[interpreter] Move temporary register allocator into own file.

src/interpreter/constant-array-builder.h

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_INTERPRETER_CONSTANT_ARRAY_BUILDER_H_
 #define V8_INTERPRETER_CONSTANT_ARRAY_BUILDER_H_
 
 #include "src/identity-map.h"
 #include "src/interpreter/bytecodes.h"
 #include "src/zone-containers.h"
 
 namespace v8 {
 namespace internal {
 
 class Isolate;
 
 namespace interpreter {
 
-// A helper class for constructing constant arrays for the interpreter.
-class ConstantArrayBuilder final : public ZoneObject {
+// A helper class for constructing constant arrays for the
+// interpreter. Each instance of this class is intended to be used to
+// generate exactly one FixedArray of constants via the ToFixedArray
+// method.
+class ConstantArrayBuilder final BASE_EMBEDDED {
  public:
   // Capacity of the 8-bit operand slice.
   static const size_t kLowCapacity = 1u << kBitsPerByte;
 
   // Capacity of the combined 8-bit and 16-bit operand slices.
   static const size_t kMaxCapacity = 1u << (2 * kBitsPerByte);
 
   // Capacity of the 16-bit operand slice.
   static const size_t kHighCapacity = kMaxCapacity - kLowCapacity;
 
   ConstantArrayBuilder(Isolate* isolate, Zone* zone);
 
   // Generate a fixed array of constants based on inserted objects.
-  Handle<FixedArray> ToFixedArray() const;
+  Handle<FixedArray> ToFixedArray();
 
   // Returns the object in the constant pool array that at index
   // |index|.
   Handle<Object> At(size_t index) const;
 
   // Returns the number of elements in the array.
   size_t size() const;
 
   // Insert an object into the constants array if it is not already
   // present. Returns the array index associated with the object.
@@ skipping 31 matching lines @@
 
    private:
     const size_t start_index_;
     const size_t capacity_;
     size_t reserved_;
     ZoneVector<Handle<Object>> constants_;
 
     DISALLOW_COPY_AND_ASSIGN(ConstantArraySlice);
   };
 
+  IdentityMap<index_t>* constants_map() { return &constants_map_; }
+
   Isolate* isolate_;
   ConstantArraySlice idx8_slice_;
   ConstantArraySlice idx16_slice_;
   IdentityMap<index_t> constants_map_;
 };
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_INTERPRETER_CONSTANT_ARRAY_BUILDER_H_