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cmd/compile: use staticValue for inlining logic

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This CL replaces the ad hoc and duplicated logic for detecting
inlinable calls with a single "inlCallee" function, which uses the
"staticValue" helper function introduced in an earlier commit.

Updates #41474.

Change-Id: I103d4091b10366fce1344ef2501222b7df68f21d
Reviewed-on: https://go-review.googlesource.com/c/go/+/256460
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Trust: Matthew Dempsky <mdempsky@google.com>
This commit is contained in:
Matthew Dempsky 2020-09-22 02:19:14 -07:00
parent 64fb6ae95f
commit 1bcf6beec5
3 changed files with 34 additions and 68 deletions
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88
src/cmd/compile/internal/gc/inl.go
View File

@ -325,18 +325,10 @@ func (v *hairyVisitor) visit(n *Node) bool {
break
}
if fn := n.Left.Func; fn != nil && fn.Inl != nil {
v.budget -= fn.Inl.Cost
if fn := inlCallee(n.Left); fn != nil && fn.Func.Inl != nil {
v.budget -= fn.Func.Inl.Cost
break
}
if n.Left.isMethodExpression() {
if d := asNode(n.Left.Sym.Def); d != nil && d.Func.Inl != nil {
v.budget -= d.Func.Inl.Cost
break
}
}
// TODO(mdempsky): Budget for OCLOSURE calls if we
// ever allow that. See #15561 and #23093.
// Call cost for non-leaf inlining.
v.budget -= v.extraCallCost
@ -679,53 +671,11 @@ func inlnode(n *Node, maxCost int32, inlMap map[*Node]bool) *Node {
if Debug['m'] > 3 {
fmt.Printf("%v:call to func %+v\n", n.Line(), n.Left)
}
if n.Left.Func != nil && n.Left.Func.Inl != nil && !isIntrinsicCall(n) { // normal case
n = mkinlcall(n, n.Left, maxCost, inlMap)
} else if n.Left.isMethodExpression() && asNode(n.Left.Sym.Def) != nil {
n = mkinlcall(n, asNode(n.Left.Sym.Def), maxCost, inlMap)
} else if n.Left.Op == OCLOSURE {
if f := inlinableClosure(n.Left); f != nil {
n = mkinlcall(n, f, maxCost, inlMap)
}
} else if n.Left.Op == ONAME && n.Left.Name != nil && n.Left.Name.Defn != nil {
if d := n.Left.Name.Defn; d.Op == OAS && d.Right.Op == OCLOSURE {
if f := inlinableClosure(d.Right); f != nil {
// NB: this check is necessary to prevent indirect re-assignment of the variable
// having the address taken after the invocation or only used for reads is actually fine
// but we have no easy way to distinguish the safe cases
if d.Left.Name.Addrtaken() {
if Debug['m'] > 1 {
fmt.Printf("%v: cannot inline escaping closure variable %v\n", n.Line(), n.Left)
}
if logopt.Enabled() {
logopt.LogOpt(n.Pos, "cannotInlineCall", "inline", Curfn.funcname(),
fmt.Sprintf("%v cannot be inlined (escaping closure variable)", n.Left))
}
if isIntrinsicCall(n) {
break
}
// ensure the variable is never re-assigned
if unsafe, a := reassigned(n.Left); unsafe {
if Debug['m'] > 1 {
if a != nil {
fmt.Printf("%v: cannot inline re-assigned closure variable at %v: %v\n", n.Line(), a.Line(), a)
if logopt.Enabled() {
logopt.LogOpt(n.Pos, "cannotInlineCall", "inline", Curfn.funcname(),
fmt.Sprintf("%v cannot be inlined (re-assigned closure variable)", a))
}
} else {
fmt.Printf("%v: cannot inline global closure variable %v\n", n.Line(), n.Left)
if logopt.Enabled() {
logopt.LogOpt(n.Pos, "cannotInlineCall", "inline", Curfn.funcname(),
fmt.Sprintf("%v cannot be inlined (global closure variable)", n.Left))
}
}
}
break
}
n = mkinlcall(n, f, maxCost, inlMap)
}
}
if fn := inlCallee(n.Left); fn != nil && fn.Func.Inl != nil {
n = mkinlcall(n, fn, maxCost, inlMap)
}
case OCALLMETH:
@ -749,16 +699,22 @@ func inlnode(n *Node, maxCost int32, inlMap map[*Node]bool) *Node {
return n
}
// inlinableClosure takes an OCLOSURE node and follows linkage to the matching ONAME with
// the inlinable body. Returns nil if the function is not inlinable.
func inlinableClosure(n *Node) *Node {
c := n.Func.Closure
caninl(c)
f := c.Func.Nname
if f == nil || f.Func.Inl == nil {
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(fn *Node) *Node {
fn = staticValue(fn)
switch {
case fn.Op == ONAME && fn.Class() == PFUNC:
if fn.isMethodExpression() {
return asNode(fn.Sym.Def)
}
return f
return fn
case fn.Op == OCLOSURE:
c := fn.Func.Closure
caninl(c)
return c.Func.Nname
}
return nil
}
func staticValue(n *Node) *Node {
@ -771,7 +727,9 @@ func staticValue(n *Node) *Node {
}
}
// staticValue1 implements a simple SSA-like optimization.
// staticValue1 implements a simple SSA-like optimization. If n is a local variable
// that is initialized and never reassigned, staticValue1 returns the initializer
// expression. Otherwise, it returns nil.
func staticValue1(n *Node) *Node {
if n.Op != ONAME || n.Class() != PAUTO || n.Name.Addrtaken() {
return nil

1
src/cmd/compile/internal/logopt/logopt_test.go
View File

@ -208,7 +208,6 @@ func s15a8(x *[15]int64) [15]int64 {
`"relatedInformation":[{"location":{"uri":"file://tmpdir/file.go","range":{"start":{"line":4,"character":11},"end":{"line":4,"character":11}}},"message":"inlineLoc"}]}`)
want(t, slogged, `{"range":{"start":{"line":11,"character":6},"end":{"line":11,"character":6}},"severity":3,"code":"isInBounds","source":"go compiler","message":""}`)
want(t, slogged, `{"range":{"start":{"line":7,"character":6},"end":{"line":7,"character":6}},"severity":3,"code":"canInlineFunction","source":"go compiler","message":"cost: 35"}`)
want(t, slogged, `{"range":{"start":{"line":21,"character":21},"end":{"line":21,"character":21}},"severity":3,"code":"cannotInlineCall","source":"go compiler","message":"foo cannot be inlined (escaping closure variable)"}`)
// escape analysis explanation
want(t, slogged, `{"range":{"start":{"line":7,"character":13},"end":{"line":7,"character":13}},"severity":3,"code":"leak","source":"go compiler","message":"parameter z leaks to ~r2 with derefs=0",`+
`"relatedInformation":[`+

9
test/inline.go
View File

@ -49,6 +49,12 @@ func j(x int) int { // ERROR "can inline j"
}
}
func _() int { // ERROR "can inline _"
tmp1 := h
tmp2 := tmp1
return tmp2(0) // ERROR "inlining call to h"
}
var somethingWrong error
// local closures can be inlined
@ -58,6 +64,9 @@ func l(x, y int) (int, int, error) {
}
if x == y {
e(somethingWrong) // ERROR "inlining call to l.func1"
} else {
f := e
f(nil) // ERROR "inlining call to l.func1"
}
return y, x, nil
}