gc: avoid false positives when using scalar struct fields.
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
diff --git a/src/cmd/gc/esc.c b/src/cmd/gc/esc.c
index 037067b..43986c6 100644
--- a/src/cmd/gc/esc.c
+++ b/src/cmd/gc/esc.c
@@ -469,10 +469,14 @@
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:
diff --git a/test/escape2.go b/test/escape2.go
index c2cbefb..73b2a7e 100644
--- a/test/escape2.go
+++ b/test/escape2.go
@@ -126,10 +126,36 @@
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) 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 @@
goto L1
L1:
- i = new(int) // ERROR "does not escape"
+ i = new(int) // ERROR "does not escape"
_ = i
}
@@ -1027,8 +1057,8 @@
var i *int
L1:
- i = new(int) // ERROR "escapes"
+ i = new(int) // ERROR "escapes"
goto L1
_ = i
-}
\ No newline at end of file
+}
