1336819Sdim/*===-- int128_builtins.cpp - Implement __muloti4 --------------------------=== 2336819Sdim * 3353358Sdim * Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4353358Sdim * See https://llvm.org/LICENSE.txt for license information. 5353358Sdim * SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6336819Sdim * 7336819Sdim * ===----------------------------------------------------------------------=== 8336819Sdim * 9336819Sdim * This file implements __muloti4, and is stolen from the compiler_rt library. 10336819Sdim * 11336819Sdim * FIXME: we steal and re-compile it into filesystem, which uses __int128_t, 12336819Sdim * and requires this builtin when sanitized. See llvm.org/PR30643 13336819Sdim * 14336819Sdim * ===----------------------------------------------------------------------=== 15336819Sdim */ 16336819Sdim#include "__config" 17336819Sdim#include "climits" 18336819Sdim 19336819Sdim#if !defined(_LIBCPP_HAS_NO_INT128) 20336819Sdim 21360784Sdimextern "C" __attribute__((no_sanitize("undefined"))) _LIBCPP_FUNC_VIS 22336819Sdim__int128_t __muloti4(__int128_t a, __int128_t b, int* overflow) { 23336819Sdim const int N = (int)(sizeof(__int128_t) * CHAR_BIT); 24336819Sdim const __int128_t MIN = (__int128_t)1 << (N - 1); 25336819Sdim const __int128_t MAX = ~MIN; 26336819Sdim *overflow = 0; 27336819Sdim __int128_t result = a * b; 28336819Sdim if (a == MIN) { 29336819Sdim if (b != 0 && b != 1) 30336819Sdim *overflow = 1; 31336819Sdim return result; 32336819Sdim } 33336819Sdim if (b == MIN) { 34336819Sdim if (a != 0 && a != 1) 35336819Sdim *overflow = 1; 36336819Sdim return result; 37336819Sdim } 38336819Sdim __int128_t sa = a >> (N - 1); 39336819Sdim __int128_t abs_a = (a ^ sa) - sa; 40336819Sdim __int128_t sb = b >> (N - 1); 41336819Sdim __int128_t abs_b = (b ^ sb) - sb; 42336819Sdim if (abs_a < 2 || abs_b < 2) 43336819Sdim return result; 44336819Sdim if (sa == sb) { 45336819Sdim if (abs_a > MAX / abs_b) 46336819Sdim *overflow = 1; 47336819Sdim } else { 48336819Sdim if (abs_a > MIN / -abs_b) 49336819Sdim *overflow = 1; 50336819Sdim } 51336819Sdim return result; 52336819Sdim} 53336819Sdim 54336819Sdim#endif 55