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go/test/escape5.go
David Chase e5060c7f75 cmd/internal/gc: move check for large-hence-heap-allocated types into escape analysis
Before this change, the check for too-large arrays (and other large
types) occurred after escape analysis.  If the data moved off stack
and onto the heap contained any pointers, it would therefore escape,
but because the too-large check occurred after escape analysis this
would not be recorded and a stack pointer would leak to the heap
(see the modified escape_array.go for an example).

Some of these appear to remain, in calls to typecheck from within walk.

Also corrected a few comments in escape_array.go about "BAD"
analysis that is now done correctly.

Enhanced to move aditional EscNone-but-large-so-heap checks into esc.c.

Change-Id: I770c111baff28a9ed5f8beb601cf09dacc561b83
Reviewed-on: https://go-review.googlesource.com/10268
Reviewed-by: Russ Cox <rsc@golang.org>
2015-05-22 02:13:54 +00:00

152 lines
3.4 KiB
Go

// errorcheck -0 -m -l
// Copyright 2012 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.
// Test, using compiler diagnostic flags, that the escape analysis is working.
// Compiles but does not run. Inlining is disabled.
package foo
func noleak(p *int) int { // ERROR "p does not escape"
return *p
}
func leaktoret(p *int) *int { // ERROR "leaking param: p to result"
return p
}
func leaktoret2(p *int) (*int, *int) { // ERROR "leaking param: p to result ~r1" "leaking param: p to result ~r2"
return p, p
}
func leaktoret22(p, q *int) (*int, *int) { // ERROR "leaking param: p to result ~r2" "leaking param: q to result ~r3"
return p, q
}
func leaktoret22b(p, q *int) (*int, *int) { // ERROR "leaking param: p to result ~r3" "leaking param: q to result ~r2"
return leaktoret22(q, p)
}
func leaktoret22c(p, q *int) (*int, *int) { // ERROR "leaking param: p to result ~r3" "leaking param: q to result ~r2"
r, s := leaktoret22(q, p)
return r, s
}
func leaktoret22d(p, q *int) (r, s *int) { // ERROR "leaking param: p to result s" "leaking param: q to result r"
r, s = leaktoret22(q, p)
return
}
func leaktoret22e(p, q *int) (r, s *int) { // ERROR "leaking param: p to result s" "leaking param: q to result r"
r, s = leaktoret22(q, p)
return r, s
}
func leaktoret22f(p, q *int) (r, s *int) { // ERROR "leaking param: p to result s" "leaking param: q to result r"
rr, ss := leaktoret22(q, p)
return rr, ss
}
var gp *int
func leaktosink(p *int) *int { // ERROR "leaking param: p"
gp = p
return p
}
func f1() {
var x int
p := noleak(&x) // ERROR "&x does not escape"
_ = p
}
func f2() {
var x int
p := leaktoret(&x) // ERROR "&x does not escape"
_ = p
}
func f3() {
var x int // ERROR "moved to heap: x"
p := leaktoret(&x) // ERROR "&x escapes to heap"
gp = p
}
func f4() {
var x int // ERROR "moved to heap: x"
p, q := leaktoret2(&x) // ERROR "&x escapes to heap"
gp = p
gp = q
}
func f5() {
var x int
leaktoret22(leaktoret2(&x)) // ERROR "&x does not escape"
}
func f6() {
var x int // ERROR "moved to heap: x"
px1, px2 := leaktoret22(leaktoret2(&x)) // ERROR "&x escapes to heap"
gp = px1
_ = px2
}
type T struct{ x int }
func (t *T) Foo(u int) (*T, bool) { // ERROR "leaking param: t to result"
t.x += u
return t, true
}
func f7() *T {
r, _ := new(T).Foo(42) // ERROR "new.T. escapes to heap"
return r
}
func leakrecursive1(p, q *int) (*int, *int) { // ERROR "leaking param: p" "leaking param: q"
return leakrecursive2(q, p)
}
func leakrecursive2(p, q *int) (*int, *int) { // ERROR "leaking param: p" "leaking param: q"
if *p > *q {
return leakrecursive1(q, p)
}
// without this, leakrecursive? are safe for p and q, b/c in fact their graph does not have leaking edges.
return p, q
}
var global interface{}
type T1 struct {
X *int
}
type T2 struct {
Y *T1
}
func f8(p *T1) (k T2) { // ERROR "leaking param: p to result k" "leaking param: p"
if p == nil {
k = T2{}
return
}
// should make p leak always
global = p // ERROR "p escapes to heap"
return T2{p}
}
func f9() {
var j T1 // ERROR "moved to heap: j"
f8(&j) // ERROR "&j escapes to heap"
}
func f10() {
// These don't escape but are too big for the stack
var x [1 << 30]byte // ERROR "moved to heap: x"
var y = make([]byte, 1<<30) // ERROR "make\(\[\]byte, 1 << 30\) escapes to heap"
_ = x[0] + y[0]
}