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// 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);
void Reserve();
void Unreserve();
size_t Allocate(Handle<Object> object);
Handle<Object> At(size_t index) const;
inline size_t available() const { return capacity() - reserved() - size(); }
inline size_t reserved() const { return reserved_; }
inline size_t capacity() const { return capacity_; }
inline size_t size() const { return constants_.size(); }
inline size_t start_index() const { return start_index_; }
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_
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