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go/test/escape_param.go
Iskander Sharipov ff468a43be cmd/compile/internal/gc: better handling of self-assignments in esc.go 
Teach escape analysis to recognize these assignment patterns
as not causing the src to leak:

	val.x = val.y
	val.x[i] = val.y[j]
	val.x1.x2 = val.x1.y2
	... etc

Helps to avoid "leaking param" with assignments showed above.
The implementation is based on somewhat similiar xs=xs[a:b]
special case that is ignored by the escape analysis.

We may figure out more generalized version of this,
but this one looks like a safe step into that direction.

Updates #14858

Change-Id: I6fe5bfedec9c03bdc1d7624883324a523bd11fde
Reviewed-on: https://go-review.googlesource.com/126395
Run-TryBot: Iskander Sharipov <iskander.sharipov@intel.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
2018-09-03 14:28:51 +00:00

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// errorcheck -0 -m -l
// Copyright 2015 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 escape analysis for function parameters.
// In this test almost everything is BAD except the simplest cases
// where input directly flows to output.
package escape
var sink interface{}
// in -> out
func param0(p *int) *int { // ERROR "leaking param: p to result ~r1"
return p
}
func caller0a() {
i := 0
_ = param0(&i) // ERROR "caller0a &i does not escape$"
}
func caller0b() {
i := 0 // ERROR "moved to heap: i$"
sink = param0(&i) // ERROR "&i escapes to heap$" "param0\(&i\) escapes to heap"
}
// in, in -> out, out
func param1(p1, p2 *int) (*int, *int) { // ERROR "leaking param: p1 to result ~r2" "leaking param: p2 to result ~r3"
return p1, p2
}
func caller1() {
i := 0 // ERROR "moved to heap: i$"
j := 0
sink, _ = param1(&i, &j) // ERROR "&i escapes to heap$" "caller1 &j does not escape$"
}
// in -> other in
func param2(p1 *int, p2 **int) { // ERROR "leaking param: p1$" "param2 p2 does not escape$"
*p2 = p1
}
func caller2a() {
i := 0 // ERROR "moved to heap: i$"
var p *int
param2(&i, &p) // ERROR "&i escapes to heap$" "caller2a &p does not escape$"
_ = p
}
func caller2b() {
i := 0 // ERROR "moved to heap: i$"
var p *int
param2(&i, &p) // ERROR "&i escapes to heap$" "caller2b &p does not escape$"
sink = p // ERROR "p escapes to heap$"
}
func paramArraySelfAssign(p *PairOfPairs) { // ERROR "p does not escape"
p.pairs[0] = p.pairs[1] // ERROR "ignoring self-assignment in p.pairs\[0\] = p.pairs\[1\]"
}
type PairOfPairs struct {
pairs [2]*Pair
}
type BoxedPair struct {
pair *Pair
}
type WrappedPair struct {
pair Pair
}
func leakParam(x interface{}) { // ERROR "leaking param: x"
sink = x
}
func sinkAfterSelfAssignment1(box *BoxedPair) { // ERROR "leaking param content: box"
box.pair.p1 = box.pair.p2 // ERROR "ignoring self-assignment in box.pair.p1 = box.pair.p2"
sink = box.pair.p2 // ERROR "box.pair.p2 escapes to heap"
}
func sinkAfterSelfAssignment2(box *BoxedPair) { // ERROR "leaking param content: box"
box.pair.p1 = box.pair.p2 // ERROR "ignoring self-assignment in box.pair.p1 = box.pair.p2"
sink = box.pair // ERROR "box.pair escapes to heap"
}
func sinkAfterSelfAssignment3(box *BoxedPair) { // ERROR "leaking param content: box"
box.pair.p1 = box.pair.p2 // ERROR "ignoring self-assignment in box.pair.p1 = box.pair.p2"
leakParam(box.pair.p2) // ERROR "box.pair.p2 escapes to heap"
}
func sinkAfterSelfAssignment4(box *BoxedPair) { // ERROR "leaking param content: box"
box.pair.p1 = box.pair.p2 // ERROR "ignoring self-assignment in box.pair.p1 = box.pair.p2"
leakParam(box.pair) // ERROR "box.pair escapes to heap"
}
func selfAssignmentAndUnrelated(box1, box2 *BoxedPair) { // ERROR "leaking param content: box2" "box1 does not escape"
box1.pair.p1 = box1.pair.p2 // ERROR "ignoring self-assignment in box1.pair.p1 = box1.pair.p2"
leakParam(box2.pair.p2) // ERROR "box2.pair.p2 escapes to heap"
}
func notSelfAssignment1(box1, box2 *BoxedPair) { // ERROR "leaking param content: box2" "box1 does not escape"
box1.pair.p1 = box2.pair.p1
}
func notSelfAssignment2(p1, p2 *PairOfPairs) { // ERROR "leaking param content: p2" "p1 does not escape"
p1.pairs[0] = p2.pairs[1]
}
func notSelfAssignment3(p1, p2 *PairOfPairs) { // ERROR "leaking param content: p2" "p1 does not escape"
p1.pairs[0].p1 = p2.pairs[1].p1
}
func boxedPairSelfAssign(box *BoxedPair) { // ERROR "box does not escape"
box.pair.p1 = box.pair.p2 // ERROR "ignoring self-assignment in box.pair.p1 = box.pair.p2"
}
func wrappedPairSelfAssign(w *WrappedPair) { // ERROR "w does not escape"
w.pair.p1 = w.pair.p2 // ERROR "ignoring self-assignment in w.pair.p1 = w.pair.p2"
}
// in -> in
type Pair struct {
p1 *int
p2 *int
}
func param3(p *Pair) { // ERROR "param3 p does not escape"
p.p1 = p.p2 // ERROR "param3 ignoring self-assignment in p.p1 = p.p2"
}
func caller3a() {
i := 0
j := 0
p := Pair{&i, &j} // ERROR "caller3a &i does not escape" "caller3a &j does not escape"
param3(&p) // ERROR "caller3a &p does not escape"
_ = p
}
func caller3b() {
i := 0 // ERROR "moved to heap: i$"
j := 0 // ERROR "moved to heap: j$"
p := Pair{&i, &j} // ERROR "&i escapes to heap$" "&j escapes to heap$"
param3(&p) // ERROR "caller3b &p does not escape"
sink = p // ERROR "p escapes to heap$"
}
// in -> rcvr
func (p *Pair) param4(i *int) { // ERROR "\(\*Pair\).param4 p does not escape$" "leaking param: i$"
p.p1 = i
}
func caller4a() {
i := 0 // ERROR "moved to heap: i$"
p := Pair{}
p.param4(&i) // ERROR "&i escapes to heap$" "caller4a p does not escape$"
_ = p
}
func caller4b() {
i := 0 // ERROR "moved to heap: i$"
p := Pair{}
p.param4(&i) // ERROR "&i escapes to heap$" "caller4b p does not escape$"
sink = p // ERROR "p escapes to heap$"
}
// in -> heap
func param5(i *int) { // ERROR "leaking param: i$"
sink = i // ERROR "i escapes to heap$"
}
func caller5() {
i := 0 // ERROR "moved to heap: i$"
param5(&i) // ERROR "&i escapes to heap$"
}
// *in -> heap
func param6(i ***int) { // ERROR "leaking param content: i$"
sink = *i // ERROR "\*i escapes to heap$"
}
func caller6a() {
i := 0 // ERROR "moved to heap: i$"
p := &i // ERROR "&i escapes to heap$" "moved to heap: p$"
p2 := &p // ERROR "&p escapes to heap$"
param6(&p2) // ERROR "caller6a &p2 does not escape"
}
// **in -> heap
func param7(i ***int) { // ERROR "leaking param content: i$"
sink = **i // ERROR "\* \(\*i\) escapes to heap"
}
func caller7() {
i := 0 // ERROR "moved to heap: i$"
p := &i // ERROR "&i escapes to heap$" "moved to heap: p$"
p2 := &p // ERROR "&p escapes to heap$"
param7(&p2) // ERROR "caller7 &p2 does not escape"
}
// **in -> heap
func param8(i **int) { // ERROR "param8 i does not escape$"
sink = **i // ERROR "\* \(\*i\) escapes to heap"
}
func caller8() {
i := 0
p := &i // ERROR "caller8 &i does not escape$"
param8(&p) // ERROR "caller8 &p does not escape$"
}
// *in -> out
func param9(p ***int) **int { // ERROR "leaking param: p to result ~r1 level=1"
return *p
}
func caller9a() {
i := 0
p := &i // ERROR "caller9a &i does not escape"
p2 := &p // ERROR "caller9a &p does not escape"
_ = param9(&p2) // ERROR "caller9a &p2 does not escape$"
}
func caller9b() {
i := 0 // ERROR "moved to heap: i$"
p := &i // ERROR "&i escapes to heap$" "moved to heap: p$"
p2 := &p // ERROR "&p escapes to heap$"
sink = param9(&p2) // ERROR "caller9b &p2 does not escape$" "param9\(&p2\) escapes to heap"
}
// **in -> out
func param10(p ***int) *int { // ERROR "leaking param: p to result ~r1 level=2"
return **p
}
func caller10a() {
i := 0
p := &i // ERROR "caller10a &i does not escape"
p2 := &p // ERROR "caller10a &p does not escape"
_ = param10(&p2) // ERROR "caller10a &p2 does not escape$"
}
func caller10b() {
i := 0 // ERROR "moved to heap: i$"
p := &i // ERROR "&i escapes to heap$"
p2 := &p // ERROR "caller10b &p does not escape$"
sink = param10(&p2) // ERROR "caller10b &p2 does not escape$" "param10\(&p2\) escapes to heap"
}
// in escapes to heap (address of param taken and returned)
func param11(i **int) ***int { // ERROR "moved to heap: i$"
return &i // ERROR "&i escapes to heap$"
}
func caller11a() {
i := 0 // ERROR "moved to heap: i"
p := &i // ERROR "moved to heap: p" "&i escapes to heap"
_ = param11(&p) // ERROR "&p escapes to heap"
}
func caller11b() {
i := 0 // ERROR "moved to heap: i$"
p := &i // ERROR "&i escapes to heap$" "moved to heap: p$"
sink = param11(&p) // ERROR "&p escapes to heap$" "param11\(&p\) escapes to heap"
}
func caller11c() { // GOOD
i := 0 // ERROR "moved to heap: i$"
p := &i // ERROR "moved to heap: p" "&i escapes to heap"
sink = *param11(&p) // ERROR "&p escapes to heap" "\*param11\(&p\) escapes to heap"
}
func caller11d() {
i := 0 // ERROR "moved to heap: i$"
p := &i // ERROR "&i escapes to heap" "moved to heap: p"
p2 := &p // ERROR "&p escapes to heap"
sink = param11(p2) // ERROR "param11\(p2\) escapes to heap"
}
// &in -> rcvr
type Indir struct {
p ***int
}
func (r *Indir) param12(i **int) { // ERROR "\(\*Indir\).param12 r does not escape$" "moved to heap: i$"
r.p = &i // ERROR "&i escapes to heap$"
}
func caller12a() {
i := 0 // ERROR "moved to heap: i$"
p := &i // ERROR "&i escapes to heap$" "moved to heap: p$"
var r Indir
r.param12(&p) // ERROR "&p escapes to heap$" "caller12a r does not escape$"
_ = r
}
func caller12b() {
i := 0 // ERROR "moved to heap: i$"
p := &i // ERROR "&i escapes to heap$" "moved to heap: p$"
r := &Indir{} // ERROR "caller12b &Indir literal does not escape$"
r.param12(&p) // ERROR "&p escapes to heap$"
_ = r
}
func caller12c() {
i := 0 // ERROR "moved to heap: i$"
p := &i // ERROR "&i escapes to heap$" "moved to heap: p$"
r := Indir{}
r.param12(&p) // ERROR "&p escapes to heap$" "caller12c r does not escape$"
sink = r // ERROR "r escapes to heap$"
}
func caller12d() {
i := 0 // ERROR "moved to heap: i$"
p := &i // ERROR "&i escapes to heap$" "moved to heap: p$"
r := Indir{}
r.param12(&p) // ERROR "&p escapes to heap$" "caller12d r does not escape$"
sink = **r.p // ERROR "\* \(\*r\.p\) escapes to heap"
}
// in -> value rcvr
type Val struct {
p **int
}
func (v Val) param13(i *int) { // ERROR "Val.param13 v does not escape$" "leaking param: i$"
*v.p = i
}
func caller13a() {
i := 0 // ERROR "moved to heap: i$"
var p *int
var v Val
v.p = &p // ERROR "caller13a &p does not escape$"
v.param13(&i) // ERROR "&i escapes to heap$"
_ = v
}
func caller13b() {
i := 0 // ERROR "moved to heap: i$"
var p *int
v := Val{&p} // ERROR "caller13b &p does not escape$"
v.param13(&i) // ERROR "&i escapes to heap$"
_ = v
}
func caller13c() {
i := 0 // ERROR "moved to heap: i$"
var p *int
v := &Val{&p} // ERROR "caller13c &Val literal does not escape$" "caller13c &p does not escape$"
v.param13(&i) // ERROR "&i escapes to heap$"
_ = v
}
func caller13d() {
i := 0 // ERROR "moved to heap: i$"
var p *int // ERROR "moved to heap: p$"
var v Val
v.p = &p // ERROR "&p escapes to heap$"
v.param13(&i) // ERROR "&i escapes to heap$"
sink = v // ERROR "v escapes to heap$"
}
func caller13e() {
i := 0 // ERROR "moved to heap: i$"
var p *int // ERROR "moved to heap: p$"
v := Val{&p} // ERROR "&p escapes to heap$"
v.param13(&i) // ERROR "&i escapes to heap$"
sink = v // ERROR "v escapes to heap$"
}
func caller13f() {
i := 0 // ERROR "moved to heap: i$"
var p *int // ERROR "moved to heap: p$"
v := &Val{&p} // ERROR "&Val literal escapes to heap$" "&p escapes to heap$"
v.param13(&i) // ERROR "&i escapes to heap$"
sink = v // ERROR "v escapes to heap$"
}
func caller13g() {
i := 0 // ERROR "moved to heap: i$"
var p *int
v := Val{&p} // ERROR "caller13g &p does not escape$"
v.param13(&i) // ERROR "&i escapes to heap$"
sink = *v.p // ERROR "\*v\.p escapes to heap"
}
func caller13h() {
i := 0 // ERROR "moved to heap: i$"
var p *int
v := &Val{&p} // ERROR "caller13h &Val literal does not escape$" "caller13h &p does not escape$"
v.param13(&i) // ERROR "&i escapes to heap$"
sink = **v.p // ERROR "\* \(\*v\.p\) escapes to heap"
}
type Node struct {
p *Node
}
var Sink *Node
func f(x *Node) { // ERROR "leaking param content: x"
Sink = &Node{x.p} // ERROR "&Node literal escapes to heap"
}
func g(x *Node) *Node { // ERROR "leaking param: x to result ~r1 level=0"
return &Node{x.p} // ERROR "&Node literal escapes to heap"
}
func h(x *Node) { // ERROR "leaking param: x"
y := &Node{x} // ERROR "h &Node literal does not escape"
Sink = g(y)
f(y)
}
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