Changeset 178984 in webkit for trunk/Source/JavaScriptCore/runtime/SmallStrings.cpp

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/runtime/SmallStrings.cpp (modified) (5 diffs)

trunk/Source/JavaScriptCore/runtime/SmallStrings.cpp

@@ -69 +69 @@
     , m_nullObjectString(nullptr)
     , m_undefinedObjectString(nullptr)
+    , m_needsToBeVisited(true)
 {
     COMPILE_ASSERT(singleCharacterStringCount == sizeof(m_singleCharacterStrings) / sizeof(m_singleCharacterStrings[0]), IsNumCharactersConstInSyncWithClassUsage);
@@ -90 +91 @@
 void SmallStrings::visitStrongReferences(SlotVisitor& visitor)
 {
+    m_needsToBeVisited = false;
     visitor.appendUnbarrieredPointer(&m_emptyString);
     for (unsigned i = 0; i <= maxSingleCharacterString; ++i)
@@ -108 +110 @@
     ASSERT(!m_emptyString);
     m_emptyString = JSString::createHasOtherOwner(*vm, StringImpl::empty());
+    m_needsToBeVisited = true;
 }
 
@@ -116 +119 @@
     ASSERT(!m_singleCharacterStrings[character]);
     m_singleCharacterStrings[character] = JSString::createHasOtherOwner(*vm, PassRefPtr<StringImpl>(m_storage->rep(character)));
+    m_needsToBeVisited = true;
 }
 
@@ -125 +129 @@
 }
 
-void SmallStrings::initialize(VM* vm, JSString*& string, const char* value) const
+void SmallStrings::initialize(VM* vm, JSString*& string, const char* value)
 {
     string = JSString::create(*vm, StringImpl::create(value));
+    m_needsToBeVisited = true;
 }