1 /* ===-- mulvti3.c - Implement __mulvti3 -----------------------------------===
3 * The LLVM Compiler Infrastructure
5 * This file is dual licensed under the MIT and the University of Illinois Open
6 * Source Licenses. See LICENSE.TXT for details.
8 * ===----------------------------------------------------------------------===
10 * This file implements __mulvti3 for the compiler_rt library.
12 * ===----------------------------------------------------------------------===
21 /* Effects: aborts if a * b overflows */
24 __mulvti3(ti_int a, ti_int b)
26 const int N = (int)(sizeof(ti_int) * CHAR_BIT);
27 const ti_int MIN = (ti_int)1 << (N-1);
28 const ti_int MAX = ~MIN;
41 ti_int sa = a >> (N - 1);
42 ti_int abs_a = (a ^ sa) - sa;
43 ti_int sb = b >> (N - 1);
44 ti_int abs_b = (b ^ sb) - sb;
45 if (abs_a < 2 || abs_b < 2)
49 if (abs_a > MAX / abs_b)
54 if (abs_a > MIN / -abs_b)