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gc: avoid false positives when using scalar struct fields.

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The escape analysis code does not make a distinction between
scalar and pointers fields in structs. Non-pointer fields
that escape should not make the whole struct escape.

R=lvd, rsc
CC=golang-dev, remy
https://golang.org/cl/5489128
This commit is contained in:
Rémy Oudompheng 2012-01-12 12:08:40 +01:00 committed by Luuk van Dijk
parent e955a3cca2
commit 94ff311d1b
2 changed files with 41 additions and 7 deletions
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6
src/cmd/gc/esc.c
View File

@ -469,10 +469,14 @@ escassign(Node *dst, Node *src)
escflows(dst, src);
break;
case ODOT:
// A non-pointer escaping from a struct does not concern us.
if(src->type && !haspointers(src->type))
break;
// fallthrough
case OCONV:
case OCONVIFACE:
case OCONVNOP:
case ODOT:
case ODOTMETH: // treat recv.meth as a value with recv in it, only happens in ODEFER and OPROC
// iface.method already leaks iface in esccall, no need to put in extra ODOTINTER edge here
case ODOTTYPE:

42
test/escape2.go
View File

@ -126,10 +126,36 @@ func (b *Bar) NoLeak() int { // ERROR "b does not escape"
return *(b.ii)
}
func (b *Bar) Leak() *int { // ERROR "leaking param: b"
return &b.i // ERROR "&b.i escapes to heap"
}
func (b *Bar) AlsoNoLeak() *int { // ERROR "b does not escape"
return b.ii
}
func (b Bar) AlsoLeak() *int { // ERROR "leaking param: b"
return b.ii
}
func (b Bar) LeaksToo() *int { // ERROR "leaking param: b"
v := 0 // ERROR "moved to heap: v"
b.ii = &v // ERROR "&v escapes"
return b.ii
}
func (b *Bar) LeaksABit() *int { // ERROR "b does not escape"
v := 0 // ERROR "moved to heap: v"
b.ii = &v // ERROR "&v escapes"
return b.ii
}
func (b Bar) StillNoLeak() int { // ERROR "b does not escape"
v := 0
b.ii = &v // ERROR "&v does not escape"
return b.i
}
func goLeak(b *Bar) { // ERROR "leaking param: b"
go b.NoLeak()
}
@ -148,20 +174,24 @@ func (b *Bar2) NoLeak() int { // ERROR "b does not escape"
}
func (b *Bar2) Leak() []int { // ERROR "leaking param: b"
return b.i[:] // ERROR "b.i escapes to heap"
return b.i[:] // ERROR "b.i escapes to heap"
}
func (b *Bar2) AlsoNoLeak() []int { // ERROR "b does not escape"
return b.ii[0:1]
}
func (b Bar2) AgainNoLeak() [12]int { // ERROR "b does not escape"
return b.i
}
func (b *Bar2) LeakSelf() { // ERROR "leaking param: b"
b.ii = b.i[0:4] // ERROR "b.i escapes to heap"
b.ii = b.i[0:4] // ERROR "b.i escapes to heap"
}
func (b *Bar2) LeakSelf2() { // ERROR "leaking param: b"
var buf []int
buf = b.i[0:] // ERROR "b.i escapes to heap"
buf = b.i[0:] // ERROR "b.i escapes to heap"
b.ii = buf
}
@ -1018,7 +1048,7 @@ func foo122() {
goto L1
L1:
i = new(int) // ERROR "does not escape"
i = new(int) // ERROR "does not escape"
_ = i
}
@ -1027,8 +1057,8 @@ func foo123() {
var i *int
L1:
i = new(int) // ERROR "escapes"
i = new(int) // ERROR "escapes"
goto L1
_ = i
}
}