1 |
|
|
/* ===-- mulvsi3.c - Implement __mulvsi3 -----------------------------------=== |
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 __mulvsi3 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 |
|
|
|
21 |
|
|
COMPILER_RT_ABI si_int |
22 |
|
|
__mulvsi3(si_int a, si_int b) |
23 |
|
|
{ |
24 |
|
|
const int N = (int)(sizeof(si_int) * CHAR_BIT); |
25 |
|
|
const si_int MIN = (si_int)1 << (N-1); |
26 |
|
|
const si_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 |
|
|
si_int sa = a >> (N - 1); |
40 |
|
|
si_int abs_a = (a ^ sa) - sa; |
41 |
|
|
si_int sb = b >> (N - 1); |
42 |
|
|
si_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 |
|
|
} |