Changeset 178984 in webkit for trunk/Source/JavaScriptCore/heap

Timestamp:

Jan 22, 2015, 11:04:05 PM (10 years ago)

Author:

[email protected]

Message:

EdenCollections unnecessarily visit SmallStrings
​https://bugs.webkit.org/show_bug.cgi?id=140762

Reviewed by Geoffrey Garen.

• heap/Heap.cpp:

(JSC::Heap::copyBackingStores): Also added a GCPhase for copying
backing stores, which is a significant portion of garbage collection.
(JSC::Heap::visitSmallStrings): Check to see if we need to visit
SmallStrings based on the collection type.

• runtime/SmallStrings.cpp:

(JSC::SmallStrings::SmallStrings):
(JSC::SmallStrings::visitStrongReferences): Set the fact that we have
visited the SmallStrings since the last modification.

• runtime/SmallStrings.h:

(JSC::SmallStrings::needsToBeVisited): If we're doing a
FullCollection, we need to visit. Otherwise, it depends on whether
we've been visited since the last modification/allocation.

File:

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

trunk/Source/JavaScriptCore/heap/Heap.cpp

@@ -548 +548 @@
 void Heap::copyBackingStores()
 {
+    GCPHASE(CopyBackingStores);
     if (m_operationInProgress == EdenCollection)
         m_storageSpace.startedCopying<EdenCollection>();
@@ -612 +613 @@
 {
     GCPHASE(VisitSmallStrings);
+    if (!m_vm->smallStrings.needsToBeVisited(m_operationInProgress))
+        return;
+
     m_vm->smallStrings.visitStrongReferences(m_slotVisitor);
-
     if (Options::logGC() == GCLogging::Verbose)
         dataLog("Small strings:\n", m_slotVisitor);
-
     m_slotVisitor.donateAndDrain();
 }