Changeset 48403 in webkit for trunk/JavaScriptCore/runtime/StructureTransitionTable.h

Timestamp:

Sep 15, 2009, 4:17:19 PM (16 years ago)

Author:

[email protected]

Message:

Allow anonymous storage inside JSObject
​https://bugs.webkit.org/show_bug.cgi?id=29168

Reviewed by Geoff Garen

Add the concept of anonymous slots to Structures so that it is
possible to store references to values that need marking in the
standard JSObject storage buffer. This allows us to reduce the
malloc overhead of some objects (by allowing them to store JS
values in the inline storage of the object) and reduce the
dependence of custom mark functions (if all an objects children
are in the standard object property storage there's no need to
mark them manually).

File:

• trunk/JavaScriptCore/runtime/StructureTransitionTable.h (modified) (3 diffs)

trunk/JavaScriptCore/runtime/StructureTransitionTable.h

@@ -32 +32 @@
 #include <wtf/HashTraits.h>
 #include <wtf/PtrAndFlags.h>
+#include <wtf/OwnPtr.h>
 #include <wtf/RefPtr.h>
 
@@ -69 +70 @@
     class StructureTransitionTable {
         typedef std::pair<Structure*, Structure*> Transition;
-        typedef HashMap<StructureTransitionTableHash::Key, Transition, StructureTransitionTableHash, StructureTransitionTableHashTraits> TransitionTable;
+        struct TransitionTable : public HashMap<StructureTransitionTableHash::Key, Transition, StructureTransitionTableHash, StructureTransitionTableHashTraits> {
+            typedef HashMap<unsigned, Structure*> AnonymousSlotMap;
+
+            void addSlotTransition(unsigned count, Structure* structure)
+            {
+                ASSERT(!getSlotTransition(count));
+                if (!m_anonymousSlotTable)
+                    m_anonymousSlotTable.set(new AnonymousSlotMap);
+                m_anonymousSlotTable->add(count, structure);
+            }
+
+            void removeSlotTransition(unsigned count)
+            {
+                ASSERT(getSlotTransition(count));
+                m_anonymousSlotTable->remove(count);
+            }
+
+            Structure* getSlotTransition(unsigned count)
+            {
+                if (!m_anonymousSlotTable)
+                    return 0;
+
+                AnonymousSlotMap::iterator find = m_anonymousSlotTable->find(count);
+                if (find == m_anonymousSlotTable->end())
+                    return 0;
+                return find->second;
+            }
+        private:
+            OwnPtr<AnonymousSlotMap> m_anonymousSlotTable;
+        };
     public:
         StructureTransitionTable() {
@@ -124 +154 @@
             }
         }
+
+        Structure* getAnonymousSlotTransition(unsigned count)
+        {
+            if (usingSingleTransitionSlot())
+                return 0;
+            return table()->getSlotTransition(count);
+        }
+
+        void addAnonymousSlotTransition(unsigned count, Structure* structure)
+        {
+            if (usingSingleTransitionSlot())
+                reifySingleTransition();
+            ASSERT(!table()->getSlotTransition(count));
+            table()->addSlotTransition(count, structure);
+        }
+        
+        void removeAnonymousSlotTransition(unsigned count)
+        {
+            ASSERT(!usingSingleTransitionSlot());
+            table()->removeSlotTransition(count);
+        }
     private:
         TransitionTable* table() const { ASSERT(!usingSingleTransitionSlot()); return m_transitions.m_table; }