Don't preparse large files to find boundaries of lazy functions.

src/compiler.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 359 matching lines @@
       }
     }
   }
 
   // Notify debugger
   isolate->debugger()->OnBeforeCompile(script);
 #endif
 
   // Only allow non-global compiles for eval.
   ASSERT(info->is_eval() || info->is_global());
-
-  if (!ParserApi::Parse(info)) return Handle<SharedFunctionInfo>::null();
+  ParsingFlags flags = kNoParsingFlags;
+  if (info->pre_parse_data() != NULL ||
+      String::cast(script->source())->length() > FLAG_min_preparse_length) {
+    flags = kAllowLazy;
+  }
+  if (!ParserApi::Parse(info, flags)) {
+    return Handle<SharedFunctionInfo>::null();
+  }
 
   // Measure how long it takes to do the compilation; only take the
   // rest of the function into account to avoid overlap with the
   // parsing statistics.
   HistogramTimer* rate = info->is_eval()
       ? info->isolate()->counters()->compile_eval()
       : info->isolate()->counters()->compile();
   HistogramTimerScope timer(rate);
 
   // Compile the code.
@@ skipping 54 matching lines @@
 
   return result;
 }
 
 
 Handle<SharedFunctionInfo> Compiler::Compile(Handle<String> source,
                                              Handle<Object> script_name,
                                              int line_offset,
                                              int column_offset,
                                              v8::Extension* extension,
-                                             ScriptDataImpl* input_pre_data,
+                                             ScriptDataImpl* pre_data,
                                              Handle<Object> script_data,
                                              NativesFlag natives) {
   Isolate* isolate = source->GetIsolate();
   int source_length = source->length();
   isolate->counters()->total_load_size()->Increment(source_length);
   isolate->counters()->total_compile_size()->Increment(source_length);
 
   // The VM is in the COMPILER state until exiting this function.
   VMState state(isolate, COMPILER);
 
@@ skipping 10 matching lines @@
 
   if (result.is_null()) {
     // No cache entry found. Do pre-parsing, if it makes sense, and compile
     // the script.
     // Building preparse data that is only used immediately after is only a
     // saving if we might skip building the AST for lazily compiled functions.
     // I.e., preparse data isn't relevant when the lazy flag is off, and
     // for small sources, odds are that there aren't many functions
     // that would be compiled lazily anyway, so we skip the preparse step
     // in that case too.
-    ScriptDataImpl* pre_data = input_pre_data;
     int flags = kNoParsingFlags;
     if ((natives == NATIVES_CODE) || FLAG_allow_natives_syntax) {
       flags |= kAllowNativesSyntax;
     }
     if (natives != NATIVES_CODE && FLAG_harmony_scoping) {
-      flags |= kHarmonyScoping;
-    }
-    if (pre_data == NULL
-        && source_length >= FLAG_min_preparse_length) {
-      if (source->IsExternalTwoByteString()) {
-        ExternalTwoByteStringUC16CharacterStream stream(
-            Handle<ExternalTwoByteString>::cast(source), 0, source->length());
-        pre_data = ParserApi::PartialPreParse(&stream, extension, flags);
-      } else {
-        GenericStringUC16CharacterStream stream(source, 0, source->length());
-        pre_data = ParserApi::PartialPreParse(&stream, extension, flags);
-      }
+      flags |= EXTENDED_MODE;
     }
 
     // Create a script object describing the script to be compiled.
     Handle<Script> script = FACTORY->NewScript(source);
     if (natives == NATIVES_CODE) {
       script->set_type(Smi::FromInt(Script::TYPE_NATIVE));
     }
     if (!script_name.is_null()) {
       script->set_name(*script_name);
       script->set_line_offset(Smi::FromInt(line_offset));
       script->set_column_offset(Smi::FromInt(column_offset));
     }
 
     script->set_data(script_data.is_null() ? HEAP->undefined_value()
                                            : *script_data);
 
     // Compile the function and add it to the cache.
     CompilationInfo info(script);
     info.MarkAsGlobal();
     info.SetExtension(extension);
     info.SetPreParseData(pre_data);
     result = MakeFunctionInfo(&info);
     if (extension == NULL && !result.is_null()) {
       compilation_cache->PutScript(source, result);
     }
-
-    // Get rid of the pre-parsing data (if necessary).
-    if (input_pre_data == NULL && pre_data != NULL) {
-      delete pre_data;
-    }
   }
 
   if (result.is_null()) isolate->ReportPendingMessages();
   return result;
 }
 
 
 Handle<SharedFunctionInfo> Compiler::CompileEval(Handle<String> source,
                                                  Handle<Context> context,
                                                  bool is_global,
@@ skipping 52 matching lines @@
   // The VM is in the COMPILER state until exiting this function.
   VMState state(isolate, COMPILER);
 
   PostponeInterruptsScope postpone(isolate);
 
   Handle<SharedFunctionInfo> shared = info->shared_info();
   int compiled_size = shared->end_position() - shared->start_position();
   isolate->counters()->total_compile_size()->Increment(compiled_size);
 
   // Generate the AST for the lazily compiled function.
-  if (ParserApi::Parse(info)) {
+  if (ParserApi::Parse(info, kNoParsingFlags)) {
     // Measure how long it takes to do the lazy compilation; only take the
     // rest of the function into account to avoid overlap with the lazy
     // parsing statistics.
     HistogramTimerScope timer(isolate->counters()->compile_lazy());
 
     // After parsing we know the function's language mode. Remember it.
     LanguageMode language_mode = info->function()->language_mode();
     info->SetLanguageMode(language_mode);
     shared->set_language_mode(language_mode);
 
@@ skipping 179 matching lines @@
     }
   }
 
   GDBJIT(AddCode(Handle<String>(shared->DebugName()),
                  Handle<Script>(info->script()),
                  Handle<Code>(info->code()),
                  info));
 }
 
 } }  // namespace v8::internal