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/* ===-- mulvsi3.c - Implement __mulvsi3 -----------------------------------===
*
* The LLVM Compiler Infrastructure
*
* This file is distributed under the University of Illinois Open Source
* License. See LICENSE.TXT for details.
*
* ===----------------------------------------------------------------------===
*
* This file implements __mulvsi3 for the compiler_rt library.
*
* ===----------------------------------------------------------------------===
*/
#include "int_lib.h"
#include <stdlib.h>
/* Returns: a * b */
/* Effects: aborts if a * b overflows */
si_int
__mulvsi3(si_int a, si_int b)
{
const int N = (int)(sizeof(si_int) * CHAR_BIT);
const si_int MIN = (si_int)1 << (N-1);
const si_int MAX = ~MIN;
if (a == MIN)
{
if (b == 0 || b == 1)
return a * b;
abort();
}
if (b == MIN)
{
if (a == 0 || a == 1)
return a * b;
abort();
}
si_int sa = a >> (N - 1);
si_int abs_a = (a ^ sa) - sa;
si_int sb = b >> (N - 1);
si_int abs_b = (b ^ sb) - sb;
if (abs_a < 2 || abs_b < 2)
return a * b;
if (sa == sb)
{
if (abs_a > MAX / abs_b)
abort();
}
else
{
if (abs_a > MIN / -abs_b)
abort();
}
return a * b;
}
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