138 lines
4.2 KiB
C++
138 lines
4.2 KiB
C++
/*
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* Copyright (C) 2020-2021 Apple Inc. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
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* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
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* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#pragma once
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#include "Algorithm.h"
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#include "Mutex.h"
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#include "ObjectType.h"
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#include "Sizes.h"
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#if BOS(DARWIN)
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#include <mach/vm_param.h>
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#endif
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namespace bmalloc {
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class Chunk;
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// Querying ObjectType for Chunk without locking.
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class ObjectTypeTable {
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public:
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ObjectTypeTable();
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static constexpr unsigned shiftAmount = 20;
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static_assert((1ULL << shiftAmount) == chunkSize);
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static_assert((BOS_EFFECTIVE_ADDRESS_WIDTH - shiftAmount) <= 32);
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class Bits;
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ObjectType get(Chunk*);
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void set(UniqueLockHolder&, Chunk*, ObjectType);
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private:
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static unsigned convertToIndex(Chunk* chunk)
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{
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uintptr_t address = reinterpret_cast<uintptr_t>(chunk);
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BASSERT(!(address & (~chunkMask)));
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return static_cast<unsigned>(address >> shiftAmount);
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}
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Bits* m_bits;
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};
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class ObjectTypeTable::Bits {
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public:
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using WordType = unsigned;
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static constexpr unsigned bitCountPerWord = sizeof(WordType) * 8;
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static constexpr WordType one = 1;
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constexpr Bits(Bits* previous, unsigned begin, unsigned end)
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: m_previous(previous)
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, m_begin(begin)
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, m_end(end)
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{
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}
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bool get(unsigned index);
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void set(unsigned index, bool);
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Bits* previous() const { return m_previous; }
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unsigned begin() const { return m_begin; }
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unsigned end() const { return m_end; }
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unsigned count() const { return m_end - m_begin; }
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unsigned sizeInBytes() const { return count() / 8; }
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const WordType* words() const { return const_cast<Bits*>(this)->words(); }
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WordType* words() { return reinterpret_cast<WordType*>(reinterpret_cast<uintptr_t>(this) + sizeof(Bits)); }
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WordType* wordForIndex(unsigned);
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private:
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Bits* m_previous { nullptr }; // Keeping the previous Bits* just to suppress Leaks warnings.
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unsigned m_begin { 0 };
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unsigned m_end { 0 };
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};
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static_assert(!(sizeof(ObjectTypeTable::Bits) % sizeof(ObjectTypeTable::Bits::WordType)));
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extern BEXPORT ObjectTypeTable::Bits sentinelBits;
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inline ObjectTypeTable::ObjectTypeTable()
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: m_bits(&sentinelBits)
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{
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}
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inline ObjectType ObjectTypeTable::get(Chunk* chunk)
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{
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Bits* bits = m_bits;
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unsigned index = convertToIndex(chunk);
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BASSERT(bits);
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if (bits->begin() <= index && index < bits->end())
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return static_cast<ObjectType>(bits->get(index));
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return { };
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}
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inline bool ObjectTypeTable::Bits::get(unsigned index)
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{
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unsigned n = index - begin();
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return words()[n / bitCountPerWord] & (one << (n % bitCountPerWord));
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}
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inline void ObjectTypeTable::Bits::set(unsigned index, bool value)
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{
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unsigned n = index - begin();
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if (value)
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words()[n / bitCountPerWord] |= (one << (n % bitCountPerWord));
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else
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words()[n / bitCountPerWord] &= ~(one << (n % bitCountPerWord));
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}
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inline ObjectTypeTable::Bits::WordType* ObjectTypeTable::Bits::wordForIndex(unsigned index)
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{
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unsigned n = index - begin();
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return &words()[n / bitCountPerWord];
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}
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} // namespace bmalloc
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