Cache some global constants in Thread, to allow access via THR register.

runtime/vm/thread.h

 // Copyright (c) 2015, 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.
 
 #ifndef VM_THREAD_H_
 #define VM_THREAD_H_
 
 #include "vm/base_isolate.h"
 #include "vm/globals.h"
 #include "vm/os_thread.h"
 #include "vm/store_buffer.h"
 
 namespace dart {
 
 class CHA;
 class Isolate;
+class RawBool;
+class RawObject;
+
 
 // A VM thread; may be executing Dart code or performing helper tasks like
 // garbage collection or compilation. The Thread structure associated with
 // a thread is allocated by EnsureInit before entering an isolate, and destroyed
 // automatically when the underlying OS thread exits. NOTE: On Windows, CleanUp
 // must currently be called manually (issue 23474).
 class Thread {
  public:
   // The currently executing thread, or NULL if not yet initialized.
   static Thread* Current() {
@@ skipping 19 matching lines @@
   // Empties the store buffer block into the isolate.
   // TODO(koda): Always run GC in separate thread.
   static void PrepareForGC();
 
 #if defined(TARGET_OS_WINDOWS)
   // Clears the state of the current thread and frees the allocation.
   static void CleanUp();
 #endif
 
   // Called at VM startup.
-  static void InitOnce();
+  static void InitOnceBeforeIsolate();
+  static void InitOnceAfterObjectAndStubCode();
 
   // The topmost zone used for allocation in this thread.
   Zone* zone() {
     return reinterpret_cast<BaseIsolate*>(isolate())->current_zone();
   }
 
   // The isolate that this thread is operating on, or NULL if none.
   Isolate* isolate() const { return isolate_; }
   static intptr_t isolate_offset() {
     return OFFSET_OF(Thread, isolate_);
   }
 
   // The (topmost) CHA for the compilation in the isolate of this thread.
   // TODO(23153): Move this out of Isolate/Thread.
   CHA* cha() const;
   void set_cha(CHA* value);
 
   void StoreBufferAddObject(RawObject* obj);
   void StoreBufferAddObjectGC(RawObject* obj);
 #if defined(TESTING)
   bool StoreBufferContains(RawObject* obj) const {
     return store_buffer_block_->Contains(obj);
   }
 #endif
   void StoreBufferBlockProcess(bool check_threshold);
   static intptr_t store_buffer_block_offset() {
     return OFFSET_OF(Thread, store_buffer_block_);
   }
 
+  static intptr_t object_null_offset() {
+    return OFFSET_OF(Thread, object_null_);
+  }
+
+  static intptr_t bool_true_offset() {
+    return OFFSET_OF(Thread, bool_true_);
+  }
+
+  static intptr_t bool_false_offset() {
+    return OFFSET_OF(Thread, bool_false_);
+  }
+
+  static intptr_t update_store_buffer_entry_point_offset() {
+    return OFFSET_OF(Thread, update_store_buffer_entry_point_);
+  }
+
  private:
   static ThreadLocalKey thread_key_;
 
   Isolate* isolate_;
   StoreBufferBlock* store_buffer_block_;
+  RawObject* object_null_;
+  RawBool* bool_true_;
+  RawBool* bool_false_;
+  uword update_store_buffer_entry_point_;
 
-  Thread()
-      : isolate_(NULL), store_buffer_block_(NULL) {}
+  explicit Thread(bool init_vm_constants = true);
+
+  void InitVMConstants();
 
   static void SetCurrent(Thread* current);
 
   DISALLOW_COPY_AND_ASSIGN(Thread);
 };
 
 }  // namespace dart
 
 #endif  // VM_THREAD_H_