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
/*===-- mulvdi3.c - Implement __mulvdi3 -----------------------------------===
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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 __mulvdi3 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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di_int
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__mulvdi3(di_int a, di_int b)
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{
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const int N = (int)(sizeof(di_int) * CHAR_BIT);
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const di_int MIN = (di_int)1 << (N-1);
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const di_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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di_int sa = a >> (N - 1);
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di_int abs_a = (a ^ sa) - sa;
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di_int sb = b >> (N - 1);
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di_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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