47 lines
1.7 KiB
C++
47 lines
1.7 KiB
C++
// Copyright (C) 2020-2024 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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//
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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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//
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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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// expensive: * [1-9] * *
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#include "bits/main.h"
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template <typename V>
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void
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test()
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{
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using T = typename V::value_type;
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// V must store V::size() values of type T giving us the lower bound on the
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// sizeof
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VERIFY(sizeof(V) >= sizeof(T) * V::size());
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// For fixed_size, V should not pad more than to the next-power-of-2 of
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// sizeof(T) * V::size() (for ABI stability of V), giving us the upper bound
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// on the sizeof. For non-fixed_size we give the implementation a bit more
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// slack to trade space vs. efficiency.
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auto n = sizeof(T) * V::size();
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if (n & (n - 1))
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{
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n = ((n << 1) & ~n) & ~((n >> 1) | (n >> 3));
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while (n & (n - 1))
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n &= n - 1;
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}
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if constexpr (
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!std::is_same_v<typename V::abi_type,
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std::experimental::simd_abi::fixed_size<V::size()>>)
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n *= 2;
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VERIFY(sizeof(V) <= n) << "\nsizeof(V): " << sizeof(V) << "\nn: " << n;
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}
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