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0ba22f51d1
Use the uniform single line C++/99 style for code comments. This is part of the cleanup proposed in "[RFC] compiler-rt builtins cleanup and refactoring". Differential Revision: https://reviews.llvm.org/D60352 llvm-svn: 359411
52 lines
1.5 KiB
C
52 lines
1.5 KiB
C
//===-- multi3.c - Implement __multi3 -------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements __multi3 for the compiler_rt library.
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//
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//===----------------------------------------------------------------------===//
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#include "int_lib.h"
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#ifdef CRT_HAS_128BIT
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// Returns: a * b
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static ti_int __mulddi3(du_int a, du_int b) {
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twords r;
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const int bits_in_dword_2 = (int)(sizeof(di_int) * CHAR_BIT) / 2;
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const du_int lower_mask = (du_int)~0 >> bits_in_dword_2;
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r.s.low = (a & lower_mask) * (b & lower_mask);
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du_int t = r.s.low >> bits_in_dword_2;
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r.s.low &= lower_mask;
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t += (a >> bits_in_dword_2) * (b & lower_mask);
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r.s.low += (t & lower_mask) << bits_in_dword_2;
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r.s.high = t >> bits_in_dword_2;
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t = r.s.low >> bits_in_dword_2;
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r.s.low &= lower_mask;
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t += (b >> bits_in_dword_2) * (a & lower_mask);
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r.s.low += (t & lower_mask) << bits_in_dword_2;
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r.s.high += t >> bits_in_dword_2;
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r.s.high += (a >> bits_in_dword_2) * (b >> bits_in_dword_2);
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return r.all;
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}
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// Returns: a * b
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COMPILER_RT_ABI ti_int __multi3(ti_int a, ti_int b) {
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twords x;
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x.all = a;
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twords y;
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y.all = b;
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twords r;
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r.all = __mulddi3(x.s.low, y.s.low);
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r.s.high += x.s.high * y.s.low + x.s.low * y.s.high;
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return r.all;
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}
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#endif // CRT_HAS_128BIT
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