bbb0f2c759
Our best guess is that the two syntaxes should have exactly equivalent effects, so, let's be consistent with what we do in libcxx/include/. I've left `#include "include/x.h"` and `#include "../y.h"` alone because I'm less sure that they're interchangeable, and they aren't inconsistent with libcxx/include/ because libcxx/include/ never does that kind of thing. Also, use the `_LIBCPP_PUSH_MACROS/POP_MACROS` dance for `<__undef_macros>`, even though it's technically unnecessary in a standalone .cpp file, just so we have consistently one way to do it. Differential Revision: https://reviews.llvm.org/D119561
55 lines
1.6 KiB
C++
55 lines
1.6 KiB
C++
/*===-- int128_builtins.cpp - Implement __muloti4 --------------------------===
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*
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* Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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* See https://llvm.org/LICENSE.txt for license information.
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* SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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*
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* ===----------------------------------------------------------------------===
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*
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* This file implements __muloti4, and is stolen from the compiler_rt library.
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*
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* FIXME: we steal and re-compile it into filesystem, which uses __int128_t,
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* and requires this builtin when sanitized. See llvm.org/PR30643
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*
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* ===----------------------------------------------------------------------===
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*/
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#include <__config>
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#include <climits>
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#if !defined(_LIBCPP_HAS_NO_INT128)
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extern "C" __attribute__((no_sanitize("undefined"))) _LIBCPP_FUNC_VIS
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__int128_t __muloti4(__int128_t a, __int128_t b, int* overflow) {
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const int N = (int)(sizeof(__int128_t) * CHAR_BIT);
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const __int128_t MIN = (__int128_t)1 << (N - 1);
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const __int128_t MAX = ~MIN;
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*overflow = 0;
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__int128_t result = a * b;
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if (a == MIN) {
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if (b != 0 && b != 1)
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*overflow = 1;
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return result;
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}
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if (b == MIN) {
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if (a != 0 && a != 1)
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*overflow = 1;
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return result;
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}
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__int128_t sa = a >> (N - 1);
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__int128_t abs_a = (a ^ sa) - sa;
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__int128_t sb = b >> (N - 1);
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__int128_t abs_b = (b ^ sb) - sb;
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if (abs_a < 2 || abs_b < 2)
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return result;
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if (sa == sb) {
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if (abs_a > MAX / abs_b)
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*overflow = 1;
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} else {
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if (abs_a > MIN / -abs_b)
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*overflow = 1;
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}
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return result;
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}
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#endif
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