1 /*===-- mulodi4.c - Implement __mulodi4 -----------------------------------===
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 __mulodi4 for the compiler_rt library.
12 * ===----------------------------------------------------------------------===
19 /* Effects: sets *overflow to 1 if a * b overflows */
22 __mulodi4(di_int a, di_int b, int* overflow)
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;
28 di_int result = a * b;
41 di_int sa = a >> (N - 1);
42 di_int abs_a = (a ^ sa) - sa;
43 di_int sb = b >> (N - 1);
44 di_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)