//===-- muloti4.c - Implement __muloti4 -----------------------------------===// // // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. // See https://llvm.org/LICENSE.txt for license information. // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception // //===----------------------------------------------------------------------===// // // This file implements __muloti4 for the compiler_rt library. // //===----------------------------------------------------------------------===// #include "int_lib.h" #ifdef CRT_HAS_128BIT // Returns: a * b // Effects: sets *overflow to 1 if a * b overflows COMPILER_RT_ABI ti_int __muloti4(ti_int a, ti_int b, int *overflow) { const int N = (int)(sizeof(ti_int) * CHAR_BIT); const ti_int MIN = (ti_int)1 << (N - 1); const ti_int MAX = ~MIN; *overflow = 0; ti_int result = a * b; if (a == MIN) { if (b != 0 && b != 1) *overflow = 1; return result; } if (b == MIN) { if (a != 0 && a != 1) *overflow = 1; return result; } ti_int sa = a >> (N - 1); ti_int abs_a = (a ^ sa) - sa; ti_int sb = b >> (N - 1); ti_int abs_b = (b ^ sb) - sb; if (abs_a < 2 || abs_b < 2) return result; if (sa == sb) { if (abs_a > MAX / abs_b) *overflow = 1; } else { if (abs_a > MIN / -abs_b) *overflow = 1; } return result; } #endif // CRT_HAS_128BIT |