llvm-project
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1//===-- int_mulv_impl.inc - Implement __mulv[sdt]i3 ---------------*- C -*-===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// Helper used by __mulvsi3, __mulvdi3 and __mulvti3.
10//
11//===----------------------------------------------------------------------===//
12
13#include "int_lib.h"14
15// Returns: a * b
16
17// Effects: aborts if a * b overflows
18
19static __inline fixint_t __mulvXi3(fixint_t a, fixint_t b) {20const int N = (int)(sizeof(fixint_t) * CHAR_BIT);21const fixint_t MIN = (fixint_t)((fixuint_t)1 << (N - 1));22const fixint_t MAX = ~MIN;23if (a == MIN) {24if (b == 0 || b == 1)25return a * b;26compilerrt_abort();27}28if (b == MIN) {29if (a == 0 || a == 1)30return a * b;31compilerrt_abort();32}33fixint_t sa = a >> (N - 1);34fixint_t abs_a = (a ^ sa) - sa;35fixint_t sb = b >> (N - 1);36fixint_t abs_b = (b ^ sb) - sb;37if (abs_a < 2 || abs_b < 2)38return a * b;39if (sa == sb) {40if (abs_a > MAX / abs_b)41compilerrt_abort();42} else {43if (abs_a > MIN / -abs_b)44compilerrt_abort();45}46return a * b;47}
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