Class: Furnace::AVM2::ABC::OpcodeSequence

Inherits:
Array
  • Object
show all
Defined in:
lib/furnace-avm2/abc/primitives/opcode_sequence.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(options = {}) ⇒ OpcodeSequence

Returns a new instance of OpcodeSequence.



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# File 'lib/furnace-avm2/abc/primitives/opcode_sequence.rb', line 7

def initialize(options={})
  @root, @parent = options[:parent].root, options[:parent]
  @pos_cache    = {}
  @opcode_cache = {}

  @raw_code = nil
end

Instance Attribute Details

#parent ⇒ Object (readonly)

Returns the value of attribute parent.



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# File 'lib/furnace-avm2/abc/primitives/opcode_sequence.rb', line 5

def parent
  @parent
end

#root ⇒ Object (readonly)

Returns the value of attribute root.



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# File 'lib/furnace-avm2/abc/primitives/opcode_sequence.rb', line 5

def root
  @root
end

Instance Method Details

#build_cfg ⇒ Object 



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# File 'lib/furnace-avm2/abc/primitives/opcode_sequence.rb', line 82

def build_cfg
  graph = CFG::Graph.new

  targets = []

  each do |opcode|
    if opcode.is_a? ControlTransferOpcode
      targets << opcode.target
    elsif opcode.is_a? AS3LookupSwitch
      targets << opcode.default_target
      targets += opcode.case_targets
    end
  end

  pending_label = nil
  pending_queue = []

  cutoff = lambda do |targets|
    node = CFG::Node.new(graph, pending_label, pending_queue, nil, targets)

    if graph.nodes.empty?
      graph.entry = node
    end

    graph.nodes.add node

    pending_label = nil
    pending_queue = []
  end

  each do |opcode|
    if targets.include? opcode
      cutoff.([ opcode.offset ])
    end

    pending_label = opcode.offset if pending_label.nil?
    pending_queue << opcode

    if opcode.is_a? ControlTransferOpcode
      if opcode.conditional
        cutoff.([ opcode.target.offset, opcode.offset + opcode.byte_length ])
      else
        cutoff.([ opcode.target.offset ])
      end
    elsif opcode.is_a? AS3LookupSwitch
      cutoff.(opcode.parameters.flatten)
    end
  end

  cutoff.([])

  if exceptions.any?
    exception_node = CFG::Node.new(graph, :exception, [], nil,
        exceptions.map(&:target_offset))
    graph.nodes.add exception_node
  end

  graph
end

#byte_length ⇒ Object 



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# File 'lib/furnace-avm2/abc/primitives/opcode_sequence.rb', line 72

def byte_length
  map(&:byte_length).reduce(0, :+)
end

#disassemble ⇒ Object

Transformations



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# File 'lib/furnace-avm2/abc/primitives/opcode_sequence.rb', line 78

def disassemble
  map(&:disassemble).join("\n")
end

#each ⇒ Object 



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# File 'lib/furnace-avm2/abc/primitives/opcode_sequence.rb', line 31

def each
  parse if @raw_code

  super
end

#eliminate_dead! ⇒ Object 



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# File 'lib/furnace-avm2/abc/primitives/opcode_sequence.rb', line 142

def eliminate_dead!
  cfg = build_cfg
  dead_opcodes = []

  worklist = cfg.nodes.dup
  while worklist.any?
    node = worklist.first
    worklist.delete node

    next if node == cfg.entry

    if node.sources.count == 0 ||
          node.sources == [node]
      dead_opcodes.concat node.insns
    end
  end

  dead_opcodes.each do |opcode|
    delete opcode
  end

  recache!

  dead_opcodes.any?
end

#flush! ⇒ Object 



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# File 'lib/furnace-avm2/abc/primitives/opcode_sequence.rb', line 59

def flush!
  @pos_cache    = {}
  @opcode_cache = {}
end

#map ⇒ Object 



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# File 'lib/furnace-avm2/abc/primitives/opcode_sequence.rb', line 37

def map
  parse if @raw_code

  super
end

#offset_of(opcode) ⇒ Object 



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# File 'lib/furnace-avm2/abc/primitives/opcode_sequence.rb', line 68

def offset_of(opcode)
  @opcode_cache[opcode]
end

#opcode_at(position) ⇒ Object 



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# File 'lib/furnace-avm2/abc/primitives/opcode_sequence.rb', line 64

def opcode_at(position)
  @pos_cache[position]
end

#read(io) ⇒ Object 



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# File 'lib/furnace-avm2/abc/primitives/opcode_sequence.rb', line 15

def read(io)
  @raw_code = io.read(@parent.code_length)
end

#recache! ⇒ Object

Offsets



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# File 'lib/furnace-avm2/abc/primitives/opcode_sequence.rb', line 45

def recache!
  flush!

  pos = 0
  each do |opcode|
    @pos_cache[pos]       = opcode
    @opcode_cache[opcode] = pos

    pos += opcode.byte_length
  end

  lookup!
end

#write(io) ⇒ Object 



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# File 'lib/furnace-avm2/abc/primitives/opcode_sequence.rb', line 19

def write(io)
  if @raw_code
    io.write @raw_code
  else
    lookup!

    each do |opcode|
      opcode.write(io)
    end
  end
end