Changeset 161540 in webkit for trunk/Source/JavaScriptCore/heap/MarkStack.cpp

Timestamp:

Jan 8, 2014, 7:49:38 PM (11 years ago)

Author:

[email protected]

Message:

Marking should be generational
​https://bugs.webkit.org/show_bug.cgi?id=126552

Reviewed by Geoffrey Garen.

Source/JavaScriptCore:

Re-marking the same objects over and over is a waste of effort. This patch implements
the sticky mark bit algorithm (along with our already-present write barriers) to reduce
overhead during garbage collection caused by rescanning objects.

There are now two collection modes, EdenCollection and FullCollection. EdenCollections
only visit new objects or objects that were added to the remembered set by a write barrier.
FullCollections are normal collections that visit all objects regardless of their
generation.

In this patch EdenCollections do not do anything in CopiedSpace. This will be fixed in
​https://bugs.webkit.org/show_bug.cgi?id=126555.

• bytecode/CodeBlock.cpp:

(JSC::CodeBlock::visitAggregate):

• bytecode/CodeBlock.h:

(JSC::CodeBlockSet::mark):

• dfg/DFGOperations.cpp:
• heap/CodeBlockSet.cpp:

(JSC::CodeBlockSet::add):
(JSC::CodeBlockSet::traceMarked):
(JSC::CodeBlockSet::rememberCurrentlyExecutingCodeBlocks):

• heap/CodeBlockSet.h:
• heap/CopiedBlockInlines.h:

(JSC::CopiedBlock::reportLiveBytes):

• heap/CopiedSpace.cpp:

(JSC::CopiedSpace::didStartFullCollection):

• heap/CopiedSpace.h:

(JSC::CopiedSpace::heap):

• heap/Heap.cpp:

(JSC::Heap::Heap):
(JSC::Heap::didAbandon):
(JSC::Heap::markRoots):
(JSC::Heap::copyBackingStores):
(JSC::Heap::addToRememberedSet):
(JSC::Heap::collectAllGarbage):
(JSC::Heap::collect):
(JSC::Heap::didAllocate):
(JSC::Heap::writeBarrier):

• heap/Heap.h:

(JSC::Heap::isInRememberedSet):
(JSC::Heap::operationInProgress):
(JSC::Heap::shouldCollect):
(JSC::Heap::isCollecting):
(JSC::Heap::isWriteBarrierEnabled):
(JSC::Heap::writeBarrier):

• heap/HeapOperation.h:
• heap/MarkStack.cpp:

(JSC::MarkStackArray::~MarkStackArray):
(JSC::MarkStackArray::clear):
(JSC::MarkStackArray::fillVector):

• heap/MarkStack.h:
• heap/MarkedAllocator.cpp:

(JSC::isListPagedOut):
(JSC::MarkedAllocator::isPagedOut):
(JSC::MarkedAllocator::tryAllocateHelper):
(JSC::MarkedAllocator::addBlock):
(JSC::MarkedAllocator::removeBlock):
(JSC::MarkedAllocator::reset):

• heap/MarkedAllocator.h:

(JSC::MarkedAllocator::MarkedAllocator):

• heap/MarkedBlock.cpp:

(JSC::MarkedBlock::clearMarks):
(JSC::MarkedBlock::clearRememberedSet):
(JSC::MarkedBlock::clearMarksWithCollectionType):
(JSC::MarkedBlock::lastChanceToFinalize):

• heap/MarkedBlock.h: Changed atomSize to 16 bytes because we have no objects smaller

than 16 bytes. This is also to pay for the additional Bitmap for the remembered set.
(JSC::MarkedBlock::didConsumeEmptyFreeList):
(JSC::MarkedBlock::setRemembered):
(JSC::MarkedBlock::clearRemembered):
(JSC::MarkedBlock::atomicClearRemembered):
(JSC::MarkedBlock::isRemembered):

• heap/MarkedSpace.cpp:

(JSC::MarkedSpace::~MarkedSpace):
(JSC::MarkedSpace::resetAllocators):
(JSC::MarkedSpace::visitWeakSets):
(JSC::MarkedSpace::reapWeakSets):
(JSC::VerifyMarked::operator()):
(JSC::MarkedSpace::clearMarks):

• heap/MarkedSpace.h:

(JSC::ClearMarks::operator()):
(JSC::ClearRememberedSet::operator()):
(JSC::MarkedSpace::didAllocateInBlock):
(JSC::MarkedSpace::clearRememberedSet):

• heap/SlotVisitor.cpp:

(JSC::SlotVisitor::~SlotVisitor):
(JSC::SlotVisitor::clearMarkStack):

• heap/SlotVisitor.h:

(JSC::SlotVisitor::markStack):
(JSC::SlotVisitor::sharedData):

• heap/SlotVisitorInlines.h:

(JSC::SlotVisitor::internalAppend):
(JSC::SlotVisitor::unconditionallyAppend):
(JSC::SlotVisitor::copyLater):
(JSC::SlotVisitor::reportExtraMemoryUsage):
(JSC::SlotVisitor::heap):

• jit/Repatch.cpp:
• runtime/JSGenericTypedArrayViewInlines.h:

(JSC::JSGenericTypedArrayView<Adaptor>::visitChildren):

• runtime/JSPropertyNameIterator.h:

(JSC::StructureRareData::setEnumerationCache):

• runtime/JSString.cpp:

(JSC::JSString::visitChildren):

• runtime/StructureRareDataInlines.h:

(JSC::StructureRareData::setPreviousID):
(JSC::StructureRareData::setObjectToStringValue):

• runtime/WeakMapData.cpp:

(JSC::WeakMapData::visitChildren):

Source/WTF:

• wtf/Bitmap.h:

(WTF::WordType>::count): Added a cast that became necessary when Bitmap
is used with smaller types than int32_t.

File:

• trunk/Source/JavaScriptCore/heap/MarkStack.cpp (modified) (2 diffs)

trunk/Source/JavaScriptCore/heap/MarkStack.cpp

@@ -58 +58 @@
 MarkStackArray::~MarkStackArray()
 {
-    ASSERT(m_numberOfSegments == 1 && m_segments.size() == 1);
+    ASSERT(m_numberOfSegments == 1);
+    ASSERT(m_segments.size() == 1);
     m_blockAllocator.deallocate(MarkStackSegment::destroy(m_segments.removeHead()));
+    m_numberOfSegments--;
+    ASSERT(!m_numberOfSegments);
+    ASSERT(!m_segments.size());
+}
+
+void MarkStackArray::clear()
+{
+    if (!m_segments.head())
+        return;
+    MarkStackSegment* next;
+    for (MarkStackSegment* current = m_segments.head(); current->next(); current = next) {
+        next = current->next();
+        m_segments.remove(current);
+        m_blockAllocator.deallocate(MarkStackSegment::destroy(current));
+    }
+    m_top = 0;
+    m_numberOfSegments = 1;
+#if !ASSERT_DISABLED
+    m_segments.head()->m_top = 0;
+#endif
 }
 
@@ -168 +189 @@
 }
 
+void MarkStackArray::fillVector(Vector<const JSCell*>& vector)
+{
+    ASSERT(vector.size() == size());
+
+    MarkStackSegment* currentSegment = m_segments.head();
+    if (!currentSegment)
+        return;
+
+    unsigned count = 0;
+    for (unsigned i = 0; i < m_top; ++i) {
+        ASSERT(currentSegment->data()[i]);
+        vector[count++] = currentSegment->data()[i];
+    }
+
+    currentSegment = currentSegment->next();
+    while (currentSegment) {
+        for (unsigned i = 0; i < s_segmentCapacity; ++i) {
+            ASSERT(currentSegment->data()[i]);
+            vector[count++] = currentSegment->data()[i];
+        }
+        currentSegment = currentSegment->next();
+    }
+}
+
 } // namespace JSC