Adding upstream version 1.18.10.upstream/1.18.10upstream

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

1 files changed, 1407 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..bc7ec5c
--- /dev/null
+++ b/src/cmd/compile/internal/inline/inl.go
@@ -0,0 +1,1407 @@
+// 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 caninl 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"
+	"strings"
+
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/ir"
+	"cmd/compile/internal/logopt"
+	"cmd/compile/internal/typecheck"
+	"cmd/compile/internal/types"
+	"cmd/internal/obj"
+	"cmd/internal/src"
+)
+
+// 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.
+)
+
+// InlinePackage finds functions that can be inlined and clones them before walk expands them.
+func InlinePackage() {
+	ir.VisitFuncsBottomUp(typecheck.Target.Decls, func(list []*ir.Func, recursive bool) {
+		numfns := numNonClosures(list)
+		for _, n := range list {
+			if !recursive || numfns > 1 {
+				// We allow inlining if there is no
+				// recursion, or the recursion cycle is
+				// across more than one function.
+				CanInline(n)
+			} else {
+				if base.Flag.LowerM > 1 {
+					fmt.Printf("%v: cannot inline %v: recursive\n", ir.Line(n), n.Nname)
+				}
+			}
+			InlineCalls(n)
+		}
+	})
+}
+
+// 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) {
+	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)
+				}
+			}
+		}()
+	}
+
+	// If marked "go:noinline", don't inline
+	if fn.Pragma&ir.Noinline != 0 {
+		reason = "marked go:noinline"
+		return
+	}
+
+	// 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
+	}
+
+	// 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
+	}
+
+	// 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
+	}
+
+	// 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
+	}
+
+	// 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
+	}
+
+	// If fn has no body (is defined outside of Go), cannot inline it.
+	if len(fn.Body) == 0 {
+		reason = "no function body"
+		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.
+	}
+
+	// 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 25249 for more context.
+
+	visitor := hairyVisitor{
+		budget:        inlineMaxBudget,
+		extraCallCost: cc,
+	}
+	if visitor.tooHairy(fn) {
+		reason = visitor.reason
+		return
+	}
+
+	n.Func.Inl = &ir.Inline{
+		Cost: inlineMaxBudget - visitor.budget,
+		Dcl:  pruneUnusedAutos(n.Defn.(*ir.Func).Dcl, &visitor),
+		Body: inlcopylist(fn.Body),
+
+		CanDelayResults: canDelayResults(fn),
+	}
+
+	if base.Flag.LowerM > 1 {
+		fmt.Printf("%v: can inline %v with cost %d as: %v { %v }\n", ir.Line(fn), n, inlineMaxBudget-visitor.budget, fn.Type(), ir.Nodes(n.Func.Inl.Body))
+	} else if base.Flag.LowerM != 0 {
+		fmt.Printf("%v: can inline %v\n", ir.Line(fn), n)
+	}
+	if logopt.Enabled() {
+		logopt.LogOpt(fn.Pos(), "canInlineFunction", "inline", ir.FuncName(fn), fmt.Sprintf("cost: %d", inlineMaxBudget-visitor.budget))
+	}
+}
+
+// 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().FieldSlice() {
+		if sym := types.OrigSym(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 {
+	budget        int32
+	reason        string
+	extraCallCost int32
+	usedLocals    ir.NameSet
+	do            func(ir.Node) bool
+}
+
+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", inlineMaxBudget-v.budget, inlineMaxBudget)
+		return true
+	}
+	return false
+}
+
+func (v *hairyVisitor) doNode(n ir.Node) bool {
+	if n == nil {
+		return false
+	}
+	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.
+		if n.X.Op() == ir.ONAME {
+			name := n.X.(*ir.Name)
+			if name.Class == ir.PFUNC && types.IsRuntimePkg(name.Sym().Pkg) {
+				fn := name.Sym().Name
+				if fn == "getcallerpc" || fn == "getcallersp" {
+					v.reason = "call to " + fn
+					return true
+				}
+				if fn == "throw" {
+					v.budget -= inlineExtraThrowCost
+					break
+				}
+			}
+		}
+		if n.X.Op() == ir.OMETHEXPR {
+			if meth := ir.MethodExprName(n.X); meth != nil {
+				if fn := meth.Func; fn != nil {
+					s := fn.Sym()
+					var cheap bool
+					if types.IsRuntimePkg(s.Pkg) && s.Name == "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":
+							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 fn := inlCallee(n.X); fn != nil && typecheck.HaveInlineBody(fn) {
+			v.budget -= fn.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:
+		// 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)
+		v.budget -= 15
+		// Scan body of closure (which DoChildren doesn't automatically
+		// do) to check for disallowed ops in the body and include the
+		// body in the budget.
+		if doList(n.(*ir.ClosureExpr).Func.Body, v.do) {
+			return true
+		}
+
+	case ir.OSELECT,
+		ir.OGO,
+		ir.ODEFER,
+		ir.ODCLTYPE, // can't print yet
+		ir.OTAILCALL:
+		v.reason = "unhandled op " + n.Op().String()
+		return true
+
+	case ir.OAPPEND:
+		v.budget -= inlineExtraAppendCost
+
+	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.ODCLCONST, ir.OFALL:
+		// 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.
+	}
+
+	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)
+}
+
+func isBigFunc(fn *ir.Func) bool {
+	budget := inlineBigFunctionNodes
+	return ir.Any(fn, func(n ir.Node) bool {
+		budget--
+		return budget <= 0
+	})
+}
+
+// inlcopylist (together with inlcopy) recursively copies a list of nodes, except
+// that it keeps the same ONAME, OTYPE, and OLITERAL nodes. It is used for copying
+// the body and dcls of an inlineable function.
+func inlcopylist(ll []ir.Node) []ir.Node {
+	s := make([]ir.Node, len(ll))
+	for i, n := range ll {
+		s[i] = inlcopy(n)
+	}
+	return s
+}
+
+// inlcopy is like DeepCopy(), but does extra work to copy closures.
+func inlcopy(n ir.Node) ir.Node {
+	var edit func(ir.Node) ir.Node
+	edit = func(x ir.Node) ir.Node {
+		switch x.Op() {
+		case ir.ONAME, ir.OTYPE, ir.OLITERAL, ir.ONIL:
+			return x
+		}
+		m := ir.Copy(x)
+		ir.EditChildren(m, edit)
+		if x.Op() == ir.OCLOSURE {
+			x := x.(*ir.ClosureExpr)
+			// Need to save/duplicate x.Func.Nname,
+			// x.Func.Nname.Ntype, x.Func.Dcl, x.Func.ClosureVars, and
+			// x.Func.Body for iexport and local inlining.
+			oldfn := x.Func
+			newfn := ir.NewFunc(oldfn.Pos())
+			m.(*ir.ClosureExpr).Func = newfn
+			newfn.Nname = ir.NewNameAt(oldfn.Nname.Pos(), oldfn.Nname.Sym())
+			// XXX OK to share fn.Type() ??
+			newfn.Nname.SetType(oldfn.Nname.Type())
+			// Ntype can be nil for -G=3 mode.
+			if oldfn.Nname.Ntype != nil {
+				newfn.Nname.Ntype = inlcopy(oldfn.Nname.Ntype).(ir.Ntype)
+			}
+			newfn.Body = inlcopylist(oldfn.Body)
+			// Make shallow copy of the Dcl and ClosureVar slices
+			newfn.Dcl = append([]*ir.Name(nil), oldfn.Dcl...)
+			newfn.ClosureVars = append([]*ir.Name(nil), oldfn.ClosureVars...)
+		}
+		return m
+	}
+	return edit(n)
+}
+
+// InlineCalls/inlnode walks fn's statements and expressions and substitutes any
+// calls made to inlineable functions. This is the external entry point.
+func InlineCalls(fn *ir.Func) {
+	savefn := ir.CurFunc
+	ir.CurFunc = fn
+	maxCost := int32(inlineMaxBudget)
+	if isBigFunc(fn) {
+		maxCost = inlineBigFunctionMaxCost
+	}
+	// Map to keep track of functions that have been inlined at a 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 the map catches the unusual case.
+	inlMap := make(map[*ir.Func]bool)
+	var edit func(ir.Node) ir.Node
+	edit = func(n ir.Node) ir.Node {
+		return inlnode(n, maxCost, inlMap, edit)
+	}
+	ir.EditChildren(fn, edit)
+	ir.CurFunc = savefn
+}
+
+// inlnode recurses over the tree to find inlineable calls, which will
+// be turned into OINLCALLs by mkinlcall. When the recursion comes
+// back up will examine left, right, list, rlist, ninit, ntest, nincr,
+// nbody and nelse and use one of the 4 inlconv/glue functions above
+// to turn the OINLCALL into an expression, a statement, or patch it
+// in to this nodes list or rlist as appropriate.
+// NOTE it makes no sense to pass the glue functions down the
+// recursion to the level where the OINLCALL gets created because they
+// have to edit /this/ n, so you'd have to push that one down as well,
+// but then you may as well do it here.  so this is cleaner and
+// shorter and less complicated.
+// The result of inlnode MUST be assigned back to n, e.g.
+// 	n.Left = inlnode(n.Left)
+func inlnode(n ir.Node, maxCost int32, inlMap map[*ir.Func]bool, edit func(ir.Node) ir.Node) ir.Node {
+	if n == nil {
+		return n
+	}
+
+	switch n.Op() {
+	case ir.ODEFER, ir.OGO:
+		n := n.(*ir.GoDeferStmt)
+		switch call := n.Call; call.Op() {
+		case ir.OCALLMETH:
+			base.FatalfAt(call.Pos(), "OCALLMETH missed by typecheck")
+		case ir.OCALLFUNC:
+			call := call.(*ir.CallExpr)
+			call.NoInline = true
+		}
+	case ir.OTAILCALL:
+		n := n.(*ir.TailCallStmt)
+		n.Call.NoInline = true // Not inline a tail call for now. Maybe we could inline it just like RETURN fn(arg)?
+
+	// TODO do them here (or earlier),
+	// so escape analysis can avoid more heapmoves.
+	case ir.OCLOSURE:
+		return n
+	case ir.OCALLMETH:
+		base.FatalfAt(n.Pos(), "OCALLMETH missed by typecheck")
+	case ir.OCALLFUNC:
+		n := n.(*ir.CallExpr)
+		if n.X.Op() == ir.OMETHEXPR {
+			// Prevent inlining some reflect.Value methods when using checkptr,
+			// even when package reflect was compiled without it (#35073).
+			if meth := ir.MethodExprName(n.X); meth != nil {
+				s := meth.Sym()
+				if base.Debug.Checkptr != 0 && types.IsReflectPkg(s.Pkg) && (s.Name == "Value.UnsafeAddr" || s.Name == "Value.Pointer") {
+					return n
+				}
+			}
+		}
+	}
+
+	lno := ir.SetPos(n)
+
+	ir.EditChildren(n, edit)
+
+	// with all the branches out of the way, it is now time to
+	// transmogrify this node itself unless inhibited by the
+	// switch at the top of this function.
+	switch n.Op() {
+	case ir.OCALLMETH:
+		base.FatalfAt(n.Pos(), "OCALLMETH missed by typecheck")
+
+	case ir.OCALLFUNC:
+		call := n.(*ir.CallExpr)
+		if call.NoInline {
+			break
+		}
+		if base.Flag.LowerM > 3 {
+			fmt.Printf("%v:call to func %+v\n", ir.Line(n), call.X)
+		}
+		if ir.IsIntrinsicCall(call) {
+			break
+		}
+		if fn := inlCallee(call.X); fn != nil && typecheck.HaveInlineBody(fn) {
+			n = mkinlcall(call, fn, maxCost, inlMap, edit)
+		}
+	}
+
+	base.Pos = lno
+
+	return n
+}
+
+// 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(fn ir.Node) *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
+		CanInline(c)
+		return c
+	}
+	return nil
+}
+
+func inlParam(t *types.Field, as ir.InitNode, inlvars map[*ir.Name]*ir.Name) ir.Node {
+	if t.Nname == nil {
+		return ir.BlankNode
+	}
+	n := t.Nname.(*ir.Name)
+	if ir.IsBlank(n) {
+		return ir.BlankNode
+	}
+	inlvar := inlvars[n]
+	if inlvar == nil {
+		base.Fatalf("missing inlvar for %v", n)
+	}
+	as.PtrInit().Append(ir.NewDecl(base.Pos, ir.ODCL, inlvar))
+	inlvar.Name().Defn = as
+	return inlvar
+}
+
+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) {}
+
+// NewInline allows the inliner implementation to be overridden.
+// If it returns nil, the legacy inliner will handle this call
+// instead.
+var NewInline = func(call *ir.CallExpr, fn *ir.Func, inlIndex int) *ir.InlinedCallExpr { return nil }
+
+// If n is a OCALLFUNC node, and fn is an ONAME node for a
+// function with an inlinable body, return an OINLCALL node that can replace n.
+// The returned node's Ninit has the parameter assignments, the Nbody is the
+// inlined function body, and (List, Rlist) contain the (input, output)
+// parameters.
+// The result of mkinlcall MUST be assigned back to n, e.g.
+// 	n.Left = mkinlcall(n.Left, fn, isddd)
+func mkinlcall(n *ir.CallExpr, fn *ir.Func, maxCost int32, inlMap map[*ir.Func]bool, edit func(ir.Node) ir.Node) ir.Node {
+	if fn.Inl == nil {
+		if logopt.Enabled() {
+			logopt.LogOpt(n.Pos(), "cannotInlineCall", "inline", ir.FuncName(ir.CurFunc),
+				fmt.Sprintf("%s cannot be inlined", ir.PkgFuncName(fn)))
+		}
+		return n
+	}
+	if fn.Inl.Cost > maxCost {
+		// The inlined function body is too big. Typically we use this check to restrict
+		// inlining into very big functions.  See issue 26546 and 17566.
+		if logopt.Enabled() {
+			logopt.LogOpt(n.Pos(), "cannotInlineCall", "inline", ir.FuncName(ir.CurFunc),
+				fmt.Sprintf("cost %d of %s exceeds max large caller cost %d", fn.Inl.Cost, ir.PkgFuncName(fn), maxCost))
+		}
+		return n
+	}
+
+	if fn == ir.CurFunc {
+		// Can't recursively inline a function into itself.
+		if logopt.Enabled() {
+			logopt.LogOpt(n.Pos(), "cannotInlineCall", "inline", fmt.Sprintf("recursive call to %s", ir.FuncName(ir.CurFunc)))
+		}
+		return n
+	}
+
+	// Don't inline a function fn that has no shape parameters, but is passed at
+	// least one shape arg. This means we must be inlining a non-generic function
+	// fn that was passed into a generic function, and can be called with a shape
+	// arg because it matches an appropriate type parameters. But fn may include
+	// an interface conversion (that may be applied to a shape arg) that was not
+	// apparent when we first created the instantiation of the generic function.
+	// We can't handle this if we actually do the inlining, since we want to know
+	// all interface conversions immediately after stenciling. So, we avoid
+	// inlining in this case. See #49309.
+	if !fn.Type().HasShape() {
+		for _, arg := range n.Args {
+			if arg.Type().HasShape() {
+				if logopt.Enabled() {
+					logopt.LogOpt(n.Pos(), "cannotInlineCall", "inline", ir.FuncName(ir.CurFunc),
+						fmt.Sprintf("inlining non-shape function %v with shape args", ir.FuncName(fn)))
+				}
+				return n
+			}
+		}
+	}
+
+	if base.Flag.Cfg.Instrumenting && types.IsRuntimePkg(fn.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.
+		return n
+	}
+
+	if inlMap[fn] {
+		if base.Flag.LowerM > 1 {
+			fmt.Printf("%v: cannot inline %v into %v: repeated recursive cycle\n", ir.Line(n), fn, ir.FuncName(ir.CurFunc))
+		}
+		return n
+	}
+	inlMap[fn] = true
+	defer func() {
+		inlMap[fn] = false
+	}()
+
+	typecheck.FixVariadicCall(n)
+
+	parent := base.Ctxt.PosTable.Pos(n.Pos()).Base().InliningIndex()
+
+	sym := fn.Linksym()
+	inlIndex := base.Ctxt.InlTree.Add(parent, n.Pos(), sym)
+
+	if base.Flag.GenDwarfInl > 0 {
+		if !sym.WasInlined() {
+			base.Ctxt.DwFixups.SetPrecursorFunc(sym, fn)
+			sym.Set(obj.AttrWasInlined, true)
+		}
+	}
+
+	if base.Flag.LowerM != 0 {
+		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 := NewInline(n, fn, inlIndex)
+	if res == nil {
+		res = oldInline(n, fn, inlIndex)
+	}
+
+	// transitive inlining
+	// might be nice to do this before exporting the body,
+	// but can't emit the body with inlining expanded.
+	// instead we emit the things that the body needs
+	// and each use must redo the inlining.
+	// luckily these are small.
+	ir.EditChildren(res, edit)
+
+	if base.Flag.LowerM > 2 {
+		fmt.Printf("%v: After inlining %+v\n\n", ir.Line(res), 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)
+		}
+	}
+}
+
+// oldInline creates an InlinedCallExpr to replace the given call
+// expression. fn is the callee function to be inlined. inlIndex is
+// the inlining tree position index, for use with src.NewInliningBase
+// when rewriting positions.
+func oldInline(call *ir.CallExpr, fn *ir.Func, inlIndex int) *ir.InlinedCallExpr {
+	if base.Debug.TypecheckInl == 0 {
+		typecheck.ImportedBody(fn)
+	}
+
+	SSADumpInline(fn)
+
+	ninit := call.Init()
+
+	// For normal function calls, the function callee expression
+	// may contain side effects. Make sure to preserve these,
+	// if necessary (#42703).
+	if call.Op() == ir.OCALLFUNC {
+		CalleeEffects(&ninit, call.X)
+	}
+
+	// Make temp names to use instead of the originals.
+	inlvars := make(map[*ir.Name]*ir.Name)
+
+	// record formals/locals for later post-processing
+	var inlfvars []*ir.Name
+
+	for _, ln := range fn.Inl.Dcl {
+		if ln.Op() != ir.ONAME {
+			continue
+		}
+		if ln.Class == ir.PPARAMOUT { // return values handled below.
+			continue
+		}
+		inlf := typecheck.Expr(inlvar(ln)).(*ir.Name)
+		inlvars[ln] = inlf
+		if base.Flag.GenDwarfInl > 0 {
+			if ln.Class == ir.PPARAM {
+				inlf.Name().SetInlFormal(true)
+			} else {
+				inlf.Name().SetInlLocal(true)
+			}
+			inlf.SetPos(ln.Pos())
+			inlfvars = append(inlfvars, inlf)
+		}
+	}
+
+	// We can delay declaring+initializing result parameters if:
+	// temporaries for return values.
+	var retvars []ir.Node
+	for i, t := range fn.Type().Results().Fields().Slice() {
+		var m *ir.Name
+		if nn := t.Nname; nn != nil && !ir.IsBlank(nn.(*ir.Name)) && !strings.HasPrefix(nn.Sym().Name, "~r") {
+			n := nn.(*ir.Name)
+			m = inlvar(n)
+			m = typecheck.Expr(m).(*ir.Name)
+			inlvars[n] = m
+		} else {
+			// anonymous return values, synthesize names for use in assignment that replaces return
+			m = retvar(t, i)
+		}
+
+		if base.Flag.GenDwarfInl > 0 {
+			// Don't update the src.Pos on a return variable if it
+			// was manufactured by the inliner (e.g. "~R2"); such vars
+			// were not part of the original callee.
+			if !strings.HasPrefix(m.Sym().Name, "~R") {
+				m.Name().SetInlFormal(true)
+				m.SetPos(t.Pos)
+				inlfvars = append(inlfvars, m)
+			}
+		}
+
+		retvars = append(retvars, m)
+	}
+
+	// Assign arguments to the parameters' temp names.
+	as := ir.NewAssignListStmt(base.Pos, ir.OAS2, nil, nil)
+	as.Def = true
+	if call.Op() == ir.OCALLMETH {
+		base.FatalfAt(call.Pos(), "OCALLMETH missed by typecheck")
+	}
+	as.Rhs.Append(call.Args...)
+
+	if recv := fn.Type().Recv(); recv != nil {
+		as.Lhs.Append(inlParam(recv, as, inlvars))
+	}
+	for _, param := range fn.Type().Params().Fields().Slice() {
+		as.Lhs.Append(inlParam(param, as, inlvars))
+	}
+
+	if len(as.Rhs) != 0 {
+		ninit.Append(typecheck.Stmt(as))
+	}
+
+	if !fn.Inl.CanDelayResults {
+		// Zero the return parameters.
+		for _, n := range retvars {
+			ninit.Append(ir.NewDecl(base.Pos, ir.ODCL, n.(*ir.Name)))
+			ras := ir.NewAssignStmt(base.Pos, n, nil)
+			ninit.Append(typecheck.Stmt(ras))
+		}
+	}
+
+	retlabel := typecheck.AutoLabel(".i")
+
+	inlgen++
+
+	// Add an inline mark just before the inlined body.
+	// This mark is inline in the code so that it's a reasonable spot
+	// to put a breakpoint. Not sure if that's really necessary or not
+	// (in which case it could go at the end of the function instead).
+	// Note issue 28603.
+	ninit.Append(ir.NewInlineMarkStmt(call.Pos().WithIsStmt(), int64(inlIndex)))
+
+	subst := inlsubst{
+		retlabel:    retlabel,
+		retvars:     retvars,
+		inlvars:     inlvars,
+		defnMarker:  ir.NilExpr{},
+		bases:       make(map[*src.PosBase]*src.PosBase),
+		newInlIndex: inlIndex,
+		fn:          fn,
+	}
+	subst.edit = subst.node
+
+	body := subst.list(ir.Nodes(fn.Inl.Body))
+
+	lab := ir.NewLabelStmt(base.Pos, retlabel)
+	body = append(body, lab)
+
+	if !typecheck.Go117ExportTypes {
+		typecheck.Stmts(body)
+	}
+
+	if base.Flag.GenDwarfInl > 0 {
+		for _, v := range inlfvars {
+			v.SetPos(subst.updatedPos(v.Pos()))
+		}
+	}
+
+	//dumplist("ninit post", ninit);
+
+	res := ir.NewInlinedCallExpr(base.Pos, body, retvars)
+	res.SetInit(ninit)
+	res.SetType(call.Type())
+	res.SetTypecheck(1)
+	return res
+}
+
+// Every time we expand a function we generate a new set of tmpnames,
+// PAUTO's in the calling functions, and link them off of the
+// PPARAM's, PAUTOS and PPARAMOUTs of the called function.
+func inlvar(var_ *ir.Name) *ir.Name {
+	if base.Flag.LowerM > 3 {
+		fmt.Printf("inlvar %+v\n", var_)
+	}
+
+	n := typecheck.NewName(var_.Sym())
+	n.SetType(var_.Type())
+	n.SetTypecheck(1)
+	n.Class = ir.PAUTO
+	n.SetUsed(true)
+	n.SetAutoTemp(var_.AutoTemp())
+	n.Curfn = ir.CurFunc // the calling function, not the called one
+	n.SetAddrtaken(var_.Addrtaken())
+
+	ir.CurFunc.Dcl = append(ir.CurFunc.Dcl, n)
+	return n
+}
+
+// Synthesize a variable to store the inlined function's results in.
+func retvar(t *types.Field, i int) *ir.Name {
+	n := typecheck.NewName(typecheck.LookupNum("~R", i))
+	n.SetType(t.Type)
+	n.SetTypecheck(1)
+	n.Class = ir.PAUTO
+	n.SetUsed(true)
+	n.Curfn = ir.CurFunc // the calling function, not the called one
+	ir.CurFunc.Dcl = append(ir.CurFunc.Dcl, n)
+	return n
+}
+
+// The inlsubst type implements the actual inlining of a single
+// function call.
+type inlsubst struct {
+	// Target of the goto substituted in place of a return.
+	retlabel *types.Sym
+
+	// Temporary result variables.
+	retvars []ir.Node
+
+	inlvars map[*ir.Name]*ir.Name
+	// defnMarker is used to mark a Node for reassignment.
+	// inlsubst.clovar set this during creating new ONAME.
+	// inlsubst.node will set the correct Defn for inlvar.
+	defnMarker ir.NilExpr
+
+	// bases maps from original PosBase to PosBase with an extra
+	// inlined call frame.
+	bases map[*src.PosBase]*src.PosBase
+
+	// newInlIndex is the index of the inlined call frame to
+	// insert for inlined nodes.
+	newInlIndex int
+
+	edit func(ir.Node) ir.Node // cached copy of subst.node method value closure
+
+	// If non-nil, we are inside a closure inside the inlined function, and
+	// newclofn is the Func of the new inlined closure.
+	newclofn *ir.Func
+
+	fn *ir.Func // For debug -- the func that is being inlined
+
+	// If true, then don't update source positions during substitution
+	// (retain old source positions).
+	noPosUpdate bool
+}
+
+// list inlines a list of nodes.
+func (subst *inlsubst) list(ll ir.Nodes) []ir.Node {
+	s := make([]ir.Node, 0, len(ll))
+	for _, n := range ll {
+		s = append(s, subst.node(n))
+	}
+	return s
+}
+
+// fields returns a list of the fields of a struct type representing receiver,
+// params, or results, after duplicating the field nodes and substituting the
+// Nname nodes inside the field nodes.
+func (subst *inlsubst) fields(oldt *types.Type) []*types.Field {
+	oldfields := oldt.FieldSlice()
+	newfields := make([]*types.Field, len(oldfields))
+	for i := range oldfields {
+		newfields[i] = oldfields[i].Copy()
+		if oldfields[i].Nname != nil {
+			newfields[i].Nname = subst.node(oldfields[i].Nname.(*ir.Name))
+		}
+	}
+	return newfields
+}
+
+// clovar creates a new ONAME node for a local variable or param of a closure
+// inside a function being inlined.
+func (subst *inlsubst) clovar(n *ir.Name) *ir.Name {
+	m := ir.NewNameAt(n.Pos(), n.Sym())
+	m.Class = n.Class
+	m.SetType(n.Type())
+	m.SetTypecheck(1)
+	if n.IsClosureVar() {
+		m.SetIsClosureVar(true)
+	}
+	if n.Addrtaken() {
+		m.SetAddrtaken(true)
+	}
+	if n.Used() {
+		m.SetUsed(true)
+	}
+	m.Defn = n.Defn
+
+	m.Curfn = subst.newclofn
+
+	switch defn := n.Defn.(type) {
+	case nil:
+		// ok
+	case *ir.Name:
+		if !n.IsClosureVar() {
+			base.FatalfAt(n.Pos(), "want closure variable, got: %+v", n)
+		}
+		if n.Sym().Pkg != types.LocalPkg {
+			// If the closure came from inlining a function from
+			// another package, must change package of captured
+			// variable to localpkg, so that the fields of the closure
+			// struct are local package and can be accessed even if
+			// name is not exported. If you disable this code, you can
+			// reproduce the problem by running 'go test
+			// go/internal/srcimporter'. TODO(mdempsky) - maybe change
+			// how we create closure structs?
+			m.SetSym(types.LocalPkg.Lookup(n.Sym().Name))
+		}
+		// Make sure any inlvar which is the Defn
+		// of an ONAME closure var is rewritten
+		// during inlining. Don't substitute
+		// if Defn node is outside inlined function.
+		if subst.inlvars[n.Defn.(*ir.Name)] != nil {
+			m.Defn = subst.node(n.Defn)
+		}
+	case *ir.AssignStmt, *ir.AssignListStmt:
+		// Mark node for reassignment at the end of inlsubst.node.
+		m.Defn = &subst.defnMarker
+	case *ir.TypeSwitchGuard:
+		// TODO(mdempsky): Set m.Defn properly. See discussion on #45743.
+	case *ir.RangeStmt:
+		// TODO: Set m.Defn properly if we support inlining range statement in the future.
+	default:
+		base.FatalfAt(n.Pos(), "unexpected Defn: %+v", defn)
+	}
+
+	if n.Outer != nil {
+		// Either the outer variable is defined in function being inlined,
+		// and we will replace it with the substituted variable, or it is
+		// defined outside the function being inlined, and we should just
+		// skip the outer variable (the closure variable of the function
+		// being inlined).
+		s := subst.node(n.Outer).(*ir.Name)
+		if s == n.Outer {
+			s = n.Outer.Outer
+		}
+		m.Outer = s
+	}
+	return m
+}
+
+// closure does the necessary substitions for a ClosureExpr n and returns the new
+// closure node.
+func (subst *inlsubst) closure(n *ir.ClosureExpr) ir.Node {
+	// Prior to the subst edit, set a flag in the inlsubst to indicate
+	// that we don't want to update the source positions in the new
+	// closure function. If we do this, it will appear that the
+	// closure itself has things inlined into it, which is not the
+	// case. See issue #46234 for more details. At the same time, we
+	// do want to update the position in the new ClosureExpr (which is
+	// part of the function we're working on). See #49171 for an
+	// example of what happens if we miss that update.
+	newClosurePos := subst.updatedPos(n.Pos())
+	defer func(prev bool) { subst.noPosUpdate = prev }(subst.noPosUpdate)
+	subst.noPosUpdate = true
+
+	//fmt.Printf("Inlining func %v with closure into %v\n", subst.fn, ir.FuncName(ir.CurFunc))
+
+	oldfn := n.Func
+	newfn := ir.NewClosureFunc(oldfn.Pos(), true)
+
+	// Ntype can be nil for -G=3 mode.
+	if oldfn.Nname.Ntype != nil {
+		newfn.Nname.Ntype = subst.node(oldfn.Nname.Ntype).(ir.Ntype)
+	}
+
+	if subst.newclofn != nil {
+		//fmt.Printf("Inlining a closure with a nested closure\n")
+	}
+	prevxfunc := subst.newclofn
+
+	// Mark that we are now substituting within a closure (within the
+	// inlined function), and create new nodes for all the local
+	// vars/params inside this closure.
+	subst.newclofn = newfn
+	newfn.Dcl = nil
+	newfn.ClosureVars = nil
+	for _, oldv := range oldfn.Dcl {
+		newv := subst.clovar(oldv)
+		subst.inlvars[oldv] = newv
+		newfn.Dcl = append(newfn.Dcl, newv)
+	}
+	for _, oldv := range oldfn.ClosureVars {
+		newv := subst.clovar(oldv)
+		subst.inlvars[oldv] = newv
+		newfn.ClosureVars = append(newfn.ClosureVars, newv)
+	}
+
+	// Need to replace ONAME nodes in
+	// newfn.Type().FuncType().Receiver/Params/Results.FieldSlice().Nname
+	oldt := oldfn.Type()
+	newrecvs := subst.fields(oldt.Recvs())
+	var newrecv *types.Field
+	if len(newrecvs) > 0 {
+		newrecv = newrecvs[0]
+	}
+	newt := types.NewSignature(oldt.Pkg(), newrecv,
+		nil, subst.fields(oldt.Params()), subst.fields(oldt.Results()))
+
+	newfn.Nname.SetType(newt)
+	newfn.Body = subst.list(oldfn.Body)
+
+	// Remove the nodes for the current closure from subst.inlvars
+	for _, oldv := range oldfn.Dcl {
+		delete(subst.inlvars, oldv)
+	}
+	for _, oldv := range oldfn.ClosureVars {
+		delete(subst.inlvars, oldv)
+	}
+	// Go back to previous closure func
+	subst.newclofn = prevxfunc
+
+	// Actually create the named function for the closure, now that
+	// the closure is inlined in a specific function.
+	newclo := newfn.OClosure
+	newclo.SetPos(newClosurePos)
+	newclo.SetInit(subst.list(n.Init()))
+	return typecheck.Expr(newclo)
+}
+
+// node recursively copies a node from the saved pristine body of the
+// inlined function, substituting references to input/output
+// parameters with ones to the tmpnames, and substituting returns with
+// assignments to the output.
+func (subst *inlsubst) node(n ir.Node) ir.Node {
+	if n == nil {
+		return nil
+	}
+
+	switch n.Op() {
+	case ir.ONAME:
+		n := n.(*ir.Name)
+
+		// Handle captured variables when inlining closures.
+		if n.IsClosureVar() && subst.newclofn == nil {
+			o := n.Outer
+
+			// Deal with case where sequence of closures are inlined.
+			// TODO(danscales) - write test case to see if we need to
+			// go up multiple levels.
+			if o.Curfn != ir.CurFunc {
+				o = o.Outer
+			}
+
+			// make sure the outer param matches the inlining location
+			if o == nil || o.Curfn != ir.CurFunc {
+				base.Fatalf("%v: unresolvable capture %v\n", ir.Line(n), n)
+			}
+
+			if base.Flag.LowerM > 2 {
+				fmt.Printf("substituting captured name %+v  ->  %+v\n", n, o)
+			}
+			return o
+		}
+
+		if inlvar := subst.inlvars[n]; inlvar != nil { // These will be set during inlnode
+			if base.Flag.LowerM > 2 {
+				fmt.Printf("substituting name %+v  ->  %+v\n", n, inlvar)
+			}
+			return inlvar
+		}
+
+		if base.Flag.LowerM > 2 {
+			fmt.Printf("not substituting name %+v\n", n)
+		}
+		return n
+
+	case ir.OMETHEXPR:
+		n := n.(*ir.SelectorExpr)
+		return n
+
+	case ir.OLITERAL, ir.ONIL, ir.OTYPE:
+		// If n is a named constant or type, we can continue
+		// using it in the inline copy. Otherwise, make a copy
+		// so we can update the line number.
+		if n.Sym() != nil {
+			return n
+		}
+
+	case ir.ORETURN:
+		if subst.newclofn != nil {
+			// Don't do special substitutions if inside a closure
+			break
+		}
+		// Because of the above test for subst.newclofn,
+		// this return is guaranteed to belong to the current inlined function.
+		n := n.(*ir.ReturnStmt)
+		init := subst.list(n.Init())
+		if len(subst.retvars) != 0 && len(n.Results) != 0 {
+			as := ir.NewAssignListStmt(base.Pos, ir.OAS2, nil, nil)
+
+			// Make a shallow copy of retvars.
+			// Otherwise OINLCALL.Rlist will be the same list,
+			// and later walk and typecheck may clobber it.
+			for _, n := range subst.retvars {
+				as.Lhs.Append(n)
+			}
+			as.Rhs = subst.list(n.Results)
+
+			if subst.fn.Inl.CanDelayResults {
+				for _, n := range as.Lhs {
+					as.PtrInit().Append(ir.NewDecl(base.Pos, ir.ODCL, n.(*ir.Name)))
+					n.Name().Defn = as
+				}
+			}
+
+			init = append(init, typecheck.Stmt(as))
+		}
+		init = append(init, ir.NewBranchStmt(base.Pos, ir.OGOTO, subst.retlabel))
+		typecheck.Stmts(init)
+		return ir.NewBlockStmt(base.Pos, init)
+
+	case ir.OGOTO, ir.OBREAK, ir.OCONTINUE:
+		if subst.newclofn != nil {
+			// Don't do special substitutions if inside a closure
+			break
+		}
+		n := n.(*ir.BranchStmt)
+		m := ir.Copy(n).(*ir.BranchStmt)
+		m.SetPos(subst.updatedPos(m.Pos()))
+		m.SetInit(nil)
+		m.Label = translateLabel(n.Label)
+		return m
+
+	case ir.OLABEL:
+		if subst.newclofn != nil {
+			// Don't do special substitutions if inside a closure
+			break
+		}
+		n := n.(*ir.LabelStmt)
+		m := ir.Copy(n).(*ir.LabelStmt)
+		m.SetPos(subst.updatedPos(m.Pos()))
+		m.SetInit(nil)
+		m.Label = translateLabel(n.Label)
+		return m
+
+	case ir.OCLOSURE:
+		return subst.closure(n.(*ir.ClosureExpr))
+
+	}
+
+	m := ir.Copy(n)
+	m.SetPos(subst.updatedPos(m.Pos()))
+	ir.EditChildren(m, subst.edit)
+
+	if subst.newclofn == nil {
+		// Translate any label on FOR, RANGE loops or SWITCH
+		switch m.Op() {
+		case ir.OFOR:
+			m := m.(*ir.ForStmt)
+			m.Label = translateLabel(m.Label)
+			return m
+
+		case ir.ORANGE:
+			m := m.(*ir.RangeStmt)
+			m.Label = translateLabel(m.Label)
+			return m
+
+		case ir.OSWITCH:
+			m := m.(*ir.SwitchStmt)
+			m.Label = translateLabel(m.Label)
+			return m
+		}
+
+	}
+
+	switch m := m.(type) {
+	case *ir.AssignStmt:
+		if lhs, ok := m.X.(*ir.Name); ok && lhs.Defn == &subst.defnMarker {
+			lhs.Defn = m
+		}
+	case *ir.AssignListStmt:
+		for _, lhs := range m.Lhs {
+			if lhs, ok := lhs.(*ir.Name); ok && lhs.Defn == &subst.defnMarker {
+				lhs.Defn = m
+			}
+		}
+	}
+
+	return m
+}
+
+// translateLabel makes a label from an inlined function (if non-nil) be unique by
+// adding "·inlgen".
+func translateLabel(l *types.Sym) *types.Sym {
+	if l == nil {
+		return nil
+	}
+	p := fmt.Sprintf("%s·%d", l.Name, inlgen)
+	return typecheck.Lookup(p)
+}
+
+func (subst *inlsubst) updatedPos(xpos src.XPos) src.XPos {
+	if subst.noPosUpdate {
+		return xpos
+	}
+	pos := base.Ctxt.PosTable.Pos(xpos)
+	oldbase := pos.Base() // can be nil
+	newbase := subst.bases[oldbase]
+	if newbase == nil {
+		newbase = src.NewInliningBase(oldbase, subst.newInlIndex)
+		subst.bases[oldbase] = newbase
+	}
+	pos.SetBase(newbase)
+	return base.Ctxt.PosTable.XPos(pos)
+}
+
+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) {
+				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
+}