mirror of
https://github.com/golang/go
synced 2024-11-23 09:20:05 -07:00
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
|
|
|
|
// Copyright 2016 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 write barrier elimination for notinheap.
|
|
|
|
package p
|
|
|
|
type t1 struct {
|
|
x *nih
|
|
s []nih
|
|
y [1024]byte // Prevent write decomposition
|
|
}
|
|
|
|
type t2 struct {
|
|
x *ih
|
|
s []ih
|
|
y [1024]byte
|
|
}
|
|
|
|
//go:notinheap
|
|
type nih struct {
|
|
x uintptr
|
|
}
|
|
|
|
type ih struct { // In-heap type
|
|
x uintptr
|
|
}
|
|
|
|
var (
|
|
v1 t1
|
|
v2 t2
|
|
|
|
v1s []t1
|
|
v2s []t2
|
|
)
|
|
|
|
func f() {
|
|
// Test direct writes
|
|
v1.x = nil // no barrier
|
|
v2.x = nil // ERROR "write barrier"
|
|
v1.s = []nih(nil) // no barrier
|
|
v2.s = []ih(nil) // ERROR "write barrier"
|
|
}
|
|
|
|
func g() {
|
|
// Test aggregate writes
|
|
v1 = t1{x: nil} // no barrier
|
|
v2 = t2{x: nil} // ERROR "write barrier"
|
|
}
|
|
|
|
func h() {
|
|
// Test copies and appends.
|
|
copy(v1s, v1s[1:]) // no barrier
|
|
copy(v2s, v2s[1:]) // ERROR "write barrier"
|
|
_ = append(v1s, v1s...) // no barrier
|
|
_ = append(v2s, v2s...) // ERROR "write barrier"
|
|
}
|