Improve constant pool implementation in the assembler.

runtime/vm/assembler_arm.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_ASSEMBLER_ARM_H_
 #define VM_ASSEMBLER_ARM_H_
 
 #ifndef VM_ASSEMBLER_H_
 #error Do not include assembler_arm.h directly; use assembler.h instead.
 #endif
 
 #include "platform/assert.h"
 #include "platform/utils.h"
 #include "vm/constants_arm.h"
 #include "vm/cpu.h"
+#include "vm/hash_map.h"
 #include "vm/object.h"
 #include "vm/simulator.h"
 
 namespace dart {
 
 // Forward declarations.
 class RuntimeEntry;
 
 class Label : public ValueObject {
  public:
@@ skipping 905 matching lines @@
   bool allow_constant_pool() const {
     return allow_constant_pool_;
   }
   void set_allow_constant_pool(bool b) {
     allow_constant_pool_ = b;
   }
 
  private:
   AssemblerBuffer buffer_;  // Contains position independent code.
   GrowableObjectArray& object_pool_;  // Objects and patchable jump targets.
+
+  // Hashmap for fast lookup in object pool.
+  DirectChainedHashMap<ObjIndexPair> object_pool_index_table_;
+
   int32_t prologue_offset_;
 
   bool use_far_branches_;
 
   // If you are thinking of using one or both of these instructions directly,
   // instead LoadImmediate should probably be used.
   void movw(Register rd, uint16_t imm16, Condition cond = AL);
   void movt(Register rd, uint16_t imm16, Condition cond = AL);
 
   int32_t AddObject(const Object& obj);
@@ skipping 147 matching lines @@
   // verifying that its old value matches its shadow.
   void VerifiedWrite(const Address& address, Register new_value);
 
   DISALLOW_ALLOCATION();
   DISALLOW_COPY_AND_ASSIGN(Assembler);
 };
 
 }  // namespace dart
 
 #endif  // VM_ASSEMBLER_ARM_H_