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

runtime/vm/thread.cc

 // 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.
 
 #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"
 
 
 namespace dart {
 
 // The single thread local key which stores all the thread local data
 // for a thread.
 // TODO(koda): Can we merge this with ThreadInterrupter::thread_state_key_?
 ThreadLocalKey Thread::thread_key_ = OSThread::kUnsetThreadLocalKey;
 
 
 static void DeleteThread(void* thread) {
   delete reinterpret_cast<Thread*>(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();
+}
+
+
 void Thread::SetCurrent(Thread* current) {
   OSThread::SetThreadLocal(thread_key_, reinterpret_cast<uword>(current));
 }
 
 
 void Thread::EnsureInit() {
   if (Thread::Current() == NULL) {
     SetCurrent(new Thread());
   }
 }
 
 
 #if defined(TARGET_OS_WINDOWS)
 void Thread::CleanUp() {
   Thread* current = Current();
   if (current != NULL) {
     delete current;
   }
   SetCurrent(NULL);
 }
 #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);
   ASSERT(thread->isolate() == NULL);
   ASSERT(isolate->mutator_thread() == NULL);
   thread->isolate_ = isolate;
   isolate->set_mutator_thread(thread);
   // TODO(koda): Migrate thread_state_ and profile_data_ to Thread, to allow
   // helper threads concurrent with mutator.
   ASSERT(isolate->thread_state() == NULL);
@@ skipping 96 matching lines @@
   return isolate_->cha_;
 }
 
 
 void Thread::set_cha(CHA* value) {
   ASSERT(isolate_ != NULL);
   isolate_->cha_ = value;
 }
 
 }  // namespace dart