Changeset 50254 in webkit for trunk/JavaScriptCore/runtime

Timestamp:

Oct 28, 2009, 6:25:02 PM (16 years ago)

Author:

[email protected]

Message:

Improve for..in enumeration performance
​https://bugs.webkit.org/show_bug.cgi?id=30887

Reviewed by Geoff Garen.

Improve indexing of an object with a for..in iterator by
identifying cases where get_by_val is being used with a iterator
as the subscript and replace it with a new get_by_pname
bytecode. get_by_pname then optimizes lookups that directly access
the base object.

Location:

trunk/JavaScriptCore/runtime

Files:

• JSObject.h (modified) (1 diff)
• JSPropertyNameIterator.cpp (modified) (1 diff)
• JSPropertyNameIterator.h (modified) (2 diffs)
• Structure.cpp (modified) (7 diffs)
• Structure.h (modified) (4 diffs)

trunk/JavaScriptCore/runtime/JSObject.h

@@ -203 +203 @@
         bool isUsingInlineStorage() const { return m_structure->isUsingInlineStorage(); }
 
-        static const size_t inlineStorageCapacity = sizeof(EncodedJSValue) == 2 * sizeof(void*) ? 4 : 3;
-        static const size_t nonInlineBaseStorageCapacity = 16;
+        static const unsigned inlineStorageCapacity = sizeof(EncodedJSValue) == 2 * sizeof(void*) ? 4 : 3;
+        static const unsigned nonInlineBaseStorageCapacity = 16;
 
         static PassRefPtr<Structure> createStructure(JSValue prototype)

trunk/JavaScriptCore/runtime/JSPropertyNameIterator.cpp

@@ -44 +44 @@
     PropertyNameArray propertyNames(exec);
     o->getPropertyNames(exec, propertyNames);
-    JSPropertyNameIterator* jsPropertyNameIterator = new (exec) JSPropertyNameIterator(exec, propertyNames.data());
+    size_t numCacheableSlots = 0;
+    if (!o->structure()->hasNonEnumerableProperties() && !o->structure()->hasAnonymousSlots() &&
+        !o->structure()->isUncacheableDictionary() && !o->structure()->typeInfo().overridesGetPropertyNames())
+        numCacheableSlots = o->structure()->propertyStorageSize();
+
+    JSPropertyNameIterator* jsPropertyNameIterator = new (exec) JSPropertyNameIterator(exec, propertyNames.data(), numCacheableSlots);
 
     if (o->structure()->isDictionary())

trunk/JavaScriptCore/runtime/JSPropertyNameIterator.h

@@ -55 +55 @@
         virtual void markChildren(MarkStack&);
 
+        bool getOffset(size_t i, int& offset)
+        {
+            if (i >= m_numCacheableSlots)
+                return false;
+            offset = i;
+            return true;
+        }
+
         JSValue get(ExecState*, JSObject*, size_t i);
         size_t size() { return m_jsStringsSize; }
@@ -65 +73 @@
 
     private:
-        JSPropertyNameIterator(ExecState*, PropertyNameArrayData* propertyNameArrayData);
+        JSPropertyNameIterator(ExecState*, PropertyNameArrayData* propertyNameArrayData, size_t numCacheableSlot);
 
         Structure* m_cachedStructure;
         RefPtr<StructureChain> m_cachedPrototypeChain;
-        size_t m_jsStringsSize;
+        uint32_t m_numCacheableSlots;
+        uint32_t m_jsStringsSize;
         OwnArrayPtr<JSValue> m_jsStrings;
     };
 
-inline JSPropertyNameIterator::JSPropertyNameIterator(ExecState* exec, PropertyNameArrayData* propertyNameArrayData)
+inline JSPropertyNameIterator::JSPropertyNameIterator(ExecState* exec, PropertyNameArrayData* propertyNameArrayData, size_t numCacheableSlots)
     : JSCell(exec->globalData().propertyNameIteratorStructure.get())
     , m_cachedStructure(0)
+    , m_numCacheableSlots(numCacheableSlots)
     , m_jsStringsSize(propertyNameArrayData->propertyNameVector().size())
     , m_jsStrings(new JSValue[m_jsStringsSize])

trunk/JavaScriptCore/runtime/Structure.cpp

@@ -376 +376 @@
     transition->m_propertyStorageCapacity = structure->m_propertyStorageCapacity;
     transition->m_hasGetterSetterProperties = structure->m_hasGetterSetterProperties;
+    transition->m_hasNonEnumerableProperties = structure->m_hasNonEnumerableProperties;
 
     if (structure->m_propertyTable) {
@@ -418 +419 @@
     transition->m_propertyStorageCapacity = structure->m_propertyStorageCapacity;
     transition->m_hasGetterSetterProperties = structure->m_hasGetterSetterProperties;
+    transition->m_hasNonEnumerableProperties = structure->m_hasNonEnumerableProperties;
 
     // Don't set m_offset, as one can not transition to this.
@@ -434 +436 @@
     transition->m_propertyStorageCapacity = structure->m_propertyStorageCapacity;
     transition->m_hasGetterSetterProperties = structure->m_hasGetterSetterProperties;
+    transition->m_hasNonEnumerableProperties = structure->m_hasNonEnumerableProperties;
 
     // Don't set m_offset, as one can not transition to this.
@@ -465 +468 @@
     transition->m_propertyStorageCapacity = structure->m_propertyStorageCapacity;
     transition->m_hasGetterSetterProperties = structure->m_hasGetterSetterProperties;
+    transition->m_hasNonEnumerableProperties = structure->m_hasNonEnumerableProperties;
 
     if (structure->m_propertyTable) {
@@ -493 +497 @@
     transition->m_propertyStorageCapacity = structure->m_propertyStorageCapacity;
     transition->m_hasGetterSetterProperties = transition->m_hasGetterSetterProperties;
+    transition->m_hasNonEnumerableProperties = structure->m_hasNonEnumerableProperties;
 
     // Don't set m_offset, as one can not transition to this.
@@ -511 +516 @@
     transition->m_propertyStorageCapacity = structure->m_propertyStorageCapacity;
     transition->m_hasGetterSetterProperties = structure->m_hasGetterSetterProperties;
+    transition->m_hasNonEnumerableProperties = structure->m_hasNonEnumerableProperties;
     
     structure->materializePropertyMapIfNecessary();
@@ -551 +557 @@
 
     m_isPinnedPropertyTable = true;
+    if (attributes & DontEnum)
+        m_hasNonEnumerableProperties = true;
+
     size_t offset = put(propertyName, attributes, specificValue);
     if (propertyStorageSize() > propertyStorageCapacity())

trunk/JavaScriptCore/runtime/Structure.h

@@ -96 +96 @@
 
         void growPropertyStorageCapacity();
-        size_t propertyStorageCapacity() const { return m_propertyStorageCapacity; }
-        size_t propertyStorageSize() const { return m_propertyTable ? m_propertyTable->keyCount + m_propertyTable->anonymousSlotCount + (m_propertyTable->deletedOffsets ? m_propertyTable->deletedOffsets->size() : 0) : m_offset + 1; }
+        unsigned propertyStorageCapacity() const { return m_propertyStorageCapacity; }
+        unsigned propertyStorageSize() const { return m_propertyTable ? m_propertyTable->keyCount + m_propertyTable->anonymousSlotCount + (m_propertyTable->deletedOffsets ? m_propertyTable->deletedOffsets->size() : 0) : m_offset + 1; }
         bool isUsingInlineStorage() const;
 
@@ -120 +120 @@
         void setHasGetterSetterProperties(bool hasGetterSetterProperties) { m_hasGetterSetterProperties = hasGetterSetterProperties; }
 
+        bool hasNonEnumerableProperties() const { return m_hasNonEnumerableProperties; }
+
+        bool hasAnonymousSlots() const { return m_propertyTable && m_propertyTable->anonymousSlotCount; }
+        
         bool isEmpty() const { return m_propertyTable ? !m_propertyTable->keyCount : m_offset == noOffset; }
 
@@ -191 +195 @@
         PropertyMapHashTable* m_propertyTable;
 
-        size_t m_propertyStorageCapacity;
+        uint32_t m_propertyStorageCapacity;
         signed char m_offset;
 
@@ -197 +201 @@
         bool m_isPinnedPropertyTable : 1;
         bool m_hasGetterSetterProperties : 1;
+        bool m_hasNonEnumerableProperties : 1;
 #if COMPILER(WINSCW)
         // Workaround for Symbian WINSCW compiler that cannot resolve unsigned type of the declared