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7863f742c4
The 32-bit left shift constant folding rule should keep its result properly sign extended. Fixes #41720 Fixes #41711 Change-Id: I0fc74444d444274e911952e1725dab0b7737a846 Reviewed-on: https://go-review.googlesource.com/c/go/+/258817 Trust: Keith Randall <khr@golang.org> Run-TryBot: Keith Randall <khr@golang.org> Reviewed-by: David Chase <drchase@google.com> TryBot-Result: Go Bot <gobot@golang.org>
18 lines
570 B
Go
18 lines
570 B
Go
// compile -d=ssa/check/on
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// Copyright 2020 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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func f() uint32 {
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s := "food"
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x := uint32(s[0]) + uint32(s[1])<<8 + uint32(s[2])<<16 + uint32(s[3])<<24
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// x is a constant, but that's not known until lowering.
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// shifting it by 8 moves the high byte up into the high 32 bits of
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// a 64-bit word. That word is not properly sign-extended by the faulty
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// rule, which causes the compiler to fail.
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return x << 8
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}
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