Add thread safe constant canonicalization.

runtime/vm/isolate.h

 // 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.
 
 #ifndef VM_ISOLATE_H_
 #define VM_ISOLATE_H_
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "vm/atomic.h"
@@ skipping 304 matching lines @@
   void set_is_runnable(bool value) { is_runnable_ = value; }
 
   IsolateSpawnState* spawn_state() const { return spawn_state_; }
   void set_spawn_state(IsolateSpawnState* value) { spawn_state_ = value; }
 
   Mutex* mutex() const { return mutex_; }
   Mutex* symbols_mutex() const { return symbols_mutex_; }
   Mutex* type_canonicalization_mutex() const {
     return type_canonicalization_mutex_;
   }
+  Mutex* constant_canonicalization_mutex() const {
+    return constant_canonicalization_mutex_;
+  }
 
   Debugger* debugger() const {
     if (!FLAG_support_debugger) {
       return NULL;
     }
     ASSERT(debugger_ != NULL);
     return debugger_;
   }
 
   void set_single_step(bool value) { single_step_ = value; }
@@ skipping 416 matching lines @@
   ApiState* api_state_;
   Debugger* debugger_;
   bool resume_request_;
   int64_t last_resume_timestamp_;
   bool has_compiled_code_;  // Can check that no compilation occured.
   Random random_;
   Simulator* simulator_;
   Mutex* mutex_;  // Protects stack_limit_, saved_stack_limit_, compiler stats.
   Mutex* symbols_mutex_;  // Protects concurrent access to the symbol table.
   Mutex* type_canonicalization_mutex_;  // Protects type canonicalization.
+  Mutex* constant_canonicalization_mutex_;  // Protects const canonicalization.
   uword saved_stack_limit_;
   uword deferred_interrupts_mask_;
   uword deferred_interrupts_;
   uword stack_overflow_flags_;
   int32_t stack_overflow_count_;
   MessageHandler* message_handler_;
   IsolateSpawnState* spawn_state_;
   bool is_runnable_;
   Dart_GcPrologueCallback gc_prologue_callback_;
   Dart_GcEpilogueCallback gc_epilogue_callback_;
@@ skipping 250 matching lines @@
   intptr_t* spawn_count_;
 
   Dart_IsolateFlags isolate_flags_;
   bool paused_;
   bool errors_are_fatal_;
 };
 
 }  // namespace dart
 
 #endif  // VM_ISOLATE_H_