mirror of
https://github.com/golang/go
synced 2024-11-27 00:21:21 -07:00
9ce27feaeb
The recently added rule only works before decomposing slices. Add a rule that works after decomposing slices. The reason we need the latter is because although the length may be a constant, it can be hidden inside a slice that is not constant (its pointer or capacity might be changing). By applying this optimization after decomposing slices, we can find more cases where it applies. Fixes #56440 Change-Id: I0094e59eee3065ab4d210defdda8227a6e897420 Reviewed-on: https://go-review.googlesource.com/c/go/+/446277 Run-TryBot: Keith Randall <khr@golang.org> Reviewed-by: Cherry Mui <cherryyz@google.com> TryBot-Result: Gopher Robot <gobot@golang.org> Reviewed-by: Keith Randall <khr@google.com>
35 lines
689 B
Go
35 lines
689 B
Go
// asmcheck
|
|
|
|
// Copyright 2022 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.
|
|
|
|
// Check to make sure that we recognize when the length of an append
|
|
// is constant. We check this by making sure that the constant length
|
|
// is folded into a load offset.
|
|
|
|
package p
|
|
|
|
func f(x []int) int {
|
|
s := make([]int, 3)
|
|
s = append(s, 4, 5)
|
|
// amd64:`MOVQ\t40\(.*\),`
|
|
return x[len(s)]
|
|
}
|
|
|
|
func g(x []int, p *bool) int {
|
|
s := make([]int, 3)
|
|
for {
|
|
s = s[:3]
|
|
if cap(s) < 5 {
|
|
s = make([]int, 3, 5)
|
|
}
|
|
s = append(s, 4, 5)
|
|
if *p {
|
|
// amd64:`MOVQ\t40\(.*\),`
|
|
return x[len(s)]
|
|
}
|
|
}
|
|
return 0
|
|
}
|