ValueProfile does not make it safe to introspect cell values
after garbage collection
https://bugs.webkit.org/show_bug.cgi?id=67354
Reviewed by Gavin Barraclough.
ValueProfile buckets are now weak references, implemented using a
light-weight weak reference mechanism that this patch also adds (the
WeakReferenceHarvester). If a cell stored in a ValueProfile bucket
is not marked, then the bucket is transformed into a Structure
pointer. If the Structure is not marked either, then it is turned
into a ClassInfo pointer.
* JavaScriptCore.xcodeproj/project.pbxproj:
* bytecode/CodeBlock.cpp:
(JSC::CodeBlock::~CodeBlock):
(JSC::CodeBlock::visitAggregate):
(JSC::CodeBlock::visitWeakReferences):
* bytecode/CodeBlock.h:
* bytecode/ValueProfile.h:
(JSC::ValueProfile::ValueProfile):
(JSC::ValueProfile::classInfo):
(JSC::ValueProfile::numberOfInt32s):
(JSC::ValueProfile::numberOfDoubles):
(JSC::ValueProfile::numberOfCells):
(JSC::ValueProfile::numberOfArrays):
(JSC::ValueProfile::probabilityOfArray):
(JSC::ValueProfile::WeakBucket::WeakBucket):
(JSC::ValueProfile::WeakBucket::operator!):
(JSC::ValueProfile::WeakBucket::isEmpty):
(JSC::ValueProfile::WeakBucket::isClassInfo):
(JSC::ValueProfile::WeakBucket::isStructure):
(JSC::ValueProfile::WeakBucket::asStructure):
(JSC::ValueProfile::WeakBucket::asClassInfo):
(JSC::ValueProfile::WeakBucket::getClassInfo):
* heap/Heap.cpp:
(JSC::Heap::harvestWeakReferences):
(JSC::Heap::markRoots):
* heap/Heap.h:
* heap/MarkStack.cpp:
(JSC::SlotVisitor::drain):
(JSC::SlotVisitor::harvestWeakReferences):
* heap/MarkStack.h:
(JSC::MarkStack::addWeakReferenceHarvester):
(JSC::MarkStack::MarkStack):
(JSC::MarkStack::appendUnbarrieredPointer):
* heap/SlotVisitor.h:
* heap/WeakReferenceHarvester.h: Added.
(JSC::WeakReferenceHarvester::WeakReferenceHarvester):
(JSC::WeakReferenceHarvester::~WeakReferenceHarvester):
git-svn-id: http://svn.webkit.org/repository/webkit/trunk@94477 268f45cc-cd09-0410-ab3c-d52691b4dbfc
diff --git a/Source/JavaScriptCore/heap/Heap.cpp b/Source/JavaScriptCore/heap/Heap.cpp
index 685a601..f56cc0a 100644
--- a/Source/JavaScriptCore/heap/Heap.cpp
+++ b/Source/JavaScriptCore/heap/Heap.cpp
@@ -513,6 +513,11 @@
}
}
+void Heap::harvestWeakReferences()
+{
+ m_slotVisitor.harvestWeakReferences();
+}
+
inline RegisterFile& Heap::registerFile()
{
return m_globalData->interpreter->registerFile();
@@ -581,6 +586,8 @@
m_handleStack.visit(heapRootVisitor);
visitor.drain();
+ harvestWeakReferences();
+
// Weak handles must be marked last, because their owners use the set of
// opaque roots to determine reachability.
int lastOpaqueRootCount;
