Distinguish slow from fast sloppy arguments

src/bootstrapper.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/bootstrapper.h"
 
 #include "src/accessors.h"
 #include "src/api-natives.h"
 #include "src/base/utils/random-number-generator.h"
 #include "src/code-stubs.h"
@@ skipping 1339 matching lines @@
     DCHECK(!function->has_initial_map());
     JSFunction::SetInitialMap(function, map,
                               isolate->initial_object_prototype());
 
     DCHECK(map->inobject_properties() > Heap::kArgumentsCalleeIndex);
     DCHECK(map->inobject_properties() > Heap::kArgumentsLengthIndex);
     DCHECK(!map->is_dictionary_map());
     DCHECK(IsFastObjectElementsKind(map->elements_kind()));
   }
 
-  {  // --- aliased arguments map
-    Handle<Map> map =
-        Map::Copy(isolate->sloppy_arguments_map(), "AliasedArguments");
-    map->set_elements_kind(SLOPPY_ARGUMENTS_ELEMENTS);
+  {  // --- fast and slow aliased arguments map
+    Handle<Map> map = isolate->sloppy_arguments_map();
+    map = Map::Copy(map, "FastAliasedArguments");
+    map->set_elements_kind(FAST_SLOPPY_ARGUMENTS_ELEMENTS);
     DCHECK_EQ(2, map->pre_allocated_property_fields());
-    native_context()->set_aliased_arguments_map(*map);
+    native_context()->set_fast_aliased_arguments_map(*map);
+
+    map = Map::Copy(map, "SlowAliasedArguments");
+    map->set_elements_kind(SLOW_SLOPPY_ARGUMENTS_ELEMENTS);
+    DCHECK_EQ(2, map->pre_allocated_property_fields());
+    native_context()->set_slow_aliased_arguments_map(*map);
   }
 
   {  // --- strict mode arguments map
     const PropertyAttributes attributes =
       static_cast<PropertyAttributes>(DONT_ENUM | DONT_DELETE | READ_ONLY);
 
     // Create the ThrowTypeError functions.
     Handle<AccessorPair> callee = factory->NewAccessorPair();
     Handle<AccessorPair> caller = factory->NewAccessorPair();
 
@@ skipping 1057 matching lines @@
     {
       AccessorConstantDescriptor d(factory()->iterator_symbol(),
                                    arguments_iterator, attribs);
       Handle<Map> map(native_context()->sloppy_arguments_map());
       Map::EnsureDescriptorSlack(map, 1);
       map->AppendDescriptor(&d);
     }
     {
       AccessorConstantDescriptor d(factory()->iterator_symbol(),
                                    arguments_iterator, attribs);
-      Handle<Map> map(native_context()->aliased_arguments_map());
+      Handle<Map> map(native_context()->fast_aliased_arguments_map());
       Map::EnsureDescriptorSlack(map, 1);
       map->AppendDescriptor(&d);
     }
+    {
+      AccessorConstantDescriptor d(factory()->iterator_symbol(),
+                                   arguments_iterator, attribs);
+      Handle<Map> map(native_context()->slow_aliased_arguments_map());
+      Map::EnsureDescriptorSlack(map, 1);
+      map->AppendDescriptor(&d);
+    }
     {
       AccessorConstantDescriptor d(factory()->iterator_symbol(),
                                    arguments_iterator, attribs);
       Handle<Map> map(native_context()->strict_arguments_map());
       Map::EnsureDescriptorSlack(map, 1);
       map->AppendDescriptor(&d);
     }
   }
 
 #ifdef VERIFY_HEAP
@@ skipping 735 matching lines @@
 }
 
 
 // Called when the top-level V8 mutex is destroyed.
 void Bootstrapper::FreeThreadResources() {
   DCHECK(!IsActive());
 }
 
 }  // namespace internal
 }  // namespace v8