1*0b57cec5SDimitry Andric //===-- mulvti3.c - Implement __mulvti3 -----------------------------------===// 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 __mulvti3 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: aborts if a * b overflows 20*0b57cec5SDimitry Andric 21*0b57cec5SDimitry Andric COMPILER_RT_ABI ti_int __mulvti3(ti_int a, ti_int b) { 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 if (a == MIN) { 26*0b57cec5SDimitry Andric if (b == 0 || b == 1) 27*0b57cec5SDimitry Andric return a * b; 28*0b57cec5SDimitry Andric compilerrt_abort(); 29*0b57cec5SDimitry Andric } 30*0b57cec5SDimitry Andric if (b == MIN) { 31*0b57cec5SDimitry Andric if (a == 0 || a == 1) 32*0b57cec5SDimitry Andric return a * b; 33*0b57cec5SDimitry Andric compilerrt_abort(); 34*0b57cec5SDimitry Andric } 35*0b57cec5SDimitry Andric ti_int sa = a >> (N - 1); 36*0b57cec5SDimitry Andric ti_int abs_a = (a ^ sa) - sa; 37*0b57cec5SDimitry Andric ti_int sb = b >> (N - 1); 38*0b57cec5SDimitry Andric ti_int abs_b = (b ^ sb) - sb; 39*0b57cec5SDimitry Andric if (abs_a < 2 || abs_b < 2) 40*0b57cec5SDimitry Andric return a * b; 41*0b57cec5SDimitry Andric if (sa == sb) { 42*0b57cec5SDimitry Andric if (abs_a > MAX / abs_b) 43*0b57cec5SDimitry Andric compilerrt_abort(); 44*0b57cec5SDimitry Andric } else { 45*0b57cec5SDimitry Andric if (abs_a > MIN / -abs_b) 46*0b57cec5SDimitry Andric compilerrt_abort(); 47*0b57cec5SDimitry Andric } 48*0b57cec5SDimitry Andric return a * b; 49*0b57cec5SDimitry Andric } 50*0b57cec5SDimitry Andric 51*0b57cec5SDimitry Andric #endif // CRT_HAS_128BIT 52