1*3cab2bb3Spatrick //===-- mulvsi3.c - Implement __mulvsi3 -----------------------------------===//
2*3cab2bb3Spatrick //
3*3cab2bb3Spatrick // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4*3cab2bb3Spatrick // See https://llvm.org/LICENSE.txt for license information.
5*3cab2bb3Spatrick // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6*3cab2bb3Spatrick //
7*3cab2bb3Spatrick //===----------------------------------------------------------------------===//
8*3cab2bb3Spatrick //
9*3cab2bb3Spatrick // This file implements __mulvsi3 for the compiler_rt library.
10*3cab2bb3Spatrick //
11*3cab2bb3Spatrick //===----------------------------------------------------------------------===//
12*3cab2bb3Spatrick 
13*3cab2bb3Spatrick #include "int_lib.h"
14*3cab2bb3Spatrick 
15*3cab2bb3Spatrick // Returns: a * b
16*3cab2bb3Spatrick 
17*3cab2bb3Spatrick // Effects: aborts if a * b overflows
18*3cab2bb3Spatrick 
19*3cab2bb3Spatrick COMPILER_RT_ABI si_int __mulvsi3(si_int a, si_int b) {
20*3cab2bb3Spatrick   const int N = (int)(sizeof(si_int) * CHAR_BIT);
21*3cab2bb3Spatrick   const si_int MIN = (si_int)1 << (N - 1);
22*3cab2bb3Spatrick   const si_int MAX = ~MIN;
23*3cab2bb3Spatrick   if (a == MIN) {
24*3cab2bb3Spatrick     if (b == 0 || b == 1)
25*3cab2bb3Spatrick       return a * b;
26*3cab2bb3Spatrick     compilerrt_abort();
27*3cab2bb3Spatrick   }
28*3cab2bb3Spatrick   if (b == MIN) {
29*3cab2bb3Spatrick     if (a == 0 || a == 1)
30*3cab2bb3Spatrick       return a * b;
31*3cab2bb3Spatrick     compilerrt_abort();
32*3cab2bb3Spatrick   }
33*3cab2bb3Spatrick   si_int sa = a >> (N - 1);
34*3cab2bb3Spatrick   si_int abs_a = (a ^ sa) - sa;
35*3cab2bb3Spatrick   si_int sb = b >> (N - 1);
36*3cab2bb3Spatrick   si_int abs_b = (b ^ sb) - sb;
37*3cab2bb3Spatrick   if (abs_a < 2 || abs_b < 2)
38*3cab2bb3Spatrick     return a * b;
39*3cab2bb3Spatrick   if (sa == sb) {
40*3cab2bb3Spatrick     if (abs_a > MAX / abs_b)
41*3cab2bb3Spatrick       compilerrt_abort();
42*3cab2bb3Spatrick   } else {
43*3cab2bb3Spatrick     if (abs_a > MIN / -abs_b)
44*3cab2bb3Spatrick       compilerrt_abort();
45*3cab2bb3Spatrick   }
46*3cab2bb3Spatrick   return a * b;
47*3cab2bb3Spatrick }
48