[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/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:
+  enum class ReservationToken : uint8_t { kIdx8, kIdx16 };
+  static const size_t kMaxCapacity = 65536;

[rmcilroy, 2016/01/04 17:05:48]

nit - newline above

[rmcilroy, 2016/01/04 17:05:48]

/s/65536/kMaxUInt16 + 1/

[oth, 2016/01/05 09:30:08]

Done.

[oth, 2016/01/05 09:30:08]

Done.

+  static const size_t kLowCapacity = 256;

[rmcilroy, 2016/01/04 17:05:48]

kMaxUInt8 + 1

[oth, 2016/01/05 09:30:08]

Done.

+
+  ConstantArrayBuilder(Isolate* isolate, Zone* zone);
+
+  // Generate a fixed array of constants based on inserted objects.
+  Handle<FixedArray> ToFixedArray(Factory* factory,
+                                  PretenureFlag pretenure) const;

[rmcilroy, 2016/01/04 17:05:48]

no need for PretenureFlag argument - this should always be TENURED

[oth, 2016/01/05 09:30:08]

Done.

+
+  // 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 a
+  // token that can be subsequently committed or discarded.
+  ReservationToken CreateReservedEntry();
+
+  // Commit reserved entry and returns the constant pool index for the
+  // object.
+  size_t CommitReservedEntry(ReservationToken token, Handle<Object> object);
+
+  // Discards constant pool reservation.
+  void DiscardReservedEntry(ReservationToken token);
+
+ private:
+  typedef uint16_t index_t;
+
+  index_t AllocateEntry(Handle<Object> object);
+
+  struct ConstantArraySlice final {
+    ConstantArraySlice(Zone* zone, int width);
+
+    size_t free() const;
+    size_t reserved() const;
+    size_t capacity() const;
+    size_t size() const;
+    size_t start_index() const;
+    void reserve();
+    void unreserve();

[rmcilroy, 2016/01/04 17:05:48]

lower case only for getters / setters (which you could probably do inline here).
reserve, unreserve, allocate (and possibly at) should be upper case function
names.

[oth, 2016/01/05 09:30:08]

Done.

+    size_t allocate(Handle<Object> object);
+    Handle<Object> at(size_t index) const;
+
+   private:
+    const size_t width_;
+    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_