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3a446d8652
Currently, assigning a []T where T is a go:notinheap type generates an unnecessary write barrier for storing the slice pointer. This fixes this by teaching HasHeapPointer that this type does not have a heap pointer, and tweaking the lowering of slice assignments so the pointer store retains the correct type rather than simply lowering it to a *uint8 store. Change-Id: I8bf7c66e64a7fefdd14f2bd0de8a5a3596340bab Reviewed-on: https://go-review.googlesource.com/76027 Run-TryBot: Austin Clements <austin@google.com> Reviewed-by: Matthew Dempsky <mdempsky@google.com> TryBot-Result: Gobot Gobot <gobot@golang.org>
61 lines
1.0 KiB
Go
61 lines
1.0 KiB
Go
// errorcheck -+ -0 -l -d=wb
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// Copyright 2016 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 write barrier elimination for notinheap.
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package p
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type t1 struct {
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x *nih
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s []nih
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y [1024]byte // Prevent write decomposition
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}
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type t2 struct {
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x *ih
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s []ih
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y [1024]byte
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}
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//go:notinheap
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type nih struct {
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x uintptr
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}
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type ih struct { // In-heap type
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x uintptr
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}
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var (
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v1 t1
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v2 t2
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v1s []t1
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v2s []t2
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)
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func f() {
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// Test direct writes
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v1.x = nil // no barrier
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v2.x = nil // ERROR "write barrier"
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v1.s = []nih(nil) // no barrier
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v2.s = []ih(nil) // ERROR "write barrier"
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}
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func g() {
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// Test aggregate writes
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v1 = t1{x: nil} // no barrier
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v2 = t2{x: nil} // ERROR "write barrier"
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}
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func h() {
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// Test copies and appends.
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copy(v1s, v1s[1:]) // no barrier
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copy(v2s, v2s[1:]) // ERROR "write barrier"
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_ = append(v1s, v1s...) // no barrier
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_ = append(v2s, v2s...) // ERROR "write barrier"
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}
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