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cmd/gc: fix escape analysis bug with variable capture in loops.

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Fixes #3975.

R=rsc, lvd
CC=golang-dev, remy
https://golang.org/cl/6475061
This commit is contained in:
Rémy Oudompheng 2012-08-31 22:23:37 +02:00
parent 3efc482190
commit ba97d52b85
3 changed files with 35 additions and 6 deletions
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1
src/cmd/gc/esc.c
View File

@ -543,6 +543,7 @@ esc(EscState *e, Node *n)
continue;
a = nod(OADDR, ll->n->closure, N);
a->lineno = ll->n->lineno;
a->escloopdepth = e->loopdepth;
typecheck(&a, Erv);
escassign(e, n, a);
}

27
test/escape.go
View File

@ -18,15 +18,15 @@ var allptr = make([]*int, 0, 100)
func noalias(p, q *int, s string) {
n := len(allptr)
*p = -(n+1)
*q = -(n+2)
allptr = allptr[0:n+2]
*p = -(n + 1)
*q = -(n + 2)
allptr = allptr[0 : n+2]
allptr[n] = p
allptr[n+1] = q
n += 2
for i := 0; i < n; i++ {
if allptr[i] != nil && *allptr[i] != -(i+1) {
println("aliased pointers", -(i+1), *allptr[i], "after", s)
println("aliased pointers", -(i + 1), *allptr[i], "after", s)
allptr[i] = nil
bad = true
}
@ -141,15 +141,27 @@ func for_escapes2(x int, y int) (*int, *int) {
return p[0], p[1]
}
func for_escapes3(x int, y int) (*int, *int) {
var f [2]func() *int
n := 0
for i := x; n < 2; i = y {
p := new(int)
*p = i
f[n] = func() *int { return p }
n++
}
return f[0](), f[1]()
}
func out_escapes(i int) (x int, p *int) {
x = i
p = &x // ERROR "address of out parameter"
p = &x // ERROR "address of out parameter"
return
}
func out_escapes_2(i int) (x int, p *int) {
x = i
return x, &x // ERROR "address of out parameter"
return x, &x // ERROR "address of out parameter"
}
func defer1(i int) (x int) {
@ -187,6 +199,9 @@ func main() {
p, q = for_escapes2(103, 104)
chkalias(p, q, 103, "for_escapes2")
p, q = for_escapes3(105, 106)
chk(p, q, 105, "for_escapes3")
_, p = out_escapes(15)
_, q = out_escapes(16)
chk(p, q, 15, "out_escapes")

13
test/escape2.go
View File

@ -540,6 +540,19 @@ func foo74() {
}
}
// issue 3975
func foo74b() {
var array [3]func()
s := []int{3, 2, 1} // ERROR "\[\]int literal does not escape"
for i, v := range s {
vv := v // ERROR "moved to heap: vv"
// actually just escapes its scope
array[i] = func() { // ERROR "func literal escapes to heap"
println(vv) // ERROR "&vv escapes to heap"
}
}
}
func myprint(y *int, x ...interface{}) *int { // ERROR "x does not escape" "leaking param: y"
return y
}