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

runtime/vm/thread.cc

Index: runtime/vm/thread.cc
diff --git a/runtime/vm/thread.cc b/runtime/vm/thread.cc
index ba6db93eacd7aeb166d49bbcbba0c59c8719d911..27031776ecedf0de1483151aa3dbb60b47bc2a6f 100644
--- a/runtime/vm/thread.cc
+++ b/runtime/vm/thread.cc
@@ -5,8 +5,10 @@
 #include "vm/thread.h"
 
 #include "vm/isolate.h"
+#include "vm/object.h"
 #include "vm/os_thread.h"
 #include "vm/profiler.h"
+#include "vm/stub_code.h"
 #include "vm/thread_interrupter.h"
 
 
@@ -23,10 +25,21 @@ static void DeleteThread(void* thread) {
 }
 
 
-void Thread::InitOnce() {
+void Thread::InitOnceBeforeIsolate() {
   ASSERT(thread_key_ == OSThread::kUnsetThreadLocalKey);
   thread_key_ = OSThread::CreateThreadLocal(DeleteThread);
   ASSERT(thread_key_ != OSThread::kUnsetThreadLocalKey);
+  ASSERT(Thread::Current() == NULL);
+  // Postpone initialization of VM constants for this first thread.
+  SetCurrent(new Thread(false));
+}
+
+
+void Thread::InitOnceAfterObjectAndStubCode() {
+  Thread* thread = Thread::Current();
+  ASSERT(thread != NULL);
+  ASSERT(thread->isolate() == Dart::vm_isolate());
+  thread->InitVMConstants();
 }
 
 
@@ -53,6 +66,31 @@ void Thread::CleanUp() {
 #endif
 
 
+Thread::Thread(bool init_vm_constants)
+    : isolate_(NULL),
+      store_buffer_block_(NULL),
+      object_null_(NULL),
+      bool_true_(NULL),
+      bool_false_(NULL),
+      update_store_buffer_entry_point_(0) {
+  if (init_vm_constants) {
+    InitVMConstants();
+  }
+}
+
+
+void Thread::InitVMConstants() {
+  ASSERT(object_null_ == NULL);
+  object_null_ = Object::null();
+  ASSERT(bool_true_ == NULL);
+  bool_true_ = Object::bool_true().raw();
+  ASSERT(bool_false_ == NULL);
+  bool_false_ = Object::bool_false().raw();
+  ASSERT(update_store_buffer_entry_point_ == 0);
+  update_store_buffer_entry_point_ = StubCode::UpdateStoreBufferEntryPoint();
+}
+
+
 void Thread::EnterIsolate(Isolate* isolate) {
   Thread* thread = Thread::Current();
   ASSERT(thread != NULL);