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