77 lines
2.3 KiB
C++
77 lines
2.3 KiB
C++
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/*
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <folly/container/detail/F14Table.h>
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#include <atomic>
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#include <chrono>
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namespace folly {
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namespace f14 {
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namespace detail {
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// If you get a link failure that leads you here, your build has varying
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// compiler flags across compilation units in a way that would break F14.
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// SIMD (SSE2 or NEON) needs to be either on everywhere or off everywhere
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// that uses F14. If SIMD is on then hardware CRC needs to be enabled
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// everywhere or disabled everywhere.
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void F14LinkCheck<getF14IntrinsicsMode()>::check() noexcept {}
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#if FOLLY_F14_VECTOR_INTRINSICS_AVAILABLE
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EmptyTagVectorType kEmptyTagVector = {};
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#endif
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//// Debug and ASAN stuff
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#if defined(FOLLY_TLS) && (!defined(NDEBUG) || FOLLY_LIBRARY_SANITIZE_ADDRESS)
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#define FOLLY_F14_DETAIL_TLS_SIZE_T FOLLY_TLS std::size_t
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#else
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#define FOLLY_F14_DETAIL_TLS_SIZE_T std::atomic<std::size_t>
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#endif
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bool tlsPendingSafeInserts(std::ptrdiff_t delta) {
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static FOLLY_F14_DETAIL_TLS_SIZE_T value{0};
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FOLLY_SAFE_DCHECK(delta >= -1, "");
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std::size_t v = value;
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if (delta > 0 || (delta == -1 && v > 0)) {
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v += delta;
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v = std::min(std::numeric_limits<std::size_t>::max() / 2, v);
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value = v;
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}
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return v != 0;
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}
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std::size_t tlsMinstdRand(std::size_t n) {
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FOLLY_SAFE_DCHECK(n > 0, "");
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static FOLLY_F14_DETAIL_TLS_SIZE_T state{0};
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auto s = static_cast<uint32_t>(state);
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if (s == 0) {
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uint64_t seed = static_cast<uint64_t>(
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std::chrono::steady_clock::now().time_since_epoch().count());
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s = hash::twang_32from64(seed);
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}
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s = static_cast<uint32_t>((s * uint64_t{48271}) % uint64_t{2147483647});
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state = s;
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return std::size_t{s} % n;
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}
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} // namespace detail
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} // namespace f14
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} // namespace folly
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