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// Copyright 2017 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_BYTECODE_JUMP_TABLE_H_
#define V8_INTERPRETER_BYTECODE_JUMP_TABLE_H_
#include "src/utils/bit-vector.h"
#include "src/zone/zone.h"
namespace v8 {
namespace internal {
namespace interpreter {
class ConstantArrayBuilder;
// A jump table for a set of targets in a bytecode array. When an entry in the
// table is bound, it represents a known position in the bytecode array. If no
// entries match, the switch falls through.
class V8_EXPORT_PRIVATE BytecodeJumpTable final : public ZoneObject {
public:
// Constructs a new BytecodeJumpTable starting at |constant_pool_index|, with
// the given |size|, where the case values of the table start at
// |case_value_base|.
BytecodeJumpTable(size_t constant_pool_index, int size, int case_value_base,
Zone* zone)
:
#ifdef DEBUG
bound_(size, zone),
#endif
constant_pool_index_(constant_pool_index),
switch_bytecode_offset_(kInvalidOffset),
size_(size),
case_value_base_(case_value_base) {
}
size_t constant_pool_index() const { return constant_pool_index_; }
size_t switch_bytecode_offset() const { return switch_bytecode_offset_; }
int case_value_base() const { return case_value_base_; }
int size() const { return size_; }
#ifdef DEBUG
bool is_bound(int case_value) const {
DCHECK_GE(case_value, case_value_base_);
DCHECK_LT(case_value, case_value_base_ + size());
return bound_.Contains(case_value - case_value_base_);
}
#endif
size_t ConstantPoolEntryFor(int case_value) {
DCHECK_GE(case_value, case_value_base_);
return constant_pool_index_ + case_value - case_value_base_;
}
private:
static const size_t kInvalidIndex = static_cast<size_t>(-1);
static const size_t kInvalidOffset = static_cast<size_t>(-1);
void mark_bound(int case_value) {
#ifdef DEBUG
DCHECK_GE(case_value, case_value_base_);
DCHECK_LT(case_value, case_value_base_ + size());
bound_.Add(case_value - case_value_base_);
#endif
}
void set_switch_bytecode_offset(size_t offset) {
DCHECK_EQ(switch_bytecode_offset_, kInvalidOffset);
switch_bytecode_offset_ = offset;
}
#ifdef DEBUG
// This bit vector is only used for DCHECKS, so only store the field in debug
// builds.
BitVector bound_;
#endif
size_t constant_pool_index_;
size_t switch_bytecode_offset_;
int size_;
int case_value_base_;
friend class BytecodeArrayWriter;
};
} // namespace interpreter
} // namespace internal
} // namespace v8
#endif // V8_INTERPRETER_BYTECODE_JUMP_TABLE_H_