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go/test/escape2.go
Matthew Dempsky 2a2423bd05 cmd/compile: more precise analysis of method values 
Previously for a method value "x.M", we always flowed x directly to
the heap, which led to the receiver argument generally needing to be
heap allocated.

This CL changes it to flow x to the closure and M's receiver
parameter. This allows receiver arguments to be stack allocated as
long as (1) the closure never escapes, *and* (2) method doesn't leak
its receiver parameter.

Within the standard library, this allows a handful of objects to be
stack allocated instead. Listed here are diagnostics that were
previously emitted by "go build -gcflags=-m std cmd" that are no
longer emitted:

archive/tar/writer.go:118:6: moved to heap: f
archive/tar/writer.go:208:6: moved to heap: f
archive/tar/writer.go:248:6: moved to heap: f
cmd/compile/internal/gc/initorder.go:252:2: moved to heap: d
cmd/compile/internal/gc/initorder.go:75:2: moved to heap: s
cmd/go/internal/generate/generate.go:206:7: &Generator literal escapes to heap
cmd/internal/obj/arm64/asm7.go:910:2: moved to heap: c
cmd/internal/obj/mips/asm0.go:415:2: moved to heap: c
cmd/internal/obj/pcln.go:294:22: new(pcinlineState) escapes to heap
cmd/internal/obj/s390x/asmz.go:459:2: moved to heap: c
crypto/tls/handshake_server.go:56:2: moved to heap: hs

Thanks to Cuong Manh Le for help coming up with this solution.

Fixes #27557.

Change-Id: I8c85d671d07fb9b53e11d2dd05949a34dbbd7e17
Reviewed-on: https://go-review.googlesource.com/c/go/+/228263
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
2020-04-21 20:49:34 +00:00

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// errorcheck -0 -m -l
// Copyright 2010 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.
// escape2n.go contains all the same tests but compiles with -N.
package foo
import (
"fmt"
"unsafe"
)
var gxx *int
func foo1(x int) { // ERROR "moved to heap: x$"
gxx = &x
}
func foo2(yy *int) { // ERROR "leaking param: yy$"
gxx = yy
}
func foo3(x int) *int { // ERROR "moved to heap: x$"
return &x
}
type T *T
func foo3b(t T) { // ERROR "leaking param: t$"
*t = t
}
// xx isn't going anywhere, so use of yy is ok
func foo4(xx, yy *int) { // ERROR "xx does not escape$" "yy does not escape$"
xx = yy
}
// xx isn't going anywhere, so taking address of yy is ok
func foo5(xx **int, yy *int) { // ERROR "xx does not escape$" "yy does not escape$"
xx = &yy
}
func foo6(xx **int, yy *int) { // ERROR "xx does not escape$" "leaking param: yy$"
*xx = yy
}
func foo7(xx **int, yy *int) { // ERROR "xx does not escape$" "yy does not escape$"
**xx = *yy
}
func foo8(xx, yy *int) int { // ERROR "xx does not escape$" "yy does not escape$"
xx = yy
return *xx
}
func foo9(xx, yy *int) *int { // ERROR "leaking param: xx to result ~r2 level=0$" "leaking param: yy to result ~r2 level=0$"
xx = yy
return xx
}
func foo10(xx, yy *int) { // ERROR "xx does not escape$" "yy does not escape$"
*xx = *yy
}
func foo11() int {
x, y := 0, 42
xx := &x
yy := &y
*xx = *yy
return x
}
var xxx **int
func foo12(yyy **int) { // ERROR "leaking param: yyy$"
xxx = yyy
}
// Must treat yyy as leaking because *yyy leaks, and the escape analysis
// summaries in exported metadata do not distinguish these two cases.
func foo13(yyy **int) { // ERROR "leaking param content: yyy$"
*xxx = *yyy
}
func foo14(yyy **int) { // ERROR "yyy does not escape$"
**xxx = **yyy
}
func foo15(yy *int) { // ERROR "moved to heap: yy$"
xxx = &yy
}
func foo16(yy *int) { // ERROR "leaking param: yy$"
*xxx = yy
}
func foo17(yy *int) { // ERROR "yy does not escape$"
**xxx = *yy
}
func foo18(y int) { // ERROR "moved to heap: y$"
*xxx = &y
}
func foo19(y int) {
**xxx = y
}
type Bar struct {
i int
ii *int
}
func NewBar() *Bar {
return &Bar{42, nil} // ERROR "&Bar literal escapes to heap$"
}
func NewBarp(x *int) *Bar { // ERROR "leaking param: x$"
return &Bar{42, x} // ERROR "&Bar literal escapes to heap$"
}
func NewBarp2(x *int) *Bar { // ERROR "x does not escape$"
return &Bar{*x, nil} // ERROR "&Bar literal escapes to heap$"
}
func (b *Bar) NoLeak() int { // ERROR "b does not escape$"
return *(b.ii)
}
func (b *Bar) Leak() *int { // ERROR "leaking param: b to result ~r0 level=0$"
return &b.i
}
func (b *Bar) AlsoNoLeak() *int { // ERROR "leaking param: b to result ~r0 level=1$"
return b.ii
}
func (b Bar) AlsoLeak() *int { // ERROR "leaking param: b to result ~r0 level=0$"
return b.ii
}
func (b Bar) LeaksToo() *int { // ERROR "leaking param: b to result ~r0 level=0$"
v := 0 // ERROR "moved to heap: v$"
b.ii = &v
return b.ii
}
func (b *Bar) LeaksABit() *int { // ERROR "leaking param: b to result ~r0 level=1$"
v := 0 // ERROR "moved to heap: v$"
b.ii = &v
return b.ii
}
func (b Bar) StillNoLeak() int { // ERROR "b does not escape$"
v := 0
b.ii = &v
return b.i
}
func goLeak(b *Bar) { // ERROR "leaking param: b$"
go b.NoLeak()
}
type Bar2 struct {
i [12]int
ii []int
}
func NewBar2() *Bar2 {
return &Bar2{[12]int{42}, nil} // ERROR "&Bar2 literal escapes to heap$"
}
func (b *Bar2) NoLeak() int { // ERROR "b does not escape$"
return b.i[0]
}
func (b *Bar2) Leak() []int { // ERROR "leaking param: b to result ~r0 level=0$"
return b.i[:]
}
func (b *Bar2) AlsoNoLeak() []int { // ERROR "leaking param: b to result ~r0 level=1$"
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]
}
func (b *Bar2) LeakSelf2() { // ERROR "leaking param: b$"
var buf []int
buf = b.i[0:]
b.ii = buf
}
func foo21() func() int {
x := 42
return func() int { // ERROR "func literal escapes to heap$"
return x
}
}
func foo21a() func() int {
x := 42 // ERROR "moved to heap: x$"
return func() int { // ERROR "func literal escapes to heap$"
x++
return x
}
}
func foo22() int {
x := 42
return func() int { // ERROR "func literal does not escape$"
return x
}()
}
func foo23(x int) func() int {
return func() int { // ERROR "func literal escapes to heap$"
return x
}
}
func foo23a(x int) func() int {
f := func() int { // ERROR "func literal escapes to heap$"
return x
}
return f
}
func foo23b(x int) *(func() int) {
f := func() int { return x } // ERROR "func literal escapes to heap$" "moved to heap: f$"
return &f
}
func foo23c(x int) func() int { // ERROR "moved to heap: x$"
return func() int { // ERROR "func literal escapes to heap$"
x++
return x
}
}
func foo24(x int) int {
return func() int { // ERROR "func literal does not escape$"
return x
}()
}
var x *int
func fooleak(xx *int) int { // ERROR "leaking param: xx$"
x = xx
return *x
}
func foonoleak(xx *int) int { // ERROR "xx does not escape$"
return *x + *xx
}
func foo31(x int) int { // ERROR "moved to heap: x$"
return fooleak(&x)
}
func foo32(x int) int {
return foonoleak(&x)
}
type Foo struct {
xx *int
x int
}
var F Foo
var pf *Foo
func (f *Foo) fooleak() { // ERROR "leaking param: f$"
pf = f
}
func (f *Foo) foonoleak() { // ERROR "f does not escape$"
F.x = f.x
}
func (f *Foo) Leak() { // ERROR "leaking param: f$"
f.fooleak()
}
func (f *Foo) NoLeak() { // ERROR "f does not escape$"
f.foonoleak()
}
func foo41(x int) { // ERROR "moved to heap: x$"
F.xx = &x
}
func (f *Foo) foo42(x int) { // ERROR "f does not escape$" "moved to heap: x$"
f.xx = &x
}
func foo43(f *Foo, x int) { // ERROR "f does not escape$" "moved to heap: x$"
f.xx = &x
}
func foo44(yy *int) { // ERROR "leaking param: yy$"
F.xx = yy
}
func (f *Foo) foo45() { // ERROR "f does not escape$"
F.x = f.x
}
// See foo13 above for explanation of why f leaks.
func (f *Foo) foo46() { // ERROR "leaking param content: f$"
F.xx = f.xx
}
func (f *Foo) foo47() { // ERROR "leaking param: f$"
f.xx = &f.x
}
var ptrSlice []*int
func foo50(i *int) { // ERROR "leaking param: i$"
ptrSlice[0] = i
}
var ptrMap map[*int]*int
func foo51(i *int) { // ERROR "leaking param: i$"
ptrMap[i] = i
}
func indaddr1(x int) *int { // ERROR "moved to heap: x$"
return &x
}
func indaddr2(x *int) *int { // ERROR "leaking param: x to result ~r1 level=0$"
return *&x
}
func indaddr3(x *int32) *int { // ERROR "leaking param: x to result ~r1 level=0$"
return *(**int)(unsafe.Pointer(&x))
}
// From package math:
func Float32bits(f float32) uint32 {
return *(*uint32)(unsafe.Pointer(&f))
}
func Float32frombits(b uint32) float32 {
return *(*float32)(unsafe.Pointer(&b))
}
func Float64bits(f float64) uint64 {
return *(*uint64)(unsafe.Pointer(&f))
}
func Float64frombits(b uint64) float64 {
return *(*float64)(unsafe.Pointer(&b))
}
// contrast with
func float64bitsptr(f float64) *uint64 { // ERROR "moved to heap: f$"
return (*uint64)(unsafe.Pointer(&f))
}
func float64ptrbitsptr(f *float64) *uint64 { // ERROR "leaking param: f to result ~r1 level=0$"
return (*uint64)(unsafe.Pointer(f))
}
func typesw(i interface{}) *int { // ERROR "leaking param: i to result ~r1 level=0$"
switch val := i.(type) {
case *int:
return val
case *int8:
v := int(*val) // ERROR "moved to heap: v$"
return &v
}
return nil
}
func exprsw(i *int) *int { // ERROR "leaking param: i to result ~r1 level=0$"
switch j := i; *j + 110 {
case 12:
return j
case 42:
return nil
}
return nil
}
// assigning to an array element is like assigning to the array
func foo60(i *int) *int { // ERROR "leaking param: i to result ~r1 level=0$"
var a [12]*int
a[0] = i
return a[1]
}
func foo60a(i *int) *int { // ERROR "i does not escape$"
var a [12]*int
a[0] = i
return nil
}
// assigning to a struct field is like assigning to the struct
func foo61(i *int) *int { // ERROR "leaking param: i to result ~r1 level=0$"
type S struct {
a, b *int
}
var s S
s.a = i
return s.b
}
func foo61a(i *int) *int { // ERROR "i does not escape$"
type S struct {
a, b *int
}
var s S
s.a = i
return nil
}
// assigning to a struct field is like assigning to the struct but
// here this subtlety is lost, since s.a counts as an assignment to a
// track-losing dereference.
func foo62(i *int) *int { // ERROR "leaking param: i$"
type S struct {
a, b *int
}
s := new(S) // ERROR "new\(S\) does not escape$"
s.a = i
return nil // s.b
}
type M interface {
M()
}
func foo63(m M) { // ERROR "m does not escape$"
}
func foo64(m M) { // ERROR "leaking param: m$"
m.M()
}
func foo64b(m M) { // ERROR "leaking param: m$"
defer m.M()
}
type MV int
func (MV) M() {}
func foo65() {
var mv MV
foo63(&mv)
}
func foo66() {
var mv MV // ERROR "moved to heap: mv$"
foo64(&mv)
}
func foo67() {
var mv MV
foo63(mv) // ERROR "mv does not escape$"
}
func foo68() {
var mv MV
// escapes but it's an int so irrelevant
foo64(mv) // ERROR "mv escapes to heap$"
}
func foo69(m M) { // ERROR "leaking param: m$"
foo64(m)
}
func foo70(mv1 *MV, m M) { // ERROR "leaking param: m$" "leaking param: mv1$"
m = mv1
foo64(m)
}
func foo71(x *int) []*int { // ERROR "leaking param: x$"
var y []*int
y = append(y, x)
return y
}
func foo71a(x int) []*int { // ERROR "moved to heap: x$"
var y []*int
y = append(y, &x)
return y
}
func foo72() {
var x int
var y [1]*int
y[0] = &x
}
func foo72aa() [10]*int {
var x int // ERROR "moved to heap: x$"
var y [10]*int
y[0] = &x
return y
}
func foo72a() {
var y [10]*int
for i := 0; i < 10; i++ {
// escapes its scope
x := i // ERROR "moved to heap: x$"
y[i] = &x
}
return
}
func foo72b() [10]*int {
var y [10]*int
for i := 0; i < 10; i++ {
x := i // ERROR "moved to heap: x$"
y[i] = &x
}
return y
}
// issue 2145
func foo73() {
s := []int{3, 2, 1} // ERROR "\[\]int literal does not escape$"
for _, v := range s {
vv := v
// actually just escapes its scope
defer func() { // ERROR "func literal escapes to heap$"
println(vv)
}()
}
}
func foo731() {
s := []int{3, 2, 1} // ERROR "\[\]int literal does not escape$"
for _, v := range s {
vv := v // ERROR "moved to heap: vv$"
// actually just escapes its scope
defer func() { // ERROR "func literal escapes to heap$"
vv = 42
println(vv)
}()
}
}
func foo74() {
s := []int{3, 2, 1} // ERROR "\[\]int literal does not escape$"
for _, v := range s {
vv := v
// actually just escapes its scope
fn := func() { // ERROR "func literal escapes to heap$"
println(vv)
}
defer fn()
}
}
func foo74a() {
s := []int{3, 2, 1} // ERROR "\[\]int literal does not escape$"
for _, v := range s {
vv := v // ERROR "moved to heap: vv$"
// actually just escapes its scope
fn := func() { // ERROR "func literal escapes to heap$"
vv += 1
println(vv)
}
defer fn()
}
}
// issue 3975
func foo74b() {
var array [3]func()
s := []int{3, 2, 1} // ERROR "\[\]int literal does not escape$"
for i, v := range s {
vv := v
// actually just escapes its scope
array[i] = func() { // ERROR "func literal escapes to heap$"
println(vv)
}
}
}
func foo74c() {
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$"
println(&vv)
}
}
}
func myprint(y *int, x ...interface{}) *int { // ERROR "leaking param: y to result ~r2 level=0$" "x does not escape$"
return y
}
func myprint1(y *int, x ...interface{}) *interface{} { // ERROR "leaking param: x to result ~r2 level=0$" "y does not escape$"
return &x[0]
}
func foo75(z *int) { // ERROR "z does not escape$"
myprint(z, 1, 2, 3) // ERROR "1 does not escape" "2 does not escape" "3 does not escape" "... argument does not escape$"
}
func foo75a(z *int) { // ERROR "z does not escape$"
myprint1(z, 1, 2, 3) // ERROR "1 does not escape" "2 does not escape" "3 does not escape" "... argument does not escape$"
}
func foo75esc(z *int) { // ERROR "leaking param: z$"
gxx = myprint(z, 1, 2, 3) // ERROR "1 does not escape" "2 does not escape" "3 does not escape" "... argument does not escape$"
}
func foo75aesc(z *int) { // ERROR "z does not escape$"
var ppi **interface{} // assignments to pointer dereferences lose track
*ppi = myprint1(z, 1, 2, 3) // ERROR "... argument escapes to heap$" "1 escapes to heap$" "2 escapes to heap$" "3 escapes to heap$"
}
func foo75aesc1(z *int) { // ERROR "z does not escape$"
sink = myprint1(z, 1, 2, 3) // ERROR "... argument escapes to heap$" "1 escapes to heap$" "2 escapes to heap$" "3 escapes to heap$"
}
func foo76(z *int) { // ERROR "z does not escape"
myprint(nil, z) // ERROR "... argument does not escape$"
}
func foo76a(z *int) { // ERROR "z does not escape"
myprint1(nil, z) // ERROR "... argument does not escape$"
}
func foo76b() {
myprint(nil, 1, 2, 3) // ERROR "1 does not escape" "2 does not escape" "3 does not escape" "... argument does not escape$"
}
func foo76c() {
myprint1(nil, 1, 2, 3) // ERROR "1 does not escape" "2 does not escape" "3 does not escape" "... argument does not escape$"
}
func foo76d() {
defer myprint(nil, 1, 2, 3) // ERROR "1 does not escape" "2 does not escape" "3 does not escape" "... argument does not escape$"
}
func foo76e() {
defer myprint1(nil, 1, 2, 3) // ERROR "1 does not escape" "2 does not escape" "3 does not escape" "... argument does not escape$"
}
func foo76f() {
for {
// TODO: This one really only escapes its scope, but we don't distinguish yet.
defer myprint(nil, 1, 2, 3) // ERROR "... argument escapes to heap$" "1 escapes to heap$" "2 escapes to heap$" "3 escapes to heap$"
}
}
func foo76g() {
for {
defer myprint1(nil, 1, 2, 3) // ERROR "... argument escapes to heap$" "1 escapes to heap$" "2 escapes to heap$" "3 escapes to heap$"
}
}
func foo77(z []interface{}) { // ERROR "z does not escape$"
myprint(nil, z...) // z does not escape
}
func foo77a(z []interface{}) { // ERROR "z does not escape$"
myprint1(nil, z...)
}
func foo77b(z []interface{}) { // ERROR "leaking param: z$"
var ppi **interface{}
*ppi = myprint1(nil, z...)
}
func foo77c(z []interface{}) { // ERROR "leaking param: z$"
sink = myprint1(nil, z...)
}
func dotdotdot() {
i := 0
myprint(nil, &i) // ERROR "... argument does not escape$"
j := 0
myprint1(nil, &j) // ERROR "... argument does not escape$"
}
func foo78(z int) *int { // ERROR "moved to heap: z$"
return &z
}
func foo78a(z int) *int { // ERROR "moved to heap: z$"
y := &z
x := &y
return *x // really return y
}
func foo79() *int {
return new(int) // ERROR "new\(int\) escapes to heap$"
}
func foo80() *int {
var z *int
for {
// Really just escapes its scope but we don't distinguish
z = new(int) // ERROR "new\(int\) escapes to heap$"
}
_ = z
return nil
}
func foo81() *int {
for {
z := new(int) // ERROR "new\(int\) does not escape$"
_ = z
}
return nil
}
func tee(p *int) (x, y *int) { return p, p } // ERROR "leaking param: p to result x level=0$" "leaking param: p to result y level=0$"
func noop(x, y *int) {} // ERROR "x does not escape$" "y does not escape$"
func foo82() {
var x, y, z int // ERROR "moved to heap: x$" "moved to heap: y$" "moved to heap: z$"
go noop(tee(&z))
go noop(&x, &y)
for {
var u, v, w int // ERROR "moved to heap: u$" "moved to heap: v$" "moved to heap: w$"
defer noop(tee(&u))
defer noop(&v, &w)
}
}
type Fooer interface {
Foo()
}
type LimitedFooer struct {
Fooer
N int64
}
func LimitFooer(r Fooer, n int64) Fooer { // ERROR "leaking param: r$"
return &LimitedFooer{r, n} // ERROR "&LimitedFooer literal escapes to heap$"
}
func foo90(x *int) map[*int]*int { // ERROR "leaking param: x$"
return map[*int]*int{nil: x} // ERROR "map\[\*int\]\*int literal escapes to heap$"
}
func foo91(x *int) map[*int]*int { // ERROR "leaking param: x$"
return map[*int]*int{x: nil} // ERROR "map\[\*int\]\*int literal escapes to heap$"
}
func foo92(x *int) [2]*int { // ERROR "leaking param: x to result ~r1 level=0$"
return [2]*int{x, nil}
}
// does not leak c
func foo93(c chan *int) *int { // ERROR "c does not escape$"
for v := range c {
return v
}
return nil
}
// does not leak m
func foo94(m map[*int]*int, b bool) *int { // ERROR "leaking param: m to result ~r2 level=1"
for k, v := range m {
if b {
return k
}
return v
}
return nil
}
// does leak x
func foo95(m map[*int]*int, x *int) { // ERROR "m does not escape$" "leaking param: x$"
m[x] = x
}
// does not leak m but does leak content
func foo96(m []*int) *int { // ERROR "leaking param: m to result ~r1 level=1"
return m[0]
}
// does leak m
func foo97(m [1]*int) *int { // ERROR "leaking param: m to result ~r1 level=0$"
return m[0]
}
// does not leak m
func foo98(m map[int]*int) *int { // ERROR "m does not escape$"
return m[0]
}
// does leak m
func foo99(m *[1]*int) []*int { // ERROR "leaking param: m to result ~r1 level=0$"
return m[:]
}
// does not leak m
func foo100(m []*int) *int { // ERROR "leaking param: m to result ~r1 level=1"
for _, v := range m {
return v
}
return nil
}
// does leak m
func foo101(m [1]*int) *int { // ERROR "leaking param: m to result ~r1 level=0$"
for _, v := range m {
return v
}
return nil
}
// does not leak m
func foo101a(m [1]*int) *int { // ERROR "m does not escape$"
for i := range m { // ERROR "moved to heap: i$"
return &i
}
return nil
}
// does leak x
func foo102(m []*int, x *int) { // ERROR "m does not escape$" "leaking param: x$"
m[0] = x
}
// does not leak x
func foo103(m [1]*int, x *int) { // ERROR "m does not escape$" "x does not escape$"
m[0] = x
}
var y []*int
// does not leak x but does leak content
func foo104(x []*int) { // ERROR "leaking param content: x"
copy(y, x)
}
// does not leak x but does leak content
func foo105(x []*int) { // ERROR "leaking param content: x"
_ = append(y, x...)
}
// does leak x
func foo106(x *int) { // ERROR "leaking param: x$"
_ = append(y, x)
}
func foo107(x *int) map[*int]*int { // ERROR "leaking param: x$"
return map[*int]*int{x: nil} // ERROR "map\[\*int\]\*int literal escapes to heap$"
}
func foo108(x *int) map[*int]*int { // ERROR "leaking param: x$"
return map[*int]*int{nil: x} // ERROR "map\[\*int\]\*int literal escapes to heap$"
}
func foo109(x *int) *int { // ERROR "leaking param: x$"
m := map[*int]*int{x: nil} // ERROR "map\[\*int\]\*int literal does not escape$"
for k, _ := range m {
return k
}
return nil
}
func foo110(x *int) *int { // ERROR "leaking param: x$"
m := map[*int]*int{nil: x} // ERROR "map\[\*int\]\*int literal does not escape$"
return m[nil]
}
func foo111(x *int) *int { // ERROR "leaking param: x to result ~r1 level=0"
m := []*int{x} // ERROR "\[\]\*int literal does not escape$"
return m[0]
}
func foo112(x *int) *int { // ERROR "leaking param: x to result ~r1 level=0$"
m := [1]*int{x}
return m[0]
}
func foo113(x *int) *int { // ERROR "leaking param: x to result ~r1 level=0$"
m := Bar{ii: x}
return m.ii
}
func foo114(x *int) *int { // ERROR "leaking param: x to result ~r1 level=0$"
m := &Bar{ii: x} // ERROR "&Bar literal does not escape$"
return m.ii
}
func foo115(x *int) *int { // ERROR "leaking param: x to result ~r1 level=0$"
return (*int)(unsafe.Pointer(uintptr(unsafe.Pointer(x)) + 1))
}
func foo116(b bool) *int {
if b {
x := 1 // ERROR "moved to heap: x$"
return &x
} else {
y := 1 // ERROR "moved to heap: y$"
return &y
}
return nil
}
func foo117(unknown func(interface{})) { // ERROR "unknown does not escape$"
x := 1 // ERROR "moved to heap: x$"
unknown(&x)
}
func foo118(unknown func(*int)) { // ERROR "unknown does not escape$"
x := 1 // ERROR "moved to heap: x$"
unknown(&x)
}
func external(*int)
func foo119(x *int) { // ERROR "leaking param: x$"
external(x)
}
func foo120() {
// formerly exponential time analysis
L1:
L2:
L3:
L4:
L5:
L6:
L7:
L8:
L9:
L10:
L11:
L12:
L13:
L14:
L15:
L16:
L17:
L18:
L19:
L20:
L21:
L22:
L23:
L24:
L25:
L26:
L27:
L28:
L29:
L30:
L31:
L32:
L33:
L34:
L35:
L36:
L37:
L38:
L39:
L40:
L41:
L42:
L43:
L44:
L45:
L46:
L47:
L48:
L49:
L50:
L51:
L52:
L53:
L54:
L55:
L56:
L57:
L58:
L59:
L60:
L61:
L62:
L63:
L64:
L65:
L66:
L67:
L68:
L69:
L70:
L71:
L72:
L73:
L74:
L75:
L76:
L77:
L78:
L79:
L80:
L81:
L82:
L83:
L84:
L85:
L86:
L87:
L88:
L89:
L90:
L91:
L92:
L93:
L94:
L95:
L96:
L97:
L98:
L99:
L100:
// use the labels to silence compiler errors
goto L1
goto L2
goto L3
goto L4
goto L5
goto L6
goto L7
goto L8
goto L9
goto L10
goto L11
goto L12
goto L13
goto L14
goto L15
goto L16
goto L17
goto L18
goto L19
goto L20
goto L21
goto L22
goto L23
goto L24
goto L25
goto L26
goto L27
goto L28
goto L29
goto L30
goto L31
goto L32
goto L33
goto L34
goto L35
goto L36
goto L37
goto L38
goto L39
goto L40
goto L41
goto L42
goto L43
goto L44
goto L45
goto L46
goto L47
goto L48
goto L49
goto L50
goto L51
goto L52
goto L53
goto L54
goto L55
goto L56
goto L57
goto L58
goto L59
goto L60
goto L61
goto L62
goto L63
goto L64
goto L65
goto L66
goto L67
goto L68
goto L69
goto L70
goto L71
goto L72
goto L73
goto L74
goto L75
goto L76
goto L77
goto L78
goto L79
goto L80
goto L81
goto L82
goto L83
goto L84
goto L85
goto L86
goto L87
goto L88
goto L89
goto L90
goto L91
goto L92
goto L93
goto L94
goto L95
goto L96
goto L97
goto L98
goto L99
goto L100
}
func foo121() {
for i := 0; i < 10; i++ {
defer myprint(nil, i) // ERROR "... argument escapes to heap$" "i escapes to heap$"
go myprint(nil, i) // ERROR "... argument escapes to heap$" "i escapes to heap$"
}
}
// same as foo121 but check across import
func foo121b() {
for i := 0; i < 10; i++ {
defer fmt.Printf("%d", i) // ERROR "... argument escapes to heap$" "i escapes to heap$"
go fmt.Printf("%d", i) // ERROR "... argument escapes to heap$" "i escapes to heap$"
}
}
// a harmless forward jump
func foo122() {
var i *int
goto L1
L1:
i = new(int) // ERROR "new\(int\) does not escape$"
_ = i
}
// a backward jump, increases loopdepth
func foo123() {
var i *int
L1:
i = new(int) // ERROR "new\(int\) escapes to heap$"
goto L1
_ = i
}
func foo124(x **int) { // ERROR "x does not escape$"
var i int // ERROR "moved to heap: i$"
p := &i
func() { // ERROR "func literal does not escape$"
*x = p
}()
}
func foo125(ch chan *int) { // ERROR "ch does not escape$"
var i int // ERROR "moved to heap: i$"
p := &i
func() { // ERROR "func literal does not escape$"
ch <- p
}()
}
func foo126() {
var px *int // loopdepth 0
for {
// loopdepth 1
var i int // ERROR "moved to heap: i$"
func() { // ERROR "func literal does not escape$"
px = &i
}()
}
_ = px
}
var px *int
func foo127() {
var i int // ERROR "moved to heap: i$"
p := &i
q := p
px = q
}
func foo128() {
var i int
p := &i
q := p
_ = q
}
func foo129() {
var i int // ERROR "moved to heap: i$"
p := &i
func() { // ERROR "func literal does not escape$"
q := p
func() { // ERROR "func literal does not escape$"
r := q
px = r
}()
}()
}
func foo130() {
for {
var i int // ERROR "moved to heap: i$"
func() { // ERROR "func literal does not escape$"
px = &i
}()
}
}
func foo131() {
var i int // ERROR "moved to heap: i$"
func() { // ERROR "func literal does not escape$"
px = &i
}()
}
func foo132() {
var i int // ERROR "moved to heap: i$"
go func() { // ERROR "func literal escapes to heap$"
px = &i
}()
}
func foo133() {
var i int // ERROR "moved to heap: i$"
defer func() { // ERROR "func literal does not escape$"
px = &i
}()
}
func foo134() {
var i int
p := &i
func() { // ERROR "func literal does not escape$"
q := p
func() { // ERROR "func literal does not escape$"
r := q
_ = r
}()
}()
}
func foo135() {
var i int // ERROR "moved to heap: i$"
p := &i
go func() { // ERROR "func literal escapes to heap$"
q := p
func() { // ERROR "func literal does not escape$"
r := q
_ = r
}()
}()
}
func foo136() {
var i int // ERROR "moved to heap: i$"
p := &i
go func() { // ERROR "func literal escapes to heap$"
q := p
func() { // ERROR "func literal does not escape$"
r := q
px = r
}()
}()
}
func foo137() {
var i int // ERROR "moved to heap: i$"
p := &i
func() { // ERROR "func literal does not escape$"
q := p
go func() { // ERROR "func literal escapes to heap$"
r := q
_ = r
}()
}()
}
func foo138() *byte {
type T struct {
x [1]byte
}
t := new(T) // ERROR "new\(T\) escapes to heap$"
return &t.x[0]
}
func foo139() *byte {
type T struct {
x struct {
y byte
}
}
t := new(T) // ERROR "new\(T\) escapes to heap$"
return &t.x.y
}
// issue 4751
func foo140() interface{} {
type T struct {
X string
}
type U struct {
X string
T *T
}
t := &T{} // ERROR "&T literal escapes to heap$"
return U{ // ERROR "U literal escapes to heap$"
X: t.X,
T: t,
}
}
//go:noescape
func F1([]byte)
func F2([]byte)
//go:noescape
func F3(x []byte) // ERROR "x does not escape$"
func F4(x []byte) // ERROR "leaking param: x$"
func G() {
var buf1 [10]byte
F1(buf1[:])
var buf2 [10]byte // ERROR "moved to heap: buf2$"
F2(buf2[:])
var buf3 [10]byte
F3(buf3[:])
var buf4 [10]byte // ERROR "moved to heap: buf4$"
F4(buf4[:])
}
type Tm struct {
x int
}
func (t *Tm) M() { // ERROR "t does not escape$"
}
func foo141() {
var f func()
t := new(Tm) // ERROR "new\(Tm\) does not escape$"
f = t.M // ERROR "t.M does not escape$"
_ = f
}
var gf func()
func foo142() {
t := new(Tm) // ERROR "new\(Tm\) escapes to heap$"
gf = t.M // ERROR "t.M escapes to heap$"
}
// issue 3888.
func foo143() {
for i := 0; i < 1000; i++ {
func() { // ERROR "func literal does not escape$"
for i := 0; i < 1; i++ {
var t Tm
t.M()
}
}()
}
}
// issue 5773
// Check that annotations take effect regardless of whether they
// are before or after the use in the source code.
//go:noescape
func foo144a(*int)
func foo144() {
var x int
foo144a(&x)
var y int
foo144b(&y)
}
//go:noescape
func foo144b(*int)
// issue 7313: for loop init should not be treated as "in loop"
type List struct {
Next *List
}
func foo145(l List) { // ERROR "l does not escape$"
var p *List
for p = &l; p.Next != nil; p = p.Next {
}
}
func foo146(l List) { // ERROR "l does not escape$"
var p *List
p = &l
for ; p.Next != nil; p = p.Next {
}
}
func foo147(l List) { // ERROR "l does not escape$"
var p *List
p = &l
for p.Next != nil {
p = p.Next
}
}
func foo148(l List) { // ERROR "l does not escape$"
for p := &l; p.Next != nil; p = p.Next {
}
}
// related: address of variable should have depth of variable, not of loop
func foo149(l List) { // ERROR "l does not escape$"
var p *List
for {
for p = &l; p.Next != nil; p = p.Next {
}
}
}
// issue 7934: missed ... if element type had no pointers
var save150 []byte
func foo150(x ...byte) { // ERROR "leaking param: x$"
save150 = x
}
func bar150() {
foo150(1, 2, 3) // ERROR "... argument escapes to heap$"
}
// issue 7931: bad handling of slice of array
var save151 *int
func foo151(x *int) { // ERROR "leaking param: x$"
save151 = x
}
func bar151() {
var a [64]int // ERROR "moved to heap: a$"
a[4] = 101
foo151(&(&a)[4:8][0])
}
func bar151b() {
var a [10]int // ERROR "moved to heap: a$"
b := a[:]
foo151(&b[4:8][0])
}
func bar151c() {
var a [64]int // ERROR "moved to heap: a$"
a[4] = 101
foo151(&(&a)[4:8:8][0])
}
func bar151d() {
var a [10]int // ERROR "moved to heap: a$"
b := a[:]
foo151(&b[4:8:8][0])
}
// issue 8120
type U struct {
s *string
}
func (u *U) String() *string { // ERROR "leaking param: u to result ~r0 level=1$"
return u.s
}
type V struct {
s *string
}
func NewV(u U) *V { // ERROR "leaking param: u$"
return &V{u.String()} // ERROR "&V literal escapes to heap$"
}
func foo152() {
a := "a" // ERROR "moved to heap: a$"
u := U{&a}
v := NewV(u)
println(v)
}
// issue 8176 - &x in type switch body not marked as escaping
func foo153(v interface{}) *int { // ERROR "v does not escape"
switch x := v.(type) {
case int: // ERROR "moved to heap: x$"
return &x
}
panic(0)
}
// issue 8185 - &result escaping into result
func f() (x int, y *int) { // ERROR "moved to heap: x$"
y = &x
return
}
func g() (x interface{}) { // ERROR "moved to heap: x$"
x = &x
return
}
var sink interface{}
type Lit struct {
p *int
}
func ptrlitNoescape() {
// Both literal and element do not escape.
i := 0
x := &Lit{&i} // ERROR "&Lit literal does not escape$"
_ = x
}
func ptrlitNoEscape2() {
// Literal does not escape, but element does.
i := 0 // ERROR "moved to heap: i$"
x := &Lit{&i} // ERROR "&Lit literal does not escape$"
sink = *x
}
func ptrlitEscape() {
// Both literal and element escape.
i := 0 // ERROR "moved to heap: i$"
x := &Lit{&i} // ERROR "&Lit literal escapes to heap$"
sink = x
}
// self-assignments
type Buffer struct {
arr [64]byte
arrPtr *[64]byte
buf1 []byte
buf2 []byte
str1 string
str2 string
}
func (b *Buffer) foo() { // ERROR "b does not escape$"
b.buf1 = b.buf1[1:2] // ERROR "\(\*Buffer\).foo ignoring self-assignment in b.buf1 = b.buf1\[1:2\]$"
b.buf1 = b.buf1[1:2:3] // ERROR "\(\*Buffer\).foo ignoring self-assignment in b.buf1 = b.buf1\[1:2:3\]$"
b.buf1 = b.buf2[1:2] // ERROR "\(\*Buffer\).foo ignoring self-assignment in b.buf1 = b.buf2\[1:2\]$"
b.buf1 = b.buf2[1:2:3] // ERROR "\(\*Buffer\).foo ignoring self-assignment in b.buf1 = b.buf2\[1:2:3\]$"
}
func (b *Buffer) bar() { // ERROR "leaking param: b$"
b.buf1 = b.arr[1:2]
}
func (b *Buffer) arrayPtr() { // ERROR "b does not escape"
b.buf1 = b.arrPtr[1:2] // ERROR "\(\*Buffer\).arrayPtr ignoring self-assignment in b.buf1 = b.arrPtr\[1:2\]$"
b.buf1 = b.arrPtr[1:2:3] // ERROR "\(\*Buffer\).arrayPtr ignoring self-assignment in b.buf1 = b.arrPtr\[1:2:3\]$"
}
func (b *Buffer) baz() { // ERROR "b does not escape$"
b.str1 = b.str1[1:2] // ERROR "\(\*Buffer\).baz ignoring self-assignment in b.str1 = b.str1\[1:2\]$"
b.str1 = b.str2[1:2] // ERROR "\(\*Buffer\).baz ignoring self-assignment in b.str1 = b.str2\[1:2\]$"
}
func (b *Buffer) bat() { // ERROR "leaking param content: b$"
o := new(Buffer) // ERROR "new\(Buffer\) escapes to heap$"
o.buf1 = b.buf1[1:2]
sink = o
}
func quux(sp *string, bp *[]byte) { // ERROR "bp does not escape$" "sp does not escape$"
*sp = (*sp)[1:2] // ERROR "quux ignoring self-assignment in \*sp = \(\*sp\)\[1:2\]$"
*bp = (*bp)[1:2] // ERROR "quux ignoring self-assignment in \*bp = \(\*bp\)\[1:2\]$"
}
type StructWithString struct {
p *int
s string
}
// This is escape analysis false negative.
// We assign the pointer to x.p but leak x.s. Escape analysis coarsens flows
// to just x, and thus &i looks escaping.
func fieldFlowTracking() {
var x StructWithString
i := 0 // ERROR "moved to heap: i$"
x.p = &i
sink = x.s // ERROR "x.s escapes to heap$"
}
// String operations.
func slicebytetostring0() {
b := make([]byte, 20) // ERROR "make\(\[\]byte, 20\) does not escape$"
s := string(b) // ERROR "string\(b\) does not escape$"
_ = s
}
func slicebytetostring1() {
b := make([]byte, 20) // ERROR "make\(\[\]byte, 20\) does not escape$"
s := string(b) // ERROR "string\(b\) does not escape$"
s1 := s[0:1]
_ = s1
}
func slicebytetostring2() {
b := make([]byte, 20) // ERROR "make\(\[\]byte, 20\) does not escape$"
s := string(b) // ERROR "string\(b\) escapes to heap$"
s1 := s[0:1] // ERROR "moved to heap: s1$"
sink = &s1
}
func slicebytetostring3() {
b := make([]byte, 20) // ERROR "make\(\[\]byte, 20\) does not escape$"
s := string(b) // ERROR "string\(b\) escapes to heap$"
s1 := s[0:1]
sink = s1 // ERROR "s1 escapes to heap$"
}
func addstr0() {
s0 := "a"
s1 := "b"
s := s0 + s1 // ERROR "s0 \+ s1 does not escape$"
_ = s
}
func addstr1() {
s0 := "a"
s1 := "b"
s := "c"
s += s0 + s1 // ERROR "s0 \+ s1 does not escape$"
_ = s
}
func addstr2() {
b := make([]byte, 20) // ERROR "make\(\[\]byte, 20\) does not escape$"
s0 := "a"
s := string(b) + s0 // ERROR "string\(b\) \+ s0 does not escape$" "string\(b\) does not escape$"
_ = s
}
func addstr3() {
s0 := "a"
s1 := "b"
s := s0 + s1 // ERROR "s0 \+ s1 escapes to heap$"
s2 := s[0:1]
sink = s2 // ERROR "s2 escapes to heap$"
}
func intstring0() bool {
// string does not escape
x := '0'
s := string(x) // ERROR "string\(x\) does not escape$"
return s == "0"
}
func intstring1() string {
// string does not escape, but the buffer does
x := '0'
s := string(x) // ERROR "string\(x\) escapes to heap$"
return s
}
func intstring2() {
// string escapes to heap
x := '0'
s := string(x) // ERROR "moved to heap: s$" "string\(x\) escapes to heap$"
sink = &s
}
func stringtoslicebyte0() {
s := "foo"
x := []byte(s) // ERROR "\(\[\]byte\)\(s\) does not escape$"
_ = x
}
func stringtoslicebyte1() []byte {
s := "foo"
return []byte(s) // ERROR "\(\[\]byte\)\(s\) escapes to heap$"
}
func stringtoslicebyte2() {
s := "foo"
sink = []byte(s) // ERROR "\(\[\]byte\)\(s\) escapes to heap$"
}
func stringtoslicerune0() {
s := "foo"
x := []rune(s) // ERROR "\(\[\]rune\)\(s\) does not escape$"
_ = x
}
func stringtoslicerune1() []rune {
s := "foo"
return []rune(s) // ERROR "\(\[\]rune\)\(s\) escapes to heap$"
}
func stringtoslicerune2() {
s := "foo"
sink = []rune(s) // ERROR "\(\[\]rune\)\(s\) escapes to heap$"
}
func slicerunetostring0() {
r := []rune{1, 2, 3} // ERROR "\[\]rune literal does not escape$"
s := string(r) // ERROR "string\(r\) does not escape$"
_ = s
}
func slicerunetostring1() string {
r := []rune{1, 2, 3} // ERROR "\[\]rune literal does not escape$"
return string(r) // ERROR "string\(r\) escapes to heap$"
}
func slicerunetostring2() {
r := []rune{1, 2, 3} // ERROR "\[\]rune literal does not escape$"
sink = string(r) // ERROR "string\(r\) escapes to heap$"
}
func makemap0() {
m := make(map[int]int) // ERROR "make\(map\[int\]int\) does not escape$"
m[0] = 0
m[1]++
delete(m, 1)
sink = m[0] // ERROR "m\[0\] escapes to heap$"
}
func makemap1() map[int]int {
return make(map[int]int) // ERROR "make\(map\[int\]int\) escapes to heap$"
}
func makemap2() {
m := make(map[int]int) // ERROR "make\(map\[int\]int\) escapes to heap$"
sink = m
}
func nonescapingEface(m map[interface{}]bool) bool { // ERROR "m does not escape$"
return m["foo"] // ERROR ".foo. does not escape$"
}
func nonescapingIface(m map[M]bool) bool { // ERROR "m does not escape$"
return m[MV(0)] // ERROR "MV\(0\) does not escape$"
}
func issue10353() {
x := new(int) // ERROR "new\(int\) escapes to heap$"
issue10353a(x)()
}
func issue10353a(x *int) func() { // ERROR "leaking param: x$"
return func() { // ERROR "func literal escapes to heap$"
println(*x)
}
}
func issue10353b() {
var f func()
for {
x := new(int) // ERROR "new\(int\) escapes to heap$"
f = func() { // ERROR "func literal escapes to heap$"
println(*x)
}
}
_ = f
}
func issue11387(x int) func() int {
f := func() int { return x } // ERROR "func literal escapes to heap"
slice1 := []func() int{f} // ERROR "\[\].* does not escape"
slice2 := make([]func() int, 1) // ERROR "make\(.*\) does not escape"
copy(slice2, slice1)
return slice2[0]
}
func issue12397(x, y int) { // ERROR "moved to heap: y$"
// x does not escape below, because all relevant code is dead.
if false {
gxx = &x
} else {
gxx = &y
}
if true {
gxx = &y
} else {
gxx = &x
}
}
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