Improve constant pool implementation in the assembler.

runtime/vm/assembler_arm64.h

 // Copyright (c) 2014, 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_ARM64_H_
 #define VM_ASSEMBLER_ARM64_H_
 
 #ifndef VM_ASSEMBLER_H_
 #error Do not include assembler_arm64.h directly; use assembler.h instead.
 #endif
@@ skipping 1412 matching lines @@
 
  private:
   AssemblerBuffer buffer_;  // Contains position independent code.
 
   // Objects and patchable jump targets.
   GrowableObjectArray& object_pool_;
 
   // Patchability of pool entries.
   GrowableArray<Patchability> patchable_pool_entries_;
 
-  // Pair type parameter for DirectChainedHashMap.
-  class ObjIndexPair {
-   public:
-    // TODO(zra): A WeakTable should be used here instead, but then it would
-    // also have to be possible to register and de-register WeakTables with the
-    // heap. Also, the Assembler would need to become a StackResource.
-    // Issue 13305. In the meantime...
-    // CAUTION: the RawObject* below is only safe because:
-    // The HashMap that will use this pair type will not contain any RawObject*
-    // keys that are not in the object_pool_ array. Since the keys will be
-    // visited by the GC when it visits the object_pool_, and since all objects
-    // in the object_pool_ are Old (and so will not be moved) the GC does not
-    // also need to visit the keys here in the HashMap.
-
-    // Typedefs needed for the DirectChainedHashMap template.
-    typedef RawObject* Key;
-    typedef intptr_t Value;
-    typedef ObjIndexPair Pair;
-
-    ObjIndexPair(Key key, Value value) : key_(key), value_(value) { }
-
-    static Key KeyOf(Pair kv) { return kv.key_; }
-
-    static Value ValueOf(Pair kv) { return kv.value_; }
-
-    static intptr_t Hashcode(Key key) {
-      return reinterpret_cast<intptr_t>(key) >> kObjectAlignmentLog2;
-    }
-
-    static inline bool IsKeyEqual(Pair kv, Key key) {
-      return kv.key_ == key;
-    }
-
-   private:
-    Key key_;
-    Value value_;
-  };
-
   // Hashmap for fast lookup in object pool.
   DirectChainedHashMap<ObjIndexPair> object_pool_index_table_;
 
   int32_t prologue_offset_;
 
   bool use_far_branches_;
 
   class CodeComment : public ZoneAllocated {
    public:
     CodeComment(intptr_t pc_offset, const String& comment)
@@ skipping 490 matching lines @@
                                   Register value,
                                   Label* no_update);
 
   DISALLOW_ALLOCATION();
   DISALLOW_COPY_AND_ASSIGN(Assembler);
 };
 
 }  // namespace dart
 
 #endif  // VM_ASSEMBLER_ARM64_H_