Optimized scanner to avoid virtual calls for every character read.

src/compiler.cc

Index: src/compiler.cc
diff --git a/src/compiler.cc b/src/compiler.cc
index 29bbbc7034e92deef346bb0d85e7c3e2aad4e4f8..3f9d532b34817658d2a235d7541935e8b6b419ad 100755
--- a/src/compiler.cc
+++ b/src/compiler.cc
@@ -280,7 +280,14 @@ Handle<SharedFunctionInfo> Compiler::Compile(Handle<String> source,
     ScriptDataImpl* pre_data = input_pre_data;
     if (pre_data == NULL
         && source_length >= FLAG_min_preparse_length) {
-      pre_data = ParserApi::PartialPreParse(source, NULL, extension);
+      if (source->IsExternalTwoByteString()) {
+        ExternalTwoByteStringUC16CharacterStream stream(
+            Handle<ExternalTwoByteString>::cast(source), 0, source->length());

[Erik Corry, 2010/12/07 12:27:30]

This is found several places.  Perhaps the constructor should just take a string
and do the cast in the constructor.  That way you concentrate the ugliness in
one place.

[Lasse Reichstein, 2010/12/07 14:05:54]

As discussed offline, let's leave it so that the case is near the test.

+        pre_data = ParserApi::PartialPreParse(&stream, extension);
+      } else {
+        GenericStringUC16CharacterStream stream(source, 0, source->length());
+        pre_data = ParserApi::PartialPreParse(&stream, extension);
+      }
     }
 
     // Create a script object describing the script to be compiled.