| /* |
| * Copyright (C) 2016-2017 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 "MarkedBlock.h" |
| #include "WeakSet.h" |
| |
| namespace JSC { |
| |
| class SlotVisitor; |
| |
| // WebKit has a good malloc that already knows what to do for large allocations. The GC shouldn't |
| // have to think about such things. That's where LargeAllocation comes in. We will allocate large |
| // objects directly using malloc, and put the LargeAllocation header just before them. We can detect |
| // when a HeapCell* is a LargeAllocation because it will have the MarkedBlock::atomSize / 2 bit set. |
| |
| class LargeAllocation : public BasicRawSentinelNode<LargeAllocation> { |
| public: |
| static LargeAllocation* tryCreate(Heap&, size_t, Subspace*); |
| |
| ~LargeAllocation(); |
| |
| static LargeAllocation* fromCell(const void* cell) |
| { |
| return bitwise_cast<LargeAllocation*>(bitwise_cast<char*>(cell) - headerSize()); |
| } |
| |
| HeapCell* cell() const |
| { |
| return bitwise_cast<HeapCell*>(bitwise_cast<char*>(this) + headerSize()); |
| } |
| |
| static bool isLargeAllocation(HeapCell* cell) |
| { |
| return bitwise_cast<uintptr_t>(cell) & halfAlignment; |
| } |
| |
| Subspace* subspace() const { return m_subspace; } |
| |
| void lastChanceToFinalize(); |
| |
| Heap* heap() const { return m_weakSet.heap(); } |
| VM* vm() const { return m_weakSet.vm(); } |
| WeakSet& weakSet() { return m_weakSet; } |
| |
| void shrink(); |
| |
| void visitWeakSet(SlotVisitor&); |
| void reapWeakSet(); |
| |
| void clearNewlyAllocated() { m_isNewlyAllocated = false; } |
| void flip(); |
| |
| bool isNewlyAllocated() const { return m_isNewlyAllocated; } |
| ALWAYS_INLINE bool isMarked() { return m_isMarked.load(std::memory_order_relaxed); } |
| ALWAYS_INLINE bool isMarked(HeapCell*) { return isMarked(); } |
| ALWAYS_INLINE bool isMarked(HeapCell*, Dependency) { return isMarked(); } |
| ALWAYS_INLINE bool isMarked(HeapVersion, HeapCell*) { return isMarked(); } |
| bool isLive() { return isMarked() || isNewlyAllocated(); } |
| |
| bool hasValidCell() const { return m_hasValidCell; } |
| |
| bool isEmpty(); |
| |
| size_t cellSize() const { return m_cellSize; } |
| |
| bool aboveLowerBound(const void* rawPtr) |
| { |
| char* ptr = bitwise_cast<char*>(rawPtr); |
| char* begin = bitwise_cast<char*>(cell()); |
| return ptr >= begin; |
| } |
| |
| bool belowUpperBound(const void* rawPtr) |
| { |
| char* ptr = bitwise_cast<char*>(rawPtr); |
| char* begin = bitwise_cast<char*>(cell()); |
| char* end = begin + cellSize(); |
| // We cannot #include IndexingHeader.h because reasons. The fact that IndexingHeader is 8 |
| // bytes is wired deep into our engine, so this isn't so bad. |
| size_t sizeOfIndexingHeader = 8; |
| return ptr <= end + sizeOfIndexingHeader; |
| } |
| |
| bool contains(const void* rawPtr) |
| { |
| return aboveLowerBound(rawPtr) && belowUpperBound(rawPtr); |
| } |
| |
| const CellAttributes& attributes() const { return m_attributes; } |
| |
| Dependency aboutToMark(HeapVersion) { return Dependency(); } |
| |
| ALWAYS_INLINE bool testAndSetMarked() |
| { |
| // This method is usually called when the object is already marked. This avoids us |
| // having to CAS in that case. It's profitable to reduce the total amount of CAS |
| // traffic. |
| if (isMarked()) |
| return true; |
| return m_isMarked.compareExchangeStrong(false, true); |
| } |
| ALWAYS_INLINE bool testAndSetMarked(HeapCell*, Dependency) { return testAndSetMarked(); } |
| void clearMarked() { m_isMarked.store(false); } |
| |
| void noteMarked() { } |
| |
| #if ASSERT_DISABLED |
| void assertValidCell(VM&, HeapCell*) const { } |
| #else |
| void assertValidCell(VM&, HeapCell*) const; |
| #endif |
| |
| void sweep(); |
| |
| void destroy(); |
| |
| void dump(PrintStream&) const; |
| |
| private: |
| LargeAllocation(Heap&, size_t, Subspace*); |
| |
| static const unsigned alignment = MarkedBlock::atomSize; |
| static const unsigned halfAlignment = alignment / 2; |
| |
| static unsigned headerSize(); |
| |
| size_t m_cellSize; |
| bool m_isNewlyAllocated; |
| bool m_hasValidCell; |
| Atomic<bool> m_isMarked; |
| CellAttributes m_attributes; |
| Subspace* m_subspace; |
| WeakSet m_weakSet; |
| }; |
| |
| inline unsigned LargeAllocation::headerSize() |
| { |
| return ((sizeof(LargeAllocation) + halfAlignment - 1) & ~(halfAlignment - 1)) | halfAlignment; |
| } |
| |
| } // namespace JSC |
| |