Adding upstream version 1.22.1.upstream/1.22.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1217 insertions, 0 deletions

diff --git a/src/cmd/compile/internal/inline/inl.go b/src/cmd/compile/internal/inline/inl.go
new file mode 100644
index 0000000..b365008
--- /dev/null
+++ b/src/cmd/compile/internal/inline/inl.go
@@ -0,0 +1,1217 @@
+// Copyright 2011 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.
+//
+// The inlining facility makes 2 passes: first CanInline determines which
+// functions are suitable for inlining, and for those that are it
+// saves a copy of the body. Then InlineCalls walks each function body to
+// expand calls to inlinable functions.
+//
+// The Debug.l flag controls the aggressiveness. Note that main() swaps level 0 and 1,
+// making 1 the default and -l disable. Additional levels (beyond -l) may be buggy and
+// are not supported.
+//      0: disabled
+//      1: 80-nodes leaf functions, oneliners, panic, lazy typechecking (default)
+//      2: (unassigned)
+//      3: (unassigned)
+//      4: allow non-leaf functions
+//
+// At some point this may get another default and become switch-offable with -N.
+//
+// The -d typcheckinl flag enables early typechecking of all imported bodies,
+// which is useful to flush out bugs.
+//
+// The Debug.m flag enables diagnostic output.  a single -m is useful for verifying
+// which calls get inlined or not, more is for debugging, and may go away at any point.
+
+package inline
+
+import (
+	"fmt"
+	"go/constant"
+	"internal/buildcfg"
+	"strconv"
+
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/inline/inlheur"
+	"cmd/compile/internal/ir"
+	"cmd/compile/internal/logopt"
+	"cmd/compile/internal/pgo"
+	"cmd/compile/internal/typecheck"
+	"cmd/compile/internal/types"
+	"cmd/internal/obj"
+)
+
+// Inlining budget parameters, gathered in one place
+const (
+	inlineMaxBudget       = 80
+	inlineExtraAppendCost = 0
+	// default is to inline if there's at most one call. -l=4 overrides this by using 1 instead.
+	inlineExtraCallCost  = 57              // 57 was benchmarked to provided most benefit with no bad surprises; see https://github.com/golang/go/issues/19348#issuecomment-439370742
+	inlineExtraPanicCost = 1               // do not penalize inlining panics.
+	inlineExtraThrowCost = inlineMaxBudget // with current (2018-05/1.11) code, inlining runtime.throw does not help.
+
+	inlineBigFunctionNodes   = 5000 // Functions with this many nodes are considered "big".
+	inlineBigFunctionMaxCost = 20   // Max cost of inlinee when inlining into a "big" function.
+)
+
+var (
+	// List of all hot callee nodes.
+	// TODO(prattmic): Make this non-global.
+	candHotCalleeMap = make(map[*pgo.IRNode]struct{})
+
+	// List of all hot call sites. CallSiteInfo.Callee is always nil.
+	// TODO(prattmic): Make this non-global.
+	candHotEdgeMap = make(map[pgo.CallSiteInfo]struct{})
+
+	// Threshold in percentage for hot callsite inlining.
+	inlineHotCallSiteThresholdPercent float64
+
+	// Threshold in CDF percentage for hot callsite inlining,
+	// that is, for a threshold of X the hottest callsites that
+	// make up the top X% of total edge weight will be
+	// considered hot for inlining candidates.
+	inlineCDFHotCallSiteThresholdPercent = float64(99)
+
+	// Budget increased due to hotness.
+	inlineHotMaxBudget int32 = 2000
+)
+
+// PGOInlinePrologue records the hot callsites from ir-graph.
+func PGOInlinePrologue(p *pgo.Profile, funcs []*ir.Func) {
+	if base.Debug.PGOInlineCDFThreshold != "" {
+		if s, err := strconv.ParseFloat(base.Debug.PGOInlineCDFThreshold, 64); err == nil && s >= 0 && s <= 100 {
+			inlineCDFHotCallSiteThresholdPercent = s
+		} else {
+			base.Fatalf("invalid PGOInlineCDFThreshold, must be between 0 and 100")
+		}
+	}
+	var hotCallsites []pgo.NamedCallEdge
+	inlineHotCallSiteThresholdPercent, hotCallsites = hotNodesFromCDF(p)
+	if base.Debug.PGODebug > 0 {
+		fmt.Printf("hot-callsite-thres-from-CDF=%v\n", inlineHotCallSiteThresholdPercent)
+	}
+
+	if x := base.Debug.PGOInlineBudget; x != 0 {
+		inlineHotMaxBudget = int32(x)
+	}
+
+	for _, n := range hotCallsites {
+		// mark inlineable callees from hot edges
+		if callee := p.WeightedCG.IRNodes[n.CalleeName]; callee != nil {
+			candHotCalleeMap[callee] = struct{}{}
+		}
+		// mark hot call sites
+		if caller := p.WeightedCG.IRNodes[n.CallerName]; caller != nil && caller.AST != nil {
+			csi := pgo.CallSiteInfo{LineOffset: n.CallSiteOffset, Caller: caller.AST}
+			candHotEdgeMap[csi] = struct{}{}
+		}
+	}
+
+	if base.Debug.PGODebug >= 3 {
+		fmt.Printf("hot-cg before inline in dot format:")
+		p.PrintWeightedCallGraphDOT(inlineHotCallSiteThresholdPercent)
+	}
+}
+
+// hotNodesFromCDF computes an edge weight threshold and the list of hot
+// nodes that make up the given percentage of the CDF. The threshold, as
+// a percent, is the lower bound of weight for nodes to be considered hot
+// (currently only used in debug prints) (in case of equal weights,
+// comparing with the threshold may not accurately reflect which nodes are
+// considiered hot).
+func hotNodesFromCDF(p *pgo.Profile) (float64, []pgo.NamedCallEdge) {
+	cum := int64(0)
+	for i, n := range p.NamedEdgeMap.ByWeight {
+		w := p.NamedEdgeMap.Weight[n]
+		cum += w
+		if pgo.WeightInPercentage(cum, p.TotalWeight) > inlineCDFHotCallSiteThresholdPercent {
+			// nodes[:i+1] to include the very last node that makes it to go over the threshold.
+			// (Say, if the CDF threshold is 50% and one hot node takes 60% of weight, we want to
+			// include that node instead of excluding it.)
+			return pgo.WeightInPercentage(w, p.TotalWeight), p.NamedEdgeMap.ByWeight[:i+1]
+		}
+	}
+	return 0, p.NamedEdgeMap.ByWeight
+}
+
+// CanInlineFuncs computes whether a batch of functions are inlinable.
+func CanInlineFuncs(funcs []*ir.Func, profile *pgo.Profile) {
+	if profile != nil {
+		PGOInlinePrologue(profile, funcs)
+	}
+
+	ir.VisitFuncsBottomUp(funcs, func(list []*ir.Func, recursive bool) {
+		CanInlineSCC(list, recursive, profile)
+	})
+}
+
+// CanInlineSCC computes the inlinability of functions within an SCC
+// (strongly connected component).
+//
+// CanInlineSCC is designed to be used by ir.VisitFuncsBottomUp
+// callbacks.
+func CanInlineSCC(funcs []*ir.Func, recursive bool, profile *pgo.Profile) {
+	if base.Flag.LowerL == 0 {
+		return
+	}
+
+	numfns := numNonClosures(funcs)
+
+	for _, fn := range funcs {
+		if !recursive || numfns > 1 {
+			// We allow inlining if there is no
+			// recursion, or the recursion cycle is
+			// across more than one function.
+			CanInline(fn, profile)
+		} else {
+			if base.Flag.LowerM > 1 && fn.OClosure == nil {
+				fmt.Printf("%v: cannot inline %v: recursive\n", ir.Line(fn), fn.Nname)
+			}
+		}
+		if inlheur.Enabled() {
+			analyzeFuncProps(fn, profile)
+		}
+	}
+}
+
+// GarbageCollectUnreferencedHiddenClosures makes a pass over all the
+// top-level (non-hidden-closure) functions looking for nested closure
+// functions that are reachable, then sweeps through the Target.Decls
+// list and marks any non-reachable hidden closure function as dead.
+// See issues #59404 and #59638 for more context.
+func GarbageCollectUnreferencedHiddenClosures() {
+
+	liveFuncs := make(map[*ir.Func]bool)
+
+	var markLiveFuncs func(fn *ir.Func)
+	markLiveFuncs = func(fn *ir.Func) {
+		if liveFuncs[fn] {
+			return
+		}
+		liveFuncs[fn] = true
+		ir.Visit(fn, func(n ir.Node) {
+			if clo, ok := n.(*ir.ClosureExpr); ok {
+				markLiveFuncs(clo.Func)
+			}
+		})
+	}
+
+	for i := 0; i < len(typecheck.Target.Funcs); i++ {
+		fn := typecheck.Target.Funcs[i]
+		if fn.IsHiddenClosure() {
+			continue
+		}
+		markLiveFuncs(fn)
+	}
+
+	for i := 0; i < len(typecheck.Target.Funcs); i++ {
+		fn := typecheck.Target.Funcs[i]
+		if !fn.IsHiddenClosure() {
+			continue
+		}
+		if fn.IsDeadcodeClosure() {
+			continue
+		}
+		if liveFuncs[fn] {
+			continue
+		}
+		fn.SetIsDeadcodeClosure(true)
+		if base.Flag.LowerM > 2 {
+			fmt.Printf("%v: unreferenced closure %v marked as dead\n", ir.Line(fn), fn)
+		}
+		if fn.Inl != nil && fn.LSym == nil {
+			ir.InitLSym(fn, true)
+		}
+	}
+}
+
+// inlineBudget determines the max budget for function 'fn' prior to
+// analyzing the hairyness of the body of 'fn'. We pass in the pgo
+// profile if available (which can change the budget), also a
+// 'relaxed' flag, which expands the budget slightly to allow for the
+// possibility that a call to the function might have its score
+// adjusted downwards. If 'verbose' is set, then print a remark where
+// we boost the budget due to PGO.
+func inlineBudget(fn *ir.Func, profile *pgo.Profile, relaxed bool, verbose bool) int32 {
+	// Update the budget for profile-guided inlining.
+	budget := int32(inlineMaxBudget)
+	if profile != nil {
+		if n, ok := profile.WeightedCG.IRNodes[ir.LinkFuncName(fn)]; ok {
+			if _, ok := candHotCalleeMap[n]; ok {
+				budget = int32(inlineHotMaxBudget)
+				if verbose {
+					fmt.Printf("hot-node enabled increased budget=%v for func=%v\n", budget, ir.PkgFuncName(fn))
+				}
+			}
+		}
+	}
+	if relaxed {
+		budget += inlheur.BudgetExpansion(inlineMaxBudget)
+	}
+	return budget
+}
+
+// CanInline determines whether fn is inlineable.
+// If so, CanInline saves copies of fn.Body and fn.Dcl in fn.Inl.
+// fn and fn.Body will already have been typechecked.
+func CanInline(fn *ir.Func, profile *pgo.Profile) {
+	if fn.Nname == nil {
+		base.Fatalf("CanInline no nname %+v", fn)
+	}
+
+	var reason string // reason, if any, that the function was not inlined
+	if base.Flag.LowerM > 1 || logopt.Enabled() {
+		defer func() {
+			if reason != "" {
+				if base.Flag.LowerM > 1 {
+					fmt.Printf("%v: cannot inline %v: %s\n", ir.Line(fn), fn.Nname, reason)
+				}
+				if logopt.Enabled() {
+					logopt.LogOpt(fn.Pos(), "cannotInlineFunction", "inline", ir.FuncName(fn), reason)
+				}
+			}
+		}()
+	}
+
+	reason = InlineImpossible(fn)
+	if reason != "" {
+		return
+	}
+	if fn.Typecheck() == 0 {
+		base.Fatalf("CanInline on non-typechecked function %v", fn)
+	}
+
+	n := fn.Nname
+	if n.Func.InlinabilityChecked() {
+		return
+	}
+	defer n.Func.SetInlinabilityChecked(true)
+
+	cc := int32(inlineExtraCallCost)
+	if base.Flag.LowerL == 4 {
+		cc = 1 // this appears to yield better performance than 0.
+	}
+
+	// Used a "relaxed" inline budget if the new inliner is enabled.
+	relaxed := inlheur.Enabled()
+
+	// Compute the inline budget for this func.
+	budget := inlineBudget(fn, profile, relaxed, base.Debug.PGODebug > 0)
+
+	// At this point in the game the function we're looking at may
+	// have "stale" autos, vars that still appear in the Dcl list, but
+	// which no longer have any uses in the function body (due to
+	// elimination by deadcode). We'd like to exclude these dead vars
+	// when creating the "Inline.Dcl" field below; to accomplish this,
+	// the hairyVisitor below builds up a map of used/referenced
+	// locals, and we use this map to produce a pruned Inline.Dcl
+	// list. See issue 25459 for more context.
+
+	visitor := hairyVisitor{
+		curFunc:       fn,
+		isBigFunc:     IsBigFunc(fn),
+		budget:        budget,
+		maxBudget:     budget,
+		extraCallCost: cc,
+		profile:       profile,
+	}
+	if visitor.tooHairy(fn) {
+		reason = visitor.reason
+		return
+	}
+
+	n.Func.Inl = &ir.Inline{
+		Cost:    budget - visitor.budget,
+		Dcl:     pruneUnusedAutos(n.Func.Dcl, &visitor),
+		HaveDcl: true,
+
+		CanDelayResults: canDelayResults(fn),
+	}
+	if base.Flag.LowerM != 0 || logopt.Enabled() {
+		noteInlinableFunc(n, fn, budget-visitor.budget)
+	}
+}
+
+// noteInlinableFunc issues a message to the user that the specified
+// function is inlinable.
+func noteInlinableFunc(n *ir.Name, fn *ir.Func, cost int32) {
+	if base.Flag.LowerM > 1 {
+		fmt.Printf("%v: can inline %v with cost %d as: %v { %v }\n", ir.Line(fn), n, cost, fn.Type(), ir.Nodes(fn.Body))
+	} else if base.Flag.LowerM != 0 {
+		fmt.Printf("%v: can inline %v\n", ir.Line(fn), n)
+	}
+	// JSON optimization log output.
+	if logopt.Enabled() {
+		logopt.LogOpt(fn.Pos(), "canInlineFunction", "inline", ir.FuncName(fn), fmt.Sprintf("cost: %d", cost))
+	}
+}
+
+// InlineImpossible returns a non-empty reason string if fn is impossible to
+// inline regardless of cost or contents.
+func InlineImpossible(fn *ir.Func) string {
+	var reason string // reason, if any, that the function can not be inlined.
+	if fn.Nname == nil {
+		reason = "no name"
+		return reason
+	}
+
+	// If marked "go:noinline", don't inline.
+	if fn.Pragma&ir.Noinline != 0 {
+		reason = "marked go:noinline"
+		return reason
+	}
+
+	// If marked "go:norace" and -race compilation, don't inline.
+	if base.Flag.Race && fn.Pragma&ir.Norace != 0 {
+		reason = "marked go:norace with -race compilation"
+		return reason
+	}
+
+	// If marked "go:nocheckptr" and -d checkptr compilation, don't inline.
+	if base.Debug.Checkptr != 0 && fn.Pragma&ir.NoCheckPtr != 0 {
+		reason = "marked go:nocheckptr"
+		return reason
+	}
+
+	// If marked "go:cgo_unsafe_args", don't inline, since the function
+	// makes assumptions about its argument frame layout.
+	if fn.Pragma&ir.CgoUnsafeArgs != 0 {
+		reason = "marked go:cgo_unsafe_args"
+		return reason
+	}
+
+	// If marked as "go:uintptrkeepalive", don't inline, since the keep
+	// alive information is lost during inlining.
+	//
+	// TODO(prattmic): This is handled on calls during escape analysis,
+	// which is after inlining. Move prior to inlining so the keep-alive is
+	// maintained after inlining.
+	if fn.Pragma&ir.UintptrKeepAlive != 0 {
+		reason = "marked as having a keep-alive uintptr argument"
+		return reason
+	}
+
+	// If marked as "go:uintptrescapes", don't inline, since the escape
+	// information is lost during inlining.
+	if fn.Pragma&ir.UintptrEscapes != 0 {
+		reason = "marked as having an escaping uintptr argument"
+		return reason
+	}
+
+	// The nowritebarrierrec checker currently works at function
+	// granularity, so inlining yeswritebarrierrec functions can confuse it
+	// (#22342). As a workaround, disallow inlining them for now.
+	if fn.Pragma&ir.Yeswritebarrierrec != 0 {
+		reason = "marked go:yeswritebarrierrec"
+		return reason
+	}
+
+	// If a local function has no fn.Body (is defined outside of Go), cannot inline it.
+	// Imported functions don't have fn.Body but might have inline body in fn.Inl.
+	if len(fn.Body) == 0 && !typecheck.HaveInlineBody(fn) {
+		reason = "no function body"
+		return reason
+	}
+
+	return ""
+}
+
+// canDelayResults reports whether inlined calls to fn can delay
+// declaring the result parameter until the "return" statement.
+func canDelayResults(fn *ir.Func) bool {
+	// We can delay declaring+initializing result parameters if:
+	// (1) there's exactly one "return" statement in the inlined function;
+	// (2) it's not an empty return statement (#44355); and
+	// (3) the result parameters aren't named.
+
+	nreturns := 0
+	ir.VisitList(fn.Body, func(n ir.Node) {
+		if n, ok := n.(*ir.ReturnStmt); ok {
+			nreturns++
+			if len(n.Results) == 0 {
+				nreturns++ // empty return statement (case 2)
+			}
+		}
+	})
+
+	if nreturns != 1 {
+		return false // not exactly one return statement (case 1)
+	}
+
+	// temporaries for return values.
+	for _, param := range fn.Type().Results() {
+		if sym := param.Sym; sym != nil && !sym.IsBlank() {
+			return false // found a named result parameter (case 3)
+		}
+	}
+
+	return true
+}
+
+// hairyVisitor visits a function body to determine its inlining
+// hairiness and whether or not it can be inlined.
+type hairyVisitor struct {
+	// This is needed to access the current caller in the doNode function.
+	curFunc       *ir.Func
+	isBigFunc     bool
+	budget        int32
+	maxBudget     int32
+	reason        string
+	extraCallCost int32
+	usedLocals    ir.NameSet
+	do            func(ir.Node) bool
+	profile       *pgo.Profile
+}
+
+func (v *hairyVisitor) tooHairy(fn *ir.Func) bool {
+	v.do = v.doNode // cache closure
+	if ir.DoChildren(fn, v.do) {
+		return true
+	}
+	if v.budget < 0 {
+		v.reason = fmt.Sprintf("function too complex: cost %d exceeds budget %d", v.maxBudget-v.budget, v.maxBudget)
+		return true
+	}
+	return false
+}
+
+// doNode visits n and its children, updates the state in v, and returns true if
+// n makes the current function too hairy for inlining.
+func (v *hairyVisitor) doNode(n ir.Node) bool {
+	if n == nil {
+		return false
+	}
+opSwitch:
+	switch n.Op() {
+	// Call is okay if inlinable and we have the budget for the body.
+	case ir.OCALLFUNC:
+		n := n.(*ir.CallExpr)
+		// Functions that call runtime.getcaller{pc,sp} can not be inlined
+		// because getcaller{pc,sp} expect a pointer to the caller's first argument.
+		//
+		// runtime.throw is a "cheap call" like panic in normal code.
+		var cheap bool
+		if n.Fun.Op() == ir.ONAME {
+			name := n.Fun.(*ir.Name)
+			if name.Class == ir.PFUNC {
+				switch fn := types.RuntimeSymName(name.Sym()); fn {
+				case "getcallerpc", "getcallersp":
+					v.reason = "call to " + fn
+					return true
+				case "throw":
+					v.budget -= inlineExtraThrowCost
+					break opSwitch
+				case "panicrangeexit":
+					cheap = true
+				}
+				// Special case for reflect.noescape. It does just type
+				// conversions to appease the escape analysis, and doesn't
+				// generate code.
+				if types.ReflectSymName(name.Sym()) == "noescape" {
+					cheap = true
+				}
+			}
+			// Special case for coverage counter updates; although
+			// these correspond to real operations, we treat them as
+			// zero cost for the moment. This is due to the existence
+			// of tests that are sensitive to inlining-- if the
+			// insertion of coverage instrumentation happens to tip a
+			// given function over the threshold and move it from
+			// "inlinable" to "not-inlinable", this can cause changes
+			// in allocation behavior, which can then result in test
+			// failures (a good example is the TestAllocations in
+			// crypto/ed25519).
+			if isAtomicCoverageCounterUpdate(n) {
+				return false
+			}
+		}
+		if n.Fun.Op() == ir.OMETHEXPR {
+			if meth := ir.MethodExprName(n.Fun); meth != nil {
+				if fn := meth.Func; fn != nil {
+					s := fn.Sym()
+					if types.RuntimeSymName(s) == "heapBits.nextArena" {
+						// Special case: explicitly allow mid-stack inlining of
+						// runtime.heapBits.next even though it calls slow-path
+						// runtime.heapBits.nextArena.
+						cheap = true
+					}
+					// Special case: on architectures that can do unaligned loads,
+					// explicitly mark encoding/binary methods as cheap,
+					// because in practice they are, even though our inlining
+					// budgeting system does not see that. See issue 42958.
+					if base.Ctxt.Arch.CanMergeLoads && s.Pkg.Path == "encoding/binary" {
+						switch s.Name {
+						case "littleEndian.Uint64", "littleEndian.Uint32", "littleEndian.Uint16",
+							"bigEndian.Uint64", "bigEndian.Uint32", "bigEndian.Uint16",
+							"littleEndian.PutUint64", "littleEndian.PutUint32", "littleEndian.PutUint16",
+							"bigEndian.PutUint64", "bigEndian.PutUint32", "bigEndian.PutUint16",
+							"littleEndian.AppendUint64", "littleEndian.AppendUint32", "littleEndian.AppendUint16",
+							"bigEndian.AppendUint64", "bigEndian.AppendUint32", "bigEndian.AppendUint16":
+							cheap = true
+						}
+					}
+				}
+			}
+		}
+		if cheap {
+			break // treat like any other node, that is, cost of 1
+		}
+
+		if ir.IsIntrinsicCall(n) {
+			// Treat like any other node.
+			break
+		}
+
+		if callee := inlCallee(v.curFunc, n.Fun, v.profile); callee != nil && typecheck.HaveInlineBody(callee) {
+			// Check whether we'd actually inline this call. Set
+			// log == false since we aren't actually doing inlining
+			// yet.
+			if ok, _ := canInlineCallExpr(v.curFunc, n, callee, v.isBigFunc, false); ok {
+				// mkinlcall would inline this call [1], so use
+				// the cost of the inline body as the cost of
+				// the call, as that is what will actually
+				// appear in the code.
+				//
+				// [1] This is almost a perfect match to the
+				// mkinlcall logic, except that
+				// canInlineCallExpr considers inlining cycles
+				// by looking at what has already been inlined.
+				// Since we haven't done any inlining yet we
+				// will miss those.
+				v.budget -= callee.Inl.Cost
+				break
+			}
+		}
+
+		// Call cost for non-leaf inlining.
+		v.budget -= v.extraCallCost
+
+	case ir.OCALLMETH:
+		base.FatalfAt(n.Pos(), "OCALLMETH missed by typecheck")
+
+	// Things that are too hairy, irrespective of the budget
+	case ir.OCALL, ir.OCALLINTER:
+		// Call cost for non-leaf inlining.
+		v.budget -= v.extraCallCost
+
+	case ir.OPANIC:
+		n := n.(*ir.UnaryExpr)
+		if n.X.Op() == ir.OCONVIFACE && n.X.(*ir.ConvExpr).Implicit() {
+			// Hack to keep reflect.flag.mustBe inlinable for TestIntendedInlining.
+			// Before CL 284412, these conversions were introduced later in the
+			// compiler, so they didn't count against inlining budget.
+			v.budget++
+		}
+		v.budget -= inlineExtraPanicCost
+
+	case ir.ORECOVER:
+		base.FatalfAt(n.Pos(), "ORECOVER missed typecheck")
+	case ir.ORECOVERFP:
+		// recover matches the argument frame pointer to find
+		// the right panic value, so it needs an argument frame.
+		v.reason = "call to recover"
+		return true
+
+	case ir.OCLOSURE:
+		if base.Debug.InlFuncsWithClosures == 0 {
+			v.reason = "not inlining functions with closures"
+			return true
+		}
+
+		// TODO(danscales): Maybe make budget proportional to number of closure
+		// variables, e.g.:
+		//v.budget -= int32(len(n.(*ir.ClosureExpr).Func.ClosureVars) * 3)
+		// TODO(austin): However, if we're able to inline this closure into
+		// v.curFunc, then we actually pay nothing for the closure captures. We
+		// should try to account for that if we're going to account for captures.
+		v.budget -= 15
+
+	case ir.OGO, ir.ODEFER, ir.OTAILCALL:
+		v.reason = "unhandled op " + n.Op().String()
+		return true
+
+	case ir.OAPPEND:
+		v.budget -= inlineExtraAppendCost
+
+	case ir.OADDR:
+		n := n.(*ir.AddrExpr)
+		// Make "&s.f" cost 0 when f's offset is zero.
+		if dot, ok := n.X.(*ir.SelectorExpr); ok && (dot.Op() == ir.ODOT || dot.Op() == ir.ODOTPTR) {
+			if _, ok := dot.X.(*ir.Name); ok && dot.Selection.Offset == 0 {
+				v.budget += 2 // undo ir.OADDR+ir.ODOT/ir.ODOTPTR
+			}
+		}
+
+	case ir.ODEREF:
+		// *(*X)(unsafe.Pointer(&x)) is low-cost
+		n := n.(*ir.StarExpr)
+
+		ptr := n.X
+		for ptr.Op() == ir.OCONVNOP {
+			ptr = ptr.(*ir.ConvExpr).X
+		}
+		if ptr.Op() == ir.OADDR {
+			v.budget += 1 // undo half of default cost of ir.ODEREF+ir.OADDR
+		}
+
+	case ir.OCONVNOP:
+		// This doesn't produce code, but the children might.
+		v.budget++ // undo default cost
+
+	case ir.OFALL, ir.OTYPE:
+		// These nodes don't produce code; omit from inlining budget.
+		return false
+
+	case ir.OIF:
+		n := n.(*ir.IfStmt)
+		if ir.IsConst(n.Cond, constant.Bool) {
+			// This if and the condition cost nothing.
+			if doList(n.Init(), v.do) {
+				return true
+			}
+			if ir.BoolVal(n.Cond) {
+				return doList(n.Body, v.do)
+			} else {
+				return doList(n.Else, v.do)
+			}
+		}
+
+	case ir.ONAME:
+		n := n.(*ir.Name)
+		if n.Class == ir.PAUTO {
+			v.usedLocals.Add(n)
+		}
+
+	case ir.OBLOCK:
+		// The only OBLOCK we should see at this point is an empty one.
+		// In any event, let the visitList(n.List()) below take care of the statements,
+		// and don't charge for the OBLOCK itself. The ++ undoes the -- below.
+		v.budget++
+
+	case ir.OMETHVALUE, ir.OSLICELIT:
+		v.budget-- // Hack for toolstash -cmp.
+
+	case ir.OMETHEXPR:
+		v.budget++ // Hack for toolstash -cmp.
+
+	case ir.OAS2:
+		n := n.(*ir.AssignListStmt)
+
+		// Unified IR unconditionally rewrites:
+		//
+		//	a, b = f()
+		//
+		// into:
+		//
+		//	DCL tmp1
+		//	DCL tmp2
+		//	tmp1, tmp2 = f()
+		//	a, b = tmp1, tmp2
+		//
+		// so that it can insert implicit conversions as necessary. To
+		// minimize impact to the existing inlining heuristics (in
+		// particular, to avoid breaking the existing inlinability regress
+		// tests), we need to compensate for this here.
+		//
+		// See also identical logic in IsBigFunc.
+		if len(n.Rhs) > 0 {
+			if init := n.Rhs[0].Init(); len(init) == 1 {
+				if _, ok := init[0].(*ir.AssignListStmt); ok {
+					// 4 for each value, because each temporary variable now
+					// appears 3 times (DCL, LHS, RHS), plus an extra DCL node.
+					//
+					// 1 for the extra "tmp1, tmp2 = f()" assignment statement.
+					v.budget += 4*int32(len(n.Lhs)) + 1
+				}
+			}
+		}
+
+	case ir.OAS:
+		// Special case for coverage counter updates and coverage
+		// function registrations. Although these correspond to real
+		// operations, we treat them as zero cost for the moment. This
+		// is primarily due to the existence of tests that are
+		// sensitive to inlining-- if the insertion of coverage
+		// instrumentation happens to tip a given function over the
+		// threshold and move it from "inlinable" to "not-inlinable",
+		// this can cause changes in allocation behavior, which can
+		// then result in test failures (a good example is the
+		// TestAllocations in crypto/ed25519).
+		n := n.(*ir.AssignStmt)
+		if n.X.Op() == ir.OINDEX && isIndexingCoverageCounter(n.X) {
+			return false
+		}
+	}
+
+	v.budget--
+
+	// When debugging, don't stop early, to get full cost of inlining this function
+	if v.budget < 0 && base.Flag.LowerM < 2 && !logopt.Enabled() {
+		v.reason = "too expensive"
+		return true
+	}
+
+	return ir.DoChildren(n, v.do)
+}
+
+// IsBigFunc reports whether fn is a "big" function.
+//
+// Note: The criteria for "big" is heuristic and subject to change.
+func IsBigFunc(fn *ir.Func) bool {
+	budget := inlineBigFunctionNodes
+	return ir.Any(fn, func(n ir.Node) bool {
+		// See logic in hairyVisitor.doNode, explaining unified IR's
+		// handling of "a, b = f()" assignments.
+		if n, ok := n.(*ir.AssignListStmt); ok && n.Op() == ir.OAS2 && len(n.Rhs) > 0 {
+			if init := n.Rhs[0].Init(); len(init) == 1 {
+				if _, ok := init[0].(*ir.AssignListStmt); ok {
+					budget += 4*len(n.Lhs) + 1
+				}
+			}
+		}
+
+		budget--
+		return budget <= 0
+	})
+}
+
+// TryInlineCall returns an inlined call expression for call, or nil
+// if inlining is not possible.
+func TryInlineCall(callerfn *ir.Func, call *ir.CallExpr, bigCaller bool, profile *pgo.Profile) *ir.InlinedCallExpr {
+	if base.Flag.LowerL == 0 {
+		return nil
+	}
+	if call.Op() != ir.OCALLFUNC {
+		return nil
+	}
+	if call.GoDefer || call.NoInline {
+		return nil
+	}
+
+	// Prevent inlining some reflect.Value methods when using checkptr,
+	// even when package reflect was compiled without it (#35073).
+	if base.Debug.Checkptr != 0 && call.Fun.Op() == ir.OMETHEXPR {
+		if method := ir.MethodExprName(call.Fun); method != nil {
+			switch types.ReflectSymName(method.Sym()) {
+			case "Value.UnsafeAddr", "Value.Pointer":
+				return nil
+			}
+		}
+	}
+
+	if base.Flag.LowerM > 3 {
+		fmt.Printf("%v:call to func %+v\n", ir.Line(call), call.Fun)
+	}
+	if ir.IsIntrinsicCall(call) {
+		return nil
+	}
+	if fn := inlCallee(callerfn, call.Fun, profile); fn != nil && typecheck.HaveInlineBody(fn) {
+		return mkinlcall(callerfn, call, fn, bigCaller)
+	}
+	return nil
+}
+
+// inlCallee takes a function-typed expression and returns the underlying function ONAME
+// that it refers to if statically known. Otherwise, it returns nil.
+func inlCallee(caller *ir.Func, fn ir.Node, profile *pgo.Profile) (res *ir.Func) {
+	fn = ir.StaticValue(fn)
+	switch fn.Op() {
+	case ir.OMETHEXPR:
+		fn := fn.(*ir.SelectorExpr)
+		n := ir.MethodExprName(fn)
+		// Check that receiver type matches fn.X.
+		// TODO(mdempsky): Handle implicit dereference
+		// of pointer receiver argument?
+		if n == nil || !types.Identical(n.Type().Recv().Type, fn.X.Type()) {
+			return nil
+		}
+		return n.Func
+	case ir.ONAME:
+		fn := fn.(*ir.Name)
+		if fn.Class == ir.PFUNC {
+			return fn.Func
+		}
+	case ir.OCLOSURE:
+		fn := fn.(*ir.ClosureExpr)
+		c := fn.Func
+		if len(c.ClosureVars) != 0 && c.ClosureVars[0].Outer.Curfn != caller {
+			return nil // inliner doesn't support inlining across closure frames
+		}
+		CanInline(c, profile)
+		return c
+	}
+	return nil
+}
+
+var inlgen int
+
+// SSADumpInline gives the SSA back end a chance to dump the function
+// when producing output for debugging the compiler itself.
+var SSADumpInline = func(*ir.Func) {}
+
+// InlineCall allows the inliner implementation to be overridden.
+// If it returns nil, the function will not be inlined.
+var InlineCall = func(callerfn *ir.Func, call *ir.CallExpr, fn *ir.Func, inlIndex int) *ir.InlinedCallExpr {
+	base.Fatalf("inline.InlineCall not overridden")
+	panic("unreachable")
+}
+
+// inlineCostOK returns true if call n from caller to callee is cheap enough to
+// inline. bigCaller indicates that caller is a big function.
+//
+// In addition to the "cost OK" boolean, it also returns the "max
+// cost" limit used to make the decision (which may differ depending
+// on func size), and the score assigned to this specific callsite.
+func inlineCostOK(n *ir.CallExpr, caller, callee *ir.Func, bigCaller bool) (bool, int32, int32) {
+	maxCost := int32(inlineMaxBudget)
+	if bigCaller {
+		// We use this to restrict inlining into very big functions.
+		// See issue 26546 and 17566.
+		maxCost = inlineBigFunctionMaxCost
+	}
+
+	metric := callee.Inl.Cost
+	if inlheur.Enabled() {
+		score, ok := inlheur.GetCallSiteScore(caller, n)
+		if ok {
+			metric = int32(score)
+		}
+	}
+
+	if metric <= maxCost {
+		// Simple case. Function is already cheap enough.
+		return true, 0, metric
+	}
+
+	// We'll also allow inlining of hot functions below inlineHotMaxBudget,
+	// but only in small functions.
+
+	lineOffset := pgo.NodeLineOffset(n, caller)
+	csi := pgo.CallSiteInfo{LineOffset: lineOffset, Caller: caller}
+	if _, ok := candHotEdgeMap[csi]; !ok {
+		// Cold
+		return false, maxCost, metric
+	}
+
+	// Hot
+
+	if bigCaller {
+		if base.Debug.PGODebug > 0 {
+			fmt.Printf("hot-big check disallows inlining for call %s (cost %d) at %v in big function %s\n", ir.PkgFuncName(callee), callee.Inl.Cost, ir.Line(n), ir.PkgFuncName(caller))
+		}
+		return false, maxCost, metric
+	}
+
+	if metric > inlineHotMaxBudget {
+		return false, inlineHotMaxBudget, metric
+	}
+
+	if !base.PGOHash.MatchPosWithInfo(n.Pos(), "inline", nil) {
+		// De-selected by PGO Hash.
+		return false, maxCost, metric
+	}
+
+	if base.Debug.PGODebug > 0 {
+		fmt.Printf("hot-budget check allows inlining for call %s (cost %d) at %v in function %s\n", ir.PkgFuncName(callee), callee.Inl.Cost, ir.Line(n), ir.PkgFuncName(caller))
+	}
+
+	return true, 0, metric
+}
+
+// canInlineCallsite returns true if the call n from caller to callee
+// can be inlined, plus the score computed for the call expr in
+// question. bigCaller indicates that caller is a big function. log
+// indicates that the 'cannot inline' reason should be logged.
+//
+// Preconditions: CanInline(callee) has already been called.
+func canInlineCallExpr(callerfn *ir.Func, n *ir.CallExpr, callee *ir.Func, bigCaller bool, log bool) (bool, int32) {
+	if callee.Inl == nil {
+		// callee is never inlinable.
+		if log && logopt.Enabled() {
+			logopt.LogOpt(n.Pos(), "cannotInlineCall", "inline", ir.FuncName(callerfn),
+				fmt.Sprintf("%s cannot be inlined", ir.PkgFuncName(callee)))
+		}
+		return false, 0
+	}
+
+	ok, maxCost, callSiteScore := inlineCostOK(n, callerfn, callee, bigCaller)
+	if !ok {
+		// callee cost too high for this call site.
+		if log && logopt.Enabled() {
+			logopt.LogOpt(n.Pos(), "cannotInlineCall", "inline", ir.FuncName(callerfn),
+				fmt.Sprintf("cost %d of %s exceeds max caller cost %d", callee.Inl.Cost, ir.PkgFuncName(callee), maxCost))
+		}
+		return false, 0
+	}
+
+	if callee == callerfn {
+		// Can't recursively inline a function into itself.
+		if log && logopt.Enabled() {
+			logopt.LogOpt(n.Pos(), "cannotInlineCall", "inline", fmt.Sprintf("recursive call to %s", ir.FuncName(callerfn)))
+		}
+		return false, 0
+	}
+
+	if base.Flag.Cfg.Instrumenting && types.IsNoInstrumentPkg(callee.Sym().Pkg) {
+		// Runtime package must not be instrumented.
+		// Instrument skips runtime package. However, some runtime code can be
+		// inlined into other packages and instrumented there. To avoid this,
+		// we disable inlining of runtime functions when instrumenting.
+		// The example that we observed is inlining of LockOSThread,
+		// which lead to false race reports on m contents.
+		if log && logopt.Enabled() {
+			logopt.LogOpt(n.Pos(), "cannotInlineCall", "inline", ir.FuncName(callerfn),
+				fmt.Sprintf("call to runtime function %s in instrumented build", ir.PkgFuncName(callee)))
+		}
+		return false, 0
+	}
+
+	if base.Flag.Race && types.IsNoRacePkg(callee.Sym().Pkg) {
+		if log && logopt.Enabled() {
+			logopt.LogOpt(n.Pos(), "cannotInlineCall", "inline", ir.FuncName(callerfn),
+				fmt.Sprintf(`call to into "no-race" package function %s in race build`, ir.PkgFuncName(callee)))
+		}
+		return false, 0
+	}
+
+	// Check if we've already inlined this function at this particular
+	// call site, in order to stop inlining when we reach the beginning
+	// of a recursion cycle again. We don't inline immediately recursive
+	// functions, but allow inlining if there is a recursion cycle of
+	// many functions. Most likely, the inlining will stop before we
+	// even hit the beginning of the cycle again, but this catches the
+	// unusual case.
+	parent := base.Ctxt.PosTable.Pos(n.Pos()).Base().InliningIndex()
+	sym := callee.Linksym()
+	for inlIndex := parent; inlIndex >= 0; inlIndex = base.Ctxt.InlTree.Parent(inlIndex) {
+		if base.Ctxt.InlTree.InlinedFunction(inlIndex) == sym {
+			if log {
+				if base.Flag.LowerM > 1 {
+					fmt.Printf("%v: cannot inline %v into %v: repeated recursive cycle\n", ir.Line(n), callee, ir.FuncName(callerfn))
+				}
+				if logopt.Enabled() {
+					logopt.LogOpt(n.Pos(), "cannotInlineCall", "inline", ir.FuncName(callerfn),
+						fmt.Sprintf("repeated recursive cycle to %s", ir.PkgFuncName(callee)))
+				}
+			}
+			return false, 0
+		}
+	}
+
+	return true, callSiteScore
+}
+
+// mkinlcall returns an OINLCALL node that can replace OCALLFUNC n, or
+// nil if it cannot be inlined. callerfn is the function that contains
+// n, and fn is the function being called.
+//
+// The result of mkinlcall MUST be assigned back to n, e.g.
+//
+//	n.Left = mkinlcall(n.Left, fn, isddd)
+func mkinlcall(callerfn *ir.Func, n *ir.CallExpr, fn *ir.Func, bigCaller bool) *ir.InlinedCallExpr {
+	ok, score := canInlineCallExpr(callerfn, n, fn, bigCaller, true)
+	if !ok {
+		return nil
+	}
+	typecheck.AssertFixedCall(n)
+
+	parent := base.Ctxt.PosTable.Pos(n.Pos()).Base().InliningIndex()
+	sym := fn.Linksym()
+	inlIndex := base.Ctxt.InlTree.Add(parent, n.Pos(), sym, ir.FuncName(fn))
+
+	closureInitLSym := func(n *ir.CallExpr, fn *ir.Func) {
+		// The linker needs FuncInfo metadata for all inlined
+		// functions. This is typically handled by gc.enqueueFunc
+		// calling ir.InitLSym for all function declarations in
+		// typecheck.Target.Decls (ir.UseClosure adds all closures to
+		// Decls).
+		//
+		// However, non-trivial closures in Decls are ignored, and are
+		// insteaded enqueued when walk of the calling function
+		// discovers them.
+		//
+		// This presents a problem for direct calls to closures.
+		// Inlining will replace the entire closure definition with its
+		// body, which hides the closure from walk and thus suppresses
+		// symbol creation.
+		//
+		// Explicitly create a symbol early in this edge case to ensure
+		// we keep this metadata.
+		//
+		// TODO: Refactor to keep a reference so this can all be done
+		// by enqueueFunc.
+
+		if n.Op() != ir.OCALLFUNC {
+			// Not a standard call.
+			return
+		}
+		if n.Fun.Op() != ir.OCLOSURE {
+			// Not a direct closure call.
+			return
+		}
+
+		clo := n.Fun.(*ir.ClosureExpr)
+		if ir.IsTrivialClosure(clo) {
+			// enqueueFunc will handle trivial closures anyways.
+			return
+		}
+
+		ir.InitLSym(fn, true)
+	}
+
+	closureInitLSym(n, fn)
+
+	if base.Flag.GenDwarfInl > 0 {
+		if !sym.WasInlined() {
+			base.Ctxt.DwFixups.SetPrecursorFunc(sym, fn)
+			sym.Set(obj.AttrWasInlined, true)
+		}
+	}
+
+	if base.Flag.LowerM != 0 {
+		if buildcfg.Experiment.NewInliner {
+			fmt.Printf("%v: inlining call to %v with score %d\n",
+				ir.Line(n), fn, score)
+		} else {
+			fmt.Printf("%v: inlining call to %v\n", ir.Line(n), fn)
+		}
+	}
+	if base.Flag.LowerM > 2 {
+		fmt.Printf("%v: Before inlining: %+v\n", ir.Line(n), n)
+	}
+
+	res := InlineCall(callerfn, n, fn, inlIndex)
+
+	if res == nil {
+		base.FatalfAt(n.Pos(), "inlining call to %v failed", fn)
+	}
+
+	if base.Flag.LowerM > 2 {
+		fmt.Printf("%v: After inlining %+v\n\n", ir.Line(res), res)
+	}
+
+	if inlheur.Enabled() {
+		inlheur.UpdateCallsiteTable(callerfn, n, res)
+	}
+
+	return res
+}
+
+// CalleeEffects appends any side effects from evaluating callee to init.
+func CalleeEffects(init *ir.Nodes, callee ir.Node) {
+	for {
+		init.Append(ir.TakeInit(callee)...)
+
+		switch callee.Op() {
+		case ir.ONAME, ir.OCLOSURE, ir.OMETHEXPR:
+			return // done
+
+		case ir.OCONVNOP:
+			conv := callee.(*ir.ConvExpr)
+			callee = conv.X
+
+		case ir.OINLCALL:
+			ic := callee.(*ir.InlinedCallExpr)
+			init.Append(ic.Body.Take()...)
+			callee = ic.SingleResult()
+
+		default:
+			base.FatalfAt(callee.Pos(), "unexpected callee expression: %v", callee)
+		}
+	}
+}
+
+func pruneUnusedAutos(ll []*ir.Name, vis *hairyVisitor) []*ir.Name {
+	s := make([]*ir.Name, 0, len(ll))
+	for _, n := range ll {
+		if n.Class == ir.PAUTO {
+			if !vis.usedLocals.Has(n) {
+				// TODO(mdempsky): Simplify code after confident that this
+				// never happens anymore.
+				base.FatalfAt(n.Pos(), "unused auto: %v", n)
+				continue
+			}
+		}
+		s = append(s, n)
+	}
+	return s
+}
+
+// numNonClosures returns the number of functions in list which are not closures.
+func numNonClosures(list []*ir.Func) int {
+	count := 0
+	for _, fn := range list {
+		if fn.OClosure == nil {
+			count++
+		}
+	}
+	return count
+}
+
+func doList(list []ir.Node, do func(ir.Node) bool) bool {
+	for _, x := range list {
+		if x != nil {
+			if do(x) {
+				return true
+			}
+		}
+	}
+	return false
+}
+
+// isIndexingCoverageCounter returns true if the specified node 'n' is indexing
+// into a coverage counter array.
+func isIndexingCoverageCounter(n ir.Node) bool {
+	if n.Op() != ir.OINDEX {
+		return false
+	}
+	ixn := n.(*ir.IndexExpr)
+	if ixn.X.Op() != ir.ONAME || !ixn.X.Type().IsArray() {
+		return false
+	}
+	nn := ixn.X.(*ir.Name)
+	return nn.CoverageCounter()
+}
+
+// isAtomicCoverageCounterUpdate examines the specified node to
+// determine whether it represents a call to sync/atomic.AddUint32 to
+// increment a coverage counter.
+func isAtomicCoverageCounterUpdate(cn *ir.CallExpr) bool {
+	if cn.Fun.Op() != ir.ONAME {
+		return false
+	}
+	name := cn.Fun.(*ir.Name)
+	if name.Class != ir.PFUNC {
+		return false
+	}
+	fn := name.Sym().Name
+	if name.Sym().Pkg.Path != "sync/atomic" ||
+		(fn != "AddUint32" && fn != "StoreUint32") {
+		return false
+	}
+	if len(cn.Args) != 2 || cn.Args[0].Op() != ir.OADDR {
+		return false
+	}
+	adn := cn.Args[0].(*ir.AddrExpr)
+	v := isIndexingCoverageCounter(adn.X)
+	return v
+}
+
+func PostProcessCallSites(profile *pgo.Profile) {
+	if base.Debug.DumpInlCallSiteScores != 0 {
+		budgetCallback := func(fn *ir.Func, prof *pgo.Profile) (int32, bool) {
+			v := inlineBudget(fn, prof, false, false)
+			return v, v == inlineHotMaxBudget
+		}
+		inlheur.DumpInlCallSiteScores(profile, budgetCallback)
+	}
+}
+
+func analyzeFuncProps(fn *ir.Func, p *pgo.Profile) {
+	canInline := func(fn *ir.Func) { CanInline(fn, p) }
+	budgetForFunc := func(fn *ir.Func) int32 {
+		return inlineBudget(fn, p, true, false)
+	}
+	inlheur.AnalyzeFunc(fn, canInline, budgetForFunc, inlineMaxBudget)
+}