Changeset 36401 in webkit for trunk/JavaScriptCore/kjs/StructureID.cpp

Timestamp:

Sep 14, 2008, 1:18:49 AM (17 years ago)

Author:

[email protected]

Message:

Bug 20821: Cache property transitions to speed up object initialization
​https://bugs.webkit.org/show_bug.cgi?id=20821

Reviewed by Cameron Zwarich.

Implement a transition cache to improve the performance of new properties
being added to objects. This is extremely beneficial in constructors and
shows up as a 34% improvement on access-binary-trees in SunSpider (0.8%
overall)

File:

• trunk/JavaScriptCore/kjs/StructureID.cpp (modified) (3 diffs)

trunk/JavaScriptCore/kjs/StructureID.cpp

@@ -46 +46 @@
     ASSERT(m_prototype);
     ASSERT(m_prototype->isObject() || m_prototype->isNull());
+}
+
+void StructureID::transitionTo(StructureID* oldStructureID, StructureID* newStructureID, JSObject* slotBase)
+{
+    if (!slotBase->usingInlineStorage() && oldStructureID->m_propertyMap.size() != newStructureID->m_propertyMap.size())
+        slotBase->allocatePropertyStorage(oldStructureID->m_propertyMap.size(), newStructureID->m_propertyMap.size());
 }
 
@@ -140 +146 @@
     }
     
-    m_vector.set(new RefPtr<StructureID>[size]);
+    m_vector.set(new RefPtr<StructureID>[size + 1]);
 
     size_t i;
@@ -148 +154 @@
     }
     m_vector[i] = structureID;
+    m_vector[i + 1] = 0;
 }