146035553Spatrick /*===-- int128_builtins.cpp - Implement __muloti4 --------------------------=== 246035553Spatrick * 346035553Spatrick * Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 446035553Spatrick * See https://llvm.org/LICENSE.txt for license information. 546035553Spatrick * SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 646035553Spatrick * 746035553Spatrick * ===----------------------------------------------------------------------=== 846035553Spatrick * 946035553Spatrick * This file implements __muloti4, and is stolen from the compiler_rt library. 1046035553Spatrick * 1146035553Spatrick * FIXME: we steal and re-compile it into filesystem, which uses __int128_t, 1246035553Spatrick * and requires this builtin when sanitized. See llvm.org/PR30643 1346035553Spatrick * 1446035553Spatrick * ===----------------------------------------------------------------------=== 1546035553Spatrick */ 16*4bdff4beSrobert #include <__config> 17*4bdff4beSrobert #include <climits> 1846035553Spatrick 1946035553Spatrick #if !defined(_LIBCPP_HAS_NO_INT128) 2046035553Spatrick 2146035553Spatrick extern "C" __attribute__((no_sanitize("undefined"))) _LIBCPP_FUNC_VIS __muloti4(__int128_t a,__int128_t b,int * overflow)2246035553Spatrick__int128_t __muloti4(__int128_t a, __int128_t b, int* overflow) { 2346035553Spatrick const int N = (int)(sizeof(__int128_t) * CHAR_BIT); 2446035553Spatrick const __int128_t MIN = (__int128_t)1 << (N - 1); 2546035553Spatrick const __int128_t MAX = ~MIN; 2646035553Spatrick *overflow = 0; 2746035553Spatrick __int128_t result = a * b; 2846035553Spatrick if (a == MIN) { 2946035553Spatrick if (b != 0 && b != 1) 3046035553Spatrick *overflow = 1; 3146035553Spatrick return result; 3246035553Spatrick } 3346035553Spatrick if (b == MIN) { 3446035553Spatrick if (a != 0 && a != 1) 3546035553Spatrick *overflow = 1; 3646035553Spatrick return result; 3746035553Spatrick } 3846035553Spatrick __int128_t sa = a >> (N - 1); 3946035553Spatrick __int128_t abs_a = (a ^ sa) - sa; 4046035553Spatrick __int128_t sb = b >> (N - 1); 4146035553Spatrick __int128_t abs_b = (b ^ sb) - sb; 4246035553Spatrick if (abs_a < 2 || abs_b < 2) 4346035553Spatrick return result; 4446035553Spatrick if (sa == sb) { 4546035553Spatrick if (abs_a > MAX / abs_b) 4646035553Spatrick *overflow = 1; 4746035553Spatrick } else { 4846035553Spatrick if (abs_a > MIN / -abs_b) 4946035553Spatrick *overflow = 1; 5046035553Spatrick } 5146035553Spatrick return result; 5246035553Spatrick } 5346035553Spatrick 5446035553Spatrick #endif 55