sys/external/bsd/compiler_rt/dist/lib/subvti3.c

   1 /* ===-- subvti3.c - Implement __subvti3 -----------------------------------===
   2  *
   3  *                     The LLVM Compiler Infrastructure
   4  *
   5  * This file is dual licensed under the MIT and the University of Illinois Open
   6  * Source Licenses. See LICENSE.TXT for details.
   7  *
   8  * ===----------------------------------------------------------------------===
   9  *
  10  * This file implements __subvti3 for the compiler_rt library.
  11  *
  12  * ===----------------------------------------------------------------------===
  13  */
  14
  15 #include "int_lib.h"
  16
  17 #if __x86_64
  18
  19 /* Returns: a - b */
  20
  21 /* Effects: aborts if a - b overflows */
  22
  23 ti_int
  24 __subvti3(ti_int a, ti_int b)
  25 {
  26     ti_int s = a - b;
  27     if (b >= 0)
  28     {
  29         if (s > a)
  30             compilerrt_abort();
  31     }
  32     else
  33     {
  34         if (s <= a)
  35             compilerrt_abort();
  36     }
  37     return s;
  38 }
  39
  40 #endif /* __x86_64 */