1*0b57cec5SDimitry Andric //===-- muloti4.c - Implement __muloti4 -----------------------------------===// 2*0b57cec5SDimitry Andric // 3*0b57cec5SDimitry Andric // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4*0b57cec5SDimitry Andric // See https://llvm.org/LICENSE.txt for license information. 5*0b57cec5SDimitry Andric // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6*0b57cec5SDimitry Andric // 7*0b57cec5SDimitry Andric //===----------------------------------------------------------------------===// 8*0b57cec5SDimitry Andric // 9*0b57cec5SDimitry Andric // This file implements __muloti4 for the compiler_rt library. 10*0b57cec5SDimitry Andric // 11*0b57cec5SDimitry Andric //===----------------------------------------------------------------------===// 12*0b57cec5SDimitry Andric 13*0b57cec5SDimitry Andric #include "int_lib.h" 14*0b57cec5SDimitry Andric 15*0b57cec5SDimitry Andric #ifdef CRT_HAS_128BIT 16*0b57cec5SDimitry Andric 17*0b57cec5SDimitry Andric // Returns: a * b 18*0b57cec5SDimitry Andric 19*0b57cec5SDimitry Andric // Effects: sets *overflow to 1 if a * b overflows 20*0b57cec5SDimitry Andric 21*0b57cec5SDimitry Andric COMPILER_RT_ABI ti_int __muloti4(ti_int a, ti_int b, int *overflow) { 22*0b57cec5SDimitry Andric const int N = (int)(sizeof(ti_int) * CHAR_BIT); 23*0b57cec5SDimitry Andric const ti_int MIN = (ti_int)1 << (N - 1); 24*0b57cec5SDimitry Andric const ti_int MAX = ~MIN; 25*0b57cec5SDimitry Andric *overflow = 0; 26*0b57cec5SDimitry Andric ti_int result = a * b; 27*0b57cec5SDimitry Andric if (a == MIN) { 28*0b57cec5SDimitry Andric if (b != 0 && b != 1) 29*0b57cec5SDimitry Andric *overflow = 1; 30*0b57cec5SDimitry Andric return result; 31*0b57cec5SDimitry Andric } 32*0b57cec5SDimitry Andric if (b == MIN) { 33*0b57cec5SDimitry Andric if (a != 0 && a != 1) 34*0b57cec5SDimitry Andric *overflow = 1; 35*0b57cec5SDimitry Andric return result; 36*0b57cec5SDimitry Andric } 37*0b57cec5SDimitry Andric ti_int sa = a >> (N - 1); 38*0b57cec5SDimitry Andric ti_int abs_a = (a ^ sa) - sa; 39*0b57cec5SDimitry Andric ti_int sb = b >> (N - 1); 40*0b57cec5SDimitry Andric ti_int abs_b = (b ^ sb) - sb; 41*0b57cec5SDimitry Andric if (abs_a < 2 || abs_b < 2) 42*0b57cec5SDimitry Andric return result; 43*0b57cec5SDimitry Andric if (sa == sb) { 44*0b57cec5SDimitry Andric if (abs_a > MAX / abs_b) 45*0b57cec5SDimitry Andric *overflow = 1; 46*0b57cec5SDimitry Andric } else { 47*0b57cec5SDimitry Andric if (abs_a > MIN / -abs_b) 48*0b57cec5SDimitry Andric *overflow = 1; 49*0b57cec5SDimitry Andric } 50*0b57cec5SDimitry Andric return result; 51*0b57cec5SDimitry Andric } 52*0b57cec5SDimitry Andric 53*0b57cec5SDimitry Andric #endif // CRT_HAS_128BIT 54