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![Keith Randall](/assets/img/avatar_default.png)
Make sure the side effects inside short-circuited operations (&& and ||) happen correctly. Before this CL, we attached the side effects to the node itself using exprInPlace. That caused other side effects in sibling expressions to get reordered with respect to the short circuit side effect. Instead, rewrite a && b like: r := a if r { r = b } That code we can keep correctly ordered with respect to other side-effects extracted from part of a big expression. exprInPlace seems generally unsafe. But this was the only case where exprInPlace is called not at the top level of an expression, so I don't think the other uses can actually trigger an issue (there can't be a sibling expression). TODO: maybe those cases don't need "in place", and we can retire that function generally. This CL needed a small tweak to the SSA generation of OIF so that the short circuit optimization still triggers. The short circuit optimization looks for triangle but not diamonds, so don't bother allocating a block if it will be empty. Go 1 benchmarks are in the noise. Fixes #30566 Change-Id: I19c04296bea63cbd6ad05f87a63b005029123610 Reviewed-on: https://go-review.googlesource.com/c/go/+/165617 Run-TryBot: Keith Randall <khr@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: David Chase <drchase@google.com>
28 lines
426 B
Go
28 lines
426 B
Go
// run
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// Copyright 2019 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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"bytes"
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"fmt"
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)
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func main() {
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_, _ = false || g(1), g(2)
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if !bytes.Equal(x, []byte{1, 2}) {
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panic(fmt.Sprintf("wanted [1,2], got %v", x))
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}
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}
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var x []byte
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//go:noinline
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func g(b byte) bool {
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x = append(x, b)
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return false
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}
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