[Interpreter] Add support for jumps using constants with wide operands.

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 Factory;
+class Isolate;
+
+namespace interpreter {
+
+// A helper class for constructing constant arrays for the interpreter.
+class ConstantArrayBuilder final : public ZoneObject {
+ 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(Factory* factory) const;
+
+  // 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.
+  size_t Insert(Handle<Object> object);
+
+  // Creates a reserved entry in the constant pool and returns
+  // the size of the operand that'll be required to hold the entry
+  // when committed.
+  OperandSize CreateReservedEntry();
+
+  // Commit reserved entry and returns the constant pool index for the
+  // object.
+  size_t CommitReservedEntry(OperandSize operand_size, Handle<Object> object);
+
+  // Discards constant pool reservation.
+  void DiscardReservedEntry(OperandSize operand_size);
+
+ private:
+  typedef uint16_t index_t;
+
+  index_t AllocateEntry(Handle<Object> object);
+
+  struct ConstantArraySlice final {
+    ConstantArraySlice(Zone* zone, size_t start_index, size_t capacity);
+
+    size_t available() const;
+    size_t reserved() const;
+    size_t capacity() const;
+    size_t size() const;
+    size_t start_index() const;

[rmcilroy, 2016/01/05 13:46:10]

nit - accessors are usually below the other functions.

[oth, 2016/01/05 18:31:59]

Done.

+    void Reserve();
+    void Unreserve();
+    size_t Allocate(Handle<Object> object);
+    Handle<Object> At(size_t index) const;
+
+   private:
+    const size_t start_index_;
+    const size_t capacity_;
+    size_t reserved_;
+    ZoneVector<Handle<Object>> constants_;
+
+    DISALLOW_COPY_AND_ASSIGN(ConstantArraySlice);
+  };
+
+  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_