Changeset 74829 in webkit for trunk/JavaScriptCore

Timestamp:

Dec 31, 2010, 4:43:34 AM (14 years ago)

Author:

Patrick Gansterer

Message:

2010-12-31 Patrick Gansterer <Patrick Gansterer>

Reviewed by Darin Adler.

Add a fast case for ASCII strings in HashAndUTF8CharactersTranslator::equal
​https://bugs.webkit.org/show_bug.cgi?id=50517

This change shows about 2% performance win on the xml-parser benchmark.

• wtf/text/AtomicString.cpp: (WTF::HashAndUTF8CharactersTranslator::equal):

Location:

trunk/JavaScriptCore

Files:

• ChangeLog (modified) (1 diff)
• wtf/text/AtomicString.cpp (modified) (1 diff)

trunk/JavaScriptCore/ChangeLog

@@ +1 @@
+2010-12-31  Patrick Gansterer  <[email protected]>
+
+        Reviewed by Darin Adler.
+
+        Add a fast case for ASCII strings in HashAndUTF8CharactersTranslator::equal
+        https://bugs.webkit.org/show_bug.cgi?id=50517
+
+        This change shows about 2% performance win on the xml-parser benchmark.
+
+        * wtf/text/AtomicString.cpp:
+        (WTF::HashAndUTF8CharactersTranslator::equal):
+
 2010-12-30  Patrick Gansterer  <[email protected]>
 

trunk/JavaScriptCore/wtf/text/AtomicString.cpp

@@ -226 +226 @@
     static bool equal(StringImpl* const& string, const HashAndUTF8Characters& buffer)
     {
-        return equalUTF16WithUTF8(string->characters(), string->characters() + string->length(), buffer.characters, buffer.characters + buffer.length);
+        if (buffer.utf16Length != string->length())
+            return false;
+
+        const UChar* stringCharacters = string->characters();
+
+        // If buffer contains only ASCII characters UTF-8 and UTF16 length are the same.
+        if (buffer.utf16Length != buffer.length)
+            return equalUTF16WithUTF8(stringCharacters, stringCharacters + string->length(), buffer.characters, buffer.characters + buffer.length);
+
+        for (unsigned i = 0; i < buffer.length; ++i) {
+            ASSERT(isASCII(buffer.characters[i]));
+            if (stringCharacters[i] != buffer.characters[i])
+                return false;
+        }
+
+        return true;
     }