1/*===-- mulvdi3.c - Implement __mulvdi3 -----------------------------------===
2 *
3 *                     The LLVM Compiler Infrastructure
4 *
5 * This file is dual licensed under the MIT and the University of Illinois Open
6 * Source Licenses. See LICENSE.TXT for details.
7 *
8 * ===----------------------------------------------------------------------===
9 *
10 * This file implements __mulvdi3 for the compiler_rt library.
11 *
12 * ===----------------------------------------------------------------------===
13 */
14
15#include "int_lib.h"
16
17/* Returns: a * b */
18
19/* Effects: aborts if a * b overflows */
20
21COMPILER_RT_ABI di_int
22__mulvdi3(di_int a, di_int b)
23{
24    const int N = (int)(sizeof(di_int) * CHAR_BIT);
25    const di_int MIN = (di_int)1 << (N-1);
26    const di_int MAX = ~MIN;
27    if (a == MIN)
28    {
29        if (b == 0 || b == 1)
30            return a * b;
31        compilerrt_abort();
32    }
33    if (b == MIN)
34    {
35        if (a == 0 || a == 1)
36            return a * b;
37        compilerrt_abort();
38    }
39    di_int sa = a >> (N - 1);
40    di_int abs_a = (a ^ sa) - sa;
41    di_int sb = b >> (N - 1);
42    di_int abs_b = (b ^ sb) - sb;
43    if (abs_a < 2 || abs_b < 2)
44        return a * b;
45    if (sa == sb)
46    {
47        if (abs_a > MAX / abs_b)
48            compilerrt_abort();
49    }
50    else
51    {
52        if (abs_a > MIN / -abs_b)
53            compilerrt_abort();
54    }
55    return a * b;
56}
57