Changeset 36847 in webkit for trunk/JavaScriptCore/kjs/PropertyMap.h

Timestamp:

Sep 24, 2008, 1:11:35 AM (17 years ago)

Author:

[email protected]

Message:

2008-09-24 Maciej Stachowiak <​[email protected]>

Reviewed by Oliver Hunt.

• inline PropertyMap::getOffset to speed up polymorphic lookups

~1.5% speedup on v8 benchmark
no effect on SunSpider

• JavaScriptCore.exp:
• kjs/PropertyMap.cpp:
• kjs/PropertyMap.h: (JSC::PropertyMap::getOffset):

File:

• trunk/JavaScriptCore/kjs/PropertyMap.h (modified) (3 diffs)

trunk/JavaScriptCore/kjs/PropertyMap.h

@@ -26 +26 @@
 #include <wtf/OwnArrayPtr.h>
 #include <wtf/NotFound.h>
+
+#ifndef NDEBUG
+#define DUMP_PROPERTYMAP_STATS 0
+#else
+#define DUMP_PROPERTYMAP_STATS 0
+#endif
 
 namespace JSC {
@@ -103 +109 @@
         unsigned storageSize() const { return m_table ? m_table->keyCount + m_table->deletedSentinelCount : 0; }
 
+        static const unsigned emptyEntryIndex = 0;
+
     private:
         typedef PropertyMapEntry Entry;
@@ -126 +134 @@
     }
 
+    inline size_t PropertyMap::getOffset(const Identifier& propertyName)
+    {
+        ASSERT(!propertyName.isNull());
+
+        if (!m_table)
+            return WTF::notFound;
+
+        UString::Rep* rep = propertyName._ustring.rep();
+
+        unsigned i = rep->computedHash();
+
+#if DUMP_PROPERTYMAP_STATS
+        ++numProbes;
+#endif
+
+        unsigned entryIndex = m_table->entryIndices[i & m_table->sizeMask];
+        if (entryIndex == emptyEntryIndex)
+            return WTF::notFound;
+
+        if (rep == m_table->entries()[entryIndex - 1].key)
+            return entryIndex - 2;
+
+#if DUMP_PROPERTYMAP_STATS
+        ++numCollisions;
+#endif
+
+        unsigned k = 1 | WTF::doubleHash(rep->computedHash());
+
+        while (1) {
+            i += k;
+
+#if DUMP_PROPERTYMAP_STATS
+            ++numRehashes;
+#endif
+
+            entryIndex = m_table->entryIndices[i & m_table->sizeMask];
+            if (entryIndex == emptyEntryIndex)
+                return WTF::notFound;
+
+            if (rep == m_table->entries()[entryIndex - 1].key)
+                return entryIndex - 2;
+        }
+    }
+
 } // namespace JSC