// Copyright 2017 the V8 project authors. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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#ifndef V8_INTERPRETER_BYTECODE_JUMP_TABLE_H_
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#define V8_INTERPRETER_BYTECODE_JUMP_TABLE_H_
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#include "src/bit-vector.h"
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#include "src/zone/zone.h"
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namespace v8 {
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namespace internal {
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namespace interpreter {
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class ConstantArrayBuilder;
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// A jump table for a set of targets in a bytecode array. When an entry in the
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// table is bound, it represents a known position in the bytecode array. If no
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// entries match, the switch falls through.
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class V8_EXPORT_PRIVATE BytecodeJumpTable final : public ZoneObject {
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public:
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// Constructs a new BytecodeJumpTable starting at |constant_pool_index|, with
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// the given |size|, where the case values of the table start at
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// |case_value_base|.
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BytecodeJumpTable(size_t constant_pool_index, int size, int case_value_base,
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Zone* zone)
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:
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#ifdef DEBUG
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bound_(size, zone),
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#endif
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constant_pool_index_(constant_pool_index),
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switch_bytecode_offset_(kInvalidOffset),
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size_(size),
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case_value_base_(case_value_base) {
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}
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size_t constant_pool_index() const { return constant_pool_index_; }
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size_t switch_bytecode_offset() const { return switch_bytecode_offset_; }
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int case_value_base() const { return case_value_base_; }
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int size() const { return size_; }
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#ifdef DEBUG
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bool is_bound(int case_value) const {
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DCHECK_GE(case_value, case_value_base_);
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DCHECK_LT(case_value, case_value_base_ + size());
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return bound_.Contains(case_value - case_value_base_);
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}
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#endif
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size_t ConstantPoolEntryFor(int case_value) {
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DCHECK_GE(case_value, case_value_base_);
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return constant_pool_index_ + case_value - case_value_base_;
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}
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private:
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static const size_t kInvalidIndex = static_cast<size_t>(-1);
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static const size_t kInvalidOffset = static_cast<size_t>(-1);
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void mark_bound(int case_value) {
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#ifdef DEBUG
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DCHECK_GE(case_value, case_value_base_);
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DCHECK_LT(case_value, case_value_base_ + size());
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bound_.Add(case_value - case_value_base_);
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#endif
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}
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void set_switch_bytecode_offset(size_t offset) {
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DCHECK_EQ(switch_bytecode_offset_, kInvalidOffset);
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switch_bytecode_offset_ = offset;
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}
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#ifdef DEBUG
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// This bit vector is only used for DCHECKS, so only store the field in debug
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// builds.
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BitVector bound_;
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#endif
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size_t constant_pool_index_;
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size_t switch_bytecode_offset_;
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int size_;
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int case_value_base_;
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friend class BytecodeArrayWriter;
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};
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} // namespace interpreter
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} // namespace internal
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} // namespace v8
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#endif // V8_INTERPRETER_BYTECODE_JUMP_TABLE_H_
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