1 //===-- mulvdi3.c - Implement __mulvdi3 -----------------------------------===//
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
7 //===----------------------------------------------------------------------===//
9 // This file implements __mulvdi3 for the compiler_rt library.
11 //===----------------------------------------------------------------------===//
17 // Effects: aborts if a * b overflows
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;
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)
40 if (abs_a > MAX / abs_b)
43 if (abs_a > MIN / -abs_b)