cmd/compile: sparse conditional constant propagation

[gostls13.git] / src / cmd / compile / internal / ssa / _gen / genericOps.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 main

// Generic opcodes typically specify a width. The inputs and outputs
// of that op are the given number of bits wide. There is no notion of
// "sign", so Add32 can be used both for signed and unsigned 32-bit
// addition.

// Signed/unsigned is explicit with the extension ops
// (SignExt*/ZeroExt*) and implicit as the arg to some opcodes
// (e.g. the second argument to shifts is unsigned). If not mentioned,
// all args take signed inputs, or don't care whether their inputs
// are signed or unsigned.

var genericOps = []opData{
        // 2-input arithmetic
        // Types must be consistent with Go typing. Add, for example, must take two values
        // of the same type and produces that same type.
        {name: "Add8", argLength: 2, commutative: true}, // arg0 + arg1
        {name: "Add16", argLength: 2, commutative: true},
        {name: "Add32", argLength: 2, commutative: true},
        {name: "Add64", argLength: 2, commutative: true},
        {name: "AddPtr", argLength: 2}, // For address calculations.  arg0 is a pointer and arg1 is an int.
        {name: "Add32F", argLength: 2, commutative: true},
        {name: "Add64F", argLength: 2, commutative: true},

        {name: "Sub8", argLength: 2}, // arg0 - arg1
        {name: "Sub16", argLength: 2},
        {name: "Sub32", argLength: 2},
        {name: "Sub64", argLength: 2},
        {name: "SubPtr", argLength: 2},
        {name: "Sub32F", argLength: 2},
        {name: "Sub64F", argLength: 2},

        {name: "Mul8", argLength: 2, commutative: true}, // arg0 * arg1
        {name: "Mul16", argLength: 2, commutative: true},
        {name: "Mul32", argLength: 2, commutative: true},
        {name: "Mul64", argLength: 2, commutative: true},
        {name: "Mul32F", argLength: 2, commutative: true},
        {name: "Mul64F", argLength: 2, commutative: true},

        {name: "Div32F", argLength: 2}, // arg0 / arg1
        {name: "Div64F", argLength: 2},

        {name: "Hmul32", argLength: 2, commutative: true},
        {name: "Hmul32u", argLength: 2, commutative: true},
        {name: "Hmul64", argLength: 2, commutative: true},
        {name: "Hmul64u", argLength: 2, commutative: true},

        {name: "Mul32uhilo", argLength: 2, typ: "(UInt32,UInt32)", commutative: true}, // arg0 * arg1, returns (hi, lo)
        {name: "Mul64uhilo", argLength: 2, typ: "(UInt64,UInt64)", commutative: true}, // arg0 * arg1, returns (hi, lo)

        {name: "Mul32uover", argLength: 2, typ: "(UInt32,Bool)", commutative: true}, // Let x = arg0*arg1 (full 32x32-> 64 unsigned multiply), returns (uint32(x), (uint32(x) != x))
        {name: "Mul64uover", argLength: 2, typ: "(UInt64,Bool)", commutative: true}, // Let x = arg0*arg1 (full 64x64->128 unsigned multiply), returns (uint64(x), (uint64(x) != x))

        // Weird special instructions for use in the strength reduction of divides.
        // These ops compute unsigned (arg0 + arg1) / 2, correct to all
        // 32/64 bits, even when the intermediate result of the add has 33/65 bits.
        // These ops can assume arg0 >= arg1.
        // Note: these ops aren't commutative!
        {name: "Avg32u", argLength: 2, typ: "UInt32"}, // 32-bit platforms only
        {name: "Avg64u", argLength: 2, typ: "UInt64"}, // 64-bit platforms only

        // For Div16, Div32 and Div64, AuxInt non-zero means that the divisor has been proved to be not -1
        // or that the dividend is not the most negative value.
        {name: "Div8", argLength: 2},  // arg0 / arg1, signed
        {name: "Div8u", argLength: 2}, // arg0 / arg1, unsigned
        {name: "Div16", argLength: 2, aux: "Bool"},
        {name: "Div16u", argLength: 2},
        {name: "Div32", argLength: 2, aux: "Bool"},
        {name: "Div32u", argLength: 2},
        {name: "Div64", argLength: 2, aux: "Bool"},
        {name: "Div64u", argLength: 2},
        {name: "Div128u", argLength: 3}, // arg0:arg1 / arg2 (128-bit divided by 64-bit), returns (q, r)

        // For Mod16, Mod32 and Mod64, AuxInt non-zero means that the divisor has been proved to be not -1.
        {name: "Mod8", argLength: 2},  // arg0 % arg1, signed
        {name: "Mod8u", argLength: 2}, // arg0 % arg1, unsigned
        {name: "Mod16", argLength: 2, aux: "Bool"},
        {name: "Mod16u", argLength: 2},
        {name: "Mod32", argLength: 2, aux: "Bool"},
        {name: "Mod32u", argLength: 2},
        {name: "Mod64", argLength: 2, aux: "Bool"},
        {name: "Mod64u", argLength: 2},

        {name: "And8", argLength: 2, commutative: true}, // arg0 & arg1
        {name: "And16", argLength: 2, commutative: true},
        {name: "And32", argLength: 2, commutative: true},
        {name: "And64", argLength: 2, commutative: true},

        {name: "Or8", argLength: 2, commutative: true}, // arg0 | arg1
        {name: "Or16", argLength: 2, commutative: true},
        {name: "Or32", argLength: 2, commutative: true},
        {name: "Or64", argLength: 2, commutative: true},

        {name: "Xor8", argLength: 2, commutative: true}, // arg0 ^ arg1
        {name: "Xor16", argLength: 2, commutative: true},
        {name: "Xor32", argLength: 2, commutative: true},
        {name: "Xor64", argLength: 2, commutative: true},

        // For shifts, AxB means the shifted value has A bits and the shift amount has B bits.
        // Shift amounts are considered unsigned.
        // If arg1 is known to be nonnegative and less than the number of bits in arg0,
        // then auxInt may be set to 1.
        // This enables better code generation on some platforms.
        {name: "Lsh8x8", argLength: 2, aux: "Bool"}, // arg0 << arg1
        {name: "Lsh8x16", argLength: 2, aux: "Bool"},
        {name: "Lsh8x32", argLength: 2, aux: "Bool"},
        {name: "Lsh8x64", argLength: 2, aux: "Bool"},
        {name: "Lsh16x8", argLength: 2, aux: "Bool"},
        {name: "Lsh16x16", argLength: 2, aux: "Bool"},
        {name: "Lsh16x32", argLength: 2, aux: "Bool"},
        {name: "Lsh16x64", argLength: 2, aux: "Bool"},
        {name: "Lsh32x8", argLength: 2, aux: "Bool"},
        {name: "Lsh32x16", argLength: 2, aux: "Bool"},
        {name: "Lsh32x32", argLength: 2, aux: "Bool"},
        {name: "Lsh32x64", argLength: 2, aux: "Bool"},
        {name: "Lsh64x8", argLength: 2, aux: "Bool"},
        {name: "Lsh64x16", argLength: 2, aux: "Bool"},
        {name: "Lsh64x32", argLength: 2, aux: "Bool"},
        {name: "Lsh64x64", argLength: 2, aux: "Bool"},

        {name: "Rsh8x8", argLength: 2, aux: "Bool"}, // arg0 >> arg1, signed
        {name: "Rsh8x16", argLength: 2, aux: "Bool"},
        {name: "Rsh8x32", argLength: 2, aux: "Bool"},
        {name: "Rsh8x64", argLength: 2, aux: "Bool"},
        {name: "Rsh16x8", argLength: 2, aux: "Bool"},
        {name: "Rsh16x16", argLength: 2, aux: "Bool"},
        {name: "Rsh16x32", argLength: 2, aux: "Bool"},
        {name: "Rsh16x64", argLength: 2, aux: "Bool"},
        {name: "Rsh32x8", argLength: 2, aux: "Bool"},
        {name: "Rsh32x16", argLength: 2, aux: "Bool"},
        {name: "Rsh32x32", argLength: 2, aux: "Bool"},
        {name: "Rsh32x64", argLength: 2, aux: "Bool"},
        {name: "Rsh64x8", argLength: 2, aux: "Bool"},
        {name: "Rsh64x16", argLength: 2, aux: "Bool"},
        {name: "Rsh64x32", argLength: 2, aux: "Bool"},
        {name: "Rsh64x64", argLength: 2, aux: "Bool"},

        {name: "Rsh8Ux8", argLength: 2, aux: "Bool"}, // arg0 >> arg1, unsigned
        {name: "Rsh8Ux16", argLength: 2, aux: "Bool"},
        {name: "Rsh8Ux32", argLength: 2, aux: "Bool"},
        {name: "Rsh8Ux64", argLength: 2, aux: "Bool"},
        {name: "Rsh16Ux8", argLength: 2, aux: "Bool"},
        {name: "Rsh16Ux16", argLength: 2, aux: "Bool"},
        {name: "Rsh16Ux32", argLength: 2, aux: "Bool"},
        {name: "Rsh16Ux64", argLength: 2, aux: "Bool"},
        {name: "Rsh32Ux8", argLength: 2, aux: "Bool"},
        {name: "Rsh32Ux16", argLength: 2, aux: "Bool"},
        {name: "Rsh32Ux32", argLength: 2, aux: "Bool"},
        {name: "Rsh32Ux64", argLength: 2, aux: "Bool"},
        {name: "Rsh64Ux8", argLength: 2, aux: "Bool"},
        {name: "Rsh64Ux16", argLength: 2, aux: "Bool"},
        {name: "Rsh64Ux32", argLength: 2, aux: "Bool"},
        {name: "Rsh64Ux64", argLength: 2, aux: "Bool"},

        // 2-input comparisons
        {name: "Eq8", argLength: 2, commutative: true, typ: "Bool"}, // arg0 == arg1
        {name: "Eq16", argLength: 2, commutative: true, typ: "Bool"},
        {name: "Eq32", argLength: 2, commutative: true, typ: "Bool"},
        {name: "Eq64", argLength: 2, commutative: true, typ: "Bool"},
        {name: "EqPtr", argLength: 2, commutative: true, typ: "Bool"},
        {name: "EqInter", argLength: 2, typ: "Bool"}, // arg0 or arg1 is nil; other cases handled by frontend
        {name: "EqSlice", argLength: 2, typ: "Bool"}, // arg0 or arg1 is nil; other cases handled by frontend
        {name: "Eq32F", argLength: 2, commutative: true, typ: "Bool"},
        {name: "Eq64F", argLength: 2, commutative: true, typ: "Bool"},

        {name: "Neq8", argLength: 2, commutative: true, typ: "Bool"}, // arg0 != arg1
        {name: "Neq16", argLength: 2, commutative: true, typ: "Bool"},
        {name: "Neq32", argLength: 2, commutative: true, typ: "Bool"},
        {name: "Neq64", argLength: 2, commutative: true, typ: "Bool"},
        {name: "NeqPtr", argLength: 2, commutative: true, typ: "Bool"},
        {name: "NeqInter", argLength: 2, typ: "Bool"}, // arg0 or arg1 is nil; other cases handled by frontend
        {name: "NeqSlice", argLength: 2, typ: "Bool"}, // arg0 or arg1 is nil; other cases handled by frontend
        {name: "Neq32F", argLength: 2, commutative: true, typ: "Bool"},
        {name: "Neq64F", argLength: 2, commutative: true, typ: "Bool"},

        {name: "Less8", argLength: 2, typ: "Bool"},  // arg0 < arg1, signed
        {name: "Less8U", argLength: 2, typ: "Bool"}, // arg0 < arg1, unsigned
        {name: "Less16", argLength: 2, typ: "Bool"},
        {name: "Less16U", argLength: 2, typ: "Bool"},
        {name: "Less32", argLength: 2, typ: "Bool"},
        {name: "Less32U", argLength: 2, typ: "Bool"},
        {name: "Less64", argLength: 2, typ: "Bool"},
        {name: "Less64U", argLength: 2, typ: "Bool"},
        {name: "Less32F", argLength: 2, typ: "Bool"},
        {name: "Less64F", argLength: 2, typ: "Bool"},

        {name: "Leq8", argLength: 2, typ: "Bool"},  // arg0 <= arg1, signed
        {name: "Leq8U", argLength: 2, typ: "Bool"}, // arg0 <= arg1, unsigned
        {name: "Leq16", argLength: 2, typ: "Bool"},
        {name: "Leq16U", argLength: 2, typ: "Bool"},
        {name: "Leq32", argLength: 2, typ: "Bool"},
        {name: "Leq32U", argLength: 2, typ: "Bool"},
        {name: "Leq64", argLength: 2, typ: "Bool"},
        {name: "Leq64U", argLength: 2, typ: "Bool"},
        {name: "Leq32F", argLength: 2, typ: "Bool"},
        {name: "Leq64F", argLength: 2, typ: "Bool"},

        // the type of a CondSelect is the same as the type of its first
        // two arguments, which should be register-width scalars; the third
        // argument should be a boolean
        {name: "CondSelect", argLength: 3}, // arg2 ? arg0 : arg1

        // boolean ops
        {name: "AndB", argLength: 2, commutative: true, typ: "Bool"}, // arg0 && arg1 (not shortcircuited)
        {name: "OrB", argLength: 2, commutative: true, typ: "Bool"},  // arg0 || arg1 (not shortcircuited)
        {name: "EqB", argLength: 2, commutative: true, typ: "Bool"},  // arg0 == arg1
        {name: "NeqB", argLength: 2, commutative: true, typ: "Bool"}, // arg0 != arg1
        {name: "Not", argLength: 1, typ: "Bool"},                     // !arg0, boolean

        // 1-input ops
        {name: "Neg8", argLength: 1}, // -arg0
        {name: "Neg16", argLength: 1},
        {name: "Neg32", argLength: 1},
        {name: "Neg64", argLength: 1},
        {name: "Neg32F", argLength: 1},
        {name: "Neg64F", argLength: 1},

        {name: "Com8", argLength: 1}, // ^arg0
        {name: "Com16", argLength: 1},
        {name: "Com32", argLength: 1},
        {name: "Com64", argLength: 1},

        {name: "Ctz8", argLength: 1},         // Count trailing (low order) zeroes (returns 0-8)
        {name: "Ctz16", argLength: 1},        // Count trailing (low order) zeroes (returns 0-16)
        {name: "Ctz32", argLength: 1},        // Count trailing (low order) zeroes (returns 0-32)
        {name: "Ctz64", argLength: 1},        // Count trailing (low order) zeroes (returns 0-64)
        {name: "Ctz8NonZero", argLength: 1},  // same as above, but arg[0] known to be non-zero, returns 0-7
        {name: "Ctz16NonZero", argLength: 1}, // same as above, but arg[0] known to be non-zero, returns 0-15
        {name: "Ctz32NonZero", argLength: 1}, // same as above, but arg[0] known to be non-zero, returns 0-31
        {name: "Ctz64NonZero", argLength: 1}, // same as above, but arg[0] known to be non-zero, returns 0-63
        {name: "BitLen8", argLength: 1},      // Number of bits in arg[0] (returns 0-8)
        {name: "BitLen16", argLength: 1},     // Number of bits in arg[0] (returns 0-16)
        {name: "BitLen32", argLength: 1},     // Number of bits in arg[0] (returns 0-32)
        {name: "BitLen64", argLength: 1},     // Number of bits in arg[0] (returns 0-64)

        {name: "Bswap16", argLength: 1}, // Swap bytes
        {name: "Bswap32", argLength: 1}, // Swap bytes
        {name: "Bswap64", argLength: 1}, // Swap bytes

        {name: "BitRev8", argLength: 1},  // Reverse the bits in arg[0]
        {name: "BitRev16", argLength: 1}, // Reverse the bits in arg[0]
        {name: "BitRev32", argLength: 1}, // Reverse the bits in arg[0]
        {name: "BitRev64", argLength: 1}, // Reverse the bits in arg[0]

        {name: "PopCount8", argLength: 1},  // Count bits in arg[0]
        {name: "PopCount16", argLength: 1}, // Count bits in arg[0]
        {name: "PopCount32", argLength: 1}, // Count bits in arg[0]
        {name: "PopCount64", argLength: 1}, // Count bits in arg[0]

        // RotateLeftX instructions rotate the X bits of arg[0] to the left
        // by the low lg_2(X) bits of arg[1], interpreted as an unsigned value.
        // Note that this works out regardless of the bit width or signedness of
        // arg[1]. In particular, RotateLeft by x is the same as RotateRight by -x.
        {name: "RotateLeft64", argLength: 2},
        {name: "RotateLeft32", argLength: 2},
        {name: "RotateLeft16", argLength: 2},
        {name: "RotateLeft8", argLength: 2},

        // Square root.
        // Special cases:
        //   +∞  → +∞
        //   ±0  → ±0 (sign preserved)
        //   x<0 → NaN
        //   NaN → NaN
        {name: "Sqrt", argLength: 1},   // √arg0 (floating point, double precision)
        {name: "Sqrt32", argLength: 1}, // √arg0 (floating point, single precision)

        // Round to integer, float64 only.
        // Special cases:
        //   ±∞  → ±∞ (sign preserved)
        //   ±0  → ±0 (sign preserved)
        //   NaN → NaN
        {name: "Floor", argLength: 1},       // round arg0 toward -∞
        {name: "Ceil", argLength: 1},        // round arg0 toward +∞
        {name: "Trunc", argLength: 1},       // round arg0 toward 0
        {name: "Round", argLength: 1},       // round arg0 to nearest, ties away from 0
        {name: "RoundToEven", argLength: 1}, // round arg0 to nearest, ties to even

        // Modify the sign bit
        {name: "Abs", argLength: 1},      // absolute value arg0
        {name: "Copysign", argLength: 2}, // copy sign from arg0 to arg1

        // Float min/max implementation, if hardware is available.
        {name: "Min64F", argLength: 2}, // min(arg0,arg1)
        {name: "Min32F", argLength: 2}, // min(arg0,arg1)
        {name: "Max64F", argLength: 2}, // max(arg0,arg1)
        {name: "Max32F", argLength: 2}, // max(arg0,arg1)

        // 3-input opcode.
        // Fused-multiply-add, float64 only.
        // When a*b+c is exactly zero (before rounding), then the result is +0 or -0.
        // The 0's sign is determined according to the standard rules for the
        // addition (-0 if both a*b and c are -0, +0 otherwise).
        //
        // Otherwise, when a*b+c rounds to zero, then the resulting 0's sign is
        // determined by the sign of the exact result a*b+c.
        // See section 6.3 in ieee754.
        //
        // When the multiply is an infinity times a zero, the result is NaN.
        // See section 7.2 in ieee754.
        {name: "FMA", argLength: 3}, // compute (a*b)+c without intermediate rounding

        // Data movement. Max argument length for Phi is indefinite.
        {name: "Phi", argLength: -1, zeroWidth: true}, // select an argument based on which predecessor block we came from
        {name: "Copy", argLength: 1},                  // output = arg0
        // Convert converts between pointers and integers.
        // We have a special op for this so as to not confuse GC
        // (particularly stack maps).  It takes a memory arg so it
        // gets correctly ordered with respect to GC safepoints.
        // It gets compiled to nothing, so its result must in the same
        // register as its argument. regalloc knows it can use any
        // allocatable integer register for OpConvert.
        // arg0=ptr/int arg1=mem, output=int/ptr
        {name: "Convert", argLength: 2, zeroWidth: true, resultInArg0: true},

        // constants. Constant values are stored in the aux or
        // auxint fields.
        {name: "ConstBool", aux: "Bool"},     // auxint is 0 for false and 1 for true
        {name: "ConstString", aux: "String"}, // value is aux.(string)
        {name: "ConstNil", typ: "BytePtr"},   // nil pointer
        {name: "Const8", aux: "Int8"},        // auxint is sign-extended 8 bits
        {name: "Const16", aux: "Int16"},      // auxint is sign-extended 16 bits
        {name: "Const32", aux: "Int32"},      // auxint is sign-extended 32 bits
        // Note: ConstX are sign-extended even when the type of the value is unsigned.
        // For instance, uint8(0xaa) is stored as auxint=0xffffffffffffffaa.
        {name: "Const64", aux: "Int64"}, // value is auxint
        // Note: for both Const32F and Const64F, we disallow encoding NaNs.
        // Signaling NaNs are tricky because if you do anything with them, they become quiet.
        // Particularly, converting a 32 bit sNaN to 64 bit and back converts it to a qNaN.
        // See issue 36399 and 36400.
        // Encodings of +inf, -inf, and -0 are fine.
        {name: "Const32F", aux: "Float32"}, // value is math.Float64frombits(uint64(auxint)) and is exactly representable as float 32
        {name: "Const64F", aux: "Float64"}, // value is math.Float64frombits(uint64(auxint))
        {name: "ConstInterface"},           // nil interface
        {name: "ConstSlice"},               // nil slice

        // Constant-like things
        {name: "InitMem", zeroWidth: true},                               // memory input to the function.
        {name: "Arg", aux: "SymOff", symEffect: "Read", zeroWidth: true}, // argument to the function.  aux=GCNode of arg, off = offset in that arg.

        // Like Arg, these are generic ops that survive lowering. AuxInt is a register index, and the actual output register for each index is defined by the architecture.
        // AuxInt = integer argument index (not a register number). ABI-specified spill loc obtained from function
        {name: "ArgIntReg", aux: "NameOffsetInt8", zeroWidth: true},   // argument to the function in an int reg.
        {name: "ArgFloatReg", aux: "NameOffsetInt8", zeroWidth: true}, // argument to the function in a float reg.

        // The address of a variable.  arg0 is the base pointer.
        // If the variable is a global, the base pointer will be SB and
        // the Aux field will be a *obj.LSym.
        // If the variable is a local, the base pointer will be SP and
        // the Aux field will be a *gc.Node.
        {name: "Addr", argLength: 1, aux: "Sym", symEffect: "Addr"},      // Address of a variable.  Arg0=SB.  Aux identifies the variable.
        {name: "LocalAddr", argLength: 2, aux: "Sym", symEffect: "Addr"}, // Address of a variable.  Arg0=SP. Arg1=mem. Aux identifies the variable.

        {name: "SP", zeroWidth: true},                                       // stack pointer
        {name: "SB", typ: "Uintptr", zeroWidth: true},                       // static base pointer (a.k.a. globals pointer)
        {name: "Invalid"},                                                   // unused value
        {name: "SPanchored", typ: "Uintptr", argLength: 2, zeroWidth: true}, // arg0 = SP, arg1 = mem. Result is identical to arg0, but cannot be scheduled before memory state arg1.

        // Memory operations
        {name: "Load", argLength: 2},                          // Load from arg0.  arg1=memory
        {name: "Dereference", argLength: 2},                   // Load from arg0.  arg1=memory.  Helper op for arg/result passing, result is an otherwise not-SSA-able "value".
        {name: "Store", argLength: 3, typ: "Mem", aux: "Typ"}, // Store arg1 to arg0.  arg2=memory, aux=type.  Returns memory.
        // Normally we require that the source and destination of Move do not overlap.
        // There is an exception when we know all the loads will happen before all
        // the stores. In that case, overlap is ok. See
        // memmove inlining in generic.rules. When inlineablememmovesize (in ../rewrite.go)
        // returns true, we must do all loads before all stores, when lowering Move.
        // The type of Move is used for the write barrier pass to insert write barriers
        // and for alignment on some architectures.
        // For pointerless types, it is possible for the type to be inaccurate.
        // For type alignment and pointer information, use the type in Aux;
        // for type size, use the size in AuxInt.
        // The "inline runtime.memmove" rewrite rule generates Moves with inaccurate types,
        // such as type byte instead of the more accurate type [8]byte.
        {name: "Move", argLength: 3, typ: "Mem", aux: "TypSize"}, // arg0=destptr, arg1=srcptr, arg2=mem, auxint=size, aux=type.  Returns memory.
        {name: "Zero", argLength: 2, typ: "Mem", aux: "TypSize"}, // arg0=destptr, arg1=mem, auxint=size, aux=type. Returns memory.

        // Memory operations with write barriers.
        // Expand to runtime calls. Write barrier will be removed if write on stack.
        {name: "StoreWB", argLength: 3, typ: "Mem", aux: "Typ"},    // Store arg1 to arg0. arg2=memory, aux=type.  Returns memory.
        {name: "MoveWB", argLength: 3, typ: "Mem", aux: "TypSize"}, // arg0=destptr, arg1=srcptr, arg2=mem, auxint=size, aux=type.  Returns memory.
        {name: "ZeroWB", argLength: 2, typ: "Mem", aux: "TypSize"}, // arg0=destptr, arg1=mem, auxint=size, aux=type. Returns memory.
        {name: "WBend", argLength: 1, typ: "Mem"},                  // Write barrier code is done, interrupting is now allowed.

        // WB invokes runtime.gcWriteBarrier.  This is not a normal
        // call: it takes arguments in registers, doesn't clobber
        // general-purpose registers (the exact clobber set is
        // arch-dependent), and is not a safe-point.
        {name: "WB", argLength: 1, typ: "(BytePtr,Mem)", aux: "Int64"}, // arg0=mem, auxint=# of buffer entries needed. Returns buffer pointer and memory.

        {name: "HasCPUFeature", argLength: 0, typ: "bool", aux: "Sym", symEffect: "None"}, // aux=place that this feature flag can be loaded from

        // PanicBounds and PanicExtend generate a runtime panic.
        // Their arguments provide index values to use in panic messages.
        // Both PanicBounds and PanicExtend have an AuxInt value from the BoundsKind type (in ../op.go).
        // PanicBounds' index is int sized.
        // PanicExtend's index is int64 sized. (PanicExtend is only used on 32-bit archs.)
        {name: "PanicBounds", argLength: 3, aux: "Int64", typ: "Mem", call: true}, // arg0=idx, arg1=len, arg2=mem, returns memory.
        {name: "PanicExtend", argLength: 4, aux: "Int64", typ: "Mem", call: true}, // arg0=idxHi, arg1=idxLo, arg2=len, arg3=mem, returns memory.

        // Function calls. Arguments to the call have already been written to the stack.
        // Return values appear on the stack. The method receiver, if any, is treated
        // as a phantom first argument.
        // TODO(josharian): ClosureCall and InterCall should have Int32 aux
        // to match StaticCall's 32 bit arg size limit.
        // TODO(drchase,josharian): could the arg size limit be bundled into the rules for CallOff?

        // Before lowering, LECalls receive their fixed inputs (first), memory (last),
        // and a variable number of input values in the middle.
        // They produce a variable number of result values.
        // These values are not necessarily "SSA-able"; they can be too large,
        // but in that case inputs are loaded immediately before with OpDereference,
        // and outputs are stored immediately with OpStore.
        //
        // After call expansion, Calls have the same fixed-middle-memory arrangement of inputs,
        // with the difference that the "middle" is only the register-resident inputs,
        // and the non-register inputs are instead stored at ABI-defined offsets from SP
        // (and the stores thread through the memory that is ultimately an input to the call).
        // Outputs follow a similar pattern; register-resident outputs are the leading elements
        // of a Result-typed output, with memory last, and any memory-resident outputs have been
        // stored to ABI-defined locations.  Each non-memory input or output fits in a register.
        //
        // Subsequent architecture-specific lowering only changes the opcode.

        {name: "ClosureCall", argLength: -1, aux: "CallOff", call: true}, // arg0=code pointer, arg1=context ptr, arg2..argN-1 are register inputs, argN=memory.  auxint=arg size.  Returns Result of register results, plus memory.
        {name: "StaticCall", argLength: -1, aux: "CallOff", call: true},  // call function aux.(*obj.LSym), arg0..argN-1 are register inputs, argN=memory.  auxint=arg size.  Returns Result of register results, plus memory.
        {name: "InterCall", argLength: -1, aux: "CallOff", call: true},   // interface call.  arg0=code pointer, arg1..argN-1 are register inputs, argN=memory, auxint=arg size.  Returns Result of register results, plus memory.
        {name: "TailCall", argLength: -1, aux: "CallOff", call: true},    // tail call function aux.(*obj.LSym), arg0..argN-1 are register inputs, argN=memory.  auxint=arg size.  Returns Result of register results, plus memory.

        {name: "ClosureLECall", argLength: -1, aux: "CallOff", call: true}, // late-expanded closure call. arg0=code pointer, arg1=context ptr,  arg2..argN-1 are inputs, argN is mem. auxint = arg size. Result is tuple of result(s), plus mem.
        {name: "StaticLECall", argLength: -1, aux: "CallOff", call: true},  // late-expanded static call function aux.(*ssa.AuxCall.Fn). arg0..argN-1 are inputs, argN is mem. auxint = arg size. Result is tuple of result(s), plus mem.
        {name: "InterLECall", argLength: -1, aux: "CallOff", call: true},   // late-expanded interface call. arg0=code pointer, arg1..argN-1 are inputs, argN is mem. auxint = arg size. Result is tuple of result(s), plus mem.
        {name: "TailLECall", argLength: -1, aux: "CallOff", call: true},    // late-expanded static tail call function aux.(*ssa.AuxCall.Fn). arg0..argN-1 are inputs, argN is mem. auxint = arg size. Result is tuple of result(s), plus mem.

        // Conversions: signed extensions, zero (unsigned) extensions, truncations
        {name: "SignExt8to16", argLength: 1, typ: "Int16"},
        {name: "SignExt8to32", argLength: 1, typ: "Int32"},
        {name: "SignExt8to64", argLength: 1, typ: "Int64"},
        {name: "SignExt16to32", argLength: 1, typ: "Int32"},
        {name: "SignExt16to64", argLength: 1, typ: "Int64"},
        {name: "SignExt32to64", argLength: 1, typ: "Int64"},
        {name: "ZeroExt8to16", argLength: 1, typ: "UInt16"},
        {name: "ZeroExt8to32", argLength: 1, typ: "UInt32"},
        {name: "ZeroExt8to64", argLength: 1, typ: "UInt64"},
        {name: "ZeroExt16to32", argLength: 1, typ: "UInt32"},
        {name: "ZeroExt16to64", argLength: 1, typ: "UInt64"},
        {name: "ZeroExt32to64", argLength: 1, typ: "UInt64"},
        {name: "Trunc16to8", argLength: 1},
        {name: "Trunc32to8", argLength: 1},
        {name: "Trunc32to16", argLength: 1},
        {name: "Trunc64to8", argLength: 1},
        {name: "Trunc64to16", argLength: 1},
        {name: "Trunc64to32", argLength: 1},

        {name: "Cvt32to32F", argLength: 1},
        {name: "Cvt32to64F", argLength: 1},
        {name: "Cvt64to32F", argLength: 1},
        {name: "Cvt64to64F", argLength: 1},
        {name: "Cvt32Fto32", argLength: 1},
        {name: "Cvt32Fto64", argLength: 1},
        {name: "Cvt64Fto32", argLength: 1},
        {name: "Cvt64Fto64", argLength: 1},
        {name: "Cvt32Fto64F", argLength: 1},
        {name: "Cvt64Fto32F", argLength: 1},
        {name: "CvtBoolToUint8", argLength: 1},

        // Force rounding to precision of type.
        {name: "Round32F", argLength: 1},
        {name: "Round64F", argLength: 1},

        // Automatically inserted safety checks
        {name: "IsNonNil", argLength: 1, typ: "Bool"},        // arg0 != nil
        {name: "IsInBounds", argLength: 2, typ: "Bool"},      // 0 <= arg0 < arg1. arg1 is guaranteed >= 0.
        {name: "IsSliceInBounds", argLength: 2, typ: "Bool"}, // 0 <= arg0 <= arg1. arg1 is guaranteed >= 0.
        {name: "NilCheck", argLength: 2, typ: "Void"},        // arg0=ptr, arg1=mem. Panics if arg0 is nil. Returns void.

        // Pseudo-ops
        {name: "GetG", argLength: 1, zeroWidth: true}, // runtime.getg() (read g pointer). arg0=mem
        {name: "GetClosurePtr"},                       // get closure pointer from dedicated register
        {name: "GetCallerPC"},                         // for getcallerpc intrinsic
        {name: "GetCallerSP", argLength: 1},           // for getcallersp intrinsic. arg0=mem.

        // Indexing operations
        {name: "PtrIndex", argLength: 2},             // arg0=ptr, arg1=index. Computes ptr+sizeof(*v.type)*index, where index is extended to ptrwidth type
        {name: "OffPtr", argLength: 1, aux: "Int64"}, // arg0 + auxint (arg0 and result are pointers)

        // Slices
        {name: "SliceMake", argLength: 3},                // arg0=ptr, arg1=len, arg2=cap
        {name: "SlicePtr", argLength: 1, typ: "BytePtr"}, // ptr(arg0)
        {name: "SliceLen", argLength: 1},                 // len(arg0)
        {name: "SliceCap", argLength: 1},                 // cap(arg0)
        // SlicePtrUnchecked, like SlicePtr, extracts the pointer from a slice.
        // SlicePtr values are assumed non-nil, because they are guarded by bounds checks.
        // SlicePtrUnchecked values can be nil.
        {name: "SlicePtrUnchecked", argLength: 1},

        // Complex (part/whole)
        {name: "ComplexMake", argLength: 2}, // arg0=real, arg1=imag
        {name: "ComplexReal", argLength: 1}, // real(arg0)
        {name: "ComplexImag", argLength: 1}, // imag(arg0)

        // Strings
        {name: "StringMake", argLength: 2},                // arg0=ptr, arg1=len
        {name: "StringPtr", argLength: 1, typ: "BytePtr"}, // ptr(arg0)
        {name: "StringLen", argLength: 1, typ: "Int"},     // len(arg0)

        // Interfaces
        {name: "IMake", argLength: 2},                // arg0=itab, arg1=data
        {name: "ITab", argLength: 1, typ: "Uintptr"}, // arg0=interface, returns itable field
        {name: "IData", argLength: 1},                // arg0=interface, returns data field

        // Structs
        {name: "StructMake0"},                              // Returns struct with 0 fields.
        {name: "StructMake1", argLength: 1},                // arg0=field0.  Returns struct.
        {name: "StructMake2", argLength: 2},                // arg0,arg1=field0,field1.  Returns struct.
        {name: "StructMake3", argLength: 3},                // arg0..2=field0..2.  Returns struct.
        {name: "StructMake4", argLength: 4},                // arg0..3=field0..3.  Returns struct.
        {name: "StructSelect", argLength: 1, aux: "Int64"}, // arg0=struct, auxint=field index.  Returns the auxint'th field.

        // Arrays
        {name: "ArrayMake0"},                              // Returns array with 0 elements
        {name: "ArrayMake1", argLength: 1},                // Returns array with 1 element
        {name: "ArraySelect", argLength: 1, aux: "Int64"}, // arg0=array, auxint=index. Returns a[i].

        // Spill&restore ops for the register allocator. These are
        // semantically identical to OpCopy; they do not take/return
        // stores like regular memory ops do. We can get away without memory
        // args because we know there is no aliasing of spill slots on the stack.
        {name: "StoreReg", argLength: 1},
        {name: "LoadReg", argLength: 1},

        // Used during ssa construction. Like Copy, but the arg has not been specified yet.
        {name: "FwdRef", aux: "Sym", symEffect: "None"},

        // Unknown value. Used for Values whose values don't matter because they are dead code.
        {name: "Unknown"},

        {name: "VarDef", argLength: 1, aux: "Sym", typ: "Mem", symEffect: "None", zeroWidth: true}, // aux is a *gc.Node of a variable that is about to be initialized.  arg0=mem, returns mem
        // TODO: what's the difference between VarLive and KeepAlive?
        {name: "VarLive", argLength: 1, aux: "Sym", symEffect: "Read", zeroWidth: true}, // aux is a *gc.Node of a variable that must be kept live.  arg0=mem, returns mem
        {name: "KeepAlive", argLength: 2, typ: "Mem", zeroWidth: true},                  // arg[0] is a value that must be kept alive until this mark.  arg[1]=mem, returns mem

        // InlMark marks the start of an inlined function body. Its AuxInt field
        // distinguishes which entry in the local inline tree it is marking.
        {name: "InlMark", argLength: 1, aux: "Int32", typ: "Void"}, // arg[0]=mem, returns void.

        // Ops for breaking 64-bit operations on 32-bit architectures
        {name: "Int64Make", argLength: 2, typ: "UInt64"}, // arg0=hi, arg1=lo
        {name: "Int64Hi", argLength: 1, typ: "UInt32"},   // high 32-bit of arg0
        {name: "Int64Lo", argLength: 1, typ: "UInt32"},   // low 32-bit of arg0

        {name: "Add32carry", argLength: 2, commutative: true, typ: "(UInt32,Flags)"}, // arg0 + arg1, returns (value, carry)
        {name: "Add32withcarry", argLength: 3, commutative: true},                    // arg0 + arg1 + arg2, arg2=carry (0 or 1)

        {name: "Sub32carry", argLength: 2, typ: "(UInt32,Flags)"}, // arg0 - arg1, returns (value, carry)
        {name: "Sub32withcarry", argLength: 3},                    // arg0 - arg1 - arg2, arg2=carry (0 or 1)

        {name: "Add64carry", argLength: 3, commutative: true, typ: "(UInt64,UInt64)"}, // arg0 + arg1 + arg2, arg2 must be 0 or 1. returns (value, value>>64)
        {name: "Sub64borrow", argLength: 3, typ: "(UInt64,UInt64)"},                   // arg0 - (arg1 + arg2), arg2 must be 0 or 1. returns (value, value>>64&1)

        {name: "Signmask", argLength: 1, typ: "Int32"},  // 0 if arg0 >= 0, -1 if arg0 < 0
        {name: "Zeromask", argLength: 1, typ: "UInt32"}, // 0 if arg0 == 0, 0xffffffff if arg0 != 0
        {name: "Slicemask", argLength: 1},               // 0 if arg0 == 0, -1 if arg0 > 0, undef if arg0<0. Type is native int size.

        {name: "SpectreIndex", argLength: 2},      // arg0 if 0 <= arg0 < arg1, 0 otherwise. Type is native int size.
        {name: "SpectreSliceIndex", argLength: 2}, // arg0 if 0 <= arg0 <= arg1, 0 otherwise. Type is native int size.

        {name: "Cvt32Uto32F", argLength: 1}, // uint32 -> float32, only used on 32-bit arch
        {name: "Cvt32Uto64F", argLength: 1}, // uint32 -> float64, only used on 32-bit arch
        {name: "Cvt32Fto32U", argLength: 1}, // float32 -> uint32, only used on 32-bit arch
        {name: "Cvt64Fto32U", argLength: 1}, // float64 -> uint32, only used on 32-bit arch
        {name: "Cvt64Uto32F", argLength: 1}, // uint64 -> float32, only used on archs that has the instruction
        {name: "Cvt64Uto64F", argLength: 1}, // uint64 -> float64, only used on archs that has the instruction
        {name: "Cvt32Fto64U", argLength: 1}, // float32 -> uint64, only used on archs that has the instruction
        {name: "Cvt64Fto64U", argLength: 1}, // float64 -> uint64, only used on archs that has the instruction

        // pseudo-ops for breaking Tuple
        {name: "Select0", argLength: 1, zeroWidth: true},  // the first component of a tuple
        {name: "Select1", argLength: 1, zeroWidth: true},  // the second component of a tuple
        {name: "SelectN", argLength: 1, aux: "Int64"},     // arg0=result, auxint=field index.  Returns the auxint'th member.
        {name: "SelectNAddr", argLength: 1, aux: "Int64"}, // arg0=result, auxint=field index.  Returns the address of auxint'th member. Used for un-SSA-able result types.
        {name: "MakeResult", argLength: -1},               // arg0 .. are components of a "Result" (like the result from a Call). The last arg should be memory (like the result from a call).

        // Atomic operations used for semantically inlining sync/atomic and
        // runtime/internal/atomic. Atomic loads return a new memory so that
        // the loads are properly ordered with respect to other loads and
        // stores.
        {name: "AtomicLoad8", argLength: 2, typ: "(UInt8,Mem)"},                                    // Load from arg0.  arg1=memory.  Returns loaded value and new memory.
        {name: "AtomicLoad32", argLength: 2, typ: "(UInt32,Mem)"},                                  // Load from arg0.  arg1=memory.  Returns loaded value and new memory.
        {name: "AtomicLoad64", argLength: 2, typ: "(UInt64,Mem)"},                                  // Load from arg0.  arg1=memory.  Returns loaded value and new memory.
        {name: "AtomicLoadPtr", argLength: 2, typ: "(BytePtr,Mem)"},                                // Load from arg0.  arg1=memory.  Returns loaded value and new memory.
        {name: "AtomicLoadAcq32", argLength: 2, typ: "(UInt32,Mem)"},                               // Load from arg0.  arg1=memory.  Lock acquisition, returns loaded value and new memory.
        {name: "AtomicLoadAcq64", argLength: 2, typ: "(UInt64,Mem)"},                               // Load from arg0.  arg1=memory.  Lock acquisition, returns loaded value and new memory.
        {name: "AtomicStore8", argLength: 3, typ: "Mem", hasSideEffects: true},                     // Store arg1 to *arg0.  arg2=memory.  Returns memory.
        {name: "AtomicStore32", argLength: 3, typ: "Mem", hasSideEffects: true},                    // Store arg1 to *arg0.  arg2=memory.  Returns memory.
        {name: "AtomicStore64", argLength: 3, typ: "Mem", hasSideEffects: true},                    // Store arg1 to *arg0.  arg2=memory.  Returns memory.
        {name: "AtomicStorePtrNoWB", argLength: 3, typ: "Mem", hasSideEffects: true},               // Store arg1 to *arg0.  arg2=memory.  Returns memory.
        {name: "AtomicStoreRel32", argLength: 3, typ: "Mem", hasSideEffects: true},                 // Store arg1 to *arg0.  arg2=memory.  Lock release, returns memory.
        {name: "AtomicStoreRel64", argLength: 3, typ: "Mem", hasSideEffects: true},                 // Store arg1 to *arg0.  arg2=memory.  Lock release, returns memory.
        {name: "AtomicExchange32", argLength: 3, typ: "(UInt32,Mem)", hasSideEffects: true},        // Store arg1 to *arg0.  arg2=memory.  Returns old contents of *arg0 and new memory.
        {name: "AtomicExchange64", argLength: 3, typ: "(UInt64,Mem)", hasSideEffects: true},        // Store arg1 to *arg0.  arg2=memory.  Returns old contents of *arg0 and new memory.
        {name: "AtomicAdd32", argLength: 3, typ: "(UInt32,Mem)", hasSideEffects: true},             // Do *arg0 += arg1.  arg2=memory.  Returns sum and new memory.
        {name: "AtomicAdd64", argLength: 3, typ: "(UInt64,Mem)", hasSideEffects: true},             // Do *arg0 += arg1.  arg2=memory.  Returns sum and new memory.
        {name: "AtomicCompareAndSwap32", argLength: 4, typ: "(Bool,Mem)", hasSideEffects: true},    // if *arg0==arg1, then set *arg0=arg2.  Returns true if store happens and new memory.
        {name: "AtomicCompareAndSwap64", argLength: 4, typ: "(Bool,Mem)", hasSideEffects: true},    // if *arg0==arg1, then set *arg0=arg2.  Returns true if store happens and new memory.
        {name: "AtomicCompareAndSwapRel32", argLength: 4, typ: "(Bool,Mem)", hasSideEffects: true}, // if *arg0==arg1, then set *arg0=arg2.  Lock release, reports whether store happens and new memory.
        {name: "AtomicAnd8", argLength: 3, typ: "Mem", hasSideEffects: true},                       // *arg0 &= arg1.  arg2=memory.  Returns memory.
        {name: "AtomicAnd32", argLength: 3, typ: "Mem", hasSideEffects: true},                      // *arg0 &= arg1.  arg2=memory.  Returns memory.
        {name: "AtomicOr8", argLength: 3, typ: "Mem", hasSideEffects: true},                        // *arg0 |= arg1.  arg2=memory.  Returns memory.
        {name: "AtomicOr32", argLength: 3, typ: "Mem", hasSideEffects: true},                       // *arg0 |= arg1.  arg2=memory.  Returns memory.

        // Atomic operation variants
        // These variants have the same semantics as above atomic operations.
        // But they are used for generating more efficient code on certain modern machines, with run-time CPU feature detection.
        // Currently, they are used on ARM64 only.
        {name: "AtomicAdd32Variant", argLength: 3, typ: "(UInt32,Mem)", hasSideEffects: true},          // Do *arg0 += arg1.  arg2=memory.  Returns sum and new memory.
        {name: "AtomicAdd64Variant", argLength: 3, typ: "(UInt64,Mem)", hasSideEffects: true},          // Do *arg0 += arg1.  arg2=memory.  Returns sum and new memory.
        {name: "AtomicExchange32Variant", argLength: 3, typ: "(UInt32,Mem)", hasSideEffects: true},     // Store arg1 to *arg0.  arg2=memory.  Returns old contents of *arg0 and new memory.
        {name: "AtomicExchange64Variant", argLength: 3, typ: "(UInt64,Mem)", hasSideEffects: true},     // Store arg1 to *arg0.  arg2=memory.  Returns old contents of *arg0 and new memory.
        {name: "AtomicCompareAndSwap32Variant", argLength: 4, typ: "(Bool,Mem)", hasSideEffects: true}, // if *arg0==arg1, then set *arg0=arg2.  Returns true if store happens and new memory.
        {name: "AtomicCompareAndSwap64Variant", argLength: 4, typ: "(Bool,Mem)", hasSideEffects: true}, // if *arg0==arg1, then set *arg0=arg2.  Returns true if store happens and new memory.
        {name: "AtomicAnd8Variant", argLength: 3, typ: "Mem", hasSideEffects: true},                    // *arg0 &= arg1.  arg2=memory.  Returns memory.
        {name: "AtomicAnd32Variant", argLength: 3, typ: "Mem", hasSideEffects: true},                   // *arg0 &= arg1.  arg2=memory.  Returns memory.
        {name: "AtomicOr8Variant", argLength: 3, typ: "Mem", hasSideEffects: true},                     // *arg0 |= arg1.  arg2=memory.  Returns memory.
        {name: "AtomicOr32Variant", argLength: 3, typ: "Mem", hasSideEffects: true},                    // *arg0 |= arg1.  arg2=memory.  Returns memory.

        // Publication barrier
        {name: "PubBarrier", argLength: 1, hasSideEffects: true}, // Do data barrier. arg0=memory.

        // Clobber experiment op
        {name: "Clobber", argLength: 0, typ: "Void", aux: "SymOff", symEffect: "None"}, // write an invalid pointer value to the given pointer slot of a stack variable
        {name: "ClobberReg", argLength: 0, typ: "Void"},                                // clobber a register

        // Prefetch instruction
        {name: "PrefetchCache", argLength: 2, hasSideEffects: true},         // Do prefetch arg0 to cache. arg0=addr, arg1=memory.
        {name: "PrefetchCacheStreamed", argLength: 2, hasSideEffects: true}, // Do non-temporal or streamed prefetch arg0 to cache. arg0=addr, arg1=memory.
}

//     kind          controls        successors   implicit exit
//   ----------------------------------------------------------
//     Exit      [return mem]                []             yes
//      Ret      [return mem]                []             yes
//   RetJmp      [return mem]                []             yes
//    Plain                []            [next]
//       If   [boolean Value]      [then, else]
//    First                []   [always, never]
//    Defer             [mem]  [nopanic, panic]                  (control opcode should be OpStaticCall to runtime.deferproc)
//JumpTable   [integer Value]  [succ1,succ2,..]

var genericBlocks = []blockData{
        {name: "Plain"},                  // a single successor
        {name: "If", controls: 1},        // if Controls[0] goto Succs[0] else goto Succs[1]
        {name: "Defer", controls: 1},     // Succs[0]=defer queued, Succs[1]=defer recovered. Controls[0] is call op (of memory type)
        {name: "Ret", controls: 1},       // no successors, Controls[0] value is memory result
        {name: "RetJmp", controls: 1},    // no successors, Controls[0] value is a tail call
        {name: "Exit", controls: 1},      // no successors, Controls[0] value generates a panic
        {name: "JumpTable", controls: 1}, // multiple successors, the integer Controls[0] selects which one

        // transient block state used for dead code removal
        {name: "First"}, // 2 successors, always takes the first one (second is dead)
}

func init() {
        archs = append(archs, arch{
                name:    "generic",
                ops:     genericOps,
                blocks:  genericBlocks,
                generic: true,
        })
}