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//===-- mulvsi3.c - Implement __mulvsi3 -----------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements __mulvsi3 for the compiler_rt library.
//
//===----------------------------------------------------------------------===//
#include "int_lib.h"
// Returns: a * b
// Effects: aborts if a * b overflows
COMPILER_RT_ABI si_int __mulvsi3(si_int a, si_int b) {
const int N = (int)(sizeof(si_int) * CHAR_BIT);
const si_int MIN = (si_int)1 << (N - 1);
const si_int MAX = ~MIN;
if (a == MIN) {
if (b == 0 || b == 1)
return a * b;
compilerrt_abort();
}
if (b == MIN) {
if (a == 0 || a == 1)
return a * b;
compilerrt_abort();
}
si_int sa = a >> (N - 1);
si_int abs_a = (a ^ sa) - sa;
si_int sb = b >> (N - 1);
si_int abs_b = (b ^ sb) - sb;
if (abs_a < 2 || abs_b < 2)
return a * b;
if (sa == sb) {
if (abs_a > MAX / abs_b)
compilerrt_abort();
} else {
if (abs_a > MIN / -abs_b)
compilerrt_abort();
}
return a * b;
}
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