Changeset 37627 in webkit for trunk/JavaScriptCore/kjs/StructureID.h

Timestamp:

Oct 15, 2008, 9:36:12 PM (17 years ago)

Author:

[email protected]

Message:

2008-10-15 Cameron Zwarich <​[email protected]>

Reviewed by Maciej Stachowiak.

Bug 21633: Avoid using a HashMap when there is only a single transition
<​https://bugs.webkit.org/show_bug.cgi?id=21633>

This is a 0.8% speedup on SunSpider and between a 0.5% and 1.0% speedup
on the V8 benchmark suite, depending on which harness we use. It will
also slightly reduce the memory footprint of a StructureID.

• kjs/StructureID.cpp: (JSC::StructureID::StructureID): (JSC::StructureID::~StructureID): (JSC::StructureID::addPropertyTransition):
• kjs/StructureID.h: (JSC::StructureID::):

File:

• trunk/JavaScriptCore/kjs/StructureID.h (modified) (1 diff)

trunk/JavaScriptCore/kjs/StructureID.h

@@ -153 +153 @@
 
         size_t m_transitionCount;
-        TransitionTable m_transitionTable;
+        bool m_usingSingleTransitionSlot;
+        union {
+            StructureID* singleTransition;
+            TransitionTable* table;
+        } m_transitions;
 
         RefPtr<PropertyNameArrayData> m_cachedPropertyNameArrayData;