Add FLAG_trace_maps

src/runtime/runtime-literals.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #include "src/allocation-site-scopes.h"
 #include "src/arguments.h"
 #include "src/ast.h"
 #include "src/parser.h"
@@ skipping 91 matching lines @@
   if (!should_have_fast_elements) JSObject::NormalizeElements(boilerplate);
 
   // Add the constant properties to the boilerplate.
   int length = constant_properties->length();
   bool should_transform =
       !is_result_from_cache && boilerplate->HasFastProperties();
   bool should_normalize = should_transform || has_function_literal;
   if (should_normalize) {
     // TODO(verwaest): We might not want to ever normalize here.
     JSObject::NormalizeProperties(boilerplate, KEEP_INOBJECT_PROPERTIES,
-                                  length / 2);
+                                  length / 2, "Boilerplate");
   }
   // TODO(verwaest): Support tracking representations in the boilerplate.
   for (int index = 0; index < length; index += 2) {
     Handle<Object> key(constant_properties->get(index + 0), isolate);
     Handle<Object> value(constant_properties->get(index + 1), isolate);
     if (value->IsFixedArray()) {
       // The value contains the constant_properties of a
       // simple object or array literal.
       Handle<FixedArray> array = Handle<FixedArray>::cast(value);
       ASSIGN_RETURN_ON_EXCEPTION(
@@ skipping 36 matching lines @@
     // convert back to an exception.
     RETURN_ON_EXCEPTION(isolate, maybe_result, Object);
   }
 
   // Transform to fast properties if necessary. For object literals with
   // containing function literals we defer this operation until after all
   // computed properties have been assigned so that we can generate
   // constant function properties.
   if (should_transform && !has_function_literal) {
     JSObject::MigrateSlowToFast(boilerplate,
-                                boilerplate->map()->unused_property_fields());
+                                boilerplate->map()->unused_property_fields(),
+                                "FastLiteral");
   }
 
   return boilerplate;
 }
 
 
 MaybeHandle<Object> Runtime::CreateArrayLiteralBoilerplate(
     Isolate* isolate, Handle<FixedArray> literals,
     Handle<FixedArray> elements) {
   // Create the JSArray.
@@ skipping 277 matching lines @@
         JSObject::TransitionElementsKind(boilerplate_object, transitioned_kind);
       }
     }
     FixedArray* object_array = FixedArray::cast(object->elements());
     object_array->set(store_index, *value);
   }
   return *object;
 }
 }
 }  // namespace v8::internal