712b182a8b
When deciding whether to perform the memset optimization in ranges::fill_n, we were crucially neglecting to check that the output pointer's value type is a byte type. This patch adds such a check to the problematic condition in ranges::fill_n. At the same time, this patch relaxes the overly conservative __is_byte<_Tp>::__value check that requires the fill type be a byte type. It's overly conservative because it means we won't enable the memset optimization in the following example char c[100]; ranges::fill(c, 37); because the fill type is deduced to be int here. Rather than requiring that the fill type be a byte type, it seems safe to just require the fill type be an integral type, which is what this patch does. libstdc++-v3/ChangeLog: PR libstdc++/94017 * include/bits/ranges_algobase.h (__fill_n_fn::operator()): Refine condition for when to use memset, making sure to additionally check that the output pointer's value type is a non-volatile byte type. Instead of requiring that the fill type is a byte type, just require that it's an integral type. * testsuite/20_util/specialized_algorithms/uninitialized_fill/94017.cc: New test. * testsuite/20_util/specialized_algorithms/uninitialized_fill_n/94017.cc: New test. * testsuite/25_algorithms/fill/94013.cc: Uncomment part that was blocked by PR 94017. * testsuite/25_algorithms/fill/94017.cc: New test. * testsuite/25_algorithms/fill_n/94017.cc: New test.
46 lines
1.1 KiB
C++
46 lines
1.1 KiB
C++
// Copyright (C) 2020 Free Software Foundation, Inc.
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//
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// This file is part of the GNU ISO C++ Library. This library is free
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// software; you can redistribute it and/or modify it under the
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// terms of the GNU General Public License as published by the
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// Free Software Foundation; either version 3, or (at your option)
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// any later version.
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License along
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// with this library; see the file COPYING3. If not see
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// <http://www.gnu.org/licenses/>.
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// { dg-do run }
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#include <algorithm>
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#include <testsuite_hooks.h>
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void
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test01()
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{
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volatile unsigned char a[2] = { 1, 2 };
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volatile unsigned char c = 3;
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std::fill(a, a+2, c);
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VERIFY( a[0] == 3 && a[1] == 3 );
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#if __cplusplus > 201703L
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c = 4;
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std::ranges::fill(a, c);
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VERIFY( a[0] == 4 && a[1] == 4 );
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unsigned char c2 = 5;
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std::ranges::fill(a, c2);
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#endif
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}
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int
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main()
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{
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test01();
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}
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