Changeset 36124 in webkit for trunk/JavaScriptCore/kjs

Timestamp:

Sep 5, 2008, 9:58:40 PM (17 years ago)

Author:

Darin Adler

Message:

2008-09-05 Darin Adler <Darin Adler>

Reviewed by Geoff Garen.

• fix ​https://bugs.webkit.org/show_bug.cgi?id=20673 single-character strings are churning in the Identifier table

1.007x as fast on SunSpider overall
1.167x as fast on SunSpider string/fasta

• JavaScriptCore.exp: Updated.
• kjs/SmallStrings.cpp: (KJS::SmallStrings::singleCharacterStringRep): Added.
• kjs/SmallStrings.h: Added singleCharacterStringRep for clients that need just a UString, not a JSString.
• kjs/identifier.cpp: (KJS::Identifier::add): Added special cases for single character strings so that the UString::Rep that ends up in the identifier table is the one from the single-character string optimization; otherwise we end up having to look it up in the identifier table over and over again. (KJS::Identifier::addSlowCase): Ditto. (KJS::Identifier::checkSameIdentifierTable): Made this function an empty inline in release builds so that callers don't have to put #ifndef NDEBUG at each call site.
• kjs/identifier.h: (KJS::Identifier::add): Removed #ifndef NDEBUG around the calls to checkSameIdentifierTable. (KJS::Identifier::checkSameIdentifierTable): Added. Empty inline version for NDEBUG builds.

Location:

trunk/JavaScriptCore/kjs

Files:

• SmallStrings.cpp (modified) (1 diff)
• SmallStrings.h (modified) (2 diffs)
• identifier.cpp (modified) (5 diffs)
• identifier.h (modified) (3 diffs)

trunk/JavaScriptCore/kjs/SmallStrings.cpp

@@ -102 +102 @@
 }
 
+UString::Rep* SmallStrings::singleCharacterStringRep(unsigned char character)
+{
+    if (!m_storage)
+        m_storage.set(new SmallStringsStorage);
+    return m_storage->rep(character);
 }
+
+}

trunk/JavaScriptCore/kjs/SmallStrings.h

@@ -27 +27 @@
 #define SmallStrings_h
 
+#include "ustring.h"
 #include <wtf/OwnPtr.h>
 
@@ -53 +54 @@
             return m_singleCharacterStrings[character];
         }
+
+        UString::Rep* singleCharacterStringRep(unsigned char character);
         
         void mark();

trunk/JavaScriptCore/kjs/identifier.cpp

@@ -130 +130 @@
         return &UString::Rep::null;
     }
-
     if (!c[0]) {
         UString::Rep::empty.hash();
         return &UString::Rep::empty;
     }
+    if (!c[1])
+        return add(globalData, globalData->smallStrings.singleCharacterStringRep(static_cast<unsigned char>(c[0])));
 
     IdentifierTable& identifierTable = *globalData->identifierTable;
@@ -187 +188 @@
 PassRefPtr<UString::Rep> Identifier::add(JSGlobalData* globalData, const UChar* s, int length)
 {
+    if (length == 1) {
+        UChar c = s[0];
+        if (c <= 0xFF)
+            return add(globalData, globalData->smallStrings.singleCharacterStringRep(c));
+    }
     if (!length) {
         UString::Rep::empty.hash();
         return &UString::Rep::empty;
     }
-    
     UCharBuffer buf = {s, length}; 
     return *globalData->identifierTable->add<UCharBuffer, UCharBufferTranslator>(buf).first;
@@ -204 +209 @@
 {
     ASSERT(!r->identifierTable());
-
-    if (r->len == 0) {
+    if (r->len == 1) {
+        UChar c = r->data()[0];
+        if (c <= 0xFF)
+            r = globalData->smallStrings.singleCharacterStringRep(c);
+            if (r->identifierTable()) {
+                checkSameIdentifierTable(globalData, r);
+                return r;
+            }
+    }
+    if (!r->len) {
         UString::Rep::empty.hash();
         return &UString::Rep::empty;
     }
-
     return *globalData->identifierTable->add(r).first;
 }
@@ -224 +236 @@
 
 #ifndef NDEBUG
+
 void Identifier::checkSameIdentifierTable(ExecState* exec, UString::Rep* rep)
 {
@@ -233 +246 @@
     ASSERT(rep->identifierTable() == globalData->identifierTable);
 }
-#else
-void Identifier::checkSameIdentifierTable(ExecState*, UString::Rep*)
-{
-}
-
-void Identifier::checkSameIdentifierTable(JSGlobalData*, UString::Rep*)
-{
-}
+
 #endif
 

trunk/JavaScriptCore/kjs/identifier.h

@@ -93 +93 @@
         {
             if (r->identifierTable()) {
-#ifndef NDEBUG
                 checkSameIdentifierTable(exec, r);
-#endif
                 return r;
             }
@@ -103 +101 @@
         {
             if (r->identifierTable()) {
-#ifndef NDEBUG
                 checkSameIdentifierTable(globalData, r);
-#endif
                 return r;
             }
@@ -136 +132 @@
     void deleteIdentifierTable(IdentifierTable*);
 
+#ifdef NDEBUG
+    inline void Identifier::checkSameIdentifierTable(ExecState*, UString::Rep*) { }
+    inline void Identifier::checkSameIdentifierTable(JSGlobalData*, UString::Rep*) { }
+#endif
+
 } // namespace KJS