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go/test/codegen/spectre.go
David Chase 9a19481acb [dev.regabi] cmd/compile: make ordering for InvertFlags more stable
Current many architectures use a rule along the lines of

// Canonicalize the order of arguments to comparisons - helps with CSE.
((CMP|CMPW) x y) && x.ID > y.ID => (InvertFlags ((CMP|CMPW) y x))

to normalize comparisons as much as possible for CSE.  Replace the
ID comparison with something less variable across compiler changes.
This helps avoid spurious failures in some of the codegen-comparison
tests (though the current choice of comparison is sensitive to Op
ordering).

Two tests changed to accommodate modified instruction choice.

Change-Id: Ib35f450bd2bae9d4f9f7838ceaf7ec682bcf1e1a
Reviewed-on: https://go-review.googlesource.com/c/go/+/280155
Trust: David Chase <drchase@google.com>
Run-TryBot: David Chase <drchase@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
2021-01-13 02:40:43 +00:00

39 lines
722 B
Go

// +build amd64
// asmcheck -gcflags=-spectre=index
// Copyright 2020 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.
package codegen
func IndexArray(x *[10]int, i int) int {
// amd64:`CMOVQCC`
return x[i]
}
func IndexString(x string, i int) byte {
// amd64:`CMOVQLS`
return x[i]
}
func IndexSlice(x []float64, i int) float64 {
// amd64:`CMOVQLS`
return x[i]
}
func SliceArray(x *[10]int, i, j int) []int {
// amd64:`CMOVQHI`
return x[i:j]
}
func SliceString(x string, i, j int) string {
// amd64:`CMOVQHI`
return x[i:j]
}
func SliceSlice(x []float64, i, j int) []float64 {
// amd64:`CMOVQHI`
return x[i:j]
}