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This CL extends escape analysis in two ways. First, we already optimize directly called closures. For example, given: var x int // already stack allocated today p := func() *int { return &x }() we don't need to move x to the heap, because we can statically track where &x flows. This CL extends the same idea to work for indirectly called closures too, as long as we know everywhere that they're called. For example: var x int // stack allocated after this CL f := func() *int { return &x } p := f() This will allow a subsequent CL to move the generation of go/defer wrappers earlier. Second, this CL adds tracking to detect when pointer values flow to the pointee operand of an indirect assignment statement (i.e., flows to p in "*p = x") or to builtins that modify memory (append, copy, clear). This isn't utilized in the current CL, but a subsequent CL will make use of it to better optimize string->[]byte conversions. Updates #2205. Change-Id: I610f9c531e135129c947684833e288ce64406f35 Reviewed-on: https://go-review.googlesource.com/c/go/+/520259 Run-TryBot: Matthew Dempsky <mdempsky@google.com> TryBot-Result: Gopher Robot <gobot@golang.org> Auto-Submit: Matthew Dempsky <mdempsky@google.com> Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com> Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
194 lines
4.6 KiB
Go
194 lines
4.6 KiB
Go
// errorcheck -0 -m -l
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// Copyright 2015 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Test escape analysis for closure arguments.
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package escape
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var sink interface{}
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func ClosureCallArgs0() {
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x := 0
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func(p *int) { // ERROR "p does not escape" "func literal does not escape"
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*p = 1
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}(&x)
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}
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func ClosureCallArgs1() {
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x := 0
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for {
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func(p *int) { // ERROR "p does not escape" "func literal does not escape"
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*p = 1
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}(&x)
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}
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}
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func ClosureCallArgs2() {
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for {
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x := 0
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func(p *int) { // ERROR "p does not escape" "func literal does not escape"
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*p = 1
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}(&x)
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}
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}
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func ClosureCallArgs3() {
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x := 0 // ERROR "moved to heap: x"
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func(p *int) { // ERROR "leaking param: p" "func literal does not escape"
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sink = p
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}(&x)
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}
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func ClosureCallArgs4() {
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x := 0
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_ = func(p *int) *int { // ERROR "leaking param: p to result ~r0" "func literal does not escape"
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return p
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}(&x)
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}
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func ClosureCallArgs5() {
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x := 0 // ERROR "moved to heap: x"
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// TODO(mdempsky): We get "leaking param: p" here because the new escape analysis pass
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// can tell that p flows directly to sink, but it's a little weird. Re-evaluate.
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sink = func(p *int) *int { // ERROR "leaking param: p" "func literal does not escape"
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return p
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}(&x)
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}
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func ClosureCallArgs6() {
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x := 0 // ERROR "moved to heap: x"
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func(p *int) { // ERROR "moved to heap: p" "func literal does not escape"
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sink = &p
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}(&x)
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}
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func ClosureCallArgs7() {
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var pp *int
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for {
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x := 0 // ERROR "moved to heap: x"
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func(p *int) { // ERROR "leaking param: p" "func literal does not escape"
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pp = p
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}(&x)
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}
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_ = pp
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}
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func ClosureCallArgs8() {
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x := 0
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defer func(p *int) { // ERROR "p does not escape" "func literal does not escape"
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*p = 1
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}(&x)
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}
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func ClosureCallArgs9() {
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// BAD: x should not leak
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x := 0 // ERROR "moved to heap: x"
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for {
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defer func(p *int) { // ERROR "func literal escapes to heap" "p does not escape"
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*p = 1
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}(&x)
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}
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}
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func ClosureCallArgs10() {
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for {
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x := 0 // ERROR "moved to heap: x"
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defer func(p *int) { // ERROR "func literal escapes to heap" "p does not escape"
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*p = 1
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}(&x)
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}
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}
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func ClosureCallArgs11() {
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x := 0 // ERROR "moved to heap: x"
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defer func(p *int) { // ERROR "leaking param: p" "func literal does not escape"
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sink = p
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}(&x)
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}
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func ClosureCallArgs12() {
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x := 0
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defer func(p *int) *int { // ERROR "leaking param: p to result ~r0" "func literal does not escape"
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return p
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}(&x)
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}
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func ClosureCallArgs13() {
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x := 0 // ERROR "moved to heap: x"
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defer func(p *int) { // ERROR "moved to heap: p" "func literal does not escape"
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sink = &p
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}(&x)
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}
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func ClosureCallArgs14() {
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x := 0
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p := &x
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_ = func(p **int) *int { // ERROR "leaking param: p to result ~r0 level=1" "func literal does not escape"
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return *p
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}(&p)
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}
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func ClosureCallArgs15() {
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x := 0 // ERROR "moved to heap: x"
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p := &x
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sink = func(p **int) *int { // ERROR "leaking param content: p" "func literal does not escape"
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return *p
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}(&p)
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}
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func ClosureLeak1(s string) string { // ERROR "s does not escape"
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t := s + "YYYY" // ERROR "escapes to heap"
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return ClosureLeak1a(t) // ERROR "... argument does not escape"
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}
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// See #14409 -- returning part of captured var leaks it.
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func ClosureLeak1a(a ...string) string { // ERROR "leaking param: a to result ~r0 level=1$"
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return func() string { // ERROR "func literal does not escape"
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return a[0]
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}()
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}
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func ClosureLeak2(s string) string { // ERROR "s does not escape"
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t := s + "YYYY" // ERROR "escapes to heap"
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c := ClosureLeak2a(t) // ERROR "... argument does not escape"
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return c
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}
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func ClosureLeak2a(a ...string) string { // ERROR "leaking param content: a"
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return ClosureLeak2b(func() string { // ERROR "func literal does not escape"
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return a[0]
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})
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}
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func ClosureLeak2b(f func() string) string { // ERROR "f does not escape"
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return f()
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}
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func ClosureIndirect() {
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f := func(p *int) {} // ERROR "p does not escape" "func literal does not escape"
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f(new(int)) // ERROR "new\(int\) does not escape"
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g := f
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g(new(int)) // ERROR "new\(int\) does not escape"
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h := nopFunc
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h(new(int)) // ERROR "new\(int\) does not escape"
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}
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func nopFunc(p *int) {} // ERROR "p does not escape"
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func ClosureIndirect2() {
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f := func(p *int) *int { return p } // ERROR "leaking param: p to result ~r0 level=0" "func literal does not escape"
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f(new(int)) // ERROR "new\(int\) does not escape"
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g := f
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g(new(int)) // ERROR "new\(int\) does not escape"
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h := nopFunc2
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h(new(int)) // ERROR "new\(int\) does not escape"
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}
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func nopFunc2(p *int) *int { return p } // ERROR "leaking param: p to result ~r0 level=0"
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