Changeset 154471 in webkit for trunk/Source/JavaScriptCore/heap

Timestamp:

Aug 22, 2013, 5:45:38 PM (12 years ago)

Author:

[email protected]

Message:

JSObject and JSArray code shouldn't have to tiptoe around garbage collection
​https://bugs.webkit.org/show_bug.cgi?id=120179

Reviewed by Geoffrey Garen.

There are many places in the code for JSObject and JSArray where they are manipulating their
Butterfly/Structure, e.g. after expanding their out-of-line backing storage via allocating. Within
these places there are certain "critical sections" where a GC would be disastrous. Gen GC looks
like it will make this dance even more intricate. To make everybody's lives easier we should use
the DeferGC mechanism in these functions to make these GC critical sections both obvious in the
code and trivially safe. Deferring collections will usually only last marginally longer, thus we
should not incur any additional overhead.

• heap/Heap.h:
• runtime/JSArray.cpp:

(JSC::JSArray::unshiftCountSlowCase):

• runtime/JSObject.cpp:

(JSC::JSObject::enterDictionaryIndexingModeWhenArrayStorageAlreadyExists):
(JSC::JSObject::createInitialUndecided):
(JSC::JSObject::createInitialInt32):
(JSC::JSObject::createInitialDouble):
(JSC::JSObject::createInitialContiguous):
(JSC::JSObject::createArrayStorage):
(JSC::JSObject::convertUndecidedToArrayStorage):
(JSC::JSObject::convertInt32ToArrayStorage):
(JSC::JSObject::convertDoubleToArrayStorage):
(JSC::JSObject::convertContiguousToArrayStorage):
(JSC::JSObject::increaseVectorLength):
(JSC::JSObject::ensureLengthSlow):

• runtime/JSObject.h:

(JSC::JSObject::putDirectInternal):
(JSC::JSObject::setStructureAndReallocateStorageIfNecessary):
(JSC::JSObject::putDirectWithoutTransition):

File:

• trunk/Source/JavaScriptCore/heap/Heap.h (modified) (1 diff)

trunk/Source/JavaScriptCore/heap/Heap.h

@@ -236 +236 @@
         BlockAllocator& blockAllocator();
         
-        void incrementDeferralDepth();
+        JS_EXPORT_PRIVATE void incrementDeferralDepth();
         void decrementDeferralDepth();
-        void decrementDeferralDepthAndGCIfNeeded();
+        JS_EXPORT_PRIVATE void decrementDeferralDepthAndGCIfNeeded();
 
         const HeapType m_heapType;