- Exteranalize strings but not the results of toString() on non-strings.

This increases our score on the DOM Perf benchmarks by about 10%

Review URL: http://codereview.chromium.org/79055

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@14103 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 22 insertions, 13 deletions

diff --git a/webkit/port/bindings/v8/v8_binding.cpp b/webkit/port/bindings/v8/v8_binding.cpp
index 3a36fc51..0df0839 100644
--- a/webkit/port/bindings/v8/v8_binding.cpp
+++ b/webkit/port/bindings/v8/v8_binding.cpp
@@ -37,7 +37,8 @@ class WebCoreStringResource: public v8::String::ExternalStringResource {
   String impl_;
 };
 
-String v8StringToWebCoreString(v8::Handle<v8::String> v8_str) {
+String v8StringToWebCoreString(
+    v8::Handle<v8::String> v8_str, bool externalize) {
   if (v8_str->IsExternal()) {
     WebCoreStringResource* str_resource = static_cast<WebCoreStringResource*>(
         v8_str->GetExternalStringResource());
@@ -69,12 +70,14 @@ String v8StringToWebCoreString(v8::Handle<v8::String> v8_str) {
 //  TODO(mbelshe): Disable string morphing because it causes mystery
 //     perf regressions on intl1 and intl2 page cyclers.  It works fine
 //     on machines other than the buildbots.
-//
-//  WebCoreStringResource* resource = new WebCoreStringResource(result);
-//  if (!v8_str->MakeExternal(resource)) {
-//    // In case of a failure delete the external resource as it was not used.
-//    delete resource;
-//  }
+
+  if (externalize) {
+    WebCoreStringResource* resource = new WebCoreStringResource(result);
+    if (!v8_str->MakeExternal(resource)) {
+      // In case of a failure delete the external resource as it was not used.
+      delete resource;
+    }
+  }
   return result;
 }
 
@@ -83,18 +86,19 @@ String v8ValueToWebCoreString(v8::Handle<v8::Value> obj) {
   v8::Handle<v8::String> v8_str;
   if (obj->IsString()) {
     v8_str = v8::Handle<v8::String>::Cast(obj);
+    return v8StringToWebCoreString(v8_str, true);
   } else {
     v8::TryCatch block;
     v8_str = obj->ToString();
     if (v8_str.IsEmpty())
       return "";
   }
-  return v8StringToWebCoreString(v8_str);
+  return v8StringToWebCoreString(v8_str, false);
 }
 
 
 AtomicString v8StringToAtomicWebCoreString(v8::Handle<v8::String> v8_str) {
-  String str = v8StringToWebCoreString(v8_str);
+  String str = v8StringToWebCoreString(v8_str, true);
   return AtomicString(str);
 }
 
@@ -108,13 +112,13 @@ AtomicString v8ValueToAtomicWebCoreString(v8::Handle<v8::Value> v8_str) {
 v8::Handle<v8::String> v8String(const String& str) {
   if (!str.length())
     return v8::String::Empty();
-  return v8::String::NewExternal(new WebCoreStringResource(str));	
+  return v8::String::NewExternal(new WebCoreStringResource(str));
 }
 
 v8::Local<v8::String> v8ExternalString(const String& str) {
   if (!str.length())
     return v8::String::Empty();
-  return v8::String::NewExternal(new WebCoreStringResource(str));	
+  return v8::String::NewExternal(new WebCoreStringResource(str));
 }
 
 }  // namespace WebCore
diff --git a/webkit/port/bindings/v8/v8_binding.h b/webkit/port/bindings/v8/v8_binding.h
index 8300dd7..2882026 100644
--- a/webkit/port/bindings/v8/v8_binding.h
+++ b/webkit/port/bindings/v8/v8_binding.h
@@ -23,13 +23,18 @@ inline const uint16_t* FromWebCoreString(const String& str) {
 // Convert v8 types to a WebCore::String. If the V8 string is not already
 // an external string then it is transformed into an external string at this
 // point to avoid repeated conversions.
-String v8StringToWebCoreString(v8::Handle<v8::String> obj);
+String v8StringToWebCoreString(
+    v8::Handle<v8::String> obj, bool externalize);
 String v8ValueToWebCoreString(v8::Handle<v8::Value> obj);
 
 // TODO(mbelshe): drop this in favor of the type specific
 //    v8ValueToWebCoreString when we rework the code generation.
 inline String ToWebCoreString(v8::Handle<v8::Value> obj) {
-    return v8ValueToWebCoreString(obj);
+  return v8ValueToWebCoreString(obj);
+}
+
+inline String ToWebCoreString(v8::Handle<v8::String> string) {
+  return v8StringToWebCoreString(string, true);
 }
 
 // Convert v8 types to a WebCore::AtomicString.