1 // Copyright 2011 The Go Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
5 // The inlining facility makes 2 passes: first CanInline determines which
6 // functions are suitable for inlining, and for those that are it
7 // saves a copy of the body. Then InlineCalls walks each function body to
8 // expand calls to inlinable functions.
10 // The Debug.l flag controls the aggressiveness. Note that main() swaps level 0 and 1,
11 // making 1 the default and -l disable. Additional levels (beyond -l) may be buggy and
14 // 1: 80-nodes leaf functions, oneliners, panic, lazy typechecking (default)
17 // 4: allow non-leaf functions
19 // At some point this may get another default and become switch-offable with -N.
21 // The -d typcheckinl flag enables early typechecking of all imported bodies,
22 // which is useful to flush out bugs.
24 // The Debug.m flag enables diagnostic output. a single -m is useful for verifying
25 // which calls get inlined or not, more is for debugging, and may go away at any point.
35 "cmd/compile/internal/base"
36 "cmd/compile/internal/ir"
37 "cmd/compile/internal/logopt"
38 "cmd/compile/internal/pgo"
39 "cmd/compile/internal/typecheck"
40 "cmd/compile/internal/types"
44 // Inlining budget parameters, gathered in one place
47 inlineExtraAppendCost = 0
48 // default is to inline if there's at most one call. -l=4 overrides this by using 1 instead.
49 inlineExtraCallCost = 57 // 57 was benchmarked to provided most benefit with no bad surprises; see https://github.com/golang/go/issues/19348#issuecomment-439370742
50 inlineExtraPanicCost = 1 // do not penalize inlining panics.
51 inlineExtraThrowCost = inlineMaxBudget // with current (2018-05/1.11) code, inlining runtime.throw does not help.
53 inlineBigFunctionNodes = 5000 // Functions with this many nodes are considered "big".
54 inlineBigFunctionMaxCost = 20 // Max cost of inlinee when inlining into a "big" function.
58 // List of all hot callee nodes.
59 // TODO(prattmic): Make this non-global.
60 candHotCalleeMap = make(map[*pgo.IRNode]struct{})
62 // List of all hot call sites. CallSiteInfo.Callee is always nil.
63 // TODO(prattmic): Make this non-global.
64 candHotEdgeMap = make(map[pgo.CallSiteInfo]struct{})
66 // List of inlined call sites. CallSiteInfo.Callee is always nil.
67 // TODO(prattmic): Make this non-global.
68 inlinedCallSites = make(map[pgo.CallSiteInfo]struct{})
70 // Threshold in percentage for hot callsite inlining.
71 inlineHotCallSiteThresholdPercent float64
73 // Threshold in CDF percentage for hot callsite inlining,
74 // that is, for a threshold of X the hottest callsites that
75 // make up the top X% of total edge weight will be
76 // considered hot for inlining candidates.
77 inlineCDFHotCallSiteThresholdPercent = float64(99)
79 // Budget increased due to hotness.
80 inlineHotMaxBudget int32 = 2000
83 // pgoInlinePrologue records the hot callsites from ir-graph.
84 func pgoInlinePrologue(p *pgo.Profile, decls []ir.Node) {
85 if base.Debug.PGOInlineCDFThreshold != "" {
86 if s, err := strconv.ParseFloat(base.Debug.PGOInlineCDFThreshold, 64); err == nil && s >= 0 && s <= 100 {
87 inlineCDFHotCallSiteThresholdPercent = s
89 base.Fatalf("invalid PGOInlineCDFThreshold, must be between 0 and 100")
92 var hotCallsites []pgo.NodeMapKey
93 inlineHotCallSiteThresholdPercent, hotCallsites = hotNodesFromCDF(p)
94 if base.Debug.PGOInline > 0 {
95 fmt.Printf("hot-callsite-thres-from-CDF=%v\n", inlineHotCallSiteThresholdPercent)
98 if x := base.Debug.PGOInlineBudget; x != 0 {
99 inlineHotMaxBudget = int32(x)
102 for _, n := range hotCallsites {
103 // mark inlineable callees from hot edges
104 if callee := p.WeightedCG.IRNodes[n.CalleeName]; callee != nil {
105 candHotCalleeMap[callee] = struct{}{}
107 // mark hot call sites
108 if caller := p.WeightedCG.IRNodes[n.CallerName]; caller != nil {
109 csi := pgo.CallSiteInfo{LineOffset: n.CallSiteOffset, Caller: caller.AST}
110 candHotEdgeMap[csi] = struct{}{}
114 if base.Debug.PGOInline >= 2 {
115 fmt.Printf("hot-cg before inline in dot format:")
116 p.PrintWeightedCallGraphDOT(inlineHotCallSiteThresholdPercent)
120 // hotNodesFromCDF computes an edge weight threshold and the list of hot
121 // nodes that make up the given percentage of the CDF. The threshold, as
122 // a percent, is the lower bound of weight for nodes to be considered hot
123 // (currently only used in debug prints) (in case of equal weights,
124 // comparing with the threshold may not accurately reflect which nodes are
126 func hotNodesFromCDF(p *pgo.Profile) (float64, []pgo.NodeMapKey) {
127 nodes := make([]pgo.NodeMapKey, len(p.NodeMap))
129 for n := range p.NodeMap {
133 sort.Slice(nodes, func(i, j int) bool {
134 ni, nj := nodes[i], nodes[j]
135 if wi, wj := p.NodeMap[ni].EWeight, p.NodeMap[nj].EWeight; wi != wj {
136 return wi > wj // want larger weight first
138 // same weight, order by name/line number
139 if ni.CallerName != nj.CallerName {
140 return ni.CallerName < nj.CallerName
142 if ni.CalleeName != nj.CalleeName {
143 return ni.CalleeName < nj.CalleeName
145 return ni.CallSiteOffset < nj.CallSiteOffset
148 for i, n := range nodes {
149 w := p.NodeMap[n].EWeight
151 if pgo.WeightInPercentage(cum, p.TotalEdgeWeight) > inlineCDFHotCallSiteThresholdPercent {
152 // nodes[:i+1] to include the very last node that makes it to go over the threshold.
153 // (Say, if the CDF threshold is 50% and one hot node takes 60% of weight, we want to
154 // include that node instead of excluding it.)
155 return pgo.WeightInPercentage(w, p.TotalEdgeWeight), nodes[:i+1]
161 // pgoInlineEpilogue updates IRGraph after inlining.
162 func pgoInlineEpilogue(p *pgo.Profile, decls []ir.Node) {
163 if base.Debug.PGOInline >= 2 {
164 ir.VisitFuncsBottomUp(decls, func(list []*ir.Func, recursive bool) {
165 for _, f := range list {
166 name := ir.PkgFuncName(f)
167 if n, ok := p.WeightedCG.IRNodes[name]; ok {
168 p.RedirectEdges(n, inlinedCallSites)
172 // Print the call-graph after inlining. This is a debugging feature.
173 fmt.Printf("hot-cg after inline in dot:")
174 p.PrintWeightedCallGraphDOT(inlineHotCallSiteThresholdPercent)
178 // InlinePackage finds functions that can be inlined and clones them before walk expands them.
179 func InlinePackage(p *pgo.Profile) {
180 InlineDecls(p, typecheck.Target.Decls, true)
183 // InlineDecls applies inlining to the given batch of declarations.
184 func InlineDecls(p *pgo.Profile, decls []ir.Node, doInline bool) {
186 pgoInlinePrologue(p, decls)
189 ir.VisitFuncsBottomUp(decls, func(list []*ir.Func, recursive bool) {
190 numfns := numNonClosures(list)
191 for _, n := range list {
192 if !recursive || numfns > 1 {
193 // We allow inlining if there is no
194 // recursion, or the recursion cycle is
195 // across more than one function.
198 if base.Flag.LowerM > 1 {
199 fmt.Printf("%v: cannot inline %v: recursive\n", ir.Line(n), n.Nname)
209 pgoInlineEpilogue(p, decls)
213 // CanInline determines whether fn is inlineable.
214 // If so, CanInline saves copies of fn.Body and fn.Dcl in fn.Inl.
215 // fn and fn.Body will already have been typechecked.
216 func CanInline(fn *ir.Func, profile *pgo.Profile) {
218 base.Fatalf("CanInline no nname %+v", fn)
221 var reason string // reason, if any, that the function was not inlined
222 if base.Flag.LowerM > 1 || logopt.Enabled() {
225 if base.Flag.LowerM > 1 {
226 fmt.Printf("%v: cannot inline %v: %s\n", ir.Line(fn), fn.Nname, reason)
228 if logopt.Enabled() {
229 logopt.LogOpt(fn.Pos(), "cannotInlineFunction", "inline", ir.FuncName(fn), reason)
235 // If marked "go:noinline", don't inline
236 if fn.Pragma&ir.Noinline != 0 {
237 reason = "marked go:noinline"
241 // If marked "go:norace" and -race compilation, don't inline.
242 if base.Flag.Race && fn.Pragma&ir.Norace != 0 {
243 reason = "marked go:norace with -race compilation"
247 // If marked "go:nocheckptr" and -d checkptr compilation, don't inline.
248 if base.Debug.Checkptr != 0 && fn.Pragma&ir.NoCheckPtr != 0 {
249 reason = "marked go:nocheckptr"
253 // If marked "go:cgo_unsafe_args", don't inline, since the
254 // function makes assumptions about its argument frame layout.
255 if fn.Pragma&ir.CgoUnsafeArgs != 0 {
256 reason = "marked go:cgo_unsafe_args"
260 // If marked as "go:uintptrkeepalive", don't inline, since the
261 // keep alive information is lost during inlining.
263 // TODO(prattmic): This is handled on calls during escape analysis,
264 // which is after inlining. Move prior to inlining so the keep-alive is
265 // maintained after inlining.
266 if fn.Pragma&ir.UintptrKeepAlive != 0 {
267 reason = "marked as having a keep-alive uintptr argument"
271 // If marked as "go:uintptrescapes", don't inline, since the
272 // escape information is lost during inlining.
273 if fn.Pragma&ir.UintptrEscapes != 0 {
274 reason = "marked as having an escaping uintptr argument"
278 // The nowritebarrierrec checker currently works at function
279 // granularity, so inlining yeswritebarrierrec functions can
280 // confuse it (#22342). As a workaround, disallow inlining
282 if fn.Pragma&ir.Yeswritebarrierrec != 0 {
283 reason = "marked go:yeswritebarrierrec"
287 // If fn has no body (is defined outside of Go), cannot inline it.
288 if len(fn.Body) == 0 {
289 reason = "no function body"
293 if fn.Typecheck() == 0 {
294 base.Fatalf("CanInline on non-typechecked function %v", fn)
298 if n.Func.InlinabilityChecked() {
301 defer n.Func.SetInlinabilityChecked(true)
303 cc := int32(inlineExtraCallCost)
304 if base.Flag.LowerL == 4 {
305 cc = 1 // this appears to yield better performance than 0.
308 // Update the budget for profile-guided inlining.
309 budget := int32(inlineMaxBudget)
311 if n, ok := profile.WeightedCG.IRNodes[ir.PkgFuncName(fn)]; ok {
312 if _, ok := candHotCalleeMap[n]; ok {
313 budget = int32(inlineHotMaxBudget)
314 if base.Debug.PGOInline > 0 {
315 fmt.Printf("hot-node enabled increased budget=%v for func=%v\n", budget, ir.PkgFuncName(fn))
321 // At this point in the game the function we're looking at may
322 // have "stale" autos, vars that still appear in the Dcl list, but
323 // which no longer have any uses in the function body (due to
324 // elimination by deadcode). We'd like to exclude these dead vars
325 // when creating the "Inline.Dcl" field below; to accomplish this,
326 // the hairyVisitor below builds up a map of used/referenced
327 // locals, and we use this map to produce a pruned Inline.Dcl
328 // list. See issue 25249 for more context.
330 visitor := hairyVisitor{
337 if visitor.tooHairy(fn) {
338 reason = visitor.reason
342 n.Func.Inl = &ir.Inline{
343 Cost: budget - visitor.budget,
344 Dcl: pruneUnusedAutos(n.Defn.(*ir.Func).Dcl, &visitor),
345 Body: inlcopylist(fn.Body),
347 CanDelayResults: canDelayResults(fn),
350 if base.Flag.LowerM > 1 {
351 fmt.Printf("%v: can inline %v with cost %d as: %v { %v }\n", ir.Line(fn), n, budget-visitor.budget, fn.Type(), ir.Nodes(n.Func.Inl.Body))
352 } else if base.Flag.LowerM != 0 {
353 fmt.Printf("%v: can inline %v\n", ir.Line(fn), n)
355 if logopt.Enabled() {
356 logopt.LogOpt(fn.Pos(), "canInlineFunction", "inline", ir.FuncName(fn), fmt.Sprintf("cost: %d", budget-visitor.budget))
360 // canDelayResults reports whether inlined calls to fn can delay
361 // declaring the result parameter until the "return" statement.
362 func canDelayResults(fn *ir.Func) bool {
363 // We can delay declaring+initializing result parameters if:
364 // (1) there's exactly one "return" statement in the inlined function;
365 // (2) it's not an empty return statement (#44355); and
366 // (3) the result parameters aren't named.
369 ir.VisitList(fn.Body, func(n ir.Node) {
370 if n, ok := n.(*ir.ReturnStmt); ok {
372 if len(n.Results) == 0 {
373 nreturns++ // empty return statement (case 2)
379 return false // not exactly one return statement (case 1)
382 // temporaries for return values.
383 for _, param := range fn.Type().Results().FieldSlice() {
384 if sym := types.OrigSym(param.Sym); sym != nil && !sym.IsBlank() {
385 return false // found a named result parameter (case 3)
392 // hairyVisitor visits a function body to determine its inlining
393 // hairiness and whether or not it can be inlined.
394 type hairyVisitor struct {
395 // This is needed to access the current caller in the doNode function.
401 usedLocals ir.NameSet
402 do func(ir.Node) bool
406 func (v *hairyVisitor) tooHairy(fn *ir.Func) bool {
407 v.do = v.doNode // cache closure
408 if ir.DoChildren(fn, v.do) {
412 v.reason = fmt.Sprintf("function too complex: cost %d exceeds budget %d", v.maxBudget-v.budget, v.maxBudget)
418 func (v *hairyVisitor) doNode(n ir.Node) bool {
423 // Call is okay if inlinable and we have the budget for the body.
425 n := n.(*ir.CallExpr)
426 // Functions that call runtime.getcaller{pc,sp} can not be inlined
427 // because getcaller{pc,sp} expect a pointer to the caller's first argument.
429 // runtime.throw is a "cheap call" like panic in normal code.
430 if n.X.Op() == ir.ONAME {
431 name := n.X.(*ir.Name)
432 if name.Class == ir.PFUNC && types.IsRuntimePkg(name.Sym().Pkg) {
433 fn := name.Sym().Name
434 if fn == "getcallerpc" || fn == "getcallersp" {
435 v.reason = "call to " + fn
439 v.budget -= inlineExtraThrowCost
443 // Special case for coverage counter updates; although
444 // these correspond to real operations, we treat them as
445 // zero cost for the moment. This is due to the existence
446 // of tests that are sensitive to inlining-- if the
447 // insertion of coverage instrumentation happens to tip a
448 // given function over the threshold and move it from
449 // "inlinable" to "not-inlinable", this can cause changes
450 // in allocation behavior, which can then result in test
451 // failures (a good example is the TestAllocations in
453 if isAtomicCoverageCounterUpdate(n) {
457 if n.X.Op() == ir.OMETHEXPR {
458 if meth := ir.MethodExprName(n.X); meth != nil {
459 if fn := meth.Func; fn != nil {
462 if types.IsRuntimePkg(s.Pkg) && s.Name == "heapBits.nextArena" {
463 // Special case: explicitly allow mid-stack inlining of
464 // runtime.heapBits.next even though it calls slow-path
465 // runtime.heapBits.nextArena.
468 // Special case: on architectures that can do unaligned loads,
469 // explicitly mark encoding/binary methods as cheap,
470 // because in practice they are, even though our inlining
471 // budgeting system does not see that. See issue 42958.
472 if base.Ctxt.Arch.CanMergeLoads && s.Pkg.Path == "encoding/binary" {
474 case "littleEndian.Uint64", "littleEndian.Uint32", "littleEndian.Uint16",
475 "bigEndian.Uint64", "bigEndian.Uint32", "bigEndian.Uint16",
476 "littleEndian.PutUint64", "littleEndian.PutUint32", "littleEndian.PutUint16",
477 "bigEndian.PutUint64", "bigEndian.PutUint32", "bigEndian.PutUint16",
478 "littleEndian.AppendUint64", "littleEndian.AppendUint32", "littleEndian.AppendUint16",
479 "bigEndian.AppendUint64", "bigEndian.AppendUint32", "bigEndian.AppendUint16":
484 break // treat like any other node, that is, cost of 1
490 // Determine if the callee edge is for an inlinable hot callee or not.
491 if v.profile != nil && v.curFunc != nil {
492 if fn := inlCallee(n.X, v.profile); fn != nil && typecheck.HaveInlineBody(fn) {
493 lineOffset := pgo.NodeLineOffset(n, fn)
494 csi := pgo.CallSiteInfo{LineOffset: lineOffset, Caller: v.curFunc}
495 if _, o := candHotEdgeMap[csi]; o {
496 if base.Debug.PGOInline > 0 {
497 fmt.Printf("hot-callsite identified at line=%v for func=%v\n", ir.Line(n), ir.PkgFuncName(v.curFunc))
503 if ir.IsIntrinsicCall(n) {
504 // Treat like any other node.
508 if fn := inlCallee(n.X, v.profile); fn != nil && typecheck.HaveInlineBody(fn) {
509 v.budget -= fn.Inl.Cost
513 // Call cost for non-leaf inlining.
514 v.budget -= v.extraCallCost
517 base.FatalfAt(n.Pos(), "OCALLMETH missed by typecheck")
519 // Things that are too hairy, irrespective of the budget
520 case ir.OCALL, ir.OCALLINTER:
521 // Call cost for non-leaf inlining.
522 v.budget -= v.extraCallCost
525 n := n.(*ir.UnaryExpr)
526 if n.X.Op() == ir.OCONVIFACE && n.X.(*ir.ConvExpr).Implicit() {
527 // Hack to keep reflect.flag.mustBe inlinable for TestIntendedInlining.
528 // Before CL 284412, these conversions were introduced later in the
529 // compiler, so they didn't count against inlining budget.
532 v.budget -= inlineExtraPanicCost
535 // recover matches the argument frame pointer to find
536 // the right panic value, so it needs an argument frame.
537 v.reason = "call to recover"
541 if base.Debug.InlFuncsWithClosures == 0 {
542 v.reason = "not inlining functions with closures"
546 // TODO(danscales): Maybe make budget proportional to number of closure
548 //v.budget -= int32(len(n.(*ir.ClosureExpr).Func.ClosureVars) * 3)
550 // Scan body of closure (which DoChildren doesn't automatically
551 // do) to check for disallowed ops in the body and include the
552 // body in the budget.
553 if doList(n.(*ir.ClosureExpr).Func.Body, v.do) {
559 ir.ODCLTYPE, // can't print yet
561 v.reason = "unhandled op " + n.Op().String()
565 v.budget -= inlineExtraAppendCost
568 n := n.(*ir.AddrExpr)
569 // Make "&s.f" cost 0 when f's offset is zero.
570 if dot, ok := n.X.(*ir.SelectorExpr); ok && (dot.Op() == ir.ODOT || dot.Op() == ir.ODOTPTR) {
571 if _, ok := dot.X.(*ir.Name); ok && dot.Selection.Offset == 0 {
572 v.budget += 2 // undo ir.OADDR+ir.ODOT/ir.ODOTPTR
577 // *(*X)(unsafe.Pointer(&x)) is low-cost
578 n := n.(*ir.StarExpr)
581 for ptr.Op() == ir.OCONVNOP {
582 ptr = ptr.(*ir.ConvExpr).X
584 if ptr.Op() == ir.OADDR {
585 v.budget += 1 // undo half of default cost of ir.ODEREF+ir.OADDR
589 // This doesn't produce code, but the children might.
590 v.budget++ // undo default cost
592 case ir.ODCLCONST, ir.OFALL:
593 // These nodes don't produce code; omit from inlining budget.
598 if ir.IsConst(n.Cond, constant.Bool) {
599 // This if and the condition cost nothing.
600 if doList(n.Init(), v.do) {
603 if ir.BoolVal(n.Cond) {
604 return doList(n.Body, v.do)
606 return doList(n.Else, v.do)
612 if n.Class == ir.PAUTO {
617 // The only OBLOCK we should see at this point is an empty one.
618 // In any event, let the visitList(n.List()) below take care of the statements,
619 // and don't charge for the OBLOCK itself. The ++ undoes the -- below.
622 case ir.OMETHVALUE, ir.OSLICELIT:
623 v.budget-- // Hack for toolstash -cmp.
626 v.budget++ // Hack for toolstash -cmp.
629 n := n.(*ir.AssignListStmt)
631 // Unified IR unconditionally rewrites:
642 // so that it can insert implicit conversions as necessary. To
643 // minimize impact to the existing inlining heuristics (in
644 // particular, to avoid breaking the existing inlinability regress
645 // tests), we need to compensate for this here.
647 // See also identical logic in isBigFunc.
648 if init := n.Rhs[0].Init(); len(init) == 1 {
649 if _, ok := init[0].(*ir.AssignListStmt); ok {
650 // 4 for each value, because each temporary variable now
651 // appears 3 times (DCL, LHS, RHS), plus an extra DCL node.
653 // 1 for the extra "tmp1, tmp2 = f()" assignment statement.
654 v.budget += 4*int32(len(n.Lhs)) + 1
659 // Special case for coverage counter updates and coverage
660 // function registrations. Although these correspond to real
661 // operations, we treat them as zero cost for the moment. This
662 // is primarily due to the existence of tests that are
663 // sensitive to inlining-- if the insertion of coverage
664 // instrumentation happens to tip a given function over the
665 // threshold and move it from "inlinable" to "not-inlinable",
666 // this can cause changes in allocation behavior, which can
667 // then result in test failures (a good example is the
668 // TestAllocations in crypto/ed25519).
669 n := n.(*ir.AssignStmt)
670 if n.X.Op() == ir.OINDEX && isIndexingCoverageCounter(n.X) {
677 // When debugging, don't stop early, to get full cost of inlining this function
678 if v.budget < 0 && base.Flag.LowerM < 2 && !logopt.Enabled() {
679 v.reason = "too expensive"
683 return ir.DoChildren(n, v.do)
686 func isBigFunc(fn *ir.Func) bool {
687 budget := inlineBigFunctionNodes
688 return ir.Any(fn, func(n ir.Node) bool {
689 // See logic in hairyVisitor.doNode, explaining unified IR's
690 // handling of "a, b = f()" assignments.
691 if n, ok := n.(*ir.AssignListStmt); ok && n.Op() == ir.OAS2 {
692 if init := n.Rhs[0].Init(); len(init) == 1 {
693 if _, ok := init[0].(*ir.AssignListStmt); ok {
694 budget += 4*len(n.Lhs) + 1
704 // inlcopylist (together with inlcopy) recursively copies a list of nodes, except
705 // that it keeps the same ONAME, OTYPE, and OLITERAL nodes. It is used for copying
706 // the body and dcls of an inlineable function.
707 func inlcopylist(ll []ir.Node) []ir.Node {
708 s := make([]ir.Node, len(ll))
709 for i, n := range ll {
715 // inlcopy is like DeepCopy(), but does extra work to copy closures.
716 func inlcopy(n ir.Node) ir.Node {
717 var edit func(ir.Node) ir.Node
718 edit = func(x ir.Node) ir.Node {
720 case ir.ONAME, ir.OTYPE, ir.OLITERAL, ir.ONIL:
724 ir.EditChildren(m, edit)
725 if x.Op() == ir.OCLOSURE {
726 x := x.(*ir.ClosureExpr)
727 // Need to save/duplicate x.Func.Nname,
728 // x.Func.Nname.Ntype, x.Func.Dcl, x.Func.ClosureVars, and
729 // x.Func.Body for iexport and local inlining.
731 newfn := ir.NewFunc(oldfn.Pos())
732 m.(*ir.ClosureExpr).Func = newfn
733 newfn.Nname = ir.NewNameAt(oldfn.Nname.Pos(), oldfn.Nname.Sym())
734 // XXX OK to share fn.Type() ??
735 newfn.Nname.SetType(oldfn.Nname.Type())
736 newfn.Body = inlcopylist(oldfn.Body)
737 // Make shallow copy of the Dcl and ClosureVar slices
738 newfn.Dcl = append([]*ir.Name(nil), oldfn.Dcl...)
739 newfn.ClosureVars = append([]*ir.Name(nil), oldfn.ClosureVars...)
746 // InlineCalls/inlnode walks fn's statements and expressions and substitutes any
747 // calls made to inlineable functions. This is the external entry point.
748 func InlineCalls(fn *ir.Func, profile *pgo.Profile) {
751 maxCost := int32(inlineMaxBudget)
753 if base.Flag.LowerM > 1 {
754 fmt.Printf("%v: function %v considered 'big'; revising maxCost from %d to %d\n", ir.Line(fn), fn, maxCost, inlineBigFunctionMaxCost)
756 maxCost = inlineBigFunctionMaxCost
758 var inlCalls []*ir.InlinedCallExpr
759 var edit func(ir.Node) ir.Node
760 edit = func(n ir.Node) ir.Node {
761 return inlnode(n, maxCost, &inlCalls, edit, profile)
763 ir.EditChildren(fn, edit)
765 // If we inlined any calls, we want to recursively visit their
766 // bodies for further inlining. However, we need to wait until
767 // *after* the original function body has been expanded, or else
768 // inlCallee can have false positives (e.g., #54632).
769 for len(inlCalls) > 0 {
771 inlCalls = inlCalls[1:]
772 ir.EditChildren(call, edit)
778 // inlnode recurses over the tree to find inlineable calls, which will
779 // be turned into OINLCALLs by mkinlcall. When the recursion comes
780 // back up will examine left, right, list, rlist, ninit, ntest, nincr,
781 // nbody and nelse and use one of the 4 inlconv/glue functions above
782 // to turn the OINLCALL into an expression, a statement, or patch it
783 // in to this nodes list or rlist as appropriate.
784 // NOTE it makes no sense to pass the glue functions down the
785 // recursion to the level where the OINLCALL gets created because they
786 // have to edit /this/ n, so you'd have to push that one down as well,
787 // but then you may as well do it here. so this is cleaner and
788 // shorter and less complicated.
789 // The result of inlnode MUST be assigned back to n, e.g.
791 // n.Left = inlnode(n.Left)
792 func inlnode(n ir.Node, maxCost int32, inlCalls *[]*ir.InlinedCallExpr, edit func(ir.Node) ir.Node, profile *pgo.Profile) ir.Node {
798 case ir.ODEFER, ir.OGO:
799 n := n.(*ir.GoDeferStmt)
800 switch call := n.Call; call.Op() {
802 base.FatalfAt(call.Pos(), "OCALLMETH missed by typecheck")
804 call := call.(*ir.CallExpr)
808 n := n.(*ir.TailCallStmt)
809 n.Call.NoInline = true // Not inline a tail call for now. Maybe we could inline it just like RETURN fn(arg)?
811 // TODO do them here (or earlier),
812 // so escape analysis can avoid more heapmoves.
816 base.FatalfAt(n.Pos(), "OCALLMETH missed by typecheck")
818 n := n.(*ir.CallExpr)
819 if n.X.Op() == ir.OMETHEXPR {
820 // Prevent inlining some reflect.Value methods when using checkptr,
821 // even when package reflect was compiled without it (#35073).
822 if meth := ir.MethodExprName(n.X); meth != nil {
824 if base.Debug.Checkptr != 0 && types.IsReflectPkg(s.Pkg) && (s.Name == "Value.UnsafeAddr" || s.Name == "Value.Pointer") {
833 ir.EditChildren(n, edit)
835 // with all the branches out of the way, it is now time to
836 // transmogrify this node itself unless inhibited by the
837 // switch at the top of this function.
840 base.FatalfAt(n.Pos(), "OCALLMETH missed by typecheck")
843 call := n.(*ir.CallExpr)
847 if base.Flag.LowerM > 3 {
848 fmt.Printf("%v:call to func %+v\n", ir.Line(n), call.X)
850 if ir.IsIntrinsicCall(call) {
853 if fn := inlCallee(call.X, profile); fn != nil && typecheck.HaveInlineBody(fn) {
854 n = mkinlcall(call, fn, maxCost, inlCalls, edit)
863 // inlCallee takes a function-typed expression and returns the underlying function ONAME
864 // that it refers to if statically known. Otherwise, it returns nil.
865 func inlCallee(fn ir.Node, profile *pgo.Profile) *ir.Func {
866 fn = ir.StaticValue(fn)
869 fn := fn.(*ir.SelectorExpr)
870 n := ir.MethodExprName(fn)
871 // Check that receiver type matches fn.X.
872 // TODO(mdempsky): Handle implicit dereference
873 // of pointer receiver argument?
874 if n == nil || !types.Identical(n.Type().Recv().Type, fn.X.Type()) {
880 if fn.Class == ir.PFUNC {
884 fn := fn.(*ir.ClosureExpr)
886 CanInline(c, profile)
894 // SSADumpInline gives the SSA back end a chance to dump the function
895 // when producing output for debugging the compiler itself.
896 var SSADumpInline = func(*ir.Func) {}
898 // InlineCall allows the inliner implementation to be overridden.
899 // If it returns nil, the function will not be inlined.
900 var InlineCall = func(call *ir.CallExpr, fn *ir.Func, inlIndex int) *ir.InlinedCallExpr {
901 base.Fatalf("inline.InlineCall not overridden")
905 // If n is a OCALLFUNC node, and fn is an ONAME node for a
906 // function with an inlinable body, return an OINLCALL node that can replace n.
907 // The returned node's Ninit has the parameter assignments, the Nbody is the
908 // inlined function body, and (List, Rlist) contain the (input, output)
910 // The result of mkinlcall MUST be assigned back to n, e.g.
912 // n.Left = mkinlcall(n.Left, fn, isddd)
913 func mkinlcall(n *ir.CallExpr, fn *ir.Func, maxCost int32, inlCalls *[]*ir.InlinedCallExpr, edit func(ir.Node) ir.Node) ir.Node {
915 if logopt.Enabled() {
916 logopt.LogOpt(n.Pos(), "cannotInlineCall", "inline", ir.FuncName(ir.CurFunc),
917 fmt.Sprintf("%s cannot be inlined", ir.PkgFuncName(fn)))
921 if fn.Inl.Cost > maxCost {
922 // If the callsite is hot and it is under the inlineHotMaxBudget budget, then try to inline it, or else bail.
923 lineOffset := pgo.NodeLineOffset(n, ir.CurFunc)
924 csi := pgo.CallSiteInfo{LineOffset: lineOffset, Caller: ir.CurFunc}
925 if _, ok := candHotEdgeMap[csi]; ok {
926 if fn.Inl.Cost > inlineHotMaxBudget {
927 if logopt.Enabled() {
928 logopt.LogOpt(n.Pos(), "cannotInlineCall", "inline", ir.FuncName(ir.CurFunc),
929 fmt.Sprintf("cost %d of %s exceeds max large caller cost %d", fn.Inl.Cost, ir.PkgFuncName(fn), inlineHotMaxBudget))
933 if base.Debug.PGOInline > 0 {
934 fmt.Printf("hot-budget check allows inlining for call %s at %v\n", ir.PkgFuncName(fn), ir.Line(n))
937 // The inlined function body is too big. Typically we use this check to restrict
938 // inlining into very big functions. See issue 26546 and 17566.
939 if logopt.Enabled() {
940 logopt.LogOpt(n.Pos(), "cannotInlineCall", "inline", ir.FuncName(ir.CurFunc),
941 fmt.Sprintf("cost %d of %s exceeds max large caller cost %d", fn.Inl.Cost, ir.PkgFuncName(fn), maxCost))
947 if fn == ir.CurFunc {
948 // Can't recursively inline a function into itself.
949 if logopt.Enabled() {
950 logopt.LogOpt(n.Pos(), "cannotInlineCall", "inline", fmt.Sprintf("recursive call to %s", ir.FuncName(ir.CurFunc)))
955 if base.Flag.Cfg.Instrumenting && types.IsRuntimePkg(fn.Sym().Pkg) {
956 // Runtime package must not be instrumented.
957 // Instrument skips runtime package. However, some runtime code can be
958 // inlined into other packages and instrumented there. To avoid this,
959 // we disable inlining of runtime functions when instrumenting.
960 // The example that we observed is inlining of LockOSThread,
961 // which lead to false race reports on m contents.
965 parent := base.Ctxt.PosTable.Pos(n.Pos()).Base().InliningIndex()
968 // Check if we've already inlined this function at this particular
969 // call site, in order to stop inlining when we reach the beginning
970 // of a recursion cycle again. We don't inline immediately recursive
971 // functions, but allow inlining if there is a recursion cycle of
972 // many functions. Most likely, the inlining will stop before we
973 // even hit the beginning of the cycle again, but this catches the
975 for inlIndex := parent; inlIndex >= 0; inlIndex = base.Ctxt.InlTree.Parent(inlIndex) {
976 if base.Ctxt.InlTree.InlinedFunction(inlIndex) == sym {
977 if base.Flag.LowerM > 1 {
978 fmt.Printf("%v: cannot inline %v into %v: repeated recursive cycle\n", ir.Line(n), fn, ir.FuncName(ir.CurFunc))
984 typecheck.AssertFixedCall(n)
986 inlIndex := base.Ctxt.InlTree.Add(parent, n.Pos(), sym)
988 closureInitLSym := func(n *ir.CallExpr, fn *ir.Func) {
989 // The linker needs FuncInfo metadata for all inlined
990 // functions. This is typically handled by gc.enqueueFunc
991 // calling ir.InitLSym for all function declarations in
992 // typecheck.Target.Decls (ir.UseClosure adds all closures to
995 // However, non-trivial closures in Decls are ignored, and are
996 // insteaded enqueued when walk of the calling function
999 // This presents a problem for direct calls to closures.
1000 // Inlining will replace the entire closure definition with its
1001 // body, which hides the closure from walk and thus suppresses
1004 // Explicitly create a symbol early in this edge case to ensure
1005 // we keep this metadata.
1007 // TODO: Refactor to keep a reference so this can all be done
1010 if n.Op() != ir.OCALLFUNC {
1011 // Not a standard call.
1014 if n.X.Op() != ir.OCLOSURE {
1015 // Not a direct closure call.
1019 clo := n.X.(*ir.ClosureExpr)
1020 if ir.IsTrivialClosure(clo) {
1021 // enqueueFunc will handle trivial closures anyways.
1025 ir.InitLSym(fn, true)
1028 closureInitLSym(n, fn)
1030 if base.Flag.GenDwarfInl > 0 {
1031 if !sym.WasInlined() {
1032 base.Ctxt.DwFixups.SetPrecursorFunc(sym, fn)
1033 sym.Set(obj.AttrWasInlined, true)
1037 if base.Flag.LowerM != 0 {
1038 fmt.Printf("%v: inlining call to %v\n", ir.Line(n), fn)
1040 if base.Flag.LowerM > 2 {
1041 fmt.Printf("%v: Before inlining: %+v\n", ir.Line(n), n)
1044 if base.Debug.PGOInline > 0 {
1045 csi := pgo.CallSiteInfo{LineOffset: pgo.NodeLineOffset(n, fn), Caller: ir.CurFunc}
1046 if _, ok := inlinedCallSites[csi]; !ok {
1047 inlinedCallSites[csi] = struct{}{}
1051 res := InlineCall(n, fn, inlIndex)
1054 base.FatalfAt(n.Pos(), "inlining call to %v failed", fn)
1057 if base.Flag.LowerM > 2 {
1058 fmt.Printf("%v: After inlining %+v\n\n", ir.Line(res), res)
1061 *inlCalls = append(*inlCalls, res)
1066 // CalleeEffects appends any side effects from evaluating callee to init.
1067 func CalleeEffects(init *ir.Nodes, callee ir.Node) {
1069 init.Append(ir.TakeInit(callee)...)
1071 switch callee.Op() {
1072 case ir.ONAME, ir.OCLOSURE, ir.OMETHEXPR:
1076 conv := callee.(*ir.ConvExpr)
1080 ic := callee.(*ir.InlinedCallExpr)
1081 init.Append(ic.Body.Take()...)
1082 callee = ic.SingleResult()
1085 base.FatalfAt(callee.Pos(), "unexpected callee expression: %v", callee)
1090 func pruneUnusedAutos(ll []*ir.Name, vis *hairyVisitor) []*ir.Name {
1091 s := make([]*ir.Name, 0, len(ll))
1092 for _, n := range ll {
1093 if n.Class == ir.PAUTO {
1094 if !vis.usedLocals.Has(n) {
1103 // numNonClosures returns the number of functions in list which are not closures.
1104 func numNonClosures(list []*ir.Func) int {
1106 for _, fn := range list {
1107 if fn.OClosure == nil {
1114 func doList(list []ir.Node, do func(ir.Node) bool) bool {
1115 for _, x := range list {
1125 // isIndexingCoverageCounter returns true if the specified node 'n' is indexing
1126 // into a coverage counter array.
1127 func isIndexingCoverageCounter(n ir.Node) bool {
1128 if n.Op() != ir.OINDEX {
1131 ixn := n.(*ir.IndexExpr)
1132 if ixn.X.Op() != ir.ONAME || !ixn.X.Type().IsArray() {
1135 nn := ixn.X.(*ir.Name)
1136 return nn.CoverageCounter()
1139 // isAtomicCoverageCounterUpdate examines the specified node to
1140 // determine whether it represents a call to sync/atomic.AddUint32 to
1141 // increment a coverage counter.
1142 func isAtomicCoverageCounterUpdate(cn *ir.CallExpr) bool {
1143 if cn.X.Op() != ir.ONAME {
1146 name := cn.X.(*ir.Name)
1147 if name.Class != ir.PFUNC {
1150 fn := name.Sym().Name
1151 if name.Sym().Pkg.Path != "sync/atomic" ||
1152 (fn != "AddUint32" && fn != "StoreUint32") {
1155 if len(cn.Args) != 2 || cn.Args[0].Op() != ir.OADDR {
1158 adn := cn.Args[0].(*ir.AddrExpr)
1159 v := isIndexingCoverageCounter(adn.X)