Changeset 28777 in webkit for trunk/JavaScriptCore/kjs/SymbolTable.h

Timestamp:

Dec 16, 2007, 2:53:51 PM (17 years ago)

Author:

[email protected]

Message:

Reviewed by Darin Adler and Maciej Stachowiak.

More refactoring to support global variable optimization.

Changed SymbolTable to use RefPtr<UString::Rep> as its key instead of
UString::Rep*. With globals, the symbol table can outlast the
declaration node for any given symbol, so the symbol table needs to ref
its symbol names.

In support, specialized HashMaps with RefPtr keys to allow lookup
via raw pointer, avoiding refcount churn.

SunSpider reports a .6% speedup (prolly just noise).

• JavaScriptCore.vcproj/WTF/WTF.vcproj: Added new file: wtf/RefPtrHashMap.h
• JavaScriptCore.xcodeproj/project.pbxproj: ditto

• kjs/JSVariableObject.cpp: (KJS::JSVariableObject::getPropertyNames): Symbol table keys are RefPtrs now.

• kjs/SymbolTable.h: Modified key traits to match RefPtr. Added a static Rep* for null, which helps compute the deletedValue() trait.

• wtf/HashMap.h: #include the RefPtr specialization so everyone can use it.

• wtf/RefPtrHashMap.h: Copied from wtf/HashMap.h. Added overloaded versions of find(), contains(), get(), set(), add(), remove(), and take() that take raw pointers as keys.

File:

• trunk/JavaScriptCore/kjs/SymbolTable.h (modified) (2 diffs)

trunk/JavaScriptCore/kjs/SymbolTable.h

@@ -30 +30 @@
 #define SymbolTable_h
 
-#include "property_map.h"
-#include "AlwaysInline.h"
+#include "ustring.h"
+#include <wtf/AlwaysInline.h>
 
 namespace KJS {
 
-    class JSValue;
+    struct IdentifierRepHash {
+        static unsigned hash(const RefPtr<UString::Rep>& key) { return key->computedHash(); }
+        static bool equal(const RefPtr<UString::Rep>& a, const RefPtr<UString::Rep>& b) { return a == b; }
+        static const bool safeToCompareToEmptyOrDeleted = true;
+    };
 
-    struct IdentifierRepHash {
-        static unsigned hash(const KJS::UString::Rep *key) { return key->computedHash(); }
-        static bool equal(const KJS::UString::Rep *a, const KJS::UString::Rep *b) { return a == b; }
-        static const bool safeToCompareToEmptyOrDeleted = true;
+    struct IdentifierRepHashTraits : HashTraits<RefPtr<UString::Rep> > {
+        static const RefPtr<UString::Rep>& deletedValue()
+        {
+            return *reinterpret_cast<RefPtr<UString::Rep>*>(&nullRepPtr);
+        }
+
+    private:
+        static UString::Rep* nullRepPtr;
     };
 
@@ -54 +62 @@
     };
 
-    typedef HashMap<UString::Rep*, size_t, IdentifierRepHash, HashTraits<UString::Rep*>, SymbolTableIndexHashTraits> SymbolTable;
+    typedef HashMap<RefPtr<UString::Rep>, size_t, IdentifierRepHash, IdentifierRepHashTraits, SymbolTableIndexHashTraits> SymbolTable;
 
 } // namespace KJS