Make CTX allocatable by the register allocator.

runtime/vm/isolate.cc

 // Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/isolate.h"
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "platform/json.h"
 #include "vm/code_observers.h"
@@ skipping 383 matching lines @@
 Isolate::Isolate()
     : store_buffer_(),
       message_notify_callback_(NULL),
       name_(NULL),
       start_time_(OS::GetCurrentTimeMicros()),
       main_port_(0),
       pause_capability_(0),
       terminate_capability_(0),
       heap_(NULL),
       object_store_(NULL),
-      top_context_(Context::null()),
       top_exit_frame_info_(0),
       init_callback_data_(NULL),
       environment_callback_(NULL),
       library_tag_handler_(NULL),
       api_state_(NULL),
       stub_code_(NULL),
       debugger_(NULL),
       single_step_(false),
       resume_request_(false),
       random_(),
@@ skipping 39 matching lines @@
     : store_buffer_(true),
       class_table_(original->class_table()),
       message_notify_callback_(NULL),
       name_(NULL),
       start_time_(OS::GetCurrentTimeMicros()),
       main_port_(0),
       pause_capability_(0),
       terminate_capability_(0),
       heap_(NULL),
       object_store_(NULL),
-      top_context_(Context::null()),
       top_exit_frame_info_(0),
       init_callback_data_(NULL),
       environment_callback_(NULL),
       library_tag_handler_(NULL),
       api_state_(NULL),
       stub_code_(NULL),
       debugger_(NULL),
       single_step_(false),
       resume_request_(false),
       random_(),
@@ skipping 648 matching lines @@
   while (frame != NULL) {
     frame->VisitObjectPointers(visitor);
     frame = frames_iterator.NextFrame();
   }
 
   // Visit the dart api state for all local and persistent handles.
   if (api_state() != NULL) {
     api_state()->VisitObjectPointers(visitor, visit_prologue_weak_handles);
   }
 
-  // Visit the top context which is stored in the isolate.
-  visitor->VisitPointer(reinterpret_cast<RawObject**>(&top_context_));
-
   // Visit the current tag which is stored in the isolate.
   visitor->VisitPointer(reinterpret_cast<RawObject**>(&current_tag_));
 
   // Visit the default tag which is stored in the isolate.
   visitor->VisitPointer(reinterpret_cast<RawObject**>(&default_tag_));
 
   // Visit the tag table which is stored in the isolate.
   visitor->VisitPointer(reinterpret_cast<RawObject**>(&tag_table_));
 
   // Visit objects in the debugger.
@@ skipping 435 matching lines @@
                            serialized_message_, serialized_message_len_);
 }
 
 
 void IsolateSpawnState::Cleanup() {
   SwitchIsolateScope switch_scope(I);
   Dart::ShutdownIsolate();
 }
 
 }  // namespace dart