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e99e9a6e01
The compiler renames anonymous and blank result parameters to ~rN or ~bN, but the current semantics for computing N are rather annoying and difficult to reproduce cleanly. They also lead to difficult to read escape analysis results in tests. This CL changes N to always be calculated as the parameter's index within the function's result parameter tuple. E.g., if a function has a single result, it will now always be named "~r0". The normative change to this CL is fairly simple, but it requires updating a lot of test expectations. Change-Id: I58a3c94de00cb822cb94efe52d115531193c993c Reviewed-on: https://go-review.googlesource.com/c/go/+/323010 Trust: Matthew Dempsky <mdempsky@google.com> Trust: Dan Scales <danscales@google.com> Run-TryBot: Matthew Dempsky <mdempsky@google.com> TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Dan Scales <danscales@google.com>
130 lines
3.6 KiB
Go
130 lines
3.6 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 arrays and some large things
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package foo
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var Ssink *string
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type U [2]*string
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func bar(a, b *string) U { // ERROR "leaking param: a to result ~r0 level=0$" "leaking param: b to result ~r0 level=0$"
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return U{a, b}
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}
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func foo(x U) U { // ERROR "leaking param: x to result ~r0 level=0$"
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return U{x[1], x[0]}
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}
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func bff(a, b *string) U { // ERROR "leaking param: a to result ~r0 level=0$" "leaking param: b to result ~r0 level=0$"
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return foo(foo(bar(a, b)))
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}
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func tbff1() *string {
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a := "cat"
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b := "dog" // ERROR "moved to heap: b$"
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u := bff(&a, &b)
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_ = u[0]
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return &b
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}
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// BAD: need fine-grained analysis to track u[0] and u[1] differently.
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func tbff2() *string {
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a := "cat" // ERROR "moved to heap: a$"
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b := "dog" // ERROR "moved to heap: b$"
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u := bff(&a, &b)
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_ = u[0]
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return u[1]
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}
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func car(x U) *string { // ERROR "leaking param: x to result ~r0 level=0$"
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return x[0]
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}
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// BAD: need fine-grained analysis to track x[0] and x[1] differently.
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func fun(x U, y *string) *string { // ERROR "leaking param: x to result ~r0 level=0$" "leaking param: y to result ~r0 level=0$"
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x[0] = y
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return x[1]
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}
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func fup(x *U, y *string) *string { // ERROR "leaking param: x to result ~r0 level=1$" "leaking param: y$"
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x[0] = y // leaking y to heap is intended
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return x[1]
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}
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func fum(x *U, y **string) *string { // ERROR "leaking param: x to result ~r0 level=1$" "leaking param content: y$"
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x[0] = *y
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return x[1]
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}
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func fuo(x *U, y *U) *string { // ERROR "leaking param: x to result ~r0 level=1$" "leaking param content: y$"
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x[0] = y[0]
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return x[1]
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}
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// These two tests verify that:
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// small array literals are stack allocated;
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// pointers stored in small array literals do not escape;
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// large array literals are heap allocated;
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// pointers stored in large array literals escape.
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func hugeLeaks1(x **string, y **string) { // ERROR "leaking param content: x" "y does not escape"
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a := [10]*string{*y}
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_ = a
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// 4 x 4,000,000 exceeds MaxStackVarSize, therefore it must be heap allocated if pointers are 4 bytes or larger.
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b := [4000000]*string{*x} // ERROR "moved to heap: b"
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_ = b
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}
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func hugeLeaks2(x *string, y *string) { // ERROR "leaking param: x" "y does not escape"
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a := [10]*string{y}
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_ = a
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// 4 x 4,000,000 exceeds MaxStackVarSize, therefore it must be heap allocated if pointers are 4 bytes or larger.
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b := [4000000]*string{x} // ERROR "moved to heap: b"
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_ = b
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}
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// BAD: x need not leak.
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func doesNew1(x *string, y *string) { // ERROR "leaking param: x" "leaking param: y"
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a := new([10]*string) // ERROR "new\(\[10\]\*string\) does not escape"
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a[0] = x
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b := new([65537]*string) // ERROR "new\(\[65537\]\*string\) escapes to heap"
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b[0] = y
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}
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type a10 struct {
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s *string
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i [10]int32
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}
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type a65537 struct {
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s *string
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i [65537]int32
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}
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// BAD: x need not leak.
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func doesNew2(x *string, y *string) { // ERROR "leaking param: x" "leaking param: y"
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a := new(a10) // ERROR "new\(a10\) does not escape"
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a.s = x
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b := new(a65537) // ERROR "new\(a65537\) escapes to heap"
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b.s = y
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}
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// BAD: x need not leak.
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func doesMakeSlice(x *string, y *string) { // ERROR "leaking param: x" "leaking param: y"
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a := make([]*string, 10) // ERROR "make\(\[\]\*string, 10\) does not escape"
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a[0] = x
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b := make([]*string, 65537) // ERROR "make\(\[\]\*string, 65537\) escapes to heap"
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b[0] = y
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}
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func nonconstArray() {
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n := 32
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s1 := make([]int, n) // ERROR "make\(\[\]int, n\) escapes to heap"
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s2 := make([]int, 0, n) // ERROR "make\(\[\]int, 0, n\) escapes to heap"
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_, _ = s1, s2
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}
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