| /* |
| * Copyright (C) 2003-2018 Apple Inc. All rights reserved. |
| * Copyright (C) 2007 Eric Seidel <eric@webkit.org> |
| * |
| * This library is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU Lesser General Public |
| * License as published by the Free Software Foundation; either |
| * version 2 of the License, or (at your option) any later version. |
| * |
| * This library is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| * Lesser General Public License for more details. |
| * |
| * You should have received a copy of the GNU Lesser General Public |
| * License along with this library; if not, write to the Free Software |
| * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| * |
| */ |
| |
| #include "config.h" |
| #include "MarkedSpace.h" |
| |
| #include "BlockDirectoryInlines.h" |
| #include "FunctionCodeBlock.h" |
| #include "IncrementalSweeper.h" |
| #include "JSObject.h" |
| #include "JSCInlines.h" |
| #include "MarkedBlockInlines.h" |
| #include <wtf/ListDump.h> |
| |
| namespace JSC { |
| |
| std::array<size_t, MarkedSpace::numSizeClasses> MarkedSpace::s_sizeClassForSizeStep; |
| |
| namespace { |
| |
| const Vector<size_t>& sizeClasses() |
| { |
| static Vector<size_t>* result; |
| static std::once_flag once; |
| std::call_once( |
| once, |
| [] { |
| result = new Vector<size_t>(); |
| |
| if (Options::dumpSizeClasses()) { |
| dataLog("Block size: ", MarkedBlock::blockSize, "\n"); |
| dataLog("Footer size: ", sizeof(MarkedBlock::Footer), "\n"); |
| } |
| |
| auto add = [&] (size_t sizeClass) { |
| sizeClass = WTF::roundUpToMultipleOf<MarkedBlock::atomSize>(sizeClass); |
| if (Options::dumpSizeClasses()) |
| dataLog("Adding JSC MarkedSpace size class: ", sizeClass, "\n"); |
| // Perform some validation as we go. |
| RELEASE_ASSERT(!(sizeClass % MarkedSpace::sizeStep)); |
| if (result->isEmpty()) |
| RELEASE_ASSERT(sizeClass == MarkedSpace::sizeStep); |
| result->append(sizeClass); |
| }; |
| |
| // This is a definition of the size classes in our GC. It must define all of the |
| // size classes from sizeStep up to largeCutoff. |
| |
| // Have very precise size classes for the small stuff. This is a loop to make it easy to reduce |
| // atomSize. |
| for (size_t size = MarkedSpace::sizeStep; size < MarkedSpace::preciseCutoff; size += MarkedSpace::sizeStep) |
| add(size); |
| |
| // We want to make sure that the remaining size classes minimize internal fragmentation (i.e. |
| // the wasted space at the tail end of a MarkedBlock) while proceeding roughly in an exponential |
| // way starting at just above the precise size classes to four cells per block. |
| |
| if (Options::dumpSizeClasses()) |
| dataLog(" Marked block payload size: ", static_cast<size_t>(MarkedSpace::blockPayload), "\n"); |
| |
| for (unsigned i = 0; ; ++i) { |
| double approximateSize = MarkedSpace::preciseCutoff * pow(Options::sizeClassProgression(), i); |
| |
| if (Options::dumpSizeClasses()) |
| dataLog(" Next size class as a double: ", approximateSize, "\n"); |
| |
| size_t approximateSizeInBytes = static_cast<size_t>(approximateSize); |
| |
| if (Options::dumpSizeClasses()) |
| dataLog(" Next size class as bytes: ", approximateSizeInBytes, "\n"); |
| |
| // Make sure that the computer did the math correctly. |
| RELEASE_ASSERT(approximateSizeInBytes >= MarkedSpace::preciseCutoff); |
| |
| if (approximateSizeInBytes > MarkedSpace::largeCutoff) |
| break; |
| |
| size_t sizeClass = |
| WTF::roundUpToMultipleOf<MarkedSpace::sizeStep>(approximateSizeInBytes); |
| |
| if (Options::dumpSizeClasses()) |
| dataLog(" Size class: ", sizeClass, "\n"); |
| |
| // Optimize the size class so that there isn't any slop at the end of the block's |
| // payload. |
| unsigned cellsPerBlock = MarkedSpace::blockPayload / sizeClass; |
| size_t possiblyBetterSizeClass = (MarkedSpace::blockPayload / cellsPerBlock) & ~(MarkedSpace::sizeStep - 1); |
| |
| if (Options::dumpSizeClasses()) |
| dataLog(" Possibly better size class: ", possiblyBetterSizeClass, "\n"); |
| |
| // The size class we just came up with is better than the other one if it reduces |
| // total wastage assuming we only allocate cells of that size. |
| size_t originalWastage = MarkedSpace::blockPayload - cellsPerBlock * sizeClass; |
| size_t newWastage = (possiblyBetterSizeClass - sizeClass) * cellsPerBlock; |
| |
| if (Options::dumpSizeClasses()) |
| dataLog(" Original wastage: ", originalWastage, ", new wastage: ", newWastage, "\n"); |
| |
| size_t betterSizeClass; |
| if (newWastage > originalWastage) |
| betterSizeClass = sizeClass; |
| else |
| betterSizeClass = possiblyBetterSizeClass; |
| |
| if (Options::dumpSizeClasses()) |
| dataLog(" Choosing size class: ", betterSizeClass, "\n"); |
| |
| if (betterSizeClass == result->last()) { |
| // Defense for when expStep is small. |
| continue; |
| } |
| |
| // This is usually how we get out of the loop. |
| if (betterSizeClass > MarkedSpace::largeCutoff |
| || betterSizeClass > Options::largeAllocationCutoff()) |
| break; |
| |
| add(betterSizeClass); |
| } |
| |
| // Manually inject size classes for objects we know will be allocated in high volume. |
| // FIXME: All of these things should have IsoSubspaces. |
| // https://bugs.webkit.org/show_bug.cgi?id=179876 |
| add(sizeof(UnlinkedFunctionCodeBlock)); |
| add(sizeof(JSString)); |
| |
| { |
| // Sort and deduplicate. |
| std::sort(result->begin(), result->end()); |
| auto it = std::unique(result->begin(), result->end()); |
| result->shrinkCapacity(it - result->begin()); |
| } |
| |
| if (Options::dumpSizeClasses()) |
| dataLog("JSC Heap MarkedSpace size class dump: ", listDump(*result), "\n"); |
| |
| // We have an optimiation in MarkedSpace::optimalSizeFor() that assumes things about |
| // the size class table. This checks our results against that function's assumptions. |
| for (size_t size = MarkedSpace::sizeStep, i = 0; size <= MarkedSpace::preciseCutoff; size += MarkedSpace::sizeStep, i++) |
| RELEASE_ASSERT(result->at(i) == size); |
| }); |
| return *result; |
| } |
| |
| template<typename TableType, typename SizeClassCons, typename DefaultCons> |
| void buildSizeClassTable(TableType& table, const SizeClassCons& cons, const DefaultCons& defaultCons) |
| { |
| size_t nextIndex = 0; |
| for (size_t sizeClass : sizeClasses()) { |
| auto entry = cons(sizeClass); |
| size_t index = MarkedSpace::sizeClassToIndex(sizeClass); |
| for (size_t i = nextIndex; i <= index; ++i) |
| table[i] = entry; |
| nextIndex = index + 1; |
| } |
| ASSERT(MarkedSpace::sizeClassToIndex(MarkedSpace::largeCutoff - 1) < MarkedSpace::numSizeClasses); |
| for (size_t i = nextIndex; i < MarkedSpace::numSizeClasses; ++i) |
| table[i] = defaultCons(MarkedSpace::indexToSizeClass(i)); |
| } |
| |
| } // anonymous namespace |
| |
| void MarkedSpace::initializeSizeClassForStepSize() |
| { |
| static std::once_flag flag; |
| std::call_once( |
| flag, |
| [] { |
| buildSizeClassTable( |
| s_sizeClassForSizeStep, |
| [&] (size_t sizeClass) -> size_t { |
| return sizeClass; |
| }, |
| [&] (size_t sizeClass) -> size_t { |
| return sizeClass; |
| }); |
| }); |
| } |
| |
| MarkedSpace::MarkedSpace(Heap* heap) |
| : m_heap(heap) |
| { |
| initializeSizeClassForStepSize(); |
| } |
| |
| MarkedSpace::~MarkedSpace() |
| { |
| ASSERT(!m_blocks.set().size()); |
| } |
| |
| void MarkedSpace::freeMemory() |
| { |
| forEachBlock( |
| [&] (MarkedBlock::Handle* block) { |
| freeBlock(block); |
| }); |
| for (LargeAllocation* allocation : m_largeAllocations) |
| allocation->destroy(); |
| } |
| |
| void MarkedSpace::lastChanceToFinalize() |
| { |
| forEachDirectory( |
| [&] (BlockDirectory& directory) -> IterationStatus { |
| directory.lastChanceToFinalize(); |
| return IterationStatus::Continue; |
| }); |
| for (LargeAllocation* allocation : m_largeAllocations) |
| allocation->lastChanceToFinalize(); |
| } |
| |
| void MarkedSpace::sweep() |
| { |
| m_heap->sweeper().stopSweeping(); |
| forEachDirectory( |
| [&] (BlockDirectory& directory) -> IterationStatus { |
| directory.sweep(); |
| return IterationStatus::Continue; |
| }); |
| } |
| |
| void MarkedSpace::sweepLargeAllocations() |
| { |
| RELEASE_ASSERT(m_largeAllocationsNurseryOffset == m_largeAllocations.size()); |
| unsigned srcIndex = m_largeAllocationsNurseryOffsetForSweep; |
| unsigned dstIndex = srcIndex; |
| while (srcIndex < m_largeAllocations.size()) { |
| LargeAllocation* allocation = m_largeAllocations[srcIndex++]; |
| allocation->sweep(); |
| if (allocation->isEmpty()) { |
| m_capacity -= allocation->cellSize(); |
| allocation->destroy(); |
| continue; |
| } |
| allocation->setIndexInSpace(dstIndex); |
| m_largeAllocations[dstIndex++] = allocation; |
| } |
| m_largeAllocations.shrink(dstIndex); |
| m_largeAllocationsNurseryOffset = m_largeAllocations.size(); |
| } |
| |
| void MarkedSpace::prepareForAllocation() |
| { |
| ASSERT(!mayBeGCThread() || m_heap->worldIsStopped()); |
| for (Subspace* subspace : m_subspaces) |
| subspace->prepareForAllocation(); |
| |
| m_activeWeakSets.takeFrom(m_newActiveWeakSets); |
| |
| if (m_heap->collectionScope() == CollectionScope::Eden) |
| m_largeAllocationsNurseryOffsetForSweep = m_largeAllocationsNurseryOffset; |
| else |
| m_largeAllocationsNurseryOffsetForSweep = 0; |
| m_largeAllocationsNurseryOffset = m_largeAllocations.size(); |
| } |
| |
| void MarkedSpace::visitWeakSets(SlotVisitor& visitor) |
| { |
| auto visit = [&] (WeakSet* weakSet) { |
| weakSet->visit(visitor); |
| }; |
| |
| m_newActiveWeakSets.forEach(visit); |
| |
| if (m_heap->collectionScope() == CollectionScope::Full) |
| m_activeWeakSets.forEach(visit); |
| } |
| |
| void MarkedSpace::reapWeakSets() |
| { |
| auto visit = [&] (WeakSet* weakSet) { |
| weakSet->reap(); |
| }; |
| |
| m_newActiveWeakSets.forEach(visit); |
| |
| if (m_heap->collectionScope() == CollectionScope::Full) |
| m_activeWeakSets.forEach(visit); |
| } |
| |
| void MarkedSpace::stopAllocating() |
| { |
| ASSERT(!isIterating()); |
| forEachDirectory( |
| [&] (BlockDirectory& directory) -> IterationStatus { |
| directory.stopAllocating(); |
| return IterationStatus::Continue; |
| }); |
| } |
| |
| void MarkedSpace::stopAllocatingForGood() |
| { |
| ASSERT(!isIterating()); |
| forEachDirectory( |
| [&] (BlockDirectory& directory) -> IterationStatus { |
| directory.stopAllocatingForGood(); |
| return IterationStatus::Continue; |
| }); |
| } |
| |
| void MarkedSpace::prepareForConservativeScan() |
| { |
| m_largeAllocationsForThisCollectionBegin = m_largeAllocations.begin() + m_largeAllocationsOffsetForThisCollection; |
| m_largeAllocationsForThisCollectionSize = m_largeAllocations.size() - m_largeAllocationsOffsetForThisCollection; |
| m_largeAllocationsForThisCollectionEnd = m_largeAllocations.end(); |
| RELEASE_ASSERT(m_largeAllocationsForThisCollectionEnd == m_largeAllocationsForThisCollectionBegin + m_largeAllocationsForThisCollectionSize); |
| |
| std::sort( |
| m_largeAllocationsForThisCollectionBegin, m_largeAllocationsForThisCollectionEnd, |
| [&] (LargeAllocation* a, LargeAllocation* b) { |
| return a < b; |
| }); |
| unsigned index = m_largeAllocationsOffsetForThisCollection; |
| for (auto* start = m_largeAllocationsForThisCollectionBegin; start != m_largeAllocationsForThisCollectionEnd; ++start, ++index) { |
| (*start)->setIndexInSpace(index); |
| ASSERT(m_largeAllocations[index] == *start); |
| ASSERT(m_largeAllocations[index]->indexInSpace() == index); |
| } |
| } |
| |
| void MarkedSpace::prepareForMarking() |
| { |
| if (m_heap->collectionScope() == CollectionScope::Eden) |
| m_largeAllocationsOffsetForThisCollection = m_largeAllocationsNurseryOffset; |
| else |
| m_largeAllocationsOffsetForThisCollection = 0; |
| } |
| |
| void MarkedSpace::resumeAllocating() |
| { |
| forEachDirectory( |
| [&] (BlockDirectory& directory) -> IterationStatus { |
| directory.resumeAllocating(); |
| return IterationStatus::Continue; |
| }); |
| // Nothing to do for LargeAllocations. |
| } |
| |
| bool MarkedSpace::isPagedOut(MonotonicTime deadline) |
| { |
| bool result = false; |
| forEachDirectory( |
| [&] (BlockDirectory& directory) -> IterationStatus { |
| if (directory.isPagedOut(deadline)) { |
| result = true; |
| return IterationStatus::Done; |
| } |
| return IterationStatus::Continue; |
| }); |
| // FIXME: Consider taking LargeAllocations into account here. |
| return result; |
| } |
| |
| void MarkedSpace::freeBlock(MarkedBlock::Handle* block) |
| { |
| block->directory()->removeBlock(block); |
| m_capacity -= MarkedBlock::blockSize; |
| m_blocks.remove(&block->block()); |
| delete block; |
| } |
| |
| void MarkedSpace::freeOrShrinkBlock(MarkedBlock::Handle* block) |
| { |
| if (!block->isEmpty()) { |
| block->shrink(); |
| return; |
| } |
| |
| freeBlock(block); |
| } |
| |
| void MarkedSpace::shrink() |
| { |
| forEachDirectory( |
| [&] (BlockDirectory& directory) -> IterationStatus { |
| directory.shrink(); |
| return IterationStatus::Continue; |
| }); |
| } |
| |
| void MarkedSpace::beginMarking() |
| { |
| if (m_heap->collectionScope() == CollectionScope::Full) { |
| forEachDirectory( |
| [&] (BlockDirectory& directory) -> IterationStatus { |
| directory.beginMarkingForFullCollection(); |
| return IterationStatus::Continue; |
| }); |
| |
| if (UNLIKELY(nextVersion(m_markingVersion) == initialVersion)) { |
| forEachBlock( |
| [&] (MarkedBlock::Handle* handle) { |
| handle->block().resetMarks(); |
| }); |
| } |
| |
| m_markingVersion = nextVersion(m_markingVersion); |
| |
| for (LargeAllocation* allocation : m_largeAllocations) |
| allocation->flip(); |
| } |
| |
| if (!ASSERT_DISABLED) { |
| forEachBlock( |
| [&] (MarkedBlock::Handle* block) { |
| if (block->areMarksStale()) |
| return; |
| ASSERT(!block->isFreeListed()); |
| }); |
| } |
| |
| m_isMarking = true; |
| } |
| |
| void MarkedSpace::endMarking() |
| { |
| if (UNLIKELY(nextVersion(m_newlyAllocatedVersion) == initialVersion)) { |
| forEachBlock( |
| [&] (MarkedBlock::Handle* handle) { |
| handle->block().resetAllocated(); |
| }); |
| } |
| |
| m_newlyAllocatedVersion = nextVersion(m_newlyAllocatedVersion); |
| |
| for (unsigned i = m_largeAllocationsOffsetForThisCollection; i < m_largeAllocations.size(); ++i) |
| m_largeAllocations[i]->clearNewlyAllocated(); |
| |
| if (!ASSERT_DISABLED) { |
| for (LargeAllocation* allocation : m_largeAllocations) |
| ASSERT_UNUSED(allocation, !allocation->isNewlyAllocated()); |
| } |
| |
| forEachDirectory( |
| [&] (BlockDirectory& directory) -> IterationStatus { |
| directory.endMarking(); |
| return IterationStatus::Continue; |
| }); |
| |
| m_isMarking = false; |
| } |
| |
| void MarkedSpace::willStartIterating() |
| { |
| ASSERT(!isIterating()); |
| stopAllocating(); |
| m_isIterating = true; |
| } |
| |
| void MarkedSpace::didFinishIterating() |
| { |
| ASSERT(isIterating()); |
| resumeAllocating(); |
| m_isIterating = false; |
| } |
| |
| size_t MarkedSpace::objectCount() |
| { |
| size_t result = 0; |
| forEachBlock( |
| [&] (MarkedBlock::Handle* block) { |
| result += block->markCount(); |
| }); |
| for (LargeAllocation* allocation : m_largeAllocations) { |
| if (allocation->isMarked()) |
| result++; |
| } |
| return result; |
| } |
| |
| size_t MarkedSpace::size() |
| { |
| size_t result = 0; |
| forEachBlock( |
| [&] (MarkedBlock::Handle* block) { |
| result += block->markCount() * block->cellSize(); |
| }); |
| for (LargeAllocation* allocation : m_largeAllocations) { |
| if (allocation->isMarked()) |
| result += allocation->cellSize(); |
| } |
| return result; |
| } |
| |
| size_t MarkedSpace::capacity() |
| { |
| return m_capacity; |
| } |
| |
| void MarkedSpace::addActiveWeakSet(WeakSet* weakSet) |
| { |
| // We conservatively assume that the WeakSet should belong in the new set. In fact, some weak |
| // sets might contain new weak handles even though they are tied to old objects. This slightly |
| // increases the amount of scanning that an eden collection would have to do, but the effect |
| // ought to be small. |
| m_newActiveWeakSets.append(weakSet); |
| } |
| |
| void MarkedSpace::didAddBlock(MarkedBlock::Handle* block) |
| { |
| // WARNING: This function is called before block is fully initialized. The block will not know |
| // its cellSize() or attributes(). The latter implies that you can't ask things like |
| // needsDestruction(). |
| m_capacity += MarkedBlock::blockSize; |
| m_blocks.add(&block->block()); |
| } |
| |
| void MarkedSpace::didAllocateInBlock(MarkedBlock::Handle* block) |
| { |
| if (block->weakSet().isOnList()) { |
| block->weakSet().remove(); |
| m_newActiveWeakSets.append(&block->weakSet()); |
| } |
| } |
| |
| void MarkedSpace::snapshotUnswept() |
| { |
| if (m_heap->collectionScope() == CollectionScope::Eden) { |
| forEachDirectory( |
| [&] (BlockDirectory& directory) -> IterationStatus { |
| directory.snapshotUnsweptForEdenCollection(); |
| return IterationStatus::Continue; |
| }); |
| } else { |
| forEachDirectory( |
| [&] (BlockDirectory& directory) -> IterationStatus { |
| directory.snapshotUnsweptForFullCollection(); |
| return IterationStatus::Continue; |
| }); |
| } |
| } |
| |
| void MarkedSpace::assertNoUnswept() |
| { |
| if (ASSERT_DISABLED) |
| return; |
| forEachDirectory( |
| [&] (BlockDirectory& directory) -> IterationStatus { |
| directory.assertNoUnswept(); |
| return IterationStatus::Continue; |
| }); |
| } |
| |
| void MarkedSpace::dumpBits(PrintStream& out) |
| { |
| forEachDirectory( |
| [&] (BlockDirectory& directory) -> IterationStatus { |
| out.print("Bits for ", directory, ":\n"); |
| directory.dumpBits(out); |
| return IterationStatus::Continue; |
| }); |
| } |
| |
| void MarkedSpace::addBlockDirectory(const AbstractLocker&, BlockDirectory* directory) |
| { |
| directory->setNextDirectory(nullptr); |
| |
| WTF::storeStoreFence(); |
| |
| m_directories.append(std::mem_fn(&BlockDirectory::setNextDirectory), directory); |
| } |
| |
| } // namespace JSC |
