Changeset 55825 in webkit for trunk/JavaScriptCore/runtime/UStringImpl.h

Timestamp:

Mar 10, 2010, 6:36:08 PM (15 years ago)

Author:

[email protected]

Message:

​https://bugs.webkit.org/show_bug.cgi?id=35991
Would be faster to not use a thread specific to implement StringImpl::empty()

Reviewed by Darin Adler, Geoffrey Garen, Maciej Stachowiak.

JavaScriptCore:

Change JSC::UStringImpl's implementation of empty() match to match StringImpl's new implementation
(use a static defined within the empty() method), and change the interface to match too (return
a pointer not a reference).

~0% performance impact (possible minor progression from moving empty() from .h to .cpp).

• JavaScriptCore.exp:
• runtime/Identifier.cpp:

(JSC::Identifier::add):
(JSC::Identifier::addSlowCase):

• runtime/PropertyNameArray.cpp:

(JSC::PropertyNameArray::add):

• runtime/UString.cpp:

(JSC::initializeUString):
(JSC::UString::UString):

• runtime/UStringImpl.cpp:

(JSC::UStringImpl::empty):
(JSC::UStringImpl::create):

• runtime/UStringImpl.h:

(JSC::UStringImpl::adopt):
(JSC::UStringImpl::createUninitialized):
(JSC::UStringImpl::tryCreateUninitialized):

WebCore:

Copy JavaScriptCore in making 'static' strings threadsafe, make the empty string a static,
shared by all threads.

~2% progression on Dromaeo DOM core & JS lib tests.

• platform/ThreadGlobalData.cpp:

(WebCore::ThreadGlobalData::ThreadGlobalData):
(WebCore::ThreadGlobalData::~ThreadGlobalData):

• platform/ThreadGlobalData.h:

(WebCore::ThreadGlobalData::eventNames):

• platform/text/StringImpl.cpp:

(WebCore::StringImpl::StringImpl):
(WebCore::StringImpl::empty):

• platform/text/StringImpl.h:

(WebCore::StringImpl::deref):
(WebCore::StringImpl::hasOneRef):

File:

• trunk/JavaScriptCore/runtime/UStringImpl.h (modified) (5 diffs)

trunk/JavaScriptCore/runtime/UStringImpl.h

@@ -114 +114 @@
             return adoptRef(new UStringImpl(vector.releaseBuffer(), length));
         }
-        return &empty();
-    }
-
+        return empty();
+    }
+
+    static PassRefPtr<UStringImpl> create(const UChar* buffer, unsigned length);
+    static PassRefPtr<UStringImpl> create(const char* c, unsigned length);
     static PassRefPtr<UStringImpl> create(const char* c);
-    static PassRefPtr<UStringImpl> create(const char* c, unsigned length);
-    static PassRefPtr<UStringImpl> create(const UChar* buffer, unsigned length);
 
     static PassRefPtr<UStringImpl> create(PassRefPtr<UStringImpl> rep, unsigned offset, unsigned length)
@@ -137 +137 @@
         if (!length) {
             output = 0;
-            return &empty();
+            return empty();
         }
 
@@ -151 +151 @@
         if (!length) {
             output = 0;
-            return &empty();
+            return empty();
         }
 
@@ -204 +204 @@
     static unsigned computeHash(const char* s) { return WTF::stringHash(s); }
 
-    static UStringImpl& empty() { return *s_empty; }
+    static UStringImpl* empty();
 
     ALWAYS_INLINE void checkConsistency() const
@@ -296 +296 @@
     mutable unsigned m_hash;
 
-    JS_EXPORTDATA static UStringImpl* s_empty;
-
     friend class JIT;
     friend class SmallStringsStorage;