llvm-project/compiler-rt/lib/subvsi3.c

/* ===-- subvsi3.c - Implement __subvsi3 -----------------------------------===
 *
 *                The LLVM Compiler Infrastructure
 *
 * This file is dual licensed under the MIT and the University of Illinois Open
 * Source Licenses. See LICENSE.TXT for details.
 *
 * ===----------------------------------------------------------------------===
 *
 * This file implements __subvsi3 for the compiler_rt library.
 *
 * ===----------------------------------------------------------------------===
 */

#include "int_lib.h"

/* Returns: a - b */

/* Effects: aborts if a - b overflows */

COMPILER_RT_ABI si_int
__subvsi3(si_int a, si_int b)
{
    si_int s = a - b;
    if (b >= 0)
    {
        if (s > a)
            compilerrt_abort();
    }
    else
    {
        if (s <= a)
            compilerrt_abort();
    }
    return s;
}