev64, types.Types[types.TINT], args[0])
                },
                sys.ARM64)
        addF("math/bits", "Reverse32",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        return s.newValue1(ssa.OpBitRev32, types.Types[types.TINT], args[0])
                },
                sys.ARM64)
        addF("math/bits", "Reverse16",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        return s.newValue1(ssa.OpBitRev16, types.Types[types.TINT], args[0])
                },
                sys.ARM64)
        addF("math/bits", "Reverse8",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        return s.newValue1(ssa.OpBitRev8, types.Types[types.TINT], args[0])
                },
                sys.ARM64)
        addF("math/bits", "Reverse",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        return s.newValue1(ssa.OpBitRev64, types.Types[types.TINT], args[0])
                },
                sys.ARM64)
        addF("math/bits", "RotateLeft8",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        return s.newValue2(ssa.OpRotateLeft8, types.Types[types.TUINT8], args[0], args[1])
                },
                sys.AMD64)
        addF("math/bits", "RotateLeft16",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        return s.newValue2(ssa.OpRotateLeft16, types.Types[types.TUINT16], args[0], args[1])
                },
                sys.AMD64)
        addF("math/bits", "RotateLeft32",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        return s.newValue2(ssa.OpRotateLeft32, types.Types[types.TUINT32], args[0], args[1])
                },
                sys.AMD64, sys.ARM, sys.ARM64, sys.S390X, sys.PPC64, sys.Wasm, sys.Loong64)
        addF("math/bits", "RotateLeft64",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        return s.newValue2(ssa.OpRotateLeft64, types.Types[types.TUINT64], args[0], args[1])
                },
                sys.AMD64, sys.ARM64, sys.S390X, sys.PPC64, sys.Wasm, sys.Loong64)
        alias("math/bits", "RotateLeft", "math/bits", "RotateLeft64", p8...)

        makeOnesCountAMD64 := func(op ssa.Op) func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                return func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        if buildcfg.GOAMD64 >= 2 {
                                return s.newValue1(op, types.Types[types.TINT], args[0])
                        }

                        v := s.entryNewValue0A(ssa.OpHasCPUFeature, types.Types[types.TBOOL], ir.Syms.X86HasPOPCNT)
                        b := s.endBlock()
                        b.Kind = ssa.BlockIf
                        b.SetControl(v)
                        bTrue := s.f.NewBlock(ssa.BlockPlain)
                        bFalse := s.f.NewBlock(ssa.BlockPlain)
                        bEnd := s.f.NewBlock(ssa.BlockPlain)
                        b.AddEdgeTo(bTrue)
                        b.AddEdgeTo(bFalse)
                        b.Likely = ssa.BranchLikely // most machines have popcnt nowadays

                        // We have the intrinsic - use it directly.
                        s.startBlock(bTrue)
                        s.vars[n] = s.newValue1(op, types.Types[types.TINT], args[0])
                        s.endBlock().AddEdgeTo(bEnd)

                        // Call the pure Go version.
                        s.startBlock(bFalse)
                        s.vars[n] = s.callResult(n, callNormal) // types.Types[TINT]
                        s.endBlock().AddEdgeTo(bEnd)

                        // Merge results.
                        s.startBlock(bEnd)
                        return s.variable(n, types.Types[types.TINT])
                }
        }
        addF("math/bits", "OnesCount64",
                makeOnesCountAMD64(ssa.OpPopCount64),
                sys.AMD64)
        addF("math/bits", "OnesCount64",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        return s.newValue1(ssa.OpPopCount64, types.Types[types.TINT], args[0])
                },
                sys.PPC64, sys.ARM64, sys.S390X, sys.Wasm)
        addF("math/bits", "OnesCount32",
                makeOnesCountAMD64(ssa.OpPopCount32),
                sys.AMD64)
        addF("math/bits", "OnesCount32",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        return s.newValue1(ssa.OpPopCount32, types.Types[types.TINT], args[0])
                },
                sys.PPC64, sys.ARM64, sys.S390X, sys.Wasm)
        addF("math/bits", "OnesCount16",
                makeOnesCountAMD64(ssa.OpPopCount16),
                sys.AMD64)
        addF("math/bits", "OnesCount16",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        return s.newValue1(ssa.OpPopCount16, types.Types[types.TINT], args[0])
                },
                sys.ARM64, sys.S390X, sys.PPC64, sys.Wasm)
        addF("math/bits", "OnesCount8",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        return s.newValue1(ssa.OpPopCount8, types.Types[types.TINT], args[0])
                },
                sys.S390X, sys.PPC64, sys.Wasm)
        addF("math/bits", "OnesCount",
                makeOnesCountAMD64(ssa.OpPopCount64),
                sys.AMD64)
        addF("math/bits", "Mul64",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        return s.newValue2(ssa.OpMul64uhilo, types.NewTuple(types.Types[types.TUINT64], types.Types[types.TUINT64]), args[0], args[1])
                },
                sys.AMD64, sys.ARM64, sys.PPC64, sys.S390X, sys.MIPS64, sys.RISCV64, sys.Loong64)
        alias("math/bits", "Mul", "math/bits", "Mul64", p8...)
        alias("runtime/internal/math", "Mul64", "math/bits", "Mul64", p8...)
        addF("math/bits", "Add64",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        return s.newValue3(ssa.OpAdd64carry, types.NewTuple(types.Types[types.TUINT64], types.Types[types.TUINT64]), args[0], args[1], args[2])
                },
                sys.AMD64, sys.ARM64, sys.PPC64, sys.S390X, sys.RISCV64, sys.Loong64, sys.MIPS64)
        alias("math/bits", "Add", "math/bits", "Add64", p8...)
        alias("runtime/internal/math", "Add64", "math/bits", "Add64", all...)
        addF("math/bits", "Sub64",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        return s.newValue3(ssa.OpSub64borrow, types.NewTuple(types.Types[types.TUINT64], types.Types[types.TUINT64]), args[0], args[1], args[2])
                },
                sys.AMD64, sys.ARM64, sys.PPC64, sys.S390X, sys.RISCV64, sys.Loong64, sys.MIPS64)
        alias("math/bits", "Sub", "math/bits", "Sub64", p8...)
        addF("math/bits", "Div64",
                func(s *state, n *ir.CallExpr, args []*ssa.Value) *ssa.Value {
                        // check for divide-by-zero/overflow and panic with appropriate message
                        cmpZero := s.newValue2(s.ssaOp(ir.ONE, types.Types[types.TUINT64]), types.Types[types.TBOOL], args[2], s.zeroVal(types.Types[types.TUINT64]))
                        s.check(cmpZero, ir.Syms.Panicdivide)
                        cmpOverflow := s.newValue2(s.ssaOp(ir.OLT, types.Types[types.TUINT64]), types.Types[types.TBOOL], args[0], args[2])
                        s.check(cmpOverflow, ir.Syms.Panicoverflow)
                        return s.newValue3(ssa.OpDiv128u, types.NewTuple(types.Types[types.TUINT64], types.Types[types.TUINT64]), args[0], args[1], args[2])
                },
                sys.AMD64)
        alias("math/bits", "Div", "math/bits", "Div64", sys.ArchAMD64)

        alias("runtime/internal/sys", "TrailingZeros8", "math/bits", "TrailingZeros8", all...)
        alias("runtime/internal/sys", "TrailingZeros32", "math/bits", "TrailingZeros32", all...)
        alias("runtime/internal/sys", "TrailingZeros64", "math/bits", "TrailingZeros64", all...)
        alias("runtime/internal/sys", "Len8", "math/bits", "Len8", all...)
        alias("runtime/internal/sys", "Len64", "math/bits", "Len64", all...)
        alias("runtime/internal/sys", "OnesCount64", "math/bits", "OnesCount64", all...)

        /******** sync/atomic ********/

        // Note: these are disabled by flag_race in findIntrinsic below.
        alias("sync/atomic", "LoadInt32", "runtime/internal/atomic", "Load", all...)
        alias("sync/atomic", "LoadInt64", "runtime/internal/atomic", "Load64", all...)
        alias("sync/atomic", "LoadPointer", "runtime/internal/atomic", "Loadp", all...)
        alias("sync/atomic", "LoadUint32", "runtime/internal/atomic", "Load", all...)
        alias("sync/atomic", "LoadUint64", "runtime/internal/atomic", "Load64", all...)
        alias("sync/atomic", "LoadUintptr", "runtime/internal/atomic", "Load", p4...)
        alias("sync/atomic", "LoadUintptr", "runtime/internal/atomic", "Load64", p8...)

        alias("sync/atomic", "StoreInt32", "runtime/internal/atomic", "Store", all...)
        alias("sync/atomic", "StoreInt64", "runtime/internal/atomic", "Store64", all...)
        // Note: not StorePointer, that needs a write barrier.  Same below for {CompareAnd}Swap.
        alias("sync/atomic", "StoreUint32", "runtime/internal/atomic", "Store", all...)
        alias("sync/atomic", "StoreUint64", "runtime/internal/atomic", "Store64", all...)
        alias("sync/atomic", "StoreUintptr", "runtime/internal/atomic", "Store", p4...)
        alias("sync/atomic", "StoreUintptr", "runtime/internal/atomic", "Store64", p8...)

        alias("sync/atomic", "SwapInt32", "runtime/internal/atomic", "Xchg", all...)
        alias("sync/atomic", "SwapInt64", "runtime/internal/atomic", "Xchg64", all...)
        alias("sync/atomic", "SwapUint32", "runtime/internal/atomic", "Xchg", all...)
        alias("sync/atomic", "SwapUint64", "runtime/internal/atomic", "Xchg64", all...)
        alias("sync/atomic", "SwapUintptr", "runtime/internal/atomic", "Xchg", p4...)
        alias("sync/atomic", "SwapUintptr", "runtime/internal/atomic", "Xchg64", p8...)

        alias("sync/atomic", "CompareAndSwapInt32", "runtime/internal/atomic", "Cas", all...)
        alias("sync/atomic", "CompareAndSwapInt64", "runtime/internal/atomic", "Cas64", all...)
        alias("sync/atomic", "CompareAndSwapUint32", "runtime/internal/atomic", "Cas", all...)
        alias("sync/atomic", "CompareAndSwapUint64", "runtime/internal/atomic", "Cas64", all...)
        alias("sync/atomic", "CompareAndSwapUintptr", "runtime/internal/atomic", "Cas", p4...)
        alias("sync/atomic", "CompareAndSwapUintptr", "runtime/internal/atomic", "Cas64", p8...)

        alias("sync/atomic", "AddInt32", "runtime/internal/atomic", "Xadd", all...)
        alias("sync/atomic", "AddInt64", "runtime/internal/atomic", "Xadd64", all...)
        alias("sync/atomic", "AddUint32", "runtime/internal/atomic", "Xadd", all...)
        alias("sync/atomic", "AddUint64", "runtime/internal/atomic", "Xadd64", all...)
        alias("sync/atomic", "AddUintptr", "runtime/internal/atomic", "Xadd", p4...)
        alias("sync/atomic", "AddUintptr", "runtime/internal/atomic", "Xadd64", p8...)

        /******** math/big ********/
        alias("math/big", "mulWW", "math/bits", "Mul64", p8...)
}

// findIntrinsic returns a function which builds the SSA equivalent of the
// function identified by the symbol sym.  If sym is not an intrinsic call, returns nil.
func findIntrinsic(sym *types.Sym) intrinsicBuilder {
        if sym == nil || sym.Pkg == nil {
                return nil
        }
        pkg := sym.Pkg.Path
        if sym.Pkg == ir.Pkgs.Runtime {
                pkg = "runtime"
        }
        if base.Flag.Race && pkg == "sync/atomic" {
                // The race detector needs to be able to intercept these calls.
                // We can't intrinsify them.
                return nil
        }
        // Skip intrinsifying math functions (which may contain hard-float
        // instructions) when soft-float
        if Arch.SoftFloat && pkg == "math" {
                return nil
        }

        fn := sym.Name
        if ssa.IntrinsicsDisable {
                if pkg == "runtime" && (fn == "getcallerpc" || fn == "getcallersp" || fn == "getclosureptr") {
                        // These runtime functions don't have definitions, must be intrinsics.
                } else {
                        return nil
                }
        }
        return intrinsics[intrinsicKey{Arch.LinkArch.Arch, pkg, fn}]
}

func IsIntrinsicCall(n *ir.CallExpr) bool {
        if n == nil {
                return false
        }
        name, ok := n.X.(*ir.Name)
        if !ok {
                return false
        }
        return findIntrinsic(name.Sym()) != nil
}

// intrinsicCall converts a call to a recognized intrinsic function into the intrinsic SSA operation.
func (s *state) intrinsicCall(n *ir.CallExpr) *ssa.Value {
        v := findIntrinsic(n.X.Sym())(s, n, s.intrinsicArgs(n))
        if ssa.IntrinsicsDebug > 0 {
                x := v
                if x == nil {
                        x = s.mem()
                }
                if x.Op == ssa.OpSelect0 || x.Op == ssa.OpSelect1 {
                        x = x.Args[0]
                }
                base.WarnfAt(n.Pos(), "intrinsic substitution for %v with %s", n.X.Sym().Name, x.LongString())
        }
        return v
}

// intrinsicArgs extracts args from n, evaluates them to SSA values, and returns them.
func (s *state) intrinsicArgs(n *ir.CallExpr) []*ssa.Value {
        args := make([]*ssa.Value, len(n.Args))
        for i, n := range n.Args {
                args[i] = s.expr(n)
        }
        return args
}

// openDeferRecord adds code to evaluate and store the function for an open-code defer
// call, and records info about the defer, so we can generate proper code on the
// exit paths. n is the sub-node of the defer node that is the actual function
// call. We will also record funcdata information on where the function is stored
// (as well as the deferBits variable), and this will enable us to run the proper
// defer calls during panics.
func (s *state) openDeferRecord(n *ir.CallExpr) {
        if len(n.Args) != 0 || n.Op() != ir.OCALLFUNC || n.X.Type().NumResults() != 0 {
                s.Fatalf("defer call with arguments or results: %v", n)
        }

        opendefer := &openDeferInfo{
                n: n,
        }
        fn := n.X
        // We must always store the function value in a stack slot for the
        // runtime panic code to use. But in the defer exit code, we will
        // call the function directly if it is a static function.
        closureVal := s.expr(fn)
        closure := s.openDeferSave(fn.Type(), closureVal)
        opendefer.closureNode = closure.Aux.(*ir.Name)
        if !(fn.Op() == ir.ONAME && fn.(*ir.Name).Class == ir.PFUNC) {
                opendefer.closure = closure
        }
        index := len(s.openDefers)
        s.openDefers = append(s.openDefers, opendefer)

        // Update deferBits only after evaluation and storage to stack of
        // the function is successful.
        bitvalue := s.constInt8(types.Types[types.TUINT8], 1<<uint(index))
        newDeferBits := s.newValue2(ssa.OpOr8, types.Types[types.TUINT8], s.variable(deferBitsVar, types.Types[types.TUINT8]), bitvalue)
        s.vars[deferBitsVar] = newDeferBits
        s.store(types.Types[types.TUINT8], s.deferBitsAddr, newDeferBits)
}

// openDeferSave generates SSA nodes to store a value (with type t) for an
// open-coded defer at an explicit autotmp location on the stack, so it can be
// reloaded and used for the appropriate call on exit. Type t must be a function type
// (therefore SSAable). val is the value to be stored. The function returns an SSA
// value representing a pointer to the autotmp location.
func (s *state) openDeferSave(t *types.Type, val *ssa.Value) *ssa.Value {
        if !TypeOK(t) {
                s.Fatalf("openDeferSave of non-SSA-able type %v val=%v", t, val)
        }
        if !t.HasPointers() {
                s.Fatalf("openDeferSave of pointerless type %v val=%v", t, val)
        }
        pos := val.Pos
        temp := typecheck.TempAt(pos.WithNotStmt(), s.curfn, t)
        temp.SetOpenDeferSlot(true)
        temp.SetFrameOffset(int64(len(s.openDefers))) // so cmpstackvarlt can order them
        var addrTemp *ssa.Value
        // Use OpVarLive to make sure stack slot for the closure is not removed by
        // dead-store elimination
        if s.curBlock.ID != s.f.Entry.ID {
                // Force the tmp storing this defer function to be declared in the entry
                // block, so that it will be live for the defer exit code (which will
                // actually access it only if the associated defer call has been activated).
                if t.HasPointers() {
                        s.defvars[s.f.Entry.ID][memVar] = s.f.Entry.NewValue1A(src.NoXPos, ssa.OpVarDef, types.TypeMem, temp, s.defvars[s.f.Entry.ID][memVar])
                }
                s.defvars[s.f.Entry.ID][memVar] = s.f.Entry.NewValue1A(src.NoXPos, ssa.OpVarLive, types.TypeMem, temp, s.defvars[s.f.Entry.ID][memVar])
                addrTemp = s.f.Entry.NewValue2A(src.NoXPos, ssa.OpLocalAddr, types.NewPtr(temp.Type()), temp, s.sp, s.defvars[s.f.Entry.ID][memVar])
        } else {
                // Special case if we're still in the entry block. We can't use
                // the above code, since s.defvars[s.f.Entry.ID] isn't defined
                // until we end the entry block with s.endBlock().
                if t.HasPointers() {
                        s.vars[memVar] = s.newValue1Apos(ssa.OpVarDef, types.TypeMem, temp, s.mem(), false)
                }
                s.vars[memVar] = s.newValue1Apos(ssa.OpVarLive, types.TypeMem, temp, s.mem(), false)
                addrTemp = s.newValue2Apos(ssa.OpLocalAddr, types.NewPtr(temp.Type()), temp, s.sp, s.mem(), false)
        }
        // Since we may use this temp during exit depending on the
        // deferBits, we must define it unconditionally on entry.
        // Therefore, we must make sure it is zeroed out in the entry
        // block if it contains pointers, else GC may wrongly follow an
        // uninitialized pointer value.
        temp.SetNeedzero(true)
        // We are storing to the stack, hence we can avoid the full checks in
        // storeType() (no write barrier) and do a simple store().
        s.store(t, addrTemp, val)
        return addrTemp
}

// openDeferExit generates SSA for processing all the open coded defers at exit.
// The code involves loading deferBits, and checking each of the bits to see if
// the corresponding defer statement was executed. For each bit that is turned
// on, the associated defer call is made.
func (s *state) openDeferExit() {
        deferExit := s.f.NewBlock(ssa.BlockPlain)
        s.endBlock().AddEdgeTo(deferExit)
        s.startBlock(deferExit)
        s.lastDeferExit = deferExit
        s.lastDeferCount = len(s.openDefers)
        zeroval := s.constInt8(types.Types[types.TUINT8], 0)
        // Test for and run defers in reverse order
        for i := len(s.openDefers) - 1; i >= 0; i-- {
                r := s.openDefers[i]
                bCond := s.f.NewBlock(ssa.BlockPlain)
                bEnd := s.f.NewBlock(ssa.BlockPlain)

                deferBits := s.variable(deferBitsVar, types.Types[types.TUINT8])
                // Generate code to check if the bit associated with the current
                // defer is set.
                bitval := s.constInt8(types.Types[types.TUINT8], 1<<uint(i))
                andval := s.newValue2(ssa.OpAnd8, types.Types[types.TUINT8], deferBits, bitval)
                eqVal := s.newValue2(ssa.OpEq8, types.Types[types.TBOOL], andval, zeroval)
                b := s.endBlock()
                b.Kind = ssa.BlockIf
                b.SetControl(eqVal)
                b.AddEdgeTo(bEnd)
                b.AddEdgeTo(bCond)
                bCond.AddEdgeTo(bEnd)
                s.startBlock(bCond)

                // Clear this bit in deferBits and force store back to stack, so
                // we will not try to re-run this defer call if this defer call panics.
                nbitval := s.newValue1(ssa.OpCom8, types.Types[types.TUINT8], bitval)
                maskedval := s.newValue2(ssa.OpAnd8, types.Types[types.TUINT8], deferBits, nbitval)
                s.store(types.Types[types.TUINT8], s.deferBitsAddr, maskedval)
                // Use this value for following tests, so we keep previous
                // bits cleared.
                s.vars[deferBitsVar] = maskedval

                // Generate code to call the function call of the defer, using the
                // closure that were stored in argtmps at the point of the defer
                // statement.
                fn := r.n.X
                stksize := fn.Type().ArgWidth()
                var callArgs []*ssa.Value
                var call *ssa.Value
                if r.closure != nil {
                        v := s.load(r.closure.Type.Elem(), r.closure)
                        s.maybeNilCheckClosure(v, callDefer)
                        codeptr := s.rawLoad(types.Types[types.TUINTPTR], v)
                        aux := ssa.ClosureAuxCall(s.f.ABIDefault.ABIAnalyzeTypes(nil, nil, nil))
                        call = s.newValue2A(ssa.OpClosureLECall, aux.LateExpansionResultType(), aux, codeptr, v)
                } else {
                        aux := ssa.StaticAuxCall(fn.(*ir.Name).Linksym(), s.f.ABIDefault.ABIAnalyzeTypes(nil, nil, nil))
                        call = s.newValue0A(ssa.OpStaticLECall, aux.LateExpansionResultType(), aux)
                }
                callArgs = append(callArgs, s.mem())
                call.AddArgs(callArgs...)
                call.AuxInt = stksize
                s.vars[memVar] = s.newValue1I(ssa.OpSelectN, types.TypeMem, 0, call)
                // Make sure that the stack slots with pointers are kept live
                // through the call (which is a pre-emption point). Also, we will
                // use the first call of the last defer exit to compute liveness
                // for the deferreturn, so we want all stack slots to be live.
                if r.closureNode != nil {
                        s.vars[memVar] = s.newValue1Apos(ssa.OpVarLive, types.TypeMem, r.closureNode, s.mem(), false)
                }

                s.endBlock()
                s.startBlock(bEnd)
        }
}

func (s *state) callResult(n *ir.CallExpr, k callKind) *ssa.Value {
        return s.call(n, k, false)
}

func (s *state) callAddr(n *ir.CallExpr, k callKind) *ssa.Value {
        return s.call(n, k, true)
}

// Calls the function n using the specified call type.
// Returns the address of the return value (or nil if none).
func (s *state) call(n *ir.CallExpr, k callKind, returnResultAddr bool) *ssa.Value {
        s.prevCall = nil
        var callee *ir.Name    // target function (if static)
        var closure *ssa.Value // ptr to closure to run (if dynamic)
        var codeptr *ssa.Value // ptr to target code (if dynamic)
        var rcvr *ssa.Value    // receiver to set
        fn := n.X
        var ACArgs []*types.Type    // AuxCall args
        var ACResults []*types.Type // AuxCall results
        var callArgs []*ssa.Value   // For late-expansion, the args themselves (not stored, args to the call instead).

        callABI := s.f.ABIDefault

        if k != callNormal && k != callTail && (len(n.Args) != 0 || n.Op() == ir.OCALLINTER || n.X.Type().NumResults() != 0) {
                s.Fatalf("go/defer call with arguments: %v", n)
        }

        switch n.Op() {
        case ir.OCALLFUNC:
                if (k == callNormal || k == callTail) && fn.Op() == ir.ONAME && fn.(*ir.Name).Class == ir.PFUNC {
                        fn := fn.(*ir.Name)
                        callee = fn
                        if buildcfg.Experiment.RegabiArgs {
                                // This is a static call, so it may be
                                // a direct call to a non-ABIInternal
                                // function. fn.Func may be nil for
                                // some compiler-generated functions,
                                // but those are all ABIInternal.
                                if fn.Func != nil {
                                        callABI = abiForFunc(fn.Func, s.f.ABI0, s.f.ABI1)
                                }
                        } else {
                                // TODO(register args) remove after register abi is working
                                inRegistersImported := fn.Pragma()&ir.RegisterParams != 0
                                inRegistersSamePackage := fn.Func != nil && fn.Func.Pragma&ir.RegisterParams != 0
                                if inRegistersImported || inRegistersSamePackage {
                                        callABI = s.f.ABI1
                                }
                        }
                        break
                }
                closure = s.expr(fn)
                if k != callDefer && k != callDeferStack {
                        // Deferred nil function needs to panic when the function is invoked,
                        // not the point of defer statement.
                        s.maybeNilCheckClosure(closure, k)
                }
        case ir.OCALLINTER:
                if fn.Op() != ir.ODOTINTER {
                        s.Fatalf("OCALLINTER: n.Left not an ODOTINTER: %v", fn.Op())
                }
                fn := fn.(*ir.SelectorExpr)
                var iclosure *ssa.Value
                iclosure, rcvr = s.getClosureAndRcvr(fn)
                if k == callNormal {
                        codeptr = s.load(types.Types[types.TUINTPTR], iclosure)
                } else {
                        closure = iclosure
                }
        }

        params := callABI.ABIAnalyze(n.X.Type(), false /* Do not set (register) nNames from caller side -- can cause races. */)
        types.CalcSize(fn.Type())
        stksize := params.ArgWidth() // includes receiver, args, and results

        res := n.X.Type().Results()
        if k == callNormal || k == callTail {
                for _, p := range params.OutParams() {
                        ACResults = append(ACResults, p.Type)
                }
        }

        var call *ssa.Value
        if k == callDeferStack {
                // Make a defer struct d on the stack.
                if stksize != 0 {
                        s.Fatalf("deferprocStack with non-zero stack size %d: %v", stksize, n)
                }

                t := deferstruct()
                d := typecheck.TempAt(n.Pos(), s.curfn, t)

                if t.HasPointers() {
                        s.vars[memVar] = s.newValue1A(ssa.OpVarDef, types.TypeMem, d, s.mem())
                }
                addr := s.addr(d)

                s.store(closure.Type,
                        s.newValue1I(ssa.OpOffPtr, closure.Type.PtrTo(), t.FieldOff(deferStructFnField), addr),
                        closure)

                // Call runtime.deferprocStack with pointer to _defer record.
                ACArgs = append(ACArgs, types.Types[types.TUINTPTR])
                aux := ssa.StaticAuxCall(ir.Syms.DeferprocStack, s.f.ABIDefault.ABIAnalyzeTypes(nil, ACArgs, ACResults))
                callArgs = append(callArgs, addr, s.mem())
                call = s.newValue0A(ssa.OpStaticLECall, aux.LateExpansionResultType(), aux)
                call.AddArgs(callArgs...)
                call.AuxInt = int64(types.PtrSize) // deferprocStack takes a *_defer arg
        } else {
                // Store arguments to stack, including defer/go arguments and receiver for method calls.
                // These are written in SP-offset order.
                argStart := base.Ctxt.Arch.FixedFrameSize
                // Defer/go args.
                if k != callNormal && k != callTail {
                        // Write closure (arg to newproc/deferproc).
                        ACArgs = append(ACArgs, types.Types[types.TUINTPTR]) // not argExtra
                        callArgs = append(callArgs, closure)
                        stksize += int64(types.PtrSize)
                        argStart += int64(types.PtrSize)
                }

                // Set receiver (for interface calls).
                if rcvr != nil {
                        callArgs = append(callArgs, rcvr)
                }

                // Write args.
                t := n.X.Type()
                args := n.Args

                for _, p := range params.InParams() { // includes receiver for interface calls
                        ACArgs = append(ACArgs, p.Type)
                }

                // Split the entry block if there are open defers, because later calls to
                // openDeferSave may cause a mismatch between the mem for an OpDereference
                // and the call site which uses it. See #49282.
                if s.curBlock.ID == s.f.Entry.ID && s.hasOpenDefers {
                        b := s.endBlock()
                        b.Kind = ssa.BlockPlain
                        curb := s.f.NewBlock(ssa.BlockPlain)
                        b.AddEdgeTo(curb)
                        s.startBlock(curb)
                }

                for i, n := range args {
                        callArgs = append(callArgs, s.putArg(n, t.Params().Field(i).Type))
                }

                callArgs = append(callArgs, s.mem())

                // call target
                switch {
                case k == callDefer:
                        aux := ssa.StaticAuxCall(ir.Syms.Deferproc, s.f.ABIDefault.ABIAnalyzeTypes(nil, ACArgs, ACResults)) // TODO paramResultInfo for DeferProc
                        call = s.newValue0A(ssa.OpStaticLECall, aux.LateExpansionResultType(), aux)
                case k == callGo:
                        aux := ssa.StaticAuxCall(ir.Syms.Newproc, s.f.ABIDefault.ABIAnalyzeTypes(nil, ACArgs, ACResults))
                        call = s.newValue0A(ssa.OpStaticLECall, aux.LateExpansionResultType(), aux) // TODO paramResultInfo for NewProc
                case closure != nil:
                        // rawLoad because loading the code pointer from a
                        // closure is always safe, but IsSanitizerSafeAddr
                        // can't always figure that out currently, and it's
                        // critical that we not clobber any arguments already
                        // stored onto the stack.
                        codeptr = s.rawLoad(types.Types[types.TUINTPTR], closure)
                        aux := ssa.ClosureAuxCall(callABI.ABIAnalyzeTypes(nil, ACArgs, ACResults))
                        call = s.newValue2A(ssa.OpClosureLECall, aux.LateExpansionResultType(), aux, codeptr, closure)
                case codeptr != nil:
                        // Note that the "receiver" parameter is nil because the actual receiver is the first input parameter.
                        aux := ssa.InterfaceAuxCall(params)
                        call = s.newValue1A(ssa.OpInterLECall, aux.LateExpansionResultType(), aux, codeptr)
                case callee != nil:
                        aux := ssa.StaticAuxCall(callTargetLSym(callee), params)
                        call = s.newValue0A(ssa.OpStaticLECall, aux.LateExpansionResultType(), aux)
                        if k == callTail {
                                call.Op = ssa.OpTailLECall
                                stksize = 0 // Tail call does not use stack. We reuse caller's frame.
                        }
                default:
                        s.Fatalf("bad call type %v %v", n.Op(), n)
                }
                call.AddArgs(callArgs...)
                call.AuxInt = stksize // Call operations carry the argsize of the callee along with them
        }
        s.prevCall = call
        s.vars[memVar] = s.newValue1I(ssa.OpSelectN, types.TypeMem, int64(len(ACResults)), call)
        // Insert VarLive opcodes.
        for _, v := range n.KeepAlive {
                if !v.Addrtaken() {
                        s.Fatalf("KeepAlive variable %v must have Addrtaken set", v)
                }
                switch v.Class {
                case ir.PAUTO, ir.PPARAM, ir.PPARAMOUT:
                default:
                        s.Fatalf("KeepAlive variable %v must be Auto or Arg", v)
                }
                s.vars[memVar] = s.newValue1A(ssa.OpVarLive, types.TypeMem, v, s.mem())
        }

        // Finish block for defers
        if k == callDefer || k == callDeferStack {
                b := s.endBlock()
                b.Kind = ssa.BlockDefer
                b.SetControl(call)
                bNext := s.f.NewBlock(ssa.BlockPlain)
                b.AddEdgeTo(bNext)
                // Add recover edge to exit code.
                r := s.f.NewBlock(ssa.BlockPlain)
                s.startBlock(r)
                s.exit()
                b.AddEdgeTo(r)
                b.Likely = ssa.BranchLikely
                s.startBlock(bNext)
        }

        if res.NumFields() == 0 || k != callNormal {
                // call has no return value. Continue with the next statement.
                return nil
        }
        fp := res.Field(0)
        if returnResultAddr {
                return s.resultAddrOfCall(call, 0, fp.Type)
        }
        return s.newValue1I(ssa.OpSelectN, fp.Type, 0, call)
}

// maybeNilCheckClosure checks if a nil check of a closure is needed in some
// architecture-dependent situations and, if so, emits the nil check.
func (s *state) maybeNilCheckClosure(closure *ssa.Value, k callKind) {
        if Arch.LinkArch.Family == sys.Wasm || buildcfg.GOOS == "aix" && k != callGo {
                // On AIX, the closure needs to be verified as fn can be nil, except if it's a call go. This needs to be handled by the runtime to have the "go of nil func value" error.
                // TODO(neelance): On other architectures this should be eliminated by the optimization steps
                s.nilCheck(closure)
        }
}

// getClosureAndRcvr returns values for the appropriate closure and receiver of an
// interface call
func (s *state) getClosureAndRcvr(fn *ir.SelectorExpr) (*ssa.Value, *ssa.Value) {
        i := s.expr(fn.X)
        itab := s.newValue1(ssa.OpITab, types.Types[types.TUINTPTR], i)
        s.nilCheck(itab)
        itabidx := fn.Offset() + 2*int64(types.PtrSize) + 8 // offset of fun field in runtime.itab
        closure := s.newValue1I(ssa.OpOffPtr, s.f.Config.Types.UintptrPtr, itabidx, itab)
        rcvr := s.newValue1(ssa.OpIData, s.f.Config.Types.BytePtr, i)
        return closure, rcvr
}

// etypesign returns the signed-ness of e, for integer/pointer etypes.
// -1 means signed, +1 means unsigned, 0 means non-integer/non-pointer.
func etypesign(e types.Kind) int8 {
        switch e {
        case types.TINT8, types.TINT16, types.TINT32, types.TINT64, types.TINT:
                return -1
        case types.TUINT8, types.TUINT16, types.TUINT32, types.TUINT64, types.TUINT, types.TUINTPTR, types.TUNSAFEPTR:
                return +1
        }
        return 0
}

// addr converts the address of the expression n to SSA, adds it to s and returns the SSA result.
// The value that the returned Value represents is guaranteed to be non-nil.
func (s *state) addr(n ir.Node) *ssa.Value {
        if n.Op() != ir.ONAME {
                s.pushLine(n.Pos())
                defer s.popLine()
        }

        if s.canSSA(n) {
                s.Fatalf("addr of canSSA expression: %+v", n)
        }

        t := types.NewPtr(n.Type())
        linksymOffset := func(lsym *obj.LSym, offset int64) *ssa.Value {
                v := s.entryNewValue1A(ssa.OpAddr, t, lsym, s.sb)
                // TODO: Make OpAddr use AuxInt as well as Aux.
                if offset != 0 {
                        v = s.entryNewValue1I(ssa.OpOffPtr, v.Type, offset, v)
                }
                return v
        }
        switch n.Op() {
        case ir.OLINKSYMOFFSET:
                no := n.(*ir.LinksymOffsetExpr)
                return linksymOffset(no.Linksym, no.Offset_)
        case ir.ONAME:
                n := n.(*ir.Name)
                if n.Heapaddr != nil {
                        return s.expr(n.Heapaddr)
                }
                switch n.Class {
                case ir.PEXTERN:
                        // global variable
                        return linksymOffset(n.Linksym(), 0)
                case ir.PPARAM:
                        // parameter slot
                        v := s.decladdrs[n]
                        if v != nil {
                                return v
                        }
                        s.Fatalf("addr of undeclared ONAME %v. declared: %v", n, s.decladdrs)
                        return nil
                case ir.PAUTO:
                        return s.newValue2Apos(ssa.OpLocalAddr, t, n, s.sp, s.mem(), !ir.IsAutoTmp(n))

                case ir.PPARAMOUT: // Same as PAUTO -- cannot generate LEA early.
                        // ensure that we reuse symbols for out parameters so
                        // that cse works on their addresses
                        return s.newValue2Apos(ssa.OpLocalAddr, t, n, s.sp, s.mem(), true)
                default:
                        s.Fatalf("variable address class %v not implemented", n.Class)
                        return nil
                }
        case ir.ORESULT:
                // load return from callee
                n := n.(*ir.ResultExpr)
                return s.resultAddrOfCall(s.prevCall, n.Index, n.Type())
        case ir.OINDEX:
                n := n.(*ir.IndexExpr)
                if n.X.Type().IsSlice() {
                        a := s.expr(n.X)
                        i := s.expr(n.Index)
                        len := s.newValue1(ssa.OpSliceLen, types.Types[types.TINT], a)
                        i = s.boundsCheck(i, len, ssa.BoundsIndex, n.Bounded())
                        p := s.newValue1(ssa.OpSlicePtr, t, a)
                        return s.newValue2(ssa.OpPtrIndex, t, p, i)
                } else { // array
                        a := s.addr(n.X)
                        i := s.expr(n.Index)
                        len := s.constInt(types.Types[types.TINT], n.X.Type().NumElem())
                        i = s.boundsCheck(i, len, ssa.BoundsIndex, n.Bounded())
                        return s.newValue2(ssa.OpPtrIndex, types.NewPtr(n.X.Type().Elem()), a, i)
                }
        case ir.ODEREF:
                n := n.(*ir.StarExpr)
                return s.exprPtr(n.X, n.Bounded(), n.Pos())
        case ir.ODOT:
                n := n.(*ir.SelectorExpr)
                p := s.addr(n.X)
                return s.newValue1I(ssa.OpOffPtr, t, n.Offset(), p)
        case ir.ODOTPTR:
                n := n.(*ir.SelectorExpr)
                p := s.exprPtr(n.X, n.Bounded(), n.Pos())
                return s.newValue1I(ssa.OpOffPtr, t, n.Offset(), p)
        case ir.OCONVNOP:
                n := n.(*ir.ConvExpr)
                if n.Type() == n.X.Type() {
                        return s.addr(n.X)
                }
                addr := s.addr(n.X)
                return s.newValue1(ssa.OpCopy, t, addr) // ensure that addr has the right type
        case ir.OCALLFUNC, ir.OCALLINTER:
                n := n.(*ir.CallExpr)
                return s.callAddr(n, callNormal)
        case ir.ODOTTYPE, ir.ODYNAMICDOTTYPE:
                var v *ssa.Value
                if n.Op() == ir.ODOTTYPE {
                        v, _ = s.dottype(n.(*ir.TypeAssertExpr), false)
                } else {
                        v, _ = s.dynamicDottype(n.(*ir.DynamicTypeAssertExpr), false)
                }
                if v.Op != ssa.OpLoad {
                        s.Fatalf("dottype of non-load")
                }
                if v.Args[1] != s.mem() {
                        s.Fatalf("memory no longer live from dottype load")
                }
                return v.Args[0]
        default:
                s.Fatalf("unhandled addr %v", n.Op())
                return nil
        }
}

// canSSA reports whether n is SSA-able.
// n must be an ONAME (or an ODOT sequence with an ONAME base).
func (s *state) canSSA(n ir.Node) bool {
        if base.Flag.N != 0 {
                return false
        }
        for {
                nn := n
                if nn.Op() == ir.ODOT {
                        nn := nn.(*ir.SelectorExpr)
                        n = nn.X
                        continue
                }
                if nn.Op() == ir.OINDEX {
                        nn := nn.(*ir.IndexExpr)
                        if nn.X.Type().IsArray() {
                                n = nn.X
                                continue
                        }
                }
                break
        }
        if n.Op() != ir.ONAME {
                return false
        }
        return s.canSSAName(n.(*ir.Name)) && TypeOK(n.Type())
}

func (s *state) canSSAName(name *ir.Name) bool {
        if name.Addrtaken() || !name.OnStack() {
                return false
        }
        switch name.Class {
        case ir.PPARAMOUT:
                if s.hasdefer {
                        // TODO: handle this case? Named return values must be
                        // in memory so that the deferred function can see them.
                        // Maybe do: if !strings.HasPrefix(n.String(), "~") { return false }
                        // Or maybe not, see issue 18860.  Even unnamed return values
                        // must be written back so if a defer recovers, the caller can see them.
                        return false
                }
                if s.cgoUnsafeArgs {
                        // Cgo effectively takes the address of all result args,
                        // but the compiler can't see that.
                        return false
                }
        }
        return true
        // TODO: try to make more variables SSAable?
}

// TypeOK reports whether variables of type t are SSA-able.
func TypeOK(t *types.Type) bool {
        types.CalcSize(t)
        if t.Size() > int64(4*types.PtrSize) {
                // 4*Widthptr is an arbitrary constant. We want it
                // to be at least 3*Widthptr so slices can be registerized.
                // Too big and we'll introduce too much register pressure.
                return false
        }
        switch t.Kind() {
        case types.TARRAY:
                // We can't do larger arrays because dynamic indexing is
                // not supported on SSA variables.
                // TODO: allow if all indexes are constant.
                if t.NumElem() <= 1 {
                        return TypeOK(t.Elem())
                }
                return false
        case types.TSTRUCT:
                if t.NumFields() > ssa.MaxStruct {
                        return false
                }
                for _, t1 := range t.Fields().Slice() {
                        if !TypeOK(t1.Type) {
                                return false
                        }
                }
                return true
        default:
                return true
        }
}

// exprPtr evaluates n to a pointer and nil-checks it.
func (s *state) exprPtr(n ir.Node, bounded bool, lineno src.XPos) *ssa.Value {
        p := s.expr(n)
        if bounded || n.NonNil() {
                if s.f.Frontend().Debug_checknil() && lineno.Line() > 1 {
                        s.f.Warnl(lineno, "removed nil check")
                }
                return p
        }
        s.nilCheck(p)
        return p
}

// nilCheck generates nil pointer checking code.
// Used only for automatically inserted nil checks,
// not for user code like 'x != nil'.
func (s *state) nilCheck(ptr *ssa.Value) {
        if base.Debug.DisableNil != 0 || s.curfn.NilCheckDisabled() {
                return
        }
        s.newValue2(ssa.OpNilCheck, types.TypeVoid, ptr, s.mem())
}

// boundsCheck generates bounds checking code. Checks if 0 <= idx <[=] len, branches to exit if not.
// Starts a new block on return.
// On input, len must be converted to full int width and be nonnegative.
// Returns idx converted to full int width.
// If bounded is true then caller guarantees the index is not out of bounds
// (but boundsCheck will still extend the index to full int width).
func (s *state) boundsCheck(idx, len *ssa.Value, kind ssa.BoundsKind, bounded bool) *ssa.Value {
        idx = s.extendIndex(idx, len, kind, bounded)

        if bounded || base.Flag.B != 0 {
                // If bounded or bounds checking is flag-disabled, then no check necessary,
                // just return the extended index.
                //
                // Here, bounded == true if the compiler generated the index itself,
                // such as in the expansion of a slice initializer. These indexes are
                // compiler-generated, not Go program variables, so they cannot be
                // attacker-controlled, so we can omit Spectre masking as well.
                //
                // Note that we do not want to omit Spectre masking in code like:
                //
                //      if 0 <= i && i < len(x) {
                //              use(x[i])
                //      }
                //
                // Lucky for us, bounded==false for that code.
                // In that case (handled below), we emit a bound check (and Spectre mask)
                // and then the prove pass will remove the bounds check.
                // In theory the prove pass could potentially remove certain
                // Spectre masks, but it's very delicate and probably better
                // to be conservative and leave them all in.
                return idx
        }

        bNext := s.f.NewBlock(ssa.BlockPlain)
        bPanic := s.f.NewBlock(ssa.BlockExit)

        if !idx.Type.IsSigned() {
                switch kind {
                case ssa.BoundsIndex:
                        kind = ssa.BoundsIndexU
                case ssa.BoundsSliceAlen:
                        kind = ssa.BoundsSliceAlenU
                case ssa.BoundsSliceAcap:
                        kind = ssa.BoundsSliceAcapU
                case ssa.BoundsSliceB:
                        kind = ssa.BoundsSliceBU
                case ssa.BoundsSlice3Alen:
                        kind = ssa.BoundsSlice3AlenU
                case ssa.BoundsSlice3Acap:
                        kind = ssa.BoundsSlice3AcapU
                case ssa.BoundsSlice3B:
                        kind = ssa.BoundsSlice3BU
                case ssa.BoundsSlice3C:
                        kind = ssa.BoundsSlice3CU
                }
        }

        var cmp *ssa.Value
        if kind == ssa.BoundsIndex || kind == ssa.BoundsIndexU {
                cmp = s.newValue2(ssa.OpIsInBounds, types.Types[types.TBOOL], idx, len)
        } else {
                cmp = s.newValue2(ssa.OpIsSliceInBounds, types.Types[types.TBOOL], idx, len)
        }
        b := s.endBlock()
        b.Kind = ssa.BlockIf
        b.SetControl(cmp)
        b.Likely = ssa.BranchLikely
        b.AddEdgeTo(bNext)
        b.AddEdgeTo(bPanic)

        s.startBlock(bPanic)
        if Arch.LinkArch.Family == sys.Wasm {
                // TODO(khr): figure out how to do "register" based calling convention for bounds checks.
                // Should be similar to gcWriteBarrier, but I can't make it work.
                s.rtcall(BoundsCheckFunc[kind], false, nil, idx, len)
        } else {
                mem := s.newValue3I(ssa.OpPanicBounds, types.TypeMem, int64(kind), idx, len, s.mem())
                s.endBlock().SetControl(mem)
        }
        s.startBlock(bNext)

        // In Spectre index mode, apply an appropriate mask to avoid speculative out-of-bounds accesses.
        if base.Flag.Cfg.SpectreIndex {
                op := ssa.OpSpectreIndex
                if kind != ssa.BoundsIndex && kind != ssa.BoundsIndexU {
                        op = ssa.OpSpectreSliceIndex
                }
                idx = s.newValue2(op, types.Types[types.TINT], idx, len)
        }

        return idx
}

// If cmp (a bool) is false, panic using the given function.
func (s *state) check(cmp *ssa.Value, fn *obj.LSym) {
        b := s.endBlock()
        b.Kind = ssa.BlockIf
        b.SetControl(cmp)
        b.Likely = ssa.BranchLikely
        bNext := s.f.NewBlock(ssa.BlockPlain)
        line := s.peekPos()
        pos := base.Ctxt.PosTable.Pos(line)
        fl := funcLine{f: fn, base: pos.Base(), line: pos.Line()}
        bPanic := s.panics[fl]
        if bPanic == nil {
                bPanic = s.f.NewBlock(ssa.BlockPlain)
                s.panics[fl] = bPanic
                s.startBlock(bPanic)
                // The panic call takes/returns memory to ensure that the right
                // memory state is observed if the panic happens.
                s.rtcall(fn, false, nil)
        }
        b.AddEdgeTo(bNext)
        b.AddEdgeTo(bPanic)
        s.startBlock(bNext)
}

func (s *state) intDivide(n ir.Node, a, b *ssa.Value) *ssa.Value {
        needcheck := true
        switch b.Op {
        case ssa.OpConst8, ssa.OpConst16, ssa.OpConst32, ssa.OpConst64:
                if b.AuxInt != 0 {
                        needcheck = false
                }
        }
        if needcheck {
                // do a size-appropriate check for zero
                cmp := s.newValue2(s.ssaOp(ir.ONE, n.Type()), types.Types[types.TBOOL], b, s.zeroVal(n.Type()))
                s.check(cmp, ir.Syms.Panicdivide)
        }
        return s.newValue2(s.ssaOp(n.Op(), n.Type()), a.Type, a, b)
}

// rtcall issues a call to the given runtime function fn with the listed args.
// Returns a slice of results of the given result types.
// The call is added to the end of the current block.
// If returns is false, the block is marked as an exit block.
func (s *state) rtcall(fn *obj.LSym, returns bool, results []*types.Type, args ...*ssa.Value) []*ssa.Value {
        s.prevCall = nil
        // Write args to the stack
        off := base.Ctxt.Arch.FixedFrameSize
        var callArgs []*ssa.Value
        var callArgTypes []*types.Type

        for _, arg := range args {
                t := arg.Type
                off = types.RoundUp(off, t.Alignment())
                size := t.Size()
                callArgs = append(callArgs, arg)
                callArgTypes = append(callArgTypes, t)
                off += size
        }
        off = types.RoundUp(off, int64(types.RegSize))

        // Issue call
        var call *ssa.Value
        aux := ssa.StaticAuxCall(fn, s.f.ABIDefault.ABIAnalyzeTypes(nil, callArgTypes, results))
        callArgs = append(callArgs, s.mem())
        call = s.newValue0A(ssa.OpStaticLECall, aux.LateExpansionResultType(), aux)
        call.AddArgs(callArgs...)
        s.vars[memVar] = s.newValue1I(ssa.OpSelectN, types.TypeMem, int64(len(results)), call)

        if !returns {
                // Finish block
                b := s.endBlock()
                b.Kind = ssa.BlockExit
                b.SetControl(call)
                call.AuxInt = off - base.Ctxt.Arch.FixedFrameSize
                if len(results) > 0 {
                        s.Fatalf("panic call can't have results")
                }
                return nil
        }

        // Load results
        res := make([]*ssa.Value, len(results))
        for i, t := range results {
                off = types.RoundUp(off, t.Alignment())
                res[i] = s.resultOfCall(call, int64(i), t)
                off += t.Size()
        }
        off = types.RoundUp(off, int64(types.PtrSize))

        // Remember how much callee stack space we needed.
        call.AuxInt = off

        return res
}

// do *left = right for type t.
func (s *state) storeType(t *types.Type, left, right *ssa.Value, skip skipMask, leftIsStmt bool) {
        s.instrument(t, left, instrumentWrite)

        if skip == 0 && (!t.HasPointers() || ssa.IsStackAddr(left)) {
                // Known to not have write barrier. Store the whole type.
                s.vars[memVar] = s.newValue3Apos(ssa.OpStore, types.TypeMem, t, left, right, s.mem(), leftIsStmt)
                return
        }

        // store scalar fields first, so write barrier stores for
        // pointer fields can be grouped together, and scalar values
        // don't need to be live across the write barrier call.
        // TODO: if the writebarrier pass knows how to reorder stores,
        // we can do a single store here as long as skip==0.
        s.storeTypeScalars(t, left, right, skip)
        if skip&skipPtr == 0 && t.HasPointers() {
                s.storeTypePtrs(t, left, right)
        }
}

// do *left = right for all scalar (non-pointer) parts of t.
func (s *state) storeTypeScalars(t *types.Type, left, right *ssa.Value, skip skipMask) {
        switch {
        case t.IsBoolean() || t.IsInteger() || t.IsFloat() || t.IsComplex():
                s.store(t, left, right)
        case t.IsPtrShaped():
                if t.IsPtr() && t.Elem().NotInHeap() {
                        s.store(t, left, right) // see issue 42032
                }
                // otherwise, no scalar fields.
        case t.IsString():
                if skip&skipLen != 0 {
                        return
                }
                len := s.newValue1(ssa.OpStringLen, types.Types[types.TINT], right)
                lenAddr := s.newValue1I(ssa.OpOffPtr, s.f.Config.Types.IntPtr, s.config.PtrSize, left)
                s.store(types.Types[types.TINT], lenAddr, len)
        case t.IsSlice():
                if skip&skipLen == 0 {
                        len := s.newValue1(ssa.OpSliceLen, types.Types[types.TINT], right)
                        lenAddr := s.newValue1I(ssa.OpOffPtr, s.f.Config.Types.IntPtr, s.config.PtrSize, left)
                        s.store(types.Types[types.TINT], lenAddr, len)
                }
                if skip&skipCap == 0 {
                        cap := s.newValue1(ssa.OpSliceCap, types.Types[types.TINT], right)
                        capAddr := s.newValue1I(ssa.OpOffPtr, s.f.Config.Types.IntPtr, 2*s.config.PtrSize, left)
                        s.store(types.Types[types.TINT], capAddr, cap)
                }
        case t.IsInterface():
                // itab field doesn't need a write barrier (even though it is a pointer).
                itab := s.newValue1(ssa.OpITab, s.f.Config.Types.BytePtr, right)
                s.store(types.Types[types.TUINTPTR], left, itab)
        case t.IsStruct():
                n := t.NumFields()
                for i := 0; i < n; i++ {
                        ft := t.FieldType(i)
                        addr := s.newValue1I(ssa.OpOffPtr, ft.PtrTo(), t.FieldOff(i), left)
                        val := s.newValue1I(ssa.OpStructSelect, ft, int64(i), right)
                        s.storeTypeScalars(ft, addr, val, 0)
                }
        case t.IsArray() && t.NumElem() == 0:
                // nothing
        case t.IsArray() && t.NumElem() == 1:
                s.storeTypeScalars(t.Elem(), left, s.newValue1I(ssa.OpArraySelect, t.Elem(), 0, right), 0)
        default:
                s.Fatalf("bad write barrier type %v", t)
        }
}

// do *left = right for all pointer parts of t.
func (s *state) storeTypePtrs(t *types.Type, left, right *ssa.Value) {
        switch {
        case t.IsPtrShaped():
                if t.IsPtr() && t.Elem().NotInHeap() {
                        break // see issue 42032
                }
                s.store(t, left, right)
        case t.IsString():
                ptr := s.newValue1(ssa.OpStringPtr, s.f.Config.Types.BytePtr, right)
                s.store(s.f.Config.Types.BytePtr, left, ptr)
        case t.IsSlice():
                elType := types.NewPtr(t.Elem())
                ptr := s.newValue1(ssa.OpSlicePtr, elType, right)
                s.store(elType, left, ptr)
        case t.IsInterface():
                // itab field is treated as a scalar.
                idata := s.newValue1(ssa.OpIData, s.f.Config.Types.BytePtr, right)
                idataAddr := s.newValue1I(ssa.OpOffPtr, s.f.Config.Types.BytePtrPtr, s.config.PtrSize, left)
                s.store(s.f.Config.Types.BytePtr, idataAddr, idata)
        case t.IsStruct():
                n := t.NumFields()
                for i := 0; i < n; i++ {
                        ft := t.FieldType(i)
                        if !ft.HasPointers() {
                                continue
                        }
                        addr := s.newValue1I(ssa.OpOffPtr, ft.PtrTo(), t.FieldOff(i), left)
                        val := s.newValue1I(ssa.OpStructSelect, ft, int64(i), right)
                        s.storeTypePtrs(ft, addr, val)
                }
        case t.IsArray() && t.NumElem() == 0:
                // nothing
        case t.IsArray() && t.NumElem() == 1:
                s.storeTypePtrs(t.Elem(), left, s.newValue1I(ssa.OpArraySelect, t.Elem(), 0, right))
        default:
                s.Fatalf("bad write barrier type %v", t)
        }
}

// putArg evaluates n for the purpose of passing it as an argument to a function and returns the value for the call.
func (s *state) putArg(n ir.Node, t *types.Type) *ssa.Value {
        var a *ssa.Value
        if !TypeOK(t) {
                a = s.newValue2(ssa.OpDereference, t, s.addr(n), s.mem())
        } else {
                a = s.expr(n)
        }
        return a
}

func (s *state) storeArgWithBase(n ir.Node, t *types.Type, base *ssa.Value, off int64) {
        pt := types.NewPtr(t)
        var addr *ssa.Value
        if base == s.sp {
                // Use special routine that avoids allocation on duplicate offsets.
                addr = s.constOffPtrSP(pt, off)
        } else {
                addr = s.newValue1I(ssa.OpOffPtr, pt, off, base)
        }

        if !TypeOK(t) {
                a := s.addr(n)
                s.move(t, addr, a)
                return
        }

        a := s.expr(n)
        s.storeType(t, addr, a, 0, false)
}

// slice computes the slice v[i:j:k] and returns ptr, len, and cap of result.
// i,j,k may be nil, in which case they are set to their default value.
// v may be a slice, string or pointer to an array.
func (s *state) slice(v, i, j, k *ssa.Value, bounded bool) (p, l, c *ssa.Value) {
        t := v.Type
        var ptr, len, cap *ssa.Value
        switch {
        case t.IsSlice():
                ptr = s.newValue1(ssa.OpSlicePtr, types.NewPtr(t.Elem()), v)
                len = s.newValue1(ssa.OpSliceLen, types.Types[types.TINT], v)
                cap = s.newValue1(ssa.OpSliceCap, types.Types[types.TINT], v)
        case t.IsString():
                ptr = s.newValue1(ssa.OpStringPtr, types.NewPtr(types.Types[types.TUINT8]), v)
                len = s.newValue1(ssa.OpStringLen, types.Types[types.TINT], v)
                cap = len
        case t.IsPtr():
                if !t.Elem().IsArray() {
                        s.Fatalf("bad ptr to array in slice %v\n", t)
                }
                s.nilCheck(v)
                ptr = s.newValue1(ssa.OpCopy, types.NewPtr(t.Elem().Elem()), v)
                len = s.constInt(types.Types[types.TINT], t.Elem().NumElem())
                cap = len
        default:
                s.Fatalf("bad type in slice %v\n", t)
        }

        // Set default values
        if i == nil {
                i = s.constInt(types.Types[types.TINT], 0)
        }
        if j == nil {
                j = len
        }
        three := true
        if k == nil {
                three = false
                k = cap
        }

        // Panic if slice indices are not in bounds.
        // Make sure we check these in reverse order so that we're always
        // comparing against a value known to be nonnegative. See issue 28797.
        if three {
                if k != cap {
                        kind := ssa.BoundsSlice3Alen
                        if t.IsSlice() {
                                kind = ssa.BoundsSlice3Acap
                        }
                        k = s.boundsCheck(k, cap, kind, bounded)
                }
                if j != k {
                        j = s.boundsCheck(j, k, ssa.BoundsSlice3B, bounded)
                }
                i = s.boundsCheck(i, j, ssa.BoundsSlice3C, bounded)
        } else {
                if j != k {
                        kind := ssa.BoundsSliceAlen
                        if t.IsSlice() {
                                kind = ssa.BoundsSliceAcap
                        }
                        j = s.boundsCheck(j, k, kind, bounded)
                }
                i = s.boundsCheck(i, j, ssa.BoundsSliceB, bounded)
        }

        // Word-sized integer operations.
        subOp := s.ssaOp(ir.OSUB, types.Types[types.TINT])
        mulOp := s.ssaOp(ir.OMUL, types.Types[types.TINT])
        andOp := s.ssaOp(ir.OAND, types.Types[types.TINT])

        // Calculate the length (rlen) and capacity (rcap) of the new slice.
        // For strings the capacity of the result is unimportant. However,
        // we use rcap to test if we've generated a zero-length slice.
        // Use length of strings for that.
        rlen := s.newValue2(subOp, types.Types[types.TINT], j, i)
        rcap := rlen
        if j != k && !t.IsString() {
                rcap = s.newValue2(subOp, types.Types[types.TINT], k, i)
        }

        if (i.Op == ssa.OpConst64 || i.Op == ssa.OpConst32) && i.AuxInt == 0 {
                // No pointer arithmetic necessary.
                return ptr, rlen, rcap
        }

        // Calculate the base pointer (rptr) for the new slice.
        //
        // Generate the following code assuming that indexes are in bounds.
        // The masking is to make sure that we don't generate a slice
        // that points to the next object in memory. We cannot just set
        // the pointer to nil because then we would create a nil slice or
        // string.
        //
        //     rcap = k - i
        //     rlen = j - i
        //     rptr = ptr + (mask(rcap) & (i * stride))
        //
        // Where mask(x) is 0 if x==0 and -1 if x>0 and stride is the width
        // of the element type.
        stride := s.constInt(types.Types[types.TINT], ptr.Type.Elem().Size())

        // The delta is the number of bytes to offset ptr by.
        delta := s.newValue2(mulOp, types.Types[types.TINT], i, stride)

        // If we're slicing to the point where the capacity is zero,
        // zero out the delta.
        mask := s.newValue1(ssa.OpSlicemask, types.Types[types.TINT], rcap)
        delta = s.newValue2(andOp, types.Types[types.TINT], delta, mask)

        // Compute rptr = ptr + delta.
        rptr := s.newValue2(ssa.OpAddPtr, ptr.Type, ptr, delta)

        return rptr, rlen, rcap
}

type u642fcvtTab struct {
        leq, cvt2F, and, rsh, or, add ssa.Op
        one                           func(*state, *types.Type, int64) *ssa.Value
}

var u64_f64 = u642fcvtTab{
        leq:   ssa.OpLeq64,
        cvt2F: ssa.OpCvt64to64F,
        and:   ssa.OpAnd64,
        rsh:   ssa.OpRsh64Ux64,
        or:    ssa.OpOr64,
        add:   ssa.OpAdd64F,
        one:   (*state).constInt64,
}

var u64_f32 = u642fcvtTab{
        leq:   ssa.OpLeq64,
        cvt2F: ssa.OpCvt64to32F,
        and:   ssa.OpAnd64,
        rsh:   ssa.OpRsh64Ux64,
        or:    ssa.OpOr64,
        add:   ssa.OpAdd32F,
        one:   (*state).constInt64,
}

func (s *state) uint64Tofloat64(n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
        return s.uint64Tofloat(&u64_f64, n, x, ft, tt)
}

func (s *state) uint64Tofloat32(n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
        return s.uint64Tofloat(&u64_f32, n, x, ft, tt)
}

func (s *state) uint64Tofloat(cvttab *u642fcvtTab, n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
        // if x >= 0 {
        //    result = (floatY) x
        // } else {
        //        y = uintX(x) ; y = x & 1
        //        z = uintX(x) ; z = z >> 1
        //        z = z | y
        //        result = floatY(z)
        //        result = result + result
        // }
        //
        // Code borrowed from old code generator.
        // What's going on: large 64-bit "unsigned" looks like
        // negative number to hardware's integer-to-float
        // conversion. However, because the mantissa is only
        // 63 bits, we don't need the LSB, so instead we do an
        // unsigned right shift (divide by two), convert, and
        // double. However, before we do that, we need to be
        // sure that we do not lose a "1" if that made the
        // difference in the resulting rounding. Therefore, we
        // preserve it, and OR (not ADD) it back in. The case
        // that matters is when the eleven discarded bits are
        // equal to 10000000001; that rounds up, and the 1 cannot
        // be lost else it would round down if the LSB of the
        // candidate mantissa is 0.
        cmp := s.newValue2(cvttab.leq, types.Types[types.TBOOL], s.zeroVal(ft), x)
        b := s.endBlock()
        b.Kind = ssa.BlockIf
        b.SetControl(cmp)
        b.Likely = ssa.BranchLikely

        bThen := s.f.NewBlock(ssa.BlockPlain)
        bElse := s.f.NewBlock(ssa.BlockPlain)
        bAfter := s.f.NewBlock(ssa.BlockPlain)

        b.AddEdgeTo(bThen)
        s.startBlock(bThen)
        a0 := s.newValue1(cvttab.cvt2F, tt, x)
        s.vars[n] = a0
        s.endBlock()
        bThen.AddEdgeTo(bAfter)

        b.AddEdgeTo(bElse)
        s.startBlock(bElse)
        one := cvttab.one(s, ft, 1)
        y := s.newValue2(cvttab.and, ft, x, one)
        z := s.newValue2(cvttab.rsh, ft, x, one)
        z = s.newValue2(cvttab.or, ft, z, y)
        a := s.newValue1(cvttab.cvt2F, tt, z)
        a1 := s.newValue2(cvttab.add, tt, a, a)
        s.vars[n] = a1
        s.endBlock()
        bElse.AddEdgeTo(bAfter)

        s.startBlock(bAfter)
        return s.variable(n, n.Type())
}

type u322fcvtTab struct {
        cvtI2F, cvtF2F ssa.Op
}

var u32_f64 = u322fcvtTab{
        cvtI2F: ssa.OpCvt32to64F,
        cvtF2F: ssa.OpCopy,
}

var u32_f32 = u322fcvtTab{
        cvtI2F: ssa.OpCvt32to32F,
        cvtF2F: ssa.OpCvt64Fto32F,
}

func (s *state) uint32Tofloat64(n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
        return s.uint32Tofloat(&u32_f64, n, x, ft, tt)
}

func (s *state) uint32Tofloat32(n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
        return s.uint32Tofloat(&u32_f32, n, x, ft, tt)
}

func (s *state) uint32Tofloat(cvttab *u322fcvtTab, n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
        // if x >= 0 {
        //      result = floatY(x)
        // } else {
        //      result = floatY(float64(x) + (1<<32))
        // }
        cmp := s.newValue2(ssa.OpLeq32, types.Types[types.TBOOL], s.zeroVal(ft), x)
        b := s.endBlock()
        b.Kind = ssa.BlockIf
        b.SetControl(cmp)
        b.Likely = ssa.BranchLikely

        bThen := s.f.NewBlock(ssa.BlockPlain)
        bElse := s.f.NewBlock(ssa.BlockPlain)
        bAfter := s.f.NewBlock(ssa.BlockPlain)

        b.AddEdgeTo(bThen)
        s.startBlock(bThen)
        a0 := s.newValue1(cvttab.cvtI2F, tt, x)
        s.vars[n] = a0
        s.endBlock()
        bThen.AddEdgeTo(bAfter)

        b.AddEdgeTo(bElse)
        s.startBlock(bElse)
        a1 := s.newValue1(ssa.OpCvt32to64F, types.Types[types.TFLOAT64], x)
        twoToThe32 := s.constFloat64(types.Types[types.TFLOAT64], float64(1<<32))
        a2 := s.newValue2(ssa.OpAdd64F, types.Types[types.TFLOAT64], a1, twoToThe32)
        a3 := s.newValue1(cvttab.cvtF2F, tt, a2)

        s.vars[n] = a3
        s.endBlock()
        bElse.AddEdgeTo(bAfter)

        s.startBlock(bAfter)
        return s.variable(n, n.Type())
}

// referenceTypeBuiltin generates code for the len/cap builtins for maps and channels.
func (s *state) referenceTypeBuiltin(n *ir.UnaryExpr, x *ssa.Value) *ssa.Value {
        if !n.X.Type().IsMap() && !n.X.Type().IsChan() {
                s.Fatalf("node must be a map or a channel")
        }
        // if n == nil {
        //   return 0
        // } else {
        //   // len
        //   return *((*int)n)
        //   // cap
        //   return *(((*int)n)+1)
        // }
        lenType := n.Type()
        nilValue := s.constNil(types.Types[types.TUINTPTR])
        cmp := s.newValue2(ssa.OpEqPtr, types.Types[types.TBOOL], x, nilValue)
        b := s.endBlock()
        b.Kind = ssa.BlockIf
        b.SetControl(cmp)
        b.Likely = ssa.BranchUnlikely

        bThen := s.f.NewBlock(ssa.BlockPlain)
        bElse := s.f.NewBlock(ssa.BlockPlain)
        bAfter := s.f.NewBlock(ssa.BlockPlain)

        // length/capacity of a nil map/chan is zero
        b.AddEdgeTo(bThen)
        s.startBlock(bThen)
        s.vars[n] = s.zeroVal(lenType)
        s.endBlock()
        bThen.AddEdgeTo(bAfter)

        b.AddEdgeTo(bElse)
        s.startBlock(bElse)
        switch n.Op() {
        case ir.OLEN:
                // length is stored in the first word for map/chan
                s.vars[n] = s.load(lenType, x)
        case ir.OCAP:
                // capacity is stored in the second word for chan
                sw := s.newValue1I(ssa.OpOffPtr, lenType.PtrTo(), lenType.Size(), x)
                s.vars[n] = s.load(lenType, sw)
        default:
                s.Fatalf("op must be OLEN or OCAP")
        }
        s.endBlock()
        bElse.AddEdgeTo(bAfter)

        s.startBlock(bAfter)
        return s.variable(n, lenType)
}

type f2uCvtTab struct {
        ltf, cvt2U, subf, or ssa.Op
        floatValue           func(*state, *types.Type, float64) *ssa.Value
        intValue             func(*state, *types.Type, int64) *ssa.Value
        cutoff               uint64
}

var f32_u64 = f2uCvtTab{
        ltf:        ssa.OpLess32F,
        cvt2U:      ssa.OpCvt32Fto64,
        subf:       ssa.OpSub32F,
        or:         ssa.OpOr64,
        floatValue: (*state).constFloat32,
        intValue:   (*state).constInt64,
        cutoff:     1 << 63,
}

var f64_u64 = f2uCvtTab{
        ltf:        ssa.OpLess64F,
        cvt2U:      ssa.OpCvt64Fto64,
        subf:       ssa.OpSub64F,
        or:         ssa.OpOr64,
        floatValue: (*state).constFloat64,
        intValue:   (*state).constInt64,
        cutoff:     1 << 63,
}

var f32_u32 = f2uCvtTab{
        ltf:        ssa.OpLess32F,
        cvt2U:      ssa.OpCvt32Fto32,
        subf:       ssa.OpSub32F,
        or:         ssa.OpOr32,
        floatValue: (*state).constFloat32,
        intValue:   func(s *state, t *types.Type, v int64) *ssa.Value { return s.constInt32(t, int32(v)) },
        cutoff:     1 << 31,
}

var f64_u32 = f2uCvtTab{
        ltf:        ssa.OpLess64F,
        cvt2U:      ssa.OpCvt64Fto32,
        subf:       ssa.OpSub64F,
        or:         ssa.OpOr32,
        floatValue: (*state).constFloat64,
        intValue:   func(s *state, t *types.Type, v int64) *ssa.Value { return s.constInt32(t, int32(v)) },
        cutoff:     1 << 31,
}

func (s *state) float32ToUint64(n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
        return s.floatToUint(&f32_u64, n, x, ft, tt)
}
func (s *state) float64ToUint64(n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
        return s.floatToUint(&f64_u64, n, x, ft, tt)
}

func (s *state) float32ToUint32(n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
        return s.floatToUint(&f32_u32, n, x, ft, tt)
}

func (s *state) float64ToUint32(n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
        return s.floatToUint(&f64_u32, n, x, ft, tt)
}

func (s *state) floatToUint(cvttab *f2uCvtTab, n ir.Node, x *ssa.Value, ft, tt *types.Type) *ssa.Value {
        // cutoff:=1<<(intY_Size-1)
        // if x < floatX(cutoff) {
        //      result = uintY(x)
        // } else {
        //      y = x - floatX(cutoff)
        //      z = uintY(y)
        //      result = z | -(cutoff)
        // }
        cutoff := cvttab.floatValue(s, ft, float64(cvttab.cutoff))
        cmp := s.newValue2(cvttab.ltf, types.Types[types.TBOOL], x, cutoff)
        b := s.endBlock()
        b.Kind = ssa.BlockIf
        b.SetControl(cmp)
        b.Likely = ssa.BranchLikely

        bThen := s.f.NewBlock(ssa.BlockPlain)
        bElse := s.f.NewBlock(ssa.BlockPlain)
        bAfter := s.f.NewBlock(ssa.BlockPlain)

        b.AddEdgeTo(bThen)
        s.startBlock(bThen)
        a0 := s.newValue1(cvttab.cvt2U, tt, x)
        s.vars[n] = a0
        s.endBlock()
        bThen.AddEdgeTo(bAfter)

        b.AddEdgeTo(bElse)
        s.startBlock(bElse)
        y := s.newValue2(cvttab.subf, ft, x, cutoff)
        y = s.newValue1(cvttab.cvt2U, tt, y)
        z := cvttab.intValue(s, tt, int64(-cvttab.cutoff))
        a1 := s.newValue2(cvttab.or, tt, y, z)
        s.vars[n] = a1
        s.endBlock()
        bElse.AddEdgeTo(bAfter)

        s.startBlock(bAfter)
        return s.variable(n, n.Type())
}

// dottype generates SSA for a type assertion node.
// commaok indicates whether to panic or return a bool.
// If commaok is false, resok will be nil.
func (s *state) dottype(n *ir.TypeAssertExpr, commaok bool) (res, resok *ssa.Value) {
        iface := s.expr(n.X)              // input interface
        target := s.reflectType(n.Type()) // target type
        var targetItab *ssa.Value
        if n.ITab != nil {
                targetItab = s.expr(n.ITab)
        }
        return s.dottype1(n.Pos(), n.X.Type(), n.Type(), iface, nil, target, targetItab, commaok)
}

func (s *state) dynamicDottype(n *ir.DynamicTypeAssertExpr, commaok bool) (res, resok *ssa.Value) {
        iface := s.expr(n.X)
        var source, target, targetItab *ssa.Value
        if n.SrcRType != nil {
                source = s.expr(n.SrcRType)
        }
        if !n.X.Type().IsEmptyInterface() && !n.Type().IsInterface() {
                byteptr := s.f.Config.Types.BytePtr
                targetItab = s.expr(n.ITab)
                // TODO(mdempsky): Investigate whether compiling n.RType could be
                // better than loading itab.typ.
                target = s.load(byteptr, s.newValue1I(ssa.OpOffPtr, byteptr, int64(types.PtrSize), targetItab)) // itab.typ
        } else {
                target = s.expr(n.RType)
        }
        return s.dottype1(n.Pos(), n.X.Type(), n.Type(), iface, source, target, targetItab, commaok)
}

// dottype1 implements a x.(T) operation. iface is the argument (x), dst is the type we're asserting to (T)
// and src is the type we're asserting from.
// source is the *runtime._type of src
// target is the *runtime._type of dst.
// If src is a nonempty interface and dst is not an interface, targetItab is an itab representing (dst, src). Otherwise it is nil.
// commaok is true if the caller wants a boolean success value. Otherwise, the generated code panics if the conversion fails.
func (s *state) dottype1(pos src.XPos, src, dst *types.Type, iface, source, target, targetItab *ssa.Value, commaok bool) (res, resok *ssa.Value) {
        byteptr := s.f.Config.Types.BytePtr
        if dst.IsInterface() {
                if dst.IsEmptyInterface() {
                        // Converting to an empty interface.
                        // Input could be an empty or nonempty interface.
                        if base.Debug.TypeAssert > 0 {
                                base.WarnfAt(pos, "type assertion inlined")
                        }

                        // Get itab/type field from input.
                        itab := s.newValue1(ssa.OpITab, byteptr, iface)
                        // Conversion succeeds iff that field is not nil.
                        cond := s.newValue2(ssa.OpNeqPtr, types.Types[types.TBOOL], itab, s.constNil(byteptr))

                        if src.IsEmptyInterface() && commaok {
                                // Converting empty interface to empty interface with ,ok is just a nil check.
                                return iface, cond
                        }

                        // Branch on nilness.
                        b := s.endBlock()
                        b.Kind = ssa.BlockIf
                        b.SetControl(cond)
                        b.Likely = ssa.BranchLikely
                        bOk := s.f.NewBlock(ssa.BlockPlain)
                        bFail := s.f.NewBlock(ssa.BlockPlain)
                        b.AddEdgeTo(bOk)
                        b.AddEdgeTo(bFail)

                        if !commaok {
                                // On failure, panic by calling panicnildottype.
                                s.startBlock(bFail)
                                s.rtcall(ir.Syms.Panicnildottype, false, nil, target)

                                // On success, return (perhaps modified) input interface.
                                s.startBlock(bOk)
                                if src.IsEmptyInterface() {
                                        res = iface // Use input interface unchanged.
                                        return
                                }
                                // Load type out of itab, build interface with existing idata.
                                off := s.newValue1I(ssa.OpOffPtr, byteptr, int64(types.PtrSize), itab)
                                typ := s.load(byteptr, off)
                                idata := s.newValue1(ssa.OpIData, byteptr, iface)
                                res = s.newValue2(ssa.OpIMake, dst, typ, idata)
                                return
                        }

                        s.startBlock(bOk)
                        // nonempty -> empty
                        // Need to load type from itab
                        off := s.newValue1I(ssa.OpOffPtr, byteptr, int64(types.PtrSize), itab)
                        s.vars[typVar] = s.load(byteptr, off)
                        s.endBlock()

                        // itab is nil, might as well use that as the nil result.
                        s.startBlock(bFail)
                        s.vars[typVar] = itab
                        s.endBlock()

                        // Merge point.
                        bEnd := s.f.NewBlock(ssa.BlockPlain)
                        bOk.AddEdgeTo(bEnd)
                        bFail.AddEdgeTo(bEnd)
                        s.startBlock(bEnd)
                        idata := s.newValue1(ssa.OpIData, byteptr, iface)
                        res = s.newValue2(ssa.OpIMake, dst, s.variable(typVar, byteptr), idata)
                        resok = cond
                        delete(s.vars, typVar) // no practical effect, just to indicate typVar is no longer live.
                        return
                }
                // converting to a nonempty interface needs a runtime call.
                if base.Debug.TypeAssert > 0 {
                        base.WarnfAt(pos, "type assertion not inlined")
                }
                if !commaok {
                        fn := ir.Syms.AssertI2I
                        if src.IsEmptyInterface() {
                                fn = ir.Syms.AssertE2I
                        }
                        data := s.newValue1(ssa.OpIData, types.Types[types.TUNSAFEPTR], iface)
                        tab := s.newValue1(ssa.OpITab, byteptr, iface)
                        tab = s.rtcall(fn, true, []*types.Type{byteptr}, target, tab)[0]
                        return s.newValue2(ssa.OpIMake, dst, tab, data), nil
                }
                fn := ir.Syms.AssertI2I2
                if src.IsEmptyInterface() {
                        fn = ir.Syms.AssertE2I2
                }
                res = s.rtcall(fn, true, []*types.Type{dst}, target, iface)[0]
                resok = s.newValue2(ssa.OpNeqInter, types.Types[types.TBOOL], res, s.constInterface(dst))
                return
        }

        if base.Debug.TypeAssert > 0 {
                base.WarnfAt(pos, "type assertion inlined")
        }

        // Converting to a concrete type.
        direct := types.IsDirectIface(dst)
        itab := s.newValue1(ssa.OpITab, byteptr, iface) // type word of interface
        if base.Debug.TypeAssert > 0 {
                base.WarnfAt(pos, "type assertion inlined")
        }
        var wantedFirstWord *ssa.Value
        if src.IsEmptyInterface() {
                // Looking for pointer to target type.
                wantedFirstWord = target
        } else {
                // Looking for pointer to itab for target type and source interface.
                wantedFirstWord = targetItab
        }

        var tmp ir.Node     // temporary for use with large types
        var addr *ssa.Value // address of tmp
        if commaok && !TypeOK(dst) {
                // unSSAable type, use temporary.
                // TODO: get rid of some of these temporaries.
                tmp, addr = s.temp(pos, dst)
        }

        cond := s.newValue2(ssa.OpEqPtr, types.Types[types.TBOOL], itab, wantedFirstWord)
        b := s.endBlock()
        b.Kind = ssa.BlockIf
        b.SetControl(cond)
        b.Likely = ssa.BranchLikely

        bOk := s.f.NewBlock(ssa.BlockPlain)
        bFail := s.f.NewBlock(ssa.BlockPlain)
        b.AddEdgeTo(bOk)
        b.AddEdgeTo(bFail)

        if !commaok {
                // on failure, panic by calling panicdottype
                s.startBlock(bFail)
                taddr := source
                if taddr == nil {
                        taddr = s.reflectType(src)
                }
                if src.IsEmptyInterface() {
                        s.rtcall(ir.Syms.PanicdottypeE, false, nil, itab, target, taddr)
                } else {
                        s.rtcall(ir.Syms.PanicdottypeI, false, nil, itab, target, taddr)
                }

                // on success, return data from interface
                s.startBlock(bOk)
                if direct {
                        return s.newValue1(ssa.OpIData, dst, iface), nil
                }
                p := s.newValue1(ssa.OpIData, types.NewPtr(dst), iface)
                return s.load(dst, p), nil
        }

        // commaok is the more complicated case because we have
        // a control flow merge point.
        bEnd := s.f.NewBlock(ssa.BlockPlain)
        // Note that we need a new valVar each time (unlike okVar where we can
        // reuse the variable) because it might have a different type every time.
        valVar := ssaMarker("val")

        // type assertion succeeded
        s.startBlock(bOk)
        if tmp == nil {
                if direct {
                        s.vars[valVar] = s.newValue1(ssa.OpIData, dst, iface)
                } else {
                        p := s.newValue1(ssa.OpIData, types.NewPtr(dst), iface)
                        s.vars[valVar] = s.load(dst, p)
                }
        } else {
                p := s.newValue1(ssa.OpIData, types.NewPtr(dst), iface)
                s.move(dst, addr, p)
        }
        s.vars[okVar] = s.constBool(true)
        s.endBlock()
        bOk.AddEdgeTo(bEnd)

        // type assertion failed
        s.startBlock(bFail)
        if tmp == nil {
                s.vars[valVar] = s.zeroVal(dst)
        } else {
                s.zero(dst, addr)
        }
        s.vars[okVar] = s.constBool(false)
        s.endBlock()
        bFail.AddEdgeTo(bEnd)

        // merge point
        s.startBlock(bEnd)
        if tmp == nil {
                res = s.variable(valVar, dst)
                delete(s.vars, valVar) // no practical effect, just to indicate typVar is no longer live.
        } else {
                res = s.load(dst, addr)
        }
        resok = s.variable(okVar, types.Types[types.TBOOL])
        delete(s.vars, okVar) // ditto
        return res, resok
}

// temp allocates a temp of type t at position pos
func (s *state) temp(pos src.XPos, t *types.Type) (*ir.Name, *ssa.Value) {
        tmp := typecheck.TempAt(pos, s.curfn, t)
        if t.HasPointers() {
                s.vars[memVar] = s.newValue1A(ssa.OpVarDef, types.TypeMem, tmp, s.mem())
        }
        addr := s.addr(tmp)
        return tmp, addr
}

// variable returns the value of a variable at the current location.
func (s *state) variable(n ir.Node, t *types.Type) *ssa.Value {
        v := s.vars[n]
        if v != nil {
                return v
        }
        v = s.fwdVars[n]
        if v != nil {
                return v
        }

        if s.curBlock == s.f.Entry {
                // No variable should be live at entry.
                s.f.Fatalf("value %v (%v) incorrectly live at entry", n, v)
        }
        // Make a FwdRef, which records a value that's live on block input.
        // We'll find the matching definition as part of insertPhis.
        v = s.newValue0A(ssa.OpFwdRef, t, fwdRefAux{N: n})
        s.fwdVars[n] = v
        if n.Op() == ir.ONAME {
                s.addNamedValue(n.(*ir.Name), v)
        }
        return v
}

func (s *state) mem() *ssa.Value {
        return s.variable(memVar, types.TypeMem)
}

func (s *state) addNamedValue(n *ir.Name, v *ssa.Value) {
        if n.Class == ir.Pxxx {
                // Don't track our marker nodes (memVar etc.).
                return
        }
        if ir.IsAutoTmp(n) {
                // Don't track temporary variables.
                return
        }
        if n.Class == ir.PPARAMOUT {
                // Don't track named output values.  This prevents return values
                // from being assigned too early. See #14591 and #14762. TODO: allow this.
                return
        }
        loc := ssa.LocalSlot{N: n, Type: n.Type(), Off: 0}
        values, ok := s.f.NamedValues[loc]
        if !ok {
                s.f.Names = append(s.f.Names, &loc)
                s.f.CanonicalLocalSlots[loc] = &loc
        }
        s.f.NamedValues[loc] = append(values, v)
}

// Branch is an unresolved branch.
type Branch struct {
        P *obj.Prog  // branch instruction
        B *ssa.Block // target
}

// State contains state needed during Prog generation.
type State struct {
        ABI obj.ABI

        pp *objw.Progs

        // Branches remembers all the branch instructions we've seen
        // and where they would like to go.
        Branches []Branch

        // JumpTables remembers all the jump tables we've seen.
        JumpTables []*ssa.Block

        // bstart remembers where each block starts (indexed by block ID)
        bstart []*obj.Prog

        maxarg int64 // largest frame size for arguments to calls made by the function

        // Map from GC safe points to liveness index, generated by
        // liveness analysis.
        livenessMap liveness.Map

        // partLiveArgs includes arguments that may be partially live, for which we
        // need to generate instructions that spill the argument registers.
        partLiveArgs map[*ir.Name]bool

        // lineRunStart records the beginning of the current run of instructions
        // within a single block sharing the same line number
        // Used to move statement marks to the beginning of such runs.
        lineRunStart *obj.Prog

        // wasm: The number of values on the WebAssembly stack. This is only used as a safeguard.
        OnWasmStackSkipped int
}

func (s *State) FuncInfo() *obj.FuncInfo {
        return s.pp.CurFunc.LSym.Func()
}

// Prog appends a new Prog.
func (s *State) Prog(as obj.As) *obj.Prog {
        p := s.pp.Prog(as)
        if objw.LosesStmtMark(as) {
                return p
        }
        // Float a statement start to the beginning of any same-line run.
        // lineRunStart is reset at block boundaries, which appears to work well.
        if s.lineRunStart == nil || s.lineRunStart.Pos.Line() != p.Pos.Line() {
                s.lineRunStart = p
        } else if p.Pos.IsStmt() == src.PosIsStmt {
                s.lineRunStart.Pos = s.lineRunStart.Pos.WithIsStmt()
                p.Pos = p.Pos.WithNotStmt()
        }
        return p
}

// Pc returns the current Prog.
func (s *State) Pc() *obj.Prog {
        return s.pp.Next
}

// SetPos sets the current source position.
func (s *State) SetPos(pos src.XPos) {
        s.pp.Pos = pos
}

// Br emits a single branch instruction and returns the instruction.
// Not all architectures need the returned instruction, but otherwise
// the boilerplate is common to all.
func (s *State) Br(op obj.As, target *ssa.Block) *obj.Prog {
        p := s.Prog(op)
        p.To.Type = obj.TYPE_BRANCH
        s.Branches = append(s.Branches, Branch{P: p, B: target})
        return p
}

// DebugFriendlySetPosFrom adjusts Pos.IsStmt subject to heuristics
// that reduce "jumpy" line number churn when debugging.
// Spill/fill/copy instructions from the register allocator,
// phi functions, and instructions with a no-pos position
// are examples of instructions that can cause churn.
func (s *State) DebugFriendlySetPosFrom(v *ssa.Value) {
        switch v.Op {
        case ssa.OpPhi, ssa.OpCopy, ssa.OpLoadReg, ssa.OpStoreReg:
                // These are not statements
                s.SetPos(v.Pos.WithNotStmt())
        default:
                p := v.Pos
                if p != src.NoXPos {
                        // If the position is defined, update the position.
                        // Also convert default IsStmt to NotStmt; only
                        // explicit statement boundaries should appear
                        // in the generated code.
                        if p.IsStmt() != src.PosIsStmt {
                                if s.pp.Pos.IsStmt() == src.PosIsStmt && s.pp.Pos.SameFileAndLine(p) {
                                        // If s.pp.Pos already has a statement mark, then it was set here (below) for
                                        // the previous value.  If an actual instruction had been emitted for that
                                        // value, then the statement mark would have been reset.  Since the statement
                                        // mark of s.pp.Pos was not reset, this position (file/line) still needs a
                                        // statement mark on an instruction.  If file and line for this value are
                                        // the same as the previous value, then the first instruction for this
                                        // value will work to take the statement mark.  Return early to avoid
                                        // resetting the statement mark.
                                        //
                                        // The reset of s.pp.Pos occurs in (*Progs).Prog() -- if it emits
                                        // an instruction, and the instruction's statement mark was set,
                                        // and it is not one of the LosesStmtMark instructions,
                                        // then Prog() resets the statement mark on the (*Progs).Pos.
                                        return
                                }
                                p = p.WithNotStmt()
                                // Calls use the pos attached to v, but copy the statement mark from State
                        }
                        s.SetPos(p)
                } else {
                        s.SetPos(s.pp.Pos.WithNotStmt())
                }
        }
}

// emit argument info (locations on stack) for traceback.
func emitArgInfo(e *ssafn, f *ssa.Func, pp *objw.Progs) {
        ft := e.curfn.Type()
        if ft.NumRecvs() == 0 && ft.NumParams() == 0 {
                return
        }

        x := EmitArgInfo(e.curfn, f.OwnAux.ABIInfo())
        x.Set(obj.AttrContentAddressable, true)
        e.curfn.LSym.Func().ArgInfo = x

        // Emit a funcdata pointing at the arg info data.
        p := pp.Prog(obj.AFUNCDATA)
        p.From.SetConst(rtabi.FUNCDATA_ArgInfo)
        p.To.Type = obj.TYPE_MEM
        p.To.Name = obj.NAME_EXTERN
        p.To.Sym = x
}

// emit argument info (locations on stack) of f for traceback.
func EmitArgInfo(f *ir.Func, abiInfo *abi.ABIParamResultInfo) *obj.LSym {
        x := base.Ctxt.Lookup(fmt.Sprintf("%s.arginfo%d", f.LSym.Name, f.ABI))
        // NOTE: do not set ContentAddressable here. This may be referenced from
        // assembly code by name (in this case f is a declaration).
        // Instead, set it in emitArgInfo above.

        PtrSize := int64(types.PtrSize)
        uintptrTyp := types.Types[types.TUINTPTR]

        isAggregate := func(t *types.Type) bool {
                return t.IsStruct() || t.IsArray() || t.IsComplex() || t.IsInterface() || t.IsString() || t.IsSlice()
        }

        // Populate the data.
        // The data is a stream of bytes, which contains the offsets and sizes of the
        // non-aggregate arguments or non-aggregate fields/elements of aggregate-typed
        // arguments, along with special "operators". Specifically,
        // - for each non-aggrgate arg/field/element, its offset from FP (1 byte) and
        //   size (1 byte)
        // - special operators:
        //   - 0xff - end of sequence
        //   - 0xfe - print { (at the start of an aggregate-typed argument)
        //   - 0xfd - print } (at the end of an aggregate-typed argument)
        //   - 0xfc - print ... (more args/fields/elements)
        //   - 0xfb - print _ (offset too large)
        // These constants need to be in sync with runtime.traceback.go:printArgs.
        const (
                _endSeq         = 0xff
                _startAgg       = 0xfe
                _endAgg         = 0xfd
                _dotdotdot      = 0xfc
                _offsetTooLarge = 0xfb
                _special        = 0xf0 // above this are operators, below this are ordinary offsets
        )

        const (
                limit    = 10 // print no more than 10 args/components
                maxDepth = 5  // no more than 5 layers of nesting

                // maxLen is a (conservative) upper bound of the byte stream length. For
                // each arg/component, it has no more than 2 bytes of data (size, offset),
                // and no more than one {, }, ... at each level (it cannot have both the
                // data and ... unless it is the last one, just be conservative). Plus 1
                // for _endSeq.
                maxLen = (maxDepth*3+2)*limit + 1
        )

        wOff := 0
        n := 0
        writebyte := func(o uint8) { wOff = objw.Uint8(x, wOff, o) }

        // Write one non-aggrgate arg/field/element.
        write1 := func(sz, offset int64) {
                if offset >= _special {
                        writebyte(_offsetTooLarge)
                } else {
                        writebyte(uint8(offset))
                        writebyte(uint8(sz))
                }
                n++
        }

        // Visit t recursively and write it out.
        // Returns whether to continue visiting.
        var visitType func(baseOffset int64, t *types.Type, depth int) bool
        visitType = func(baseOffset int64, t *types.Type, depth int) bool {
                if n >= limit {
                        writebyte(_dotdotdot)
                        return false
                }
                if !isAggregate(t) {
                        write1(t.Size(), baseOffset)
                        return true
                }
                writebyte(_startAgg)
                depth++
                if depth >= maxDepth {
                        writebyte(_dotdotdot)
                        writebyte(_endAgg)
                        n++
                        return true
                }
                switch {
                case t.IsInterface(), t.IsString():
                        _ = visitType(baseOffset, uintptrTyp, depth) &&
                                visitType(baseOffset+PtrSize, uintptrTyp, depth)
                case t.IsSlice():
                        _ = visitType(baseOffset, uintptrTyp, depth) &&
                                visitType(baseOffset+PtrSize, uintptrTyp, depth) &&
                                visitType(baseOffset+PtrSize*2, uintptrTyp, depth)
                case t.IsComplex():
                        _ = visitType(baseOffset, types.FloatForComplex(t), depth) &&
                                visitType(baseOffset+t.Size()/2, types.FloatForComplex(t), depth)
                case t.IsArray():
                        if t.NumElem() == 0 {
                                n++ // {} counts as a component
                                break
                        }
                        for i := int64(0); i < t.NumElem(); i++ {
                                if !visitType(baseOffset, t.Elem(), depth) {
                                        break
                                }
                                baseOffset += t.Elem().Size()
                        }
                case t.IsStruct():
                        if t.NumFields() == 0 {
                                n++ // {} counts as a component
                                break
                        }
                        for _, field := range t.Fields().Slice() {
                                if !visitType(baseOffset+field.Offset, field.Type, depth) {
                                        break
                                }
                        }
                }
                writebyte(_endAgg)
                return true
        }

        start := 0
        if strings.Contains(f.LSym.Name, "[") {
                // Skip the dictionary argument - it is implicit and the user doesn't need to see it.
                start = 1
        }

        for _, a := range abiInfo.InParams()[start:] {
                if !visitType(a.FrameOffset(abiInfo), a.Type, 0) {
                        break
                }
        }
        writebyte(_endSeq)
        if wOff > maxLen {
                base.Fatalf("ArgInfo too large")
        }

        return x
}

// for wrapper, emit info of wrapped function.
func emitWrappedFuncInfo(e *ssafn, pp *objw.Progs) {
        if base.Ctxt.Flag_linkshared {
                // Relative reference (SymPtrOff) to another shared object doesn't work.
                // Unfortunate.
                return
        }

        wfn := e.curfn.WrappedFunc
        if wfn == nil {
                return
        }

        wsym := wfn.Linksym()
        x := base.Ctxt.LookupInit(fmt.Sprintf("%s.wrapinfo", wsym.Name), func(x *obj.LSym) {
                objw.SymPtrOff(x, 0, wsym)
                x.Set(obj.AttrContentAddressable, true)
        })
        e.curfn.LSym.Func().WrapInfo = x

        // Emit a funcdata pointing at the wrap info data.
        p := pp.Prog(obj.AFUNCDATA)
        p.From.SetConst(rtabi.FUNCDATA_WrapInfo)
        p.To.Type = obj.TYPE_MEM
        p.To.Name = obj.NAME_EXTERN
        p.To.Sym = x
}

// genssa appends entries to pp for each instruction in f.
func genssa(f *ssa.Func, pp *objw.Progs) {
        var s State
        s.ABI = f.OwnAux.Fn.ABI()

        e := f.Frontend().(*ssafn)

        s.livenessMap, s.partLiveArgs = liveness.Compute(e.curfn, f, e.stkptrsize, pp)
        emitArgInfo(e, f, pp)
        argLiveBlockMap, argLiveValueMap := liveness.ArgLiveness(e.curfn, f, pp)

        openDeferInfo := e.curfn.LSym.Func().OpenCodedDeferInfo
        if openDeferInfo != nil {
                // This function uses open-coded defers -- write out the funcdata
                // info that we computed at the end of genssa.
                p := pp.Prog(obj.AFUNCDATA)
                p.From.SetConst(rtabi.FUNCDATA_OpenCodedDeferInfo)
                p.To.Type = obj.TYPE_MEM
                p.To.Name = obj.NAME_EXTERN
                p.To.Sym = openDeferInfo
        }

        emitWrappedFuncInfo(e, pp)

        // Remember where each block starts.
        s.bstart = make([]*obj.Prog, f.NumBlocks())
        s.pp = pp
        var progToValue map[*obj.Prog]*ssa.Value
        var progToBlock map[*obj.Prog]*ssa.Block
        var valueToProgAfter []*obj.Prog // The first Prog following computation of a value v; v is visible at this point.
        gatherPrintInfo := f.PrintOrHtmlSSA || ssa.GenssaDump[f.Name]
        if gatherPrintInfo {
                progToValue = make(map[*obj.Prog]*ssa.Value, f.NumValues())
                progToBlock = make(map[*obj.Prog]*ssa.Block, f.NumBlocks())
                f.Logf("genssa %s\n", f.Name)
                progToBlock[s.pp.Next] = f.Blocks[0]
        }

        if base.Ctxt.Flag_locationlists {
                if cap(f.Cache.ValueToProgAfter) < f.NumValues() {
                        f.Cache.ValueToProgAfter = make([]*obj.Prog, f.NumValues())
                }
                valueToProgAfter = f.Cache.ValueToProgAfter[:f.NumValues()]
                for i := range valueToProgAfter {
                        valueToProgAfter[i] = nil
                }
        }

        // If the very first instruction is not tagged as a statement,
        // debuggers may attribute it to previous function in program.
        firstPos := src.NoXPos
        for _, v := range f.Entry.Values {
                if v.Pos.IsStmt() == src.PosIsStmt && v.Op != ssa.OpArg && v.Op != ssa.OpArgIntReg && v.Op != ssa.OpArgFloatReg && v.Op != ssa.OpLoadReg && v.Op != ssa.OpStoreReg {
                        firstPos = v.Pos
                        v.Pos = firstPos.WithDefaultStmt()
                        break
                }
        }

        // inlMarks has an entry for each Prog that implements an inline mark.
        // It maps from that Prog to the global inlining id of the inlined body
        // which should unwind to this Prog's location.
        var inlMarks map[*obj.Prog]int32
        var inlMarkList []*obj.Prog

        // inlMarksByPos maps from a (column 1) source position to the set of
        // Progs that are in the set above and have that source position.
        var inlMarksByPos map[src.XPos][]*obj.Prog

        var argLiveIdx int = -1 // argument liveness info index

        // Emit basic blocks
        for i, b := range f.Blocks {
                s.bstart[b.ID] = s.pp.Next
                s.lineRunStart = nil
                s.SetPos(s.pp.Pos.WithNotStmt()) // It needs a non-empty Pos, but cannot be a statement boundary (yet).

                if idx, ok := argLiveBlockMap[b.ID]; ok && idx != argLiveIdx {
                        argLiveIdx = idx
                        p := s.pp.Prog(obj.APCDATA)
                        p.From.SetConst(rtabi.PCDATA_ArgLiveIndex)
                        p.To.SetConst(int64(idx))
                }

                // Emit values in block
                Arch.SSAMarkMoves(&s, b)
                for _, v := range b.Values {
                        x := s.pp.Next
                        s.DebugFriendlySetPosFrom(v)

                        if v.Op.ResultInArg0() && v.ResultReg() != v.Args[0].Reg() {
                                v.Fatalf("input[0] and output not in same register %s", v.LongString())
                        }

                        switch v.Op {
                        case ssa.OpInitMem:
                                // memory arg needs no code
                        case ssa.OpArg:
                                // input args need no code
                        case ssa.OpSP, ssa.OpSB:
                                // nothing to do
                        case ssa.OpSelect0, ssa.OpSelect1, ssa.OpSelectN, ssa.OpMakeResult:
                                // nothing to do
                        case ssa.OpGetG:
                                // nothing to do when there's a g register,
                                // and checkLower complains if there's not
                        case ssa.OpVarDef, ssa.OpVarLive, ssa.OpKeepAlive, ssa.OpWBend:
                                // nothing to do; already used by liveness
                        case ssa.OpPhi:
                                CheckLoweredPhi(v)
                        case ssa.OpConvert:
                                // nothing to do; no-op conversion for liveness
                                if v.Args[0].Reg() != v.Reg() {
                                        v.Fatalf("OpConvert should be a no-op: %s; %s", v.Args[0].LongString(), v.LongString())
                                }
                        case ssa.OpInlMark:
                                p := Arch.Ginsnop(s.pp)
                                if inlMarks == nil {
                                        inlMarks = map[*obj.Prog]int32{}
                                        inlMarksByPos = map[src.XPos][]*obj.Prog{}
                                }
                                inlMarks[p] = v.AuxInt32()
                                inlMarkList = append(inlMarkList, p)
                                pos := v.Pos.AtColumn1()
                                inlMarksByPos[pos] = append(inlMarksByPos[pos], p)
                                firstPos = src.NoXPos

                        default:
                                // Special case for first line in function; move it to the start (which cannot be a register-valued instruction)
                                if firstPos != src.NoXPos && v.Op != ssa.OpArgIntReg && v.Op != ssa.OpArgFloatReg && v.Op != ssa.OpLoadReg && v.Op != ssa.OpStoreReg {
                                        s.SetPos(firstPos)
                                        firstPos = src.NoXPos
                                }
                                // Attach this safe point to the next
                                // instruction.
                                s.pp.NextLive = s.livenessMap.Get(v)
                                s.pp.NextUnsafe = s.livenessMap.GetUnsafe(v)

                                // let the backend handle it
                                Arch.SSAGenValue(&s, v)
                        }

                        if idx, ok := argLiveValueMap[v.ID]; ok && idx != argLiveIdx {
                                argLiveIdx = idx
                                p := s.pp.Prog(obj.APCDATA)
                                p.From.SetConst(rtabi.PCDATA_ArgLiveIndex)
                                p.To.SetConst(int64(idx))
                        }

                        if base.Ctxt.Flag_locationlists {
                                valueToProgAfter[v.ID] = s.pp.Next
                        }

                        if gatherPrintInfo {
                                for ; x != s.pp.Next; x = x.Link {
                                        progToValue[x] = v
                                }
                        }
                }
                // If this is an empty infinite loop, stick a hardware NOP in there so that debuggers are less confused.
                if s.bstart[b.ID] == s.pp.Next && len(b.Succs) == 1 && b.Succs[0].Block() == b {
                        p := Arch.Ginsnop(s.pp)
                        p.Pos = p.Pos.WithIsStmt()
                        if b.Pos == src.NoXPos {
                                b.Pos = p.Pos // It needs a file, otherwise a no-file non-zero line causes confusion.  See #35652.
                                if b.Pos == src.NoXPos {
                                        b.Pos = pp.Text.Pos // Sometimes p.Pos is empty.  See #35695.
                                }
                        }
                        b.Pos = b.Pos.WithBogusLine() // Debuggers are not good about infinite loops, force a change in line number
                }

                // Set unsafe mark for any end-of-block generated instructions
                // (normally, conditional or unconditional branches).
                // This is particularly important for empty blocks, as there
                // are no values to inherit the unsafe mark from.
                s.pp.NextUnsafe = s.livenessMap.GetUnsafeBlock(b)

                // Emit control flow instructions for block
                var next *ssa.Block
                if i < len(f.Blocks)-1 && base.Flag.N == 0 {
                        // If -N, leave next==nil so every block with successors
                        // ends in a JMP (except call blocks - plive doesn't like
                        // select{send,recv} followed by a JMP call).  Helps keep
                        // line numbers for otherwise empty blocks.
                        next = f.Blocks[i+1]
                }
                x := s.pp.Next
                s.SetPos(b.Pos)
                Arch.SSAGenBlock(&s, b, next)
                if gatherPrintInfo {
                        for ; x != s.pp.Next; x = x.Link {
                                progToBlock[x] = b
                        }
                }
        }
        if f.Blocks[len(f.Blocks)-1].Kind == ssa.BlockExit {
                // We need the return address of a panic call to
                // still be inside the function in question. So if
                // it ends in a call which doesn't return, add a
                // nop (which will never execute) after the call.
                Arch.Ginsnop(pp)
        }
        if openDeferInfo != nil {
                // When doing open-coded defers, generate a disconnected call to
                // deferreturn and a return. This will be used to during panic
                // recovery to unwind the stack and return back to the runtime.
                s.pp.NextLive = s.livenessMap.DeferReturn
                p := pp.Prog(obj.ACALL)
                p.To.Type = obj.TYPE_MEM
                p.To.Name = obj.NAME_EXTERN
                p.To.Sym = ir.Syms.Deferreturn

                // Load results into registers. So when a deferred function
                // recovers a panic, it will return to caller with right results.
                // The results are already in memory, because they are not SSA'd
                // when the function has defers (see canSSAName).
                for _, o := range f.OwnAux.ABIInfo().OutParams() {
                        n := o.Name.(*ir.Name)
                        rts, offs := o.RegisterTypesAndOffsets()
                        for i := range o.Registers {
                                Arch.LoadRegResult(&s, f, rts[i], ssa.ObjRegForAbiReg(o.Registers[i], f.Config), n, offs[i])
                        }
                }

                pp.Prog(obj.ARET)
        }

        if inlMarks != nil {
                hasCall := false

                // We have some inline marks. Try to find other instructions we're
                // going to emit anyway, and use those instructions instead of the
                // inline marks.
                for p := pp.Text; p != nil; p = p.Link {
                        if p.As == obj.ANOP || p.As == obj.AFUNCDATA || p.As == obj.APCDATA || p.As == obj.ATEXT || p.As == obj.APCALIGN || Arch.LinkArch.Family == sys.Wasm {
                                // Don't use 0-sized instructions as inline marks, because we need
                                // to identify inline mark instructions by pc offset.
                                // (Some of these instructions are sometimes zero-sized, sometimes not.
                                // We must not use anything that even might be zero-sized.)
                                // TODO: are there others?
                                continue
                        }
                        if _, ok := inlMarks[p]; ok {
                                // Don't use inline marks themselves. We don't know
                                // whether they will be zero-sized or not yet.
                                continue
                        }
                        if p.As == obj.ACALL || p.As == obj.ADUFFCOPY || p.As == obj.ADUFFZERO {
                                hasCall = true
                        }
                        pos := p.Pos.AtColumn1()
                        s := inlMarksByPos[pos]
                        if len(s) == 0 {
                                continue
                        }
                        for _, m := range s {
                                // We found an instruction with the same source position as
                                // some of the inline marks.
                                // Use this instruction instead.
                                p.Pos = p.Pos.WithIsStmt() // promote position to a statement
                                pp.CurFunc.LSym.Func().AddInlMark(p, inlMarks[m])
                                // Make the inline mark a real nop, so it doesn't generate any code.
                                m.As = obj.ANOP
                                m.Pos = src.NoXPos
                                m.From = obj.Addr{}
                                m.To = obj.Addr{}
                        }
                        delete(inlMarksByPos, pos)
                }
                // Any unmatched inline marks now need to be added to the inlining tree (and will generate a nop instruction).
                for _, p := range inlMarkList {
                        if p.As != obj.ANOP {
                                pp.CurFunc.LSym.Func().AddInlMark(p, inlMarks[p])
                        }
                }

                if e.stksize == 0 && !hasCall {
                        // Frameless leaf function. It doesn't need any preamble,
                        // so make sure its first instruction isn't from an inlined callee.
                        // If it is, add a nop at the start of the function with a position
                        // equal to the start of the function.
                        // This ensures that runtime.FuncForPC(uintptr(reflect.ValueOf(fn).Pointer())).Name()
                        // returns the right answer. See issue 58300.
                        for p := pp.Text; p != nil; p = p.Link {
                                if p.As == obj.AFUNCDATA || p.As == obj.APCDATA || p.As == obj.ATEXT || p.As == obj.ANOP {
                                        continue
                                }
                                if base.Ctxt.PosTable.Pos(p.Pos).Base().InliningIndex() >= 0 {
                                        // Make a real (not 0-sized) nop.
                                        nop := Arch.Ginsnop(pp)
                                        nop.Pos = e.curfn.Pos().WithIsStmt()

                                        // Unfortunately, Ginsnop puts the instruction at the
                                        // end of the list. Move it up to just before p.

                                        // Unlink from the current list.
                                        for x := pp.Text; x != nil; x = x.Link {
                                                if x.Link == nop {
                                                        x.Link = nop.Link
                                                        break
                                                }
                                        }
                                        // Splice in right before p.
                                        for x := pp.Text; x != nil; x = x.Link {
                                                if x.Link == p {
                                                        nop.Link = p
                                                        x.Link = nop
                                                        break
                                                }
                                        }
                                }
                                break
                        }
                }
        }

        if base.Ctxt.Flag_locationlists {
                var debugInfo *ssa.FuncDebug
                debugInfo = e.curfn.DebugInfo.(*ssa.FuncDebug)
                if e.curfn.ABI == obj.ABIInternal && base.Flag.N != 0 {
                        ssa.BuildFuncDebugNoOptimized(base.Ctxt, f, base.Debug.LocationLists > 1, StackOffset, debugInfo)
                } else {
                        ssa.BuildFuncDebug(base.Ctxt, f, base.Debug.LocationLists, StackOffset, debugInfo)
                }
                bstart := s.bstart
                idToIdx := make([]int, f.NumBlocks())
                for i, b := range f.Blocks {
                        idToIdx[b.ID] = i
                }
                // Note that at this moment, Prog.Pc is a sequence number; it's
                // not a real PC until after assembly, so this mapping has to
                // be done later.
                debugInfo.GetPC = func(b, v ssa.ID) int64 {
                        switch v {
                        case ssa.BlockStart.ID:
                                if b == f.Entry.ID {
                                        return 0 // Start at the very beginning, at the assembler-generated prologue.
                                        // this should only happen for function args (ssa.OpArg)
                                }
                                return bstart[b].Pc
                        case ssa.BlockEnd.ID:
                                blk := f.Blocks[idToIdx[b]]
                                nv := len(blk.Values)
                                return valueToProgAfter[blk.Values[nv-1].ID].Pc
                        case ssa.FuncEnd.ID:
                                return e.curfn.LSym.Size
                        default:
                                return valueToProgAfter[v].Pc
                        }
                }
        }

        // Resolve branches, and relax DefaultStmt into NotStmt
        for _, br := range s.Branches {
                br.P.To.SetTarget(s.bstart[br.B.ID])
                if br.P.Pos.IsStmt() != src.PosIsStmt {
                        br.P.Pos = br.P.Pos.WithNotStmt()
                } else if v0 := br.B.FirstPossibleStmtValue(); v0 != nil && v0.Pos.Line() == br.P.Pos.Line() && v0.Pos.IsStmt() == src.PosIsStmt {
                        br.P.Pos = br.P.Pos.WithNotStmt()
                }

        }

        // Resolve jump table destinations.
        for _, jt := range s.JumpTables {
                // Convert from *Block targets to *Prog targets.
                targets := make([]*obj.Prog, len(jt.Succs))
                for i, e := range jt.Succs {
                        targets[i] = s.bstart[e.Block().ID]
                }
                // Add to list of jump tables to be resolved at assembly time.
                // The assembler converts from *Prog entries to absolute addresses
                // once it knows instruction byte offsets.
                fi := pp.CurFunc.LSym.Func()
                fi.JumpTables = append(fi.JumpTables, obj.JumpTable{Sym: jt.Aux.(*obj.LSym), Targets: targets})
        }

        if e.log { // spew to stdout
                filename := ""
                for p := pp.Text; p != nil; p = p.Link {
                        if p.Pos.IsKnown() && p.InnermostFilename() != filename {
                                filename = p.InnermostFilename()
                                f.Logf("# %s\n", filename)
                        }

                        var s string
                        if v, ok := progToValue[p]; ok {
                                s = v.String()
                        } else if b, ok := progToBlock[p]; ok {
                                s = b.String()
                        } else {
                                s = "   " // most value and branch strings are 2-3 characters long
                        }
                        f.Logf(" %-6s\t%.5d (%s)\t%s\n", s, p.Pc, p.InnermostLineNumber(), p.InstructionString())
                }
        }
        if f.HTMLWriter != nil { // spew to ssa.html
                var buf strings.Builder
                buf.WriteString("<code>")
                buf.WriteString("<dl class=\"ssa-gen\">")
                filename := ""
                for p := pp.Text; p != nil; p = p.Link {
                        // Don't spam every line with the file name, which is often huge.
                        // Only print changes, and "unknown" is not a change.
                        if p.Pos.IsKnown() && p.InnermostFilename() != filename {
                                filename = p.InnermostFilename()
                                buf.WriteString("<dt class=\"ssa-prog-src\"></dt><dd class=\"ssa-prog\">")
                                buf.WriteString(html.EscapeString("# " + filename))
                                buf.WriteString("</dd>")
                        }

                        buf.WriteString("<dt class=\"ssa-prog-src\">")
                        if v, ok := progToValue[p]; ok {
                                buf.WriteString(v.HTML())
                        } else if b, ok := progToBlock[p]; ok {
                                buf.WriteString("<b>" + b.HTML() + "</b>")
                        }
                        buf.WriteString("</dt>")
                        buf.WriteString("<dd class=\"ssa-prog\">")
                        fmt.Fprintf(&buf, "%.5d <span class=\"l%v line-number\">(%s)</span> %s", p.Pc, p.InnermostLineNumber(), p.InnermostLineNumberHTML(), html.EscapeString(p.InstructionString()))
                        buf.WriteString("</dd>")
                }
                buf.WriteString("</dl>")
                buf.WriteString("</code>")
                f.HTMLWriter.WriteColumn("genssa", "genssa", "ssa-prog", buf.String())
        }
        if ssa.GenssaDump[f.Name] {
                fi := f.DumpFileForPhase("genssa")
                if fi != nil {

                        // inliningDiffers if any filename changes or if any line number except the innermost (last index) changes.
                        inliningDiffers := func(a, b []src.Pos) bool {
                                if len(a) != len(b) {
                                        return true
                                }
                                for i := range a {
                                        if a[i].Filename() != b[i].Filename() {
                                                return true
                                        }
                                        if i != len(a)-1 && a[i].Line() != b[i].Line() {
                                                return true
                                        }
                                }
                                return false
                        }

                        var allPosOld []src.Pos
                        var allPos []src.Pos

                        for p := pp.Text; p != nil; p = p.Link {
                                if p.Pos.IsKnown() {
                                        allPos = allPos[:0]
                                        p.Ctxt.AllPos(p.Pos, func(pos src.Pos) { allPos = append(allPos, pos) })
                                        if inliningDiffers(allPos, allPosOld) {
                                                for _, pos := range allPos {
                                                        fmt.Fprintf(fi, "# %s:%d\n", pos.Filename(), pos.Line())
                                                }
                                                allPos, allPosOld = allPosOld, allPos // swap, not copy, so that they do not share slice storage.
                                        }
                                }

                                var s string
                                if v, ok := progToValue[p]; ok {
                                        s = v.String()
                                } else if b, ok := progToBlock[p]; ok {
                                        s = b.String()
                                } else {
                                        s = "   " // most value and branch strings are 2-3 characters long
                                }
                                fmt.Fprintf(fi, " %-6s\t%.5d %s\t%s\n", s, p.Pc, ssa.StmtString(p.Pos), p.InstructionString())
                        }
                        fi.Close()
                }
        }

        defframe(&s, e, f)

        f.HTMLWriter.Close()
        f.HTMLWriter = nil
}

func defframe(s *State, e *ssafn, f *ssa.Func) {
        pp := s.pp

        s.maxarg = types.RoundUp(s.maxarg, e.stkalign)
        frame := s.maxarg + e.stksize
        if Arch.PadFrame != nil {
                frame = Arch.PadFrame(frame)
        }

        // Fill in argument and frame size.
        pp.Text.To.Type = obj.TYPE_TEXTSIZE
        pp.Text.To.Val = int32(types.RoundUp(f.OwnAux.ArgWidth(), int64(types.RegSize)))
        pp.Text.To.Offset = frame

        p := pp.Text

        // Insert code to spill argument registers if the named slot may be partially
        // live. That is, the named slot is considered live by liveness analysis,
        // (because a part of it is live), but we may not spill all parts into the
        // slot. This can only happen with aggregate-typed arguments that are SSA-able
        // and not address-taken (for non-SSA-able or address-taken arguments we always
        // spill upfront).
        // Note: spilling is unnecessary in the -N/no-optimize case, since all values
        // will be considered non-SSAable and spilled up front.
        // TODO(register args) Make liveness more fine-grained to that partial spilling is okay.
        if f.OwnAux.ABIInfo().InRegistersUsed() != 0 && base.Flag.N == 0 {
                // First, see if it is already spilled before it may be live. Look for a spill
                // in the entry block up to the first safepoint.
                type nameOff struct {
                        n   *ir.Name
                        off int64
                }
                partLiveArgsSpilled := make(map[nameOff]bool)
                for _, v := range f.Entry.Values {
                        if v.Op.IsCall() {
                                break
                        }
                        if v.Op != ssa.OpStoreReg || v.Args[0].Op != ssa.OpArgIntReg {
                                continue
                        }
                        n, off := ssa.AutoVar(v)
                        if n.Class != ir.PPARAM || n.Addrtaken() || !TypeOK(n.Type()) || !s.partLiveArgs[n] {
                                continue
                        }
                        partLiveArgsSpilled[nameOff{n, off}] = true
                }

                // Then, insert code to spill registers if not already.
                for _, a := range f.OwnAux.ABIInfo().InParams() {
                        n, ok := a.Name.(*ir.Name)
                        if !ok || n.Addrtaken() || !TypeOK(n.Type()) || !s.partLiveArgs[n] || len(a.Registers) <= 1 {
                                continue
                        }
                        rts, offs := a.RegisterTypesAndOffsets()
                        for i := range a.Registers {
                                if !rts[i].HasPointers() {
                                        continue
                                }
                                if partLiveArgsSpilled[nameOff{n, offs[i]}] {
                                        continue // already spilled
                                }
                                reg := ssa.ObjRegForAbiReg(a.Registers[i], f.Config)
                                p = Arch.SpillArgReg(pp, p, f, rts[i], reg, n, offs[i])
                        }
                }
        }

        // Insert code to zero ambiguously live variables so that the
        // garbage collector only sees initialized values when it
        // looks for pointers.
        var lo, hi int64

        // Opaque state for backend to use. Current backends use it to
        // keep track of which helper registers have been zeroed.
        var state uint32

        // Iterate through declarations. Autos are sorted in decreasing
        // frame offset order.
        for _, n := range e.curfn.Dcl {
                if !n.Needzero() {
                        continue
                }
                if n.Class != ir.PAUTO {
                        e.Fatalf(n.Pos(), "needzero class %d", n.Class)
                }
                if n.Type().Size()%int64(types.PtrSize) != 0 || n.FrameOffset()%int64(types.PtrSize) != 0 || n.Type().Size() == 0 {
                        e.Fatalf(n.Pos(), "var %L has size %d offset %d", n, n.Type().Size(), n.Offset_)
                }

                if lo != hi && n.FrameOffset()+n.Type().Size() >= lo-int64(2*types.RegSize) {
                        // Merge with range we already have.
                        lo = n.FrameOffset()
                        continue
                }

                // Zero old range
                p = Arch.ZeroRange(pp, p, frame+lo, hi-lo, &state)

                // Set new range.
                lo = n.FrameOffset()
                hi = lo + n.Type().Size()
        }

        // Zero final range.
        Arch.ZeroRange(pp, p, frame+lo, hi-lo, &state)
}

// For generating consecutive jump instructions to model a specific branching
type IndexJump struct {
        Jump  obj.As
        Index int
}

func (s *State) oneJump(b *ssa.Block, jump *IndexJump) {
        p := s.Br(jump.Jump, b.Succs[jump.Index].Block())
        p.Pos = b.Pos
}

// CombJump generates combinational instructions (2 at present) for a block jump,
// thereby the behaviour of non-standard condition codes could be simulated
func (s *State) CombJump(b, next *ssa.Block, jumps *[2][2]IndexJump) {
        switch next {
        case b.Succs[0].Block():
                s.oneJump(b, &jumps[0][0])
                s.oneJump(b, &jumps[0][1])
        case b.Succs[1].Block():
                s.oneJump(b, &jumps[1][0])
                s.oneJump(b, &jumps[1][1])
        default:
                var q *obj.Prog
                if b.Likely != ssa.BranchUnlikely {
                        s.oneJump(b, &jumps[1][0])
                        s.oneJump(b, &jumps[1][1])
                        q = s.Br(obj.AJMP, b.Succs[1].Block())
                } else {
                        s.oneJump(b, &jumps[0][0])
                        s.oneJump(b, &jumps[0][1])
                        q = s.Br(obj.AJMP, b.Succs[0].Block())
                }
                q.Pos = b.Pos
        }
}

// AddAux adds the offset in the aux fields (AuxInt and Aux) of v to a.
func AddAux(a *obj.Addr, v *ssa.Value) {
        AddAux2(a, v, v.AuxInt)
}
func AddAux2(a *obj.Addr, v *ssa.Value, offset int64) {
        if a.Type != obj.TYPE_MEM && a.Type != obj.TYPE_ADDR {
                v.Fatalf("bad AddAux addr %v", a)
        }
        // add integer offset
        a.Offset += offset

        // If no additional symbol offset, we're done.
        if v.Aux == nil {
                return
        }
        // Add symbol's offset from its base register.
        switch n := v.Aux.(type) {
        case *ssa.AuxCall:
                a.Name = obj.NAME_EXTERN
                a.Sym = n.Fn
        case *obj.LSym:
                a.Name = obj.NAME_EXTERN
                a.Sym = n
        case *ir.Name:
                if n.Class == ir.PPARAM || (n.Class == ir.PPARAMOUT && !n.IsOutputParamInRegisters()) {
                        a.Name = obj.NAME_PARAM
                        a.Sym = ir.Orig(n).(*ir.Name).Linksym()
                        a.Offset += n.FrameOffset()
                        break
                }
                a.Name = obj.NAME_AUTO
                if n.Class == ir.PPARAMOUT {
                        a.Sym = ir.Orig(n).(*ir.Name).Linksym()
                } else {
                        a.Sym = n.Linksym()
                }
                a.Offset += n.FrameOffset()
        default:
                v.Fatalf("aux in %s not implemented %#v", v, v.Aux)
        }
}

// extendIndex extends v to a full int width.
// panic with the given kind if v does not fit in an int (only on 32-bit archs).
func (s *state) extendIndex(idx, len *ssa.Value, kind ssa.BoundsKind, bounded bool) *ssa.Value {
        size := idx.Type.Size()
        if size == s.config.PtrSize {
                return idx
        }
        if size > s.config.PtrSize {
                // truncate 64-bit indexes on 32-bit pointer archs. Test the
                // high word and branch to out-of-bounds failure if it is not 0.
                var lo *ssa.Value
                if idx.Type.IsSigned() {
                        lo = s.newValue1(ssa.OpInt64Lo, types.Types[types.TINT], idx)
                } else {
                        lo = s.newValue1(ssa.OpInt64Lo, types.Types[types.TUINT], idx)
                }
                if bounded || base.Flag.B != 0 {
                        return lo
                }
                bNext := s.f.NewBlock(ssa.BlockPlain)
                bPanic := s.f.NewBlock(ssa.BlockExit)
                hi := s.newValue1(ssa.OpInt64Hi, types.Types[types.TUINT32], idx)
                cmp := s.newValue2(ssa.OpEq32, types.Types[types.TBOOL], hi, s.constInt32(types.Types[types.TUINT32], 0))
                if !idx.Type.IsSigned() {
                        switch kind {
                        case ssa.BoundsIndex:
                                kind = ssa.BoundsIndexU
                        case ssa.BoundsSliceAlen:
                                kind = ssa.BoundsSliceAlenU
                        case ssa.BoundsSliceAcap:
                                kind = ssa.BoundsSliceAcapU
                        case ssa.BoundsSliceB:
                                kind = ssa.BoundsSliceBU
                        case ssa.BoundsSlice3Alen:
                                kind = ssa.BoundsSlice3AlenU
                        case ssa.BoundsSlice3Acap:
                                kind = ssa.BoundsSlice3AcapU
                        case ssa.BoundsSlice3B:
                                kind = ssa.BoundsSlice3BU
                        case ssa.BoundsSlice3C:
                                kind = ssa.BoundsSlice3CU
                        }
                }
                b := s.endBlock()
                b.Kind = ssa.BlockIf
                b.SetControl(cmp)
                b.Likely = ssa.BranchLikely
                b.AddEdgeTo(bNext)
                b.AddEdgeTo(bPanic)

                s.startBlock(bPanic)
                mem := s.newValue4I(ssa.OpPanicExtend, types.TypeMem, int64(kind), hi, lo, len, s.mem())
                s.endBlock().SetControl(mem)
                s.startBlock(bNext)

                return lo
        }

        // Extend value to the required size
        var op ssa.Op
        if idx.Type.IsSigned() {
                switch 10*size + s.config.PtrSize {
                case 14:
                        op = ssa.OpSignExt8to32
                case 18:
                        op = ssa.OpSignExt8to64
                case 24:
                        op = ssa.OpSignExt16to32
                case 28:
                        op = ssa.OpSignExt16to64
                case 48:
                        op = ssa.OpSignExt32to64
                default:
                        s.Fatalf("bad signed index extension %s", idx.Type)
                }
        } else {
                switch 10*size + s.config.PtrSize {
                case 14:
                        op = ssa.OpZeroExt8to32
                case 18:
                        op = ssa.OpZeroExt8to64
                case 24:
                        op = ssa.OpZeroExt16to32
                case 28:
                        op = ssa.OpZeroExt16to64
                case 48:
                        op = ssa.OpZeroExt32to64
                default:
                        s.Fatalf("bad unsigned index extension %s", idx.Type)
                }
        }
        return s.newValue1(op, types.Types[types.TINT], idx)
}

// CheckLoweredPhi checks that regalloc and stackalloc correctly handled phi values.
// Called during ssaGenValue.
func CheckLoweredPhi(v *ssa.Value) {
        if v.Op != ssa.OpPhi {
                v.Fatalf("CheckLoweredPhi called with non-phi value: %v", v.LongString())
        }
        if v.Type.IsMemory() {
                return
        }
        f := v.Block.Func
        loc := f.RegAlloc[v.ID]
        for _, a := range v.Args {
                if aloc := f.RegAlloc[a.ID]; aloc != loc { // TODO: .Equal() instead?
                        v.Fatalf("phi arg at different location than phi: %v @ %s, but arg %v @ %s\n%s\n", v, loc, a, aloc, v.Block.Func)
                }
        }
}

// CheckLoweredGetClosurePtr checks that v is the first instruction in the function's entry block,
// except for incoming in-register arguments.
// The output of LoweredGetClosurePtr is generally hardwired to the correct register.
// That register contains the closure pointer on closure entry.
func CheckLoweredGetClosurePtr(v *ssa.Value) {
        entry := v.Block.Func.Entry
        if entry != v.Block {
                base.Fatalf("in %s, badly placed LoweredGetClosurePtr: %v %v", v.Block.Func.Name, v.Block, v)
        }
        for _, w := range entry.Values {
                if w == v {
                        break
                }
                switch w.Op {
                case ssa.OpArgIntReg, ssa.OpArgFloatReg:
                        // okay
                default:
                        base.Fatalf("in %s, badly placed LoweredGetClosurePtr: %v %v", v.Block.Func.Name, v.Block, v)
                }
        }
}

// CheckArgReg ensures that v is in the function's entry block.
func CheckArgReg(v *ssa.Value) {
        entry := v.Block.Func.Entry
        if entry != v.Block {
                base.Fatalf("in %s, badly placed ArgIReg or ArgFReg: %v %v", v.Block.Func.Name, v.Block, v)
        }
}

func AddrAuto(a *obj.Addr, v *ssa.Value) {
        n, off := ssa.AutoVar(v)
        a.Type = obj.TYPE_MEM
        a.Sym = n.Linksym()
        a.Reg = int16(Arch.REGSP)
        a.Offset = n.FrameOffset() + off
        if n.Class == ir.PPARAM || (n.Class == ir.PPARAMOUT && !n.IsOutputParamInRegisters()) {
                a.Name = obj.NAME_PARAM
        } else {
                a.Name = obj.NAME_AUTO
        }
}

// Call returns a new CALL instruction for the SSA value v.
// It uses PrepareCall to prepare the call.
func (s *State) Call(v *ssa.Value) *obj.Prog {
        pPosIsStmt := s.pp.Pos.IsStmt() // The statement-ness fo the call comes from ssaGenState
        s.PrepareCall(v)

        p := s.Prog(obj.ACALL)
        if pPosIsStmt == src.PosIsStmt {
                p.Pos = v.Pos.WithIsStmt()
        } else {
                p.Pos = v.Pos.WithNotStmt()
        }
        if sym, ok := v.Aux.(*ssa.AuxCall); ok && sym.Fn != nil {
                p.To.Type = obj.TYPE_MEM
                p.To.Name = obj.NAME_EXTERN
                p.To.Sym = sym.Fn
        } else {
                // TODO(mdempsky): Can these differences be eliminated?
                switch Arch.LinkArch.Family {
                case sys.AMD64, sys.I386, sys.PPC64, sys.RISCV64, sys.S390X, sys.Wasm:
                        p.To.Type = obj.TYPE_REG
                case sys.ARM, sys.ARM64, sys.Loong64, sys.MIPS, sys.MIPS64:
                        p.To.Type = obj.TYPE_MEM
                default:
                        base.Fatalf("unknown indirect call family")
                }
                p.To.Reg = v.Args[0].Reg()
        }
        return p
}

// TailCall returns a new tail call instruction for the SSA value v.
// It is like Call, but for a tail call.
func (s *State) TailCall(v *ssa.Value) *obj.Prog {
        p := s.Call(v)
        p.As = obj.ARET
        return p
}

// PrepareCall prepares to emit a CALL instruction for v and does call-related bookkeeping.
// It must be called immediately before emitting the actual CALL instruction,
// since it emits PCDATA for the stack map at the call (calls are safe points).
func (s *State) PrepareCall(v *ssa.Value) {
        idx := s.livenessMap.Get(v)
        if !idx.StackMapValid() {
                // See Liveness.hasStackMap.
                if sym, ok := v.Aux.(*ssa.AuxCall); !ok || !(sym.Fn == ir.Syms.WBZero || sym.Fn == ir.Syms.WBMove) {
                        base.Fatalf("missing stack map index for %v", v.LongString())
                }
        }

        call, ok := v.Aux.(*ssa.AuxCall)

        if ok {
                // Record call graph information for nowritebarrierrec
                // analysis.
                if nowritebarrierrecCheck != nil {
                        nowritebarrierrecCheck.recordCall(s.pp.CurFunc, call.Fn, v.Pos)
                }
        }

        if s.maxarg < v.AuxInt {
                s.maxarg = v.AuxInt
        }
}

// UseArgs records the fact that an instruction needs a certain amount of
// callee args space for its use.
func (s *State) UseArgs(n int64) {
        if s.maxarg < n {
                s.maxarg = n
        }
}

// fieldIdx finds the index of the field referred to by the ODOT node n.
func fieldIdx(n *ir.SelectorExpr) int {
        t := n.X.Type()
        if !t.IsStruct() {
                panic("ODOT's LHS is not a struct")
        }

        for i, f := range t.Fields().Slice() {
                if f.Sym == n.Sel {
                        if f.Offset != n.Offset() {
                                panic("field offset doesn't match")
                        }
                        return i
                }
        }
        panic(fmt.Sprintf("can't find field in expr %v\n", n))

        // TODO: keep the result of this function somewhere in the ODOT Node
        // so we don't have to recompute it each time we need it.
}

// ssafn holds frontend information about a function that the backend is processing.
// It also exports a bunch of compiler services for the ssa backend.
type ssafn struct {
        curfn      *ir.Func
        strings    map[string]*obj.LSym // map from constant string to data symbols
        stksize    int64                // stack size for current frame
        stkptrsize int64                // prefix of stack containing pointers

        // alignment for current frame.
        // NOTE: when stkalign > PtrSize, currently this only ensures the offsets of
        // objects in the stack frame are aligned. The stack pointer is still aligned
        // only PtrSize.
        stkalign int64

        log bool // print ssa debug to the stdout
}

// StringData returns a symbol which
// is the data component of a global string constant containing s.
func (e *ssafn) StringData(s string) *obj.LSym {
        if aux, ok := e.strings[s]; ok {
                return aux
        }
        if e.strings == nil {
                e.strings = make(map[string]*obj.LSym)
        }
        data := staticdata.StringSym(e.curfn.Pos(), s)
        e.strings[s] = data
        return data
}

func (e *ssafn) Auto(pos src.XPos, t *types.Type) *ir.Name {
        return typecheck.TempAt(pos, e.curfn, t) // Note: adds new auto to e.curfn.Func.Dcl list
}

// SplitSlot returns a slot representing the data of parent starting at offset.
func (e *ssafn) SplitSlot(parent *ssa.LocalSlot, suffix string, offset int64, t *types.Type) ssa.LocalSlot {
        node := parent.N

        if node.Class != ir.PAUTO || node.Addrtaken() {
                // addressed things and non-autos retain their parents (i.e., cannot truly be split)
                return ssa.LocalSlot{N: node, Type: t, Off: parent.Off + offset}
        }

        sym := &types.Sym{Name: node.Sym().Name + suffix, Pkg: types.LocalPkg}
        n := e.curfn.NewLocal(parent.N.Pos(), sym, ir.PAUTO, t)
        n.SetUsed(true)
        n.SetEsc(ir.EscNever)
        types.CalcSize(t)
        return ssa.LocalSlot{N: n, Type: t, Off: 0, SplitOf: parent, SplitOffset: offset}
}

func (e *ssafn) CanSSA(t *types.Type) bool {
        return TypeOK(t)
}

// Logf logs a message from the compiler.
func (e *ssafn) Logf(msg string, args ...interface{}) {
        if e.log {
                fmt.Printf(msg, args...)
        }
}

func (e *ssafn) Log() bool {
        return e.log
}

// Fatalf reports a compiler error and exits.
func (e *ssafn) Fatalf(pos src.XPos, msg string, args ...interface{}) {
        base.Pos = pos
        nargs := append([]interface{}{ir.FuncName(e.curfn)}, args...)
        base.Fatalf("'%s': "+msg, nargs...)
}

// Warnl reports a "warning", which is usually flag-triggered
// logging output for the benefit of tests.
func (e *ssafn) Warnl(pos src.XPos, fmt_ string, args ...interface{}) {
        base.WarnfAt(pos, fmt_, args...)
}

func (e *ssafn) Debug_checknil() bool {
        return base.Debug.Nil != 0
}

func (e *ssafn) UseWriteBarrier() bool {
        return base.Flag.WB
}

func (e *ssafn) Syslook(name string) *obj.LSym {
        switch name {
        case "goschedguarded":
                return ir.Syms.Goschedguarded
        case "writeBarrier":
                return ir.Syms.WriteBarrier
        case "wbZero":
                return ir.Syms.WBZero
        case "wbMove":
                return ir.Syms.WBMove
        case "cgoCheckMemmove":
                return ir.Syms.CgoCheckMemmove
        case "cgoCheckPtrWrite":
                return ir.Syms.CgoCheckPtrWrite
        }
        e.Fatalf(src.NoXPos, "unknown Syslook func %v", name)
        return nil
}

func (e *ssafn) MyImportPath() string {
        return base.Ctxt.Pkgpath
}

func (e *ssafn) Func() *ir.Func {
        return e.curfn
}

func clobberBase(n ir.Node) ir.Node {
        if n.Op() == ir.ODOT {
                n := n.(*ir.SelectorExpr)
                if n.X.Type().NumFields() == 1 {
                        return clobberBase(n.X)
                }
        }
        if n.Op() == ir.OINDEX {
                n := n.(*ir.IndexExpr)
                if n.X.Type().IsArray() && n.X.Type().NumElem() == 1 {
                        return clobberBase(n.X)
                }
        }
        return n
}

// callTargetLSym returns the correct LSym to call 'callee' using its ABI.
func callTargetLSym(callee *ir.Name) *obj.LSym {
        if callee.Func == nil {
                // TODO(austin): This happens in case of interface method I.M from imported package.
                // It's ABIInternal, and would be better if callee.Func was never nil and we didn't
                // need this case.
                return callee.Linksym()
        }

        return callee.LinksymABI(callee.Func.ABI)
}

func min8(a, b int8) int8 {
        if a < b {
                return a
        }
        return b
}

func max8(a, b int8) int8 {
        if a > b {
                return a
        }
        return b
}

const deferStructFnField = 4

// deferstruct makes a runtime._defer structure.
func deferstruct() *types.Type {
        makefield := func(name string, typ *types.Type) *types.Field {
                // Unlike the global makefield function, this one needs to set Pkg
                // because these types might be compared (in SSA CSE sorting).
                // TODO: unify this makefield and the global one above.
                sym := &types.Sym{Name: name, Pkg: types.LocalPkg}
                return types.NewField(src.NoXPos, sym, typ)
        }
        // These fields must match the ones in runtime/runtime2.go:_defer and
        // (*state).call above.
        fields := []*types.Field{
                makefield("heap", types.Types[types.TBOOL]),
                makefield("rangefunc", types.Types[types.TBOOL]),
                makefield("sp", types.Types[types.TUINTPTR]),
                makefield("pc", types.Types[types.TUINTPTR]),
                // Note: the types here don't really matter. Defer structures
                // are always scanned explicitly during stack copying and GC,
                // so we make them uintptr type even though they are real pointers.
                makefield("fn", types.Types[types.TUINTPTR]),
                makefield("link", types.Types[types.TUINTPTR]),
                makefield("head", types.Types[types.TUINTPTR]),
        }
        if name := fields[deferStructFnField].Sym.Name; name != "fn" {
                base.Fatalf("deferStructFnField is %q, not fn", name)
        }

        // build struct holding the above fields
        s := types.NewStruct(fields)
        s.SetNoalg(true)
        types.CalcStructSize(s)
        return s
}

// SpillSlotAddr uses LocalSlot information to initialize an obj.Addr
// The resulting addr is used in a non-standard context -- in the prologue
// of a function, before the frame has been constructed, so the standard
// addressing for the parameters will be wrong.
func SpillSlotAddr(spill ssa.Spill, baseReg int16, extraOffset int64) obj.Addr {
        return obj.Addr{
                Name:   obj.NAME_NONE,
                Type:   obj.TYPE_MEM,
                Reg:    baseReg,
                Offset: spill.Offset + extraOffset,
        }
}

var (
        BoundsCheckFunc [ssa.BoundsKindCount]*obj.LSym
        ExtendCheckFunc [ssa.BoundsKindCount]*obj.LSym
)