mirror of
https://github.com/golang/go.git
synced 2025-05-05 15:43:04 +00:00
ba3f568988
This change improves escape analysis by attempting to deduce static values for the len and cap parameters, allowing allocations to be made on the stack. Change-Id: I1161019aed9f60cf2c2fe4d405da94ad415231ac GitHub-Last-Rev: d78c1b4ca55fa53282e665009f689d0b013f1434 GitHub-Pull-Request: golang/go#71693 Reviewed-on: https://go-review.googlesource.com/c/go/+/649035 LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Michael Knyszek <mknyszek@google.com> Reviewed-by: Keith Randall <khr@golang.org> Auto-Submit: Keith Randall <khr@golang.org> Reviewed-by: Keith Randall <khr@google.com>
130 lines
3.6 KiB
Go
130 lines
3.6 KiB
Go
// 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 arrays and some large things
|
|
|
|
package foo
|
|
|
|
var Ssink *string
|
|
|
|
type U [2]*string
|
|
|
|
func bar(a, b *string) U { // ERROR "leaking param: a to result ~r0 level=0$" "leaking param: b to result ~r0 level=0$"
|
|
return U{a, b}
|
|
}
|
|
|
|
func foo(x U) U { // ERROR "leaking param: x to result ~r0 level=0$"
|
|
return U{x[1], x[0]}
|
|
}
|
|
|
|
func bff(a, b *string) U { // ERROR "leaking param: a to result ~r0 level=0$" "leaking param: b to result ~r0 level=0$"
|
|
return foo(foo(bar(a, b)))
|
|
}
|
|
|
|
func tbff1() *string {
|
|
a := "cat"
|
|
b := "dog" // ERROR "moved to heap: b$"
|
|
u := bff(&a, &b)
|
|
_ = u[0]
|
|
return &b
|
|
}
|
|
|
|
// BAD: need fine-grained analysis to track u[0] and u[1] differently.
|
|
func tbff2() *string {
|
|
a := "cat" // ERROR "moved to heap: a$"
|
|
b := "dog" // ERROR "moved to heap: b$"
|
|
u := bff(&a, &b)
|
|
_ = u[0]
|
|
return u[1]
|
|
}
|
|
|
|
func car(x U) *string { // ERROR "leaking param: x to result ~r0 level=0$"
|
|
return x[0]
|
|
}
|
|
|
|
// BAD: need fine-grained analysis to track x[0] and x[1] differently.
|
|
func fun(x U, y *string) *string { // ERROR "leaking param: x to result ~r0 level=0$" "leaking param: y to result ~r0 level=0$"
|
|
x[0] = y
|
|
return x[1]
|
|
}
|
|
|
|
func fup(x *U, y *string) *string { // ERROR "leaking param: x to result ~r0 level=1$" "leaking param: y$"
|
|
x[0] = y // leaking y to heap is intended
|
|
return x[1]
|
|
}
|
|
|
|
func fum(x *U, y **string) *string { // ERROR "leaking param: x to result ~r0 level=1$" "leaking param content: y$"
|
|
x[0] = *y
|
|
return x[1]
|
|
}
|
|
|
|
func fuo(x *U, y *U) *string { // ERROR "leaking param: x to result ~r0 level=1$" "leaking param content: y$"
|
|
x[0] = y[0]
|
|
return x[1]
|
|
}
|
|
|
|
// These two tests verify that:
|
|
// small array literals are stack allocated;
|
|
// pointers stored in small array literals do not escape;
|
|
// large array literals are heap allocated;
|
|
// pointers stored in large array literals escape.
|
|
func hugeLeaks1(x **string, y **string) { // ERROR "leaking param content: x" "y does not escape"
|
|
a := [10]*string{*y}
|
|
_ = a
|
|
// 4 x 4,000,000 exceeds MaxStackVarSize, therefore it must be heap allocated if pointers are 4 bytes or larger.
|
|
b := [4000000]*string{*x} // ERROR "moved to heap: b"
|
|
_ = b
|
|
}
|
|
|
|
func hugeLeaks2(x *string, y *string) { // ERROR "leaking param: x" "y does not escape"
|
|
a := [10]*string{y}
|
|
_ = a
|
|
// 4 x 4,000,000 exceeds MaxStackVarSize, therefore it must be heap allocated if pointers are 4 bytes or larger.
|
|
b := [4000000]*string{x} // ERROR "moved to heap: b"
|
|
_ = b
|
|
}
|
|
|
|
// BAD: x need not leak.
|
|
func doesNew1(x *string, y *string) { // ERROR "leaking param: x" "leaking param: y"
|
|
a := new([10]*string) // ERROR "new\(\[10\]\*string\) does not escape"
|
|
a[0] = x
|
|
b := new([65537]*string) // ERROR "new\(\[65537\]\*string\) escapes to heap"
|
|
b[0] = y
|
|
}
|
|
|
|
type a10 struct {
|
|
s *string
|
|
i [10]int32
|
|
}
|
|
|
|
type a65537 struct {
|
|
s *string
|
|
i [65537]int32
|
|
}
|
|
|
|
// BAD: x need not leak.
|
|
func doesNew2(x *string, y *string) { // ERROR "leaking param: x" "leaking param: y"
|
|
a := new(a10) // ERROR "new\(a10\) does not escape"
|
|
a.s = x
|
|
b := new(a65537) // ERROR "new\(a65537\) escapes to heap"
|
|
b.s = y
|
|
}
|
|
|
|
// BAD: x need not leak.
|
|
func doesMakeSlice(x *string, y *string) { // ERROR "leaking param: x" "leaking param: y"
|
|
a := make([]*string, 10) // ERROR "make\(\[\]\*string, 10\) does not escape"
|
|
a[0] = x
|
|
b := make([]*string, 65537) // ERROR "make\(\[\]\*string, 65537\) escapes to heap"
|
|
b[0] = y
|
|
}
|
|
|
|
func nonconstArray() {
|
|
n := 32
|
|
s1 := make([]int, n) // ERROR "make\(\[\]int, 32\) does not escape"
|
|
s2 := make([]int, 0, n) // ERROR "make\(\[\]int, 0, 32\) does not escape"
|
|
_, _ = s1, s2
|
|
}
|