1353358Sdim//===-- muloti4.c - Implement __muloti4 -----------------------------------===// 2353358Sdim// 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 6353358Sdim// 7353358Sdim//===----------------------------------------------------------------------===// 8353358Sdim// 9353358Sdim// This file implements __muloti4 for the compiler_rt library. 10353358Sdim// 11353358Sdim//===----------------------------------------------------------------------===// 12276789Sdim 13276789Sdim#include "int_lib.h" 14276789Sdim 15276789Sdim#ifdef CRT_HAS_128BIT 16276789Sdim 17353358Sdim// Returns: a * b 18276789Sdim 19353358Sdim// Effects: sets *overflow to 1 if a * b overflows 20276789Sdim 21353358SdimCOMPILER_RT_ABI ti_int __muloti4(ti_int a, ti_int b, int *overflow) { 22353358Sdim const int N = (int)(sizeof(ti_int) * CHAR_BIT); 23353358Sdim const ti_int MIN = (ti_int)1 << (N - 1); 24353358Sdim const ti_int MAX = ~MIN; 25353358Sdim *overflow = 0; 26353358Sdim ti_int result = a * b; 27353358Sdim if (a == MIN) { 28353358Sdim if (b != 0 && b != 1) 29353358Sdim *overflow = 1; 30276789Sdim return result; 31353358Sdim } 32353358Sdim if (b == MIN) { 33353358Sdim if (a != 0 && a != 1) 34353358Sdim *overflow = 1; 35353358Sdim return result; 36353358Sdim } 37353358Sdim ti_int sa = a >> (N - 1); 38353358Sdim ti_int abs_a = (a ^ sa) - sa; 39353358Sdim ti_int sb = b >> (N - 1); 40353358Sdim ti_int abs_b = (b ^ sb) - sb; 41353358Sdim if (abs_a < 2 || abs_b < 2) 42353358Sdim return result; 43353358Sdim if (sa == sb) { 44353358Sdim if (abs_a > MAX / abs_b) 45353358Sdim *overflow = 1; 46353358Sdim } else { 47353358Sdim if (abs_a > MIN / -abs_b) 48353358Sdim *overflow = 1; 49353358Sdim } 50353358Sdim return result; 51276789Sdim} 52276789Sdim 53353358Sdim#endif // CRT_HAS_128BIT 54