Proof of concept: API for doing only one parsing pass instead of first preparsing and then parsing.

src/compiler.cc

Index: src/compiler.cc
diff --git a/src/compiler.cc b/src/compiler.cc
index 21f107a7750af0daadf95ccd4465002f77d20406..bb6ce2bdca828b02ea95f918ce9d57912503f1c8 100644
--- a/src/compiler.cc
+++ b/src/compiler.cc
@@ -115,7 +115,7 @@ void CompilationInfo::Initialize(Isolate* isolate,
   scope_ = NULL;
   global_scope_ = NULL;
   extension_ = NULL;
-  pre_parse_data_ = NULL;
+  cached_data_ = NULL;
   zone_ = zone;
   deferred_handles_ = NULL;
   code_stub_ = NULL;
@@ -807,15 +807,18 @@ static Handle<SharedFunctionInfo> CompileToplevel(CompilationInfo* info) {
   ASSERT(info->is_eval() || info->is_global());
 
   bool parse_allow_lazy =
-      (info->pre_parse_data() != NULL ||
+      (info->cached_data() != NULL ||
        String::cast(script->source())->length() > FLAG_min_preparse_length) &&
       !DebuggerWantsEagerCompilation(info);
 
-  if (!parse_allow_lazy && info->pre_parse_data() != NULL) {
-    // We are going to parse eagerly, but we have preparse data produced by lazy
-    // preparsing. We cannot use it, since it won't contain all the symbols we
-    // need for eager parsing.
-    info->SetPreParseData(NULL);
+  if (!parse_allow_lazy && info->cached_data() != NULL) {
+    // We are going to parse eagerly, but we either 1) have cached data produced
+    // by lazy parsing or 2) are asked to generate cached data. We cannot use
+    // the existing data, since it won't contain all the symbols we need for
+    // eager parsing. In addition, it doesn't make sense to generate the data
+    // when parsing eagerly. That data would contain all symbols, but no
+    // functions, so it couldn't be used to aid lazy parsing later.
+    info->SetCachedData(NULL);
   }
 
   Handle<SharedFunctionInfo> result;
@@ -943,7 +946,7 @@ Handle<SharedFunctionInfo> Compiler::CompileScript(Handle<String> source,
                                                    bool is_shared_cross_origin,
                                                    Handle<Context> context,
                                                    v8::Extension* extension,
-                                                   ScriptDataImpl* pre_data,
+                                                   ScriptDataImpl** cached_data,
                                                    NativesFlag natives) {
   Isolate* isolate = source->GetIsolate();
   int source_length = source->length();
@@ -989,7 +992,7 @@ Handle<SharedFunctionInfo> Compiler::CompileScript(Handle<String> source,
     CompilationInfoWithZone info(script);
     info.MarkAsGlobal();
     info.SetExtension(extension);
-    info.SetPreParseData(pre_data);
+    info.SetCachedData(cached_data);
     info.SetContext(context);
     if (FLAG_use_strict) info.SetStrictMode(STRICT);
     result = CompileToplevel(&info);