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In the compiler frontend, walkinrange indiscriminately calls Int64() on const CTINT nodes, even though Int64's return value is undefined for anything over 2⁶³ (in practise, it'll return a negative number). This causes the introduction of bad constants during rewrites of unsigned expressions, which make the compiler reject valid Go programs. This change introduces a preliminary check that Int64() is safe to call on the consts on hand. If it isn't, walkinrange exits without doing any rewrite. Fixes #27143 Change-Id: I2017073cae65468a521ff3262d4ea8ab0d7098d9 Reviewed-on: https://go-review.googlesource.com/130735 Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
18 lines
553 B
Go
18 lines
553 B
Go
// compile
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// Copyright 2018 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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// Issue 27143: cmd/compile: erroneous application of walkinrange
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// optimization for const over 2**63
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package p
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var c uint64
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var b1 bool = 0x7fffffffffffffff < c && c < 0x8000000000000000
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var b2 bool = c < 0x8000000000000000 && 0x7fffffffffffffff < c
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var b3 bool = 0x8000000000000000 < c && c < 0x8000000000000001
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var b4 bool = c < 0x8000000000000001 && 0x8000000000000000 < c
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