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