1 //===-- mulvdi3.c - Implement __mulvdi3 -----------------------------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // This file implements __mulvdi3 for the compiler_rt library. 10 // 11 //===----------------------------------------------------------------------===// 12 13 #include "int_lib.h" 14 15 // Returns: a * b 16 17 // Effects: aborts if a * b overflows 18 19 COMPILER_RT_ABI di_int __mulvdi3(di_int a, di_int b) { 20 const int N = (int)(sizeof(di_int) * CHAR_BIT); 21 const di_int MIN = (di_int)1 << (N - 1); 22 const di_int MAX = ~MIN; 23 if (a == MIN) { 24 if (b == 0 || b == 1) 25 return a * b; 26 compilerrt_abort(); 27 } 28 if (b == MIN) { 29 if (a == 0 || a == 1) 30 return a * b; 31 compilerrt_abort(); 32 } 33 di_int sa = a >> (N - 1); 34 di_int abs_a = (a ^ sa) - sa; 35 di_int sb = b >> (N - 1); 36 di_int abs_b = (b ^ sb) - sb; 37 if (abs_a < 2 || abs_b < 2) 38 return a * b; 39 if (sa == sb) { 40 if (abs_a > MAX / abs_b) 41 compilerrt_abort(); 42 } else { 43 if (abs_a > MIN / -abs_b) 44 compilerrt_abort(); 45 } 46 return a * b; 47 } 48