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go/test/fixedbugs/issue23305.go
Cherry Zhang 7f1c4b3afb cmd/compile: disable "redundant zeroextensions" optimization for Select on AMD64
A Select Op could produce a value with upper 32 bits NOT zeroed,
for example, Div32 is lowered to (Select0 (DIVL x y)).

In theory, we could look into the argument of a Select to decide
whether the upper bits are zeroed. As it is late in release cycle,
just disable this optimization for Select for now.

Fixes #23305.

Change-Id: Icf665a2af9ccb0a7ba0ae00c683c9e349638bf85
Reviewed-on: https://go-review.googlesource.com/85736
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Ilya Tocar <ilya.tocar@intel.com>
2018-01-02 21:08:35 +00:00

29 lines
575 B
Go

// run
// Copyright 2018 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 main
func mask1(a, b uint64) uint64 {
op1 := int32(a)
op2 := int32(b)
return uint64(uint32(op1 / op2))
}
var mask2 = mask1
func main() {
res1 := mask1(0x1, 0xfffffffeffffffff)
res2 := mask2(0x1, 0xfffffffeffffffff)
if res1 != 0xffffffff {
println("got", res1, "want", 0xffffffff)
panic("FAIL")
}
if res2 != 0xffffffff {
println("got", res2, "want", 0xffffffff)
panic("FAIL")
}
}