f287008791
- Fiddling with abort directly is annoying given the way we use system includes, although it would be nice to fix this so we could make sure calling abort directly is verboten. llvm-svn: 100014
58 lines
1.3 KiB
C
58 lines
1.3 KiB
C
/* ===-- mulvsi3.c - Implement __mulvsi3 -----------------------------------===
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*
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* The LLVM Compiler Infrastructure
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*
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* This file is distributed under the University of Illinois Open Source
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* License. See LICENSE.TXT for details.
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*
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* ===----------------------------------------------------------------------===
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*
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* This file implements __mulvsi3 for the compiler_rt library.
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*
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* ===----------------------------------------------------------------------===
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*/
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#include "int_lib.h"
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#include <stdlib.h>
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/* Returns: a * b */
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/* Effects: aborts if a * b overflows */
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si_int
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__mulvsi3(si_int a, si_int b)
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{
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const int N = (int)(sizeof(si_int) * CHAR_BIT);
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const si_int MIN = (si_int)1 << (N-1);
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const si_int MAX = ~MIN;
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if (a == MIN)
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{
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if (b == 0 || b == 1)
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return a * b;
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compilerrt_abort();
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}
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if (b == MIN)
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{
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if (a == 0 || a == 1)
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return a * b;
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compilerrt_abort();
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}
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si_int sa = a >> (N - 1);
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si_int abs_a = (a ^ sa) - sa;
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si_int sb = b >> (N - 1);
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si_int abs_b = (b ^ sb) - sb;
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if (abs_a < 2 || abs_b < 2)
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return a * b;
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if (sa == sb)
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{
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if (abs_a > MAX / abs_b)
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compilerrt_abort();
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}
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else
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{
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if (abs_a > MIN / -abs_b)
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compilerrt_abort();
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}
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return a * b;
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}
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