1 /*===-- muloti4.c - Implement __muloti4 -----------------------------------===
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 __muloti4 for the compiler_rt library.
12 * ===----------------------------------------------------------------------===
21 /* Effects: sets *overflow to 1 if a * b overflows */
24 __muloti4(ti_int a, ti_int b, int* overflow)
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;
30 ti_int result = a * b;
43 ti_int sa = a >> (N - 1);
44 ti_int abs_a = (a ^ sa) - sa;
45 ti_int sb = b >> (N - 1);
46 ti_int abs_b = (b ^ sb) - sb;
47 if (abs_a < 2 || abs_b < 2)
51 if (abs_a > MAX / abs_b)
56 if (abs_a > MIN / -abs_b)