Pre-create properties on JSRegExp objects

src/runtime.cc

 // Copyright 2006-2009 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 1210 matching lines @@
   Counters::regexp_entry_runtime.Increment();
   Handle<Object> result = RegExpImpl::Exec(regexp,
                                            subject,
                                            index,
                                            last_match_info);
   if (result.is_null()) return Failure::Exception();
   return *result;
 }
 
 
+static Object* Runtime_RegExpInitializeObject(Arguments args) {
+  AssertNoAllocation no_alloc;
+  ASSERT(args.length() == 5);
+  CONVERT_CHECKED(JSRegExp, regexp, args[0]);
+  CONVERT_CHECKED(String, source, args[1]);
+
+  Object* global = args[2];
+  if (!global->IsTrue()) global = Heap::false_value();
+
+  Object* ignoreCase = args[3];
+  if (!ignoreCase->IsTrue()) ignoreCase = Heap::false_value();
+
+  Object* multiline = args[4];
+  if (!multiline->IsTrue()) multiline = Heap::false_value();
+
+  Map* map = regexp->map();
+  Object* constructor = map->constructor();
+  if (constructor->IsJSFunction() &&
+      JSFunction::cast(constructor)->initial_map() == map) {
+    // If we still have the original map, set in-object properties directly.
+    regexp->InObjectPropertyAtPut(JSRegExp::kSourceFieldIndex, source);
+    // TODO(lrn): Consider skipping write barrier on booleans as well.
+    // Both true and false should be in oldspace at all times.
+    regexp->InObjectPropertyAtPut(JSRegExp::kGlobalFieldIndex, global);
+    regexp->InObjectPropertyAtPut(JSRegExp::kIgnoreCaseFieldIndex, ignoreCase);
+    regexp->InObjectPropertyAtPut(JSRegExp::kMultilineFieldIndex, multiline);
+    regexp->InObjectPropertyAtPut(JSRegExp::kLastIndexFieldIndex,
+                                  Smi::FromInt(0),
+                                  SKIP_WRITE_BARRIER);
+    return regexp;
+  }
+
+  // Map has changed, so use generic, but slower, method.

[Erik Corry, 2010/03/26 13:51:34]

This is a strange situation.  Do we have a test of this?  Does JSC set the same
attributes on the properties in this case.

[Lasse Reichstein, 2010/03/26 14:19:09]

I guess the only way this can happen is when using RegExp.prototype.compile on a
regexp that has been fiddeled with. 
I'll add a test of this case.

+  PropertyAttributes final =
+      static_cast<PropertyAttributes>(READ_ONLY | DONT_ENUM | DONT_DELETE);
+  PropertyAttributes writable =
+      static_cast<PropertyAttributes>(DONT_ENUM | DONT_DELETE);
+  regexp->IgnoreAttributesAndSetLocalProperty(Heap::source_symbol(),
+                                              source,
+                                              final);
+  regexp->IgnoreAttributesAndSetLocalProperty(Heap::global_symbol(),
+                                              global,
+                                              final);
+  regexp->IgnoreAttributesAndSetLocalProperty(Heap::ignore_case_symbol(),
+                                              ignoreCase,
+                                              final);
+  regexp->IgnoreAttributesAndSetLocalProperty(Heap::multiline_symbol(),
+                                              multiline,
+                                              final);
+  regexp->IgnoreAttributesAndSetLocalProperty(Heap::last_index_symbol(),
+                                              Smi::FromInt(0),
+                                              writable);
+  return regexp;
+}
+
+
 static Object* Runtime_FinishArrayPrototypeSetup(Arguments args) {
   HandleScope scope;
   ASSERT(args.length() == 1);
   CONVERT_ARG_CHECKED(JSArray, prototype, 0);
   // This is necessary to enable fast checks for absence of elements
   // on Array.prototype and below.
   prototype->set_elements(Heap::empty_fixed_array());
   return Smi::FromInt(0);
 }
 
@@ skipping 8735 matching lines @@
   } else {
     // Handle last resort GC and make sure to allow future allocations
     // to grow the heap without causing GCs (if possible).
     Counters::gc_last_resort_from_js.Increment();
     Heap::CollectAllGarbage(false);
   }
 }
 
 
 } }  // namespace v8::internal