go/test/escape_closure.go

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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 closure arguments.
package escape
var sink interface{}
func ClosureCallArgs0() {
x := 0 // ERROR "moved to heap: x"
func(p *int) { // ERROR "p does not escape" "func literal does not escape"
*p = 1
// BAD: x should not escape to heap here
}(&x) // ERROR "&x escapes to heap"
}
func ClosureCallArgs1() {
x := 0 // ERROR "moved to heap: x"
for {
func(p *int) { // ERROR "p does not escape" "func literal does not escape"
*p = 1
// BAD: x should not escape to heap here
}(&x) // ERROR "&x escapes to heap"
}
}
func ClosureCallArgs2() {
for {
// BAD: x should not escape here
x := 0 // ERROR "moved to heap: x"
func(p *int) { // ERROR "p does not escape" "func literal does not escape"
*p = 1
}(&x) // ERROR "&x escapes to heap"
}
}
func ClosureCallArgs3() {
x := 0 // ERROR "moved to heap: x"
func(p *int) { // ERROR "leaking param: p" "func literal does not escape"
sink = p // ERROR "p escapes to heap"
}(&x) // ERROR "&x escapes to heap"
}
func ClosureCallArgs4() {
// BAD: x should not leak here
x := 0 // ERROR "moved to heap: x"
_ = func(p *int) *int { // ERROR "leaking param: p to result ~r1" "func literal does not escape"
return p
}(&x) // ERROR "&x escapes to heap"
}
func ClosureCallArgs5() {
x := 0 // ERROR "moved to heap: x"
sink = func(p *int) *int { // ERROR "leaking param: p to result ~r1" "func literal does not escape" "\(func literal\)\(&x\) escapes to heap"
return p
}(&x) // ERROR "&x escapes to heap"
}
func ClosureCallArgs6() {
x := 0 // ERROR "moved to heap: x"
func(p *int) { // ERROR "moved to heap: p" "func literal does not escape"
sink = &p // ERROR "&p escapes to heap"
}(&x) // ERROR "&x escapes to heap"
}
func ClosureCallArgs7() {
var pp *int
for {
x := 0 // ERROR "moved to heap: x"
func(p *int) { // ERROR "leaking param: p" "func literal does not escape"
pp = p
}(&x) // ERROR "&x escapes to heap"
}
_ = pp
}
func ClosureCallArgs8() {
x := 0 // ERROR "moved to heap: x"
defer func(p *int) { // ERROR "p does not escape" "func literal does not escape"
*p = 1
// BAD: x should not escape to heap here
}(&x) // ERROR "&x escapes to heap"
}
func ClosureCallArgs9() {
// BAD: x should not leak
x := 0 // ERROR "moved to heap: x"
for {
defer func(p *int) { // ERROR "func literal escapes to heap" "p does not escape"
*p = 1
}(&x) // ERROR "&x escapes to heap"
}
}
func ClosureCallArgs10() {
for {
x := 0 // ERROR "moved to heap: x"
defer func(p *int) { // ERROR "func literal escapes to heap" "p does not escape"
*p = 1
}(&x) // ERROR "&x escapes to heap"
}
}
func ClosureCallArgs11() {
x := 0 // ERROR "moved to heap: x"
defer func(p *int) { // ERROR "leaking param: p" "func literal does not escape"
sink = p // ERROR "p escapes to heap"
}(&x) // ERROR "&x escapes to heap"
}
func ClosureCallArgs12() {
// BAD: x should not leak
x := 0 // ERROR "moved to heap: x"
defer func(p *int) *int { // ERROR "leaking param: p to result ~r1" "func literal does not escape"
return p
}(&x) // ERROR "&x escapes to heap"
}
func ClosureCallArgs13() {
x := 0 // ERROR "moved to heap: x"
defer func(p *int) { // ERROR "moved to heap: p" "func literal does not escape"
sink = &p // ERROR "&p escapes to heap"
}(&x) // ERROR "&x escapes to heap"
}
func ClosureCallArgs14() {
x := 0 // ERROR "moved to heap: x"
// BAD: &x should not escape here
p := &x // ERROR "moved to heap: p" "&x escapes to heap"
cmd/internal/gc: improve flow of input params to output params This includes the following information in the per-function summary: outK = paramJ encoded in outK bits for paramJ outK = *paramJ encoded in outK bits for paramJ heap = paramJ EscHeap heap = *paramJ EscContentEscapes Note that (currently) if the address of a parameter is taken and returned, necessarily a heap allocation occurred to contain that reference, and the heap can never refer to stack, therefore the parameter and everything downstream from it escapes to the heap. The per-function summary information now has a tuneable number of bits (2 is probably noticeably better than 1, 3 is likely overkill, but it is now easy to check and the -m debugging output includes information that allows you to figure out if more would be better.) A new test was added to check pointer flow through struct-typed and *struct-typed parameters and returns; some of these are sensitive to the number of summary bits, and ought to yield better results with a more competent escape analysis algorithm. Another new test checks (some) correctness with array parameters, results, and operations. The old analysis inferred a piece of plan9 runtime was non-escaping by counteracting overconservative analysis with buggy analysis; with the bug fixed, the result was too conservative (and it's not easy to fix in this framework) so the source code was tweaked to get the desired result. A test was added against the discovered bug. The escape analysis was further improved splitting the "level" into 3 parts, one tracking the conventional "level" and the other two computing the highest-level-suffix-from-copy, which is used to generally model the cancelling effect of indirection applied to address-of. With the improved escape analysis enabled, it was necessary to modify one of the runtime tests because it now attempts to allocate too much on the (small, fixed-size) G0 (system) stack and this failed the test. Compiling src/std after touching src/runtime/*.go with -m logging turned on shows 420 fewer heap allocation sites (10538 vs 10968). Profiling allocations in src/html/template with for i in {1..5} ; do go tool 6g -memprofile=mastx.${i}.prof -memprofilerate=1 *.go; go tool pprof -alloc_objects -text mastx.${i}.prof ; done showed a 15% reduction in allocations performed by the compiler. Update #3753 Update #4720 Fixes #10466 Change-Id: I0fd97d5f5ac527b45f49e2218d158a6e89951432 Reviewed-on: https://go-review.googlesource.com/8202 Run-TryBot: David Chase <drchase@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Russ Cox <rsc@golang.org>
2015-03-26 20:36:15 +00:00
_ = func(p **int) *int { // ERROR "leaking param: p to result ~r1 level=1" "func literal does not escape"
return *p
// BAD: p should not escape here
}(&p) // ERROR "&p escapes to heap"
}
func ClosureCallArgs15() {
x := 0 // ERROR "moved to heap: x"
p := &x // ERROR "moved to heap: p" "&x escapes to heap"
sink = func(p **int) *int { // ERROR "leaking param: p to result ~r1 level=1" "func literal does not escape" "\(func literal\)\(&p\) escapes to heap"
return *p
// BAD: p should not escape here
}(&p) // ERROR "&p escapes to heap"
}
func ClosureLeak1(s string) string { // ERROR "ClosureLeak1 s does not escape"
t := s + "YYYY" // ERROR "escapes to heap"
return ClosureLeak1a(t) // ERROR "ClosureLeak1 ... argument does not escape"
}
// See #14409 -- returning part of captured var leaks it.
func ClosureLeak1a(a ...string) string { // ERROR "leaking param: a to result ~r1 level=1"
return func() string { // ERROR "ClosureLeak1a func literal does not escape"
return a[0]
}()
}
func ClosureLeak2(s string) string { // ERROR "ClosureLeak2 s does not escape"
t := s + "YYYY" // ERROR "escapes to heap"
c := ClosureLeak2a(t) // ERROR "ClosureLeak2 ... argument does not escape"
return c
}
func ClosureLeak2a(a ...string) string { // ERROR "leaking param: a to result ~r1 level=1"
return ClosureLeak2b(func() string { // ERROR "ClosureLeak2a func literal does not escape"
return a[0]
})
}
func ClosureLeak2b(f func() string) string { // ERROR "leaking param: f to result ~r1 level=1"
return f()
}