Changeset 36401 in webkit for trunk/JavaScriptCore/kjs/JSObject.h

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/JSObject.h (modified) (5 diffs)

trunk/JavaScriptCore/kjs/JSObject.h

@@ -151 +151 @@
         }
 
+        void transitionTo(StructureID*);
+
         void removeDirect(const Identifier& propertyName);
         bool hasCustomProperties() { return !m_structureID->propertyMap().isEmpty(); }
@@ -179 +181 @@
         bool usingInlineStorage() const { return m_propertyStorage == m_inlineStorage; }
 
+        static const size_t inlineStorageCapacity = 2;
+
     protected:
         bool getOwnPropertySlotForWrite(ExecState*, const Identifier&, PropertySlot&, bool& slotIsWriteable);
@@ -185 +189 @@
         const HashEntry* findPropertyHashEntry(ExecState*, const Identifier& propertyName) const;
         StructureID* createInheritorID();
-
-        static const size_t inlineStorageCapacity = 2;
 
         RefPtr<StructureID> m_inheritorID;
@@ -390 +392 @@
      }
 
-     unsigned currentAttributes;
-     size_t offset = m_structureID->propertyMap().getOffset(propertyName, currentAttributes);
-     if (offset != WTF::notFound) {
-         if (checkReadOnly && currentAttributes & ReadOnly)
-             return;
-         m_propertyStorage[offset] = value;
-         slot.setExistingProperty(this, offset);
-         return;
-     }
+    unsigned currentAttributes;
+    size_t offset = m_structureID->propertyMap().getOffset(propertyName, currentAttributes);
+    if (offset != WTF::notFound) {
+        if (checkReadOnly && currentAttributes & ReadOnly)
+            return;
+        m_propertyStorage[offset] = value;
+        slot.setExistingProperty(this, offset);
+        return;
+    }
 
      if (m_structureID->propertyMap().storageSize() == inlineStorageCapacity)
@@ -404 +406 @@
 
      RefPtr<StructureID> structureID = StructureID::addPropertyTransition(m_structureID, propertyName, value, attributes, this, slot, m_propertyStorage);
+     slot.setWasTransition(true);
      setStructureID(structureID.release());
+}
+
+inline void JSObject::transitionTo(StructureID* newStructureID)
+{
+    StructureID::transitionTo(m_structureID, newStructureID, this);
+    setStructureID(newStructureID);
 }