src/compiler-rt/lib/builtins/subvsi3.c

   1 /* ===-- subvsi3.c - Implement __subvsi3 -----------------------------------===
   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 __subvsi3 for the compiler_rt library.
  11  *
  12  * ===----------------------------------------------------------------------===
  13  */
  14
  15 #include "int_lib.h"
  16
  17 /* Returns: a - b */
  18
  19 /* Effects: aborts if a - b overflows */
  20
  21 COMPILER_RT_ABI si_int
  22 __subvsi3(si_int a, si_int b)
  23 {
  24     si_int s = a - b;
  25     if (b >= 0)
  26     {
  27         if (s > a)
  28             compilerrt_abort();
  29     }
  30     else
  31     {
  32         if (s <= a)
  33             compilerrt_abort();
  34     }
  35     return s;
  36 }