mirror of
https://github.com/golang/go
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7f90b960a9
v = ... compute some value, which zeros top 32 bits ... w = zero-extend v We want to remove the zero-extension operation, as it doesn't do anything. But if v is typed as a signed value, and it gets spilled/restored, it might be re-sign-extended upon restore. So the zero-extend isn't actually a NOP when there might be calls or other reasons to spill in between v and w. Fixes #68227 Change-Id: I3b30b8e56c7d70deac1fb09d2becc7395acbadf8 Reviewed-on: https://go-review.googlesource.com/c/go/+/595675 LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Joedian Reid <joedian@google.com> Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com> Reviewed-by: Cherry Mui <cherryyz@google.com>
44 lines
1.1 KiB
Go
44 lines
1.1 KiB
Go
// run
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// Copyright 2024 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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package main
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import (
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"fmt"
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)
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type someType []uint64
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func (s *someType) push(v uint64) {
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*s = append(*s, v)
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}
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func (s *someType) problematicFn(x1Lo, x1Hi, x2Lo, x2Hi uint64) {
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r1 := int32(int16(x1Lo>>0)) * int32(int16(x2Lo>>0))
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g()
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r3 := int32(int16(x1Lo>>32)) * int32(int16(x2Lo>>32))
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r4 := int32(int16(x1Lo>>48)) * int32(int16(x2Lo>>48))
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r5 := int32(int16(x1Hi>>0)) * int32(int16(x2Hi>>0))
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r7 := int32(int16(x1Hi>>32)) * int32(int16(x2Hi>>32))
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r8 := int32(int16(x1Hi>>48)) * int32(int16(x2Hi>>48))
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s.push(uint64(uint32(r1)) | (uint64(uint32(r3+r4)) << 32))
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s.push(uint64(uint32(r5)) | (uint64(uint32(r7+r8)) << 32))
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}
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//go:noinline
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func g() {
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}
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func main() {
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s := &someType{}
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s.problematicFn(0x1000100010001, 0x1000100010001, 0xffffffffffffffff, 0xffffffffffffffff)
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for i := 0; i < 2; i++ {
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if got, want := (*s)[i], uint64(0xfffffffeffffffff); got != want {
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fmt.Printf("s[%d]=%x, want %x\n", i, got, want)
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}
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}
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}
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