Current File : //usr/local/go/src/cmd/compile/internal/inline/inl.go
// 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),
}
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))
}
}
// Inline_Flood marks n's inline body for export and recursively ensures
// all called functions are marked too.
func Inline_Flood(n *ir.Name, exportsym func(*ir.Name)) {
if n == nil {
return
}
if n.Op() != ir.ONAME || n.Class != ir.PFUNC {
base.Fatalf("Inline_Flood: unexpected %v, %v, %v", n, n.Op(), n.Class)
}
fn := n.Func
if fn == nil {
base.Fatalf("Inline_Flood: missing Func on %v", n)
}
if fn.Inl == nil {
return
}
if fn.ExportInline() {
return
}
fn.SetExportInline(true)
typecheck.ImportedBody(fn)
var doFlood func(n ir.Node)
doFlood = func(n ir.Node) {
switch n.Op() {
case ir.OMETHEXPR, ir.ODOTMETH:
Inline_Flood(ir.MethodExprName(n), exportsym)
case ir.ONAME:
n := n.(*ir.Name)
switch n.Class {
case ir.PFUNC:
Inline_Flood(n, exportsym)
exportsym(n)
case ir.PEXTERN:
exportsym(n)
}
case ir.OCALLPART:
// Okay, because we don't yet inline indirect
// calls to method values.
case ir.OCLOSURE:
// VisitList doesn't visit closure bodies, so force a
// recursive call to VisitList on the body of the closure.
ir.VisitList(n.(*ir.ClosureExpr).Func.Body, doFlood)
}
}
// Recursively identify all referenced functions for
// reexport. We want to include even non-called functions,
// because after inlining they might be callable.
ir.VisitList(ir.Nodes(fn.Inl.Body), doFlood)
}
// 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 ir.IsIntrinsicCall(n) {
// Treat like any other node.
break
}
if fn := inlCallee(n.X); fn != nil && fn.Inl != nil {
v.budget -= fn.Inl.Cost
break
}
// Call cost for non-leaf inlining.
v.budget -= v.extraCallCost
// Call is okay if inlinable and we have the budget for the body.
case ir.OCALLMETH:
n := n.(*ir.CallExpr)
t := n.X.Type()
if t == nil {
base.Fatalf("no function type for [%p] %+v\n", n.X, n.X)
}
fn := ir.MethodExprName(n.X).Func
if types.IsRuntimePkg(fn.Sym().Pkg) && fn.Sym().Name == "heapBits.nextArena" {
// Special case: explicitly allow
// mid-stack inlining of
// runtime.heapBits.next even though
// it calls slow-path
// runtime.heapBits.nextArena.
break
}
if fn.Inl != nil {
v.budget -= fn.Inl.Cost
break
}
// Call cost for non-leaf inlining.
v.budget -= v.extraCallCost
// 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.ORANGE,
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.OFOR, ir.OFORUNTIL:
n := n.(*ir.ForStmt)
if n.Label != nil {
v.reason = "labeled control"
return true
}
case ir.OSWITCH:
n := n.(*ir.SwitchStmt)
if n.Label != nil {
v.reason = "labeled control"
return true
}
// case ir.ORANGE, ir.OSELECT in "unhandled" above
case ir.OBREAK, ir.OCONTINUE:
n := n.(*ir.BranchStmt)
if n.Label != nil {
// Should have short-circuited due to labeled control error above.
base.Fatalf("unexpected labeled break/continue: %v", n)
}
case ir.OIF:
n := n.(*ir.IfStmt)
if ir.IsConst(n.Cond, constant.Bool) {
// This if and the condition cost nothing.
// TODO(rsc): It seems strange that we visit the dead branch.
return doList(n.Init(), v.do) ||
doList(n.Body, v.do) ||
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.OCALLPART, 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())
if oldfn.ClosureCalled() {
newfn.SetClosureCalled(true)
}
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
}
// Turn an OINLCALL into a statement.
func inlconv2stmt(inlcall *ir.InlinedCallExpr) ir.Node {
n := ir.NewBlockStmt(inlcall.Pos(), nil)
n.List = inlcall.Init()
n.List.Append(inlcall.Body.Take()...)
return n
}
// Turn an OINLCALL into a single valued expression.
// The result of inlconv2expr MUST be assigned back to n, e.g.
// n.Left = inlconv2expr(n.Left)
func inlconv2expr(n *ir.InlinedCallExpr) ir.Node {
r := n.ReturnVars[0]
return ir.InitExpr(append(n.Init(), n.Body...), r)
}
// Turn the rlist (with the return values) of the OINLCALL in
// n into an expression list lumping the ninit and body
// containing the inlined statements on the first list element so
// order will be preserved. Used in return, oas2func and call
// statements.
func inlconv2list(n *ir.InlinedCallExpr) []ir.Node {
if n.Op() != ir.OINLCALL || len(n.ReturnVars) == 0 {
base.Fatalf("inlconv2list %+v\n", n)
}
s := n.ReturnVars
s[0] = ir.InitExpr(append(n.Init(), n.Body...), s[0])
return s
}
// 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.OCALLFUNC, ir.OCALLMETH:
call := call.(*ir.CallExpr)
call.NoInline = true
}
// TODO do them here (or earlier),
// so escape analysis can avoid more heapmoves.
case ir.OCLOSURE:
return n
case ir.OCALLMETH:
// Prevent inlining some reflect.Value methods when using checkptr,
// even when package reflect was compiled without it (#35073).
n := n.(*ir.CallExpr)
if s := ir.MethodExprName(n.X).Sym(); 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)
if as := n; as.Op() == ir.OAS2FUNC {
as := as.(*ir.AssignListStmt)
if as.Rhs[0].Op() == ir.OINLCALL {
as.Rhs = inlconv2list(as.Rhs[0].(*ir.InlinedCallExpr))
as.SetOp(ir.OAS2)
as.SetTypecheck(0)
n = typecheck.Stmt(as)
}
}
// 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.OCALLFUNC, ir.OCALLMETH:
n := n.(*ir.CallExpr)
if n.NoInline {
return n
}
}
var call *ir.CallExpr
switch n.Op() {
case ir.OCALLFUNC:
call = n.(*ir.CallExpr)
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 && fn.Inl != nil {
n = mkinlcall(call, fn, maxCost, inlMap, edit)
}
case ir.OCALLMETH:
call = n.(*ir.CallExpr)
if base.Flag.LowerM > 3 {
fmt.Printf("%v:call to meth %v\n", ir.Line(n), call.X.(*ir.SelectorExpr).Sel)
}
// typecheck should have resolved ODOTMETH->type, whose nname points to the actual function.
if call.X.Type() == nil {
base.Fatalf("no function type for [%p] %+v\n", call.X, call.X)
}
n = mkinlcall(call, ir.MethodExprName(call.X).Func, maxCost, inlMap, edit)
}
base.Pos = lno
if n.Op() == ir.OINLCALL {
ic := n.(*ir.InlinedCallExpr)
switch call.Use {
default:
ir.Dump("call", call)
base.Fatalf("call missing use")
case ir.CallUseExpr:
n = inlconv2expr(ic)
case ir.CallUseStmt:
n = inlconv2stmt(ic)
case ir.CallUseList:
// leave for caller to convert
}
}
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) {}
// If n is a call node (OCALLFUNC or OCALLMETH), 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
}
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
}()
if base.Debug.TypecheckInl == 0 {
typecheck.ImportedBody(fn)
}
// We have a function node, and it has an inlineable body.
if base.Flag.LowerM > 1 {
fmt.Printf("%v: inlining call to %v %v { %v }\n", ir.Line(n), fn.Sym(), fn.Type(), ir.Nodes(fn.Inl.Body))
} else 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)
}
SSADumpInline(fn)
ninit := n.Init()
// For normal function calls, the function callee expression
// may contain side effects (e.g., added by addinit during
// inlconv2expr or inlconv2list). Make sure to preserve these,
// if necessary (#42703).
if n.Op() == ir.OCALLFUNC {
callee := n.X
for callee.Op() == ir.OCONVNOP {
conv := callee.(*ir.ConvExpr)
ninit.Append(ir.TakeInit(conv)...)
callee = conv.X
}
if callee.Op() != ir.ONAME && callee.Op() != ir.OCLOSURE && callee.Op() != ir.OMETHEXPR {
base.Fatalf("unexpected callee expression: %v", callee)
}
}
// 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:
// (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.
delayretvars := true
nreturns := 0
ir.VisitList(ir.Nodes(fn.Inl.Body), func(n ir.Node) {
if n, ok := n.(*ir.ReturnStmt); ok {
nreturns++
if len(n.Results) == 0 {
delayretvars = false // empty return statement (case 2)
}
}
})
if nreturns != 1 {
delayretvars = false // not exactly one return statement (case 1)
}
// 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
delayretvars = false // found a named result parameter (case 3)
} 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 n.Op() == ir.OCALLMETH {
sel := n.X.(*ir.SelectorExpr)
if sel.X == nil {
base.Fatalf("method call without receiver: %+v", n)
}
as.Rhs.Append(sel.X)
}
as.Rhs.Append(n.Args...)
// For non-dotted calls to variadic functions, we assign the
// variadic parameter's temp name separately.
var vas *ir.AssignStmt
if recv := fn.Type().Recv(); recv != nil {
as.Lhs.Append(inlParam(recv, as, inlvars))
}
for _, param := range fn.Type().Params().Fields().Slice() {
// For ordinary parameters or variadic parameters in
// dotted calls, just add the variable to the
// assignment list, and we're done.
if !param.IsDDD() || n.IsDDD {
as.Lhs.Append(inlParam(param, as, inlvars))
continue
}
// Otherwise, we need to collect the remaining values
// to pass as a slice.
x := len(as.Lhs)
for len(as.Lhs) < len(as.Rhs) {
as.Lhs.Append(argvar(param.Type, len(as.Lhs)))
}
varargs := as.Lhs[x:]
vas = ir.NewAssignStmt(base.Pos, nil, nil)
vas.X = inlParam(param, vas, inlvars)
if len(varargs) == 0 {
vas.Y = typecheck.NodNil()
vas.Y.SetType(param.Type)
} else {
lit := ir.NewCompLitExpr(base.Pos, ir.OCOMPLIT, ir.TypeNode(param.Type), nil)
lit.List = varargs
vas.Y = lit
}
}
if len(as.Rhs) != 0 {
ninit.Append(typecheck.Stmt(as))
}
if vas != nil {
ninit.Append(typecheck.Stmt(vas))
}
if !delayretvars {
// 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++
parent := -1
if b := base.Ctxt.PosTable.Pos(n.Pos()).Base(); b != nil {
parent = b.InliningIndex()
}
sym := fn.Linksym()
newIndex := base.Ctxt.InlTree.Add(parent, n.Pos(), sym)
// 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.
inlMark := ir.NewInlineMarkStmt(base.Pos, types.BADWIDTH)
inlMark.SetPos(n.Pos().WithIsStmt())
inlMark.Index = int64(newIndex)
ninit.Append(inlMark)
if base.Flag.GenDwarfInl > 0 {
if !sym.WasInlined() {
base.Ctxt.DwFixups.SetPrecursorFunc(sym, fn)
sym.Set(obj.AttrWasInlined, true)
}
}
subst := inlsubst{
retlabel: retlabel,
retvars: retvars,
delayretvars: delayretvars,
inlvars: inlvars,
defnMarker: ir.NilExpr{},
bases: make(map[*src.PosBase]*src.PosBase),
newInlIndex: newIndex,
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);
call := ir.NewInlinedCallExpr(base.Pos, nil, nil)
*call.PtrInit() = ninit
call.Body = body
call.ReturnVars = retvars
call.SetType(n.Type())
call.SetTypecheck(1)
// 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(call, edit)
if base.Flag.LowerM > 2 {
fmt.Printf("%v: After inlining %+v\n\n", ir.Line(call), call)
}
return call
}
// 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.Class = ir.PAUTO
n.SetUsed(true)
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.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
}
// Synthesize a variable to store the inlined function's arguments
// when they come from a multiple return call.
func argvar(t *types.Type, i int) ir.Node {
n := typecheck.NewName(typecheck.LookupNum("~arg", i))
n.SetType(t.Elem())
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
// Whether result variables should be initialized at the
// "return" statement.
delayretvars bool
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 {
// TODO(danscales): want to get rid of this shallow copy, with code like the
// following, but it is hard to copy all the necessary flags in a maintainable way.
// m := ir.NewNameAt(n.Pos(), n.Sym())
// m.Class = n.Class
// m.SetType(n.Type())
// m.SetTypecheck(1)
//if n.IsClosureVar() {
// m.SetIsClosureVar(true)
//}
m := &ir.Name{}
*m = *n
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.
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 {
m := ir.Copy(n)
// Prior to the subst edit, set a flag in the inlsubst to
// indicated that we don't want to update the source positions in
// the new closure. 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.
defer func(prev bool) { subst.noPosUpdate = prev }(subst.noPosUpdate)
subst.noPosUpdate = true
ir.EditChildren(m, subst.edit)
//fmt.Printf("Inlining func %v with closure into %v\n", subst.fn, ir.FuncName(ir.CurFunc))
// The following is similar to funcLit
oldfn := n.Func
newfn := ir.NewFunc(oldfn.Pos())
// These three lines are not strictly necessary, but just to be clear
// that new function needs to redo typechecking and inlinability.
newfn.SetTypecheck(0)
newfn.SetInlinabilityChecked(false)
newfn.Inl = nil
newfn.SetIsHiddenClosure(true)
newfn.Nname = ir.NewNameAt(n.Pos(), ir.BlankNode.Sym())
newfn.Nname.Func = newfn
// Ntype can be nil for -G=3 mode.
if oldfn.Nname.Ntype != nil {
newfn.Nname.Ntype = subst.node(oldfn.Nname.Ntype).(ir.Ntype)
}
newfn.Nname.Defn = newfn
m.(*ir.ClosureExpr).Func = newfn
newfn.OClosure = m.(*ir.ClosureExpr)
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.
m.SetTypecheck(0)
if oldfn.ClosureCalled() {
typecheck.Callee(m)
} else {
typecheck.Expr(m)
}
return m
}
// 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
}
// Since we don't handle bodies with closures,
// 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.delayretvars {
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:
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.PtrInit() = nil
p := fmt.Sprintf("%s·%d", n.Label.Name, inlgen)
m.Label = typecheck.Lookup(p)
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.PtrInit() = nil
p := fmt.Sprintf("%s·%d", n.Label.Name, inlgen)
m.Label = typecheck.Lookup(p)
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)
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
}
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
}
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