mirror of
https://github.com/JakeHillion/object-introspection.git
synced 2024-11-14 14:26:55 +00:00
146 lines
4.2 KiB
C++
146 lines
4.2 KiB
C++
/*
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* Copyright (c) Meta Platforms, Inc. and 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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#define NDEBUG 1
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// Required for compatibility with new glibc headers
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#define __malloc__(x, y) __malloc__
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#if !__has_builtin(__builtin_free)
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#define __builtin_free(x) free(x)
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#endif
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#pragma clang diagnostic ignored "-Wunknown-attributes"
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// clang-format off
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// The header xmmintrin.h must come first. Otherwise it results in errors
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// jemalloc during JIT compilation
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#include <xmmintrin.h>
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#include <cstdint>
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#include <utility>
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#include <unistd.h>
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// clang-format on
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#define C10_USING_CUSTOM_GENERATED_MACROS
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constexpr int oidMagicId = 0x01DE8;
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#include <array>
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namespace {
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class {
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private:
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// 1 MiB of pointers
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std::array<uintptr_t, (1 << 20) / sizeof(uintptr_t)> data;
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// twang_mix64 hash function, taken from Folly where it is used
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// as the default hash function for 64-bit integers
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constexpr static uint64_t twang_mix64(uint64_t key) noexcept {
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key = (~key) + (key << 21); // key *= (1 << 21) - 1; key -= 1;
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key = key ^ (key >> 24);
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key = key + (key << 3) + (key << 8); // key *= 1 + (1 << 3) + (1 << 8)
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key = key ^ (key >> 14);
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key = key + (key << 2) + (key << 4); // key *= 1 + (1 << 2) + (1 << 4)
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key = key ^ (key >> 28);
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key = key + (key << 31); // key *= 1 + (1 << 31)
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return key;
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}
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public:
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void initialize() noexcept {
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data.fill(0);
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}
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// Adds the pointer to the set.
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// Returns `true` if the value was newly added,
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// or `false` if the value was already present.
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bool add(uintptr_t pointer) noexcept {
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__builtin_assume(pointer > 0);
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uint64_t index = twang_mix64(pointer) % data.size();
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while (true) {
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uintptr_t entry = data[index];
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if (entry == 0) {
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data[index] = pointer;
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return true;
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}
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if (entry == pointer) {
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return false;
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}
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index = (index + 1) % data.size();
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}
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}
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} static pointers;
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} // namespace
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// alignas(0) is ignored according to docs so can be default
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template <unsigned int N, unsigned int align = 0>
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struct alignas(align) DummySizedOperator {
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char c[N];
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};
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// The empty class specialization is, unfortunately, necessary. When this
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// operator is passed as a template parameter to something like unordered_map,
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// even though an empty class and a class with a single character have size one,
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// there is some empty class optimization that changes the static size of the
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// container if an empty class is passed.
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// DummySizedOperator<0,0> also collapses to this
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template <>
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struct DummySizedOperator<0> {};
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template <template <typename, size_t, size_t> typename DerivedT,
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typename T,
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size_t N,
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size_t Align>
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struct DummyAllocatorBase {
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using value_type = T;
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T* allocate(std::size_t n) {
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return nullptr;
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}
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void deallocate(T* p, std::size_t n) noexcept {
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}
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template <typename U>
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struct rebind {
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using other = DerivedT<U, N, Align>;
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};
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};
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template <typename T, size_t N, size_t Align = 0>
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struct alignas(Align) DummyAllocator
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: DummyAllocatorBase<DummyAllocator, T, N, Align> {
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char c[N];
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};
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template <typename T>
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struct DummyAllocator<T, 0> : DummyAllocatorBase<DummyAllocator, T, 0, 0> {};
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template <typename Type, size_t ExpectedSize, size_t ActualSize = 0>
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struct validate_size {
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static constexpr bool value = true;
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static_assert(ExpectedSize == ActualSize);
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};
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template <typename Type, size_t ExpectedSize>
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struct validate_size<Type, ExpectedSize>
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: validate_size<Type, ExpectedSize, sizeof(Type)> {};
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template <size_t ExpectedOffset, size_t ActualOffset>
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struct validate_offset {
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static constexpr bool value = true;
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static_assert(ExpectedOffset == ActualOffset);
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};
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