Class: Furnace::AVM2::Transform::NFNormalize

Inherits:
Object
  • Object
show all
Includes:
Visitor
Defined in:
lib/furnace-avm2/transform/nf_normalize.rb

Constant Summary collapse

LocalIncDecMatcher = 
AST::Matcher.new do
  [ either_multi[
      [:set_slot,  capture(:index), capture(:scope)],
      [:set_local, capture(:index)],
    ],
    either[
      [:convert, any,
        capture(:inner)],
      [:coerce, :any,
        capture(:inner)],
      capture(:inner)
    ]
  ]
end
LocalIncDecInnerMatcher = 
AST::Matcher.new do
  [capture(:operator),
    either[
      [:convert, any,
        capture(:getter)],
      capture(:getter),
    ]
  ]
end
LocalIncDecGetterMatcher = 
AST::Matcher.new do
  either[
    [:get_slot,  backref(:index), backref(:scope)],
    [:get_local, backref(:index)],
  ]
end
IncDecOperators = 
[
  :pre_increment, :post_increment,
  :pre_decrement, :post_decrement
]
ExpandedForInMatcher = 
AST::Matcher.new do
  [:if, [:has_next2, skip], skip]
end
ForInMatcher = 
AST::Matcher.new do
  [:while,
    [:has_next2, capture(:object_reg), capture(:index_reg)],
    [:begin,
      [ either_multi[
          [ :set_local, capture(:value_reg) ],
          [ :set_slot, capture(:value_reg), [:get_scope_object, 1] ],
        ],
        [ either[:coerce, :convert], capture(:value_type),
          [ capture(:iterator),
            [:get_local, backref(:object_reg)],
            [:get_local, backref(:index_reg)]]]],
      capture_rest(:body)]]
end
ForInIndexMatcher = 
AST::Matcher.new do
  [:set_local, backref(:index_reg), [:integer, 0]]
end
ForInObjectMatcher = 
AST::Matcher.new do
  [:set_local, backref(:object_reg),
    [:coerce, :any,
      capture(:root)]]
end
SuperfluousContinueMatcher = 
AST::Matcher.new do
  [:continue]
end
OptimizedSwitchSeed = 
AST::Matcher.new do
  [:ternary,
    [:===, capture(:case_value),
      [:get_local, capture(:local_index)]],
    [:integer, capture(:case_index)],
    capture(:nested)]
end
OptimizedSwitchNested = 
AST::Matcher.new do
  either[
    [:ternary,
      [:===, capture(:case_value),
        [:get_local, backref(:local_index)]],
      [:integer, capture(:case_index)],
      capture(:nested)],
    [:integer, capture(:default_index)]
  ]
end
NumericCase = 
AST::Matcher.new do
  [:case, [:integer, capture(:index)]]
end

Instance Method Summary collapse

Instance Method Details

#on_begin(node) ⇒ Object 



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# File 'lib/furnace-avm2/transform/nf_normalize.rb', line 182

def on_begin(node)
  # Fold (with)'s
  with_begin = node.children.index do |child|
    child.type == :push_with
  end
  with_end = nil

  if with_begin
    nesting = 0
    node.children[with_begin..-1].each_with_index do |child, index|
      if child.type == :push_with || child.type == :push_scope
        nesting += 1
      elsif child.type == :pop_scope
        nesting -= 1
        if nesting == 0
          with_end = with_begin + index
          break
        end
      end
    end

    if nesting == 0
      with_scope,  = node.children[with_begin].children
      with_content = node.children.slice (with_begin + 1)..(with_end - 1)

      with_node = AST::Node.new(:with, [
        with_scope,
        AST::Node.new(:begin,
          with_content
        )
      ])

      node.children.slice! with_begin..with_end
      node.children.insert with_begin, with_node
    end
  end

  # Remove obviously dead code
  first_ctn = node.children.index do |child|
    [:return_void, :return_value, :break, :continue, :throw].include? child.type
  end
  return unless first_ctn

  node.children.slice! (first_ctn + 1)..-1
end

#on_if(node) ⇒ Object

Loops can get expanded, but conditionals would never contain has-next2.



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# File 'lib/furnace-avm2/transform/nf_normalize.rb', line 93

def on_if(node)
  if ExpandedForInMatcher.match node
    condition, body, rest = node.children

    body.children << AST::Node.new(:break)

    loop = AST::Node.new(:while, [ condition, body ])
    on_while(loop, node.parent, node)

    if rest
      node.update(:expand, [ loop ] + rest.children)
    else
      node.update(:expand, [ loop ])
    end
  end
end

#on_nop(node) ⇒ Object 



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# File 'lib/furnace-avm2/transform/nf_normalize.rb', line 21

def on_nop(node)
  node.update(:remove)
end

#on_set_local(node) ⇒ Object Also known as: on_set_slot 



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# File 'lib/furnace-avm2/transform/nf_normalize.rb', line 62

def on_set_local(node)
  captures = {}
  if LocalIncDecMatcher.match(node, captures) &&
        LocalIncDecInnerMatcher.match(captures[:inner], captures) &&
        IncDecOperators.include?(captures[:operator])
    if captures[:getter].is_a?(AST::Node) &&
        LocalIncDecGetterMatcher.match(captures[:getter], captures)
      if captures[:scope]
        node.update(:"#{captures[:operator]}_slot", [ captures[:index], captures[:scope] ])
      else
        node.update(:"#{captures[:operator]}_local", [ captures[:index] ])
      end
    else
      node.update(:add, [
        AST::Node.new(:set_local, [
          captures[:index],
          captures[:getter]
        ]),
        AST::Node.new(:integer, [ 1 ])
      ])
    end
  end
end

#on_switch(node) ⇒ Object 



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# File 'lib/furnace-avm2/transform/nf_normalize.rb', line 251

def on_switch(node)
  condition, body = node.children

  if captures = OptimizedSwitchSeed.match(condition)
    mapping = { captures[:case_index] => captures[:case_value] }
    while captures = OptimizedSwitchNested.match(captures[:nested], captures)
      break if captures[:default_index]
      mapping[captures[:case_index]] = captures[:case_value]
    end

    return if captures.nil?

    case_mapping = {}

    body.children.each do |child|
      if case_captures = NumericCase.match(child)
        case_index = case_captures[:index]
        if captures[:default_index] == case_index
          case_mapping[child] = nil
        elsif mapping.has_key?(case_index)
          case_mapping[child] = mapping[case_index]
        else
          # fallback
          return
        end
      end
    end

    # At this point, we are sure that this switch can be transformed.

    node.children[0] = AST::Node.new(:get_local, [ captures[:local_index] ])

    case_mapping.each do |child, value|
      if value.nil?
        body.children.delete child
      else
        child.children[0] = value
      end
    end
  end
end

#on_while(node, parent = node.parent, enclosure = node) ⇒ Object 



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# File 'lib/furnace-avm2/transform/nf_normalize.rb', line 139

def on_while(node, parent=node.parent, enclosure=node)
  *whatever, code = node.children
  if SuperfluousContinueMatcher.match code.children.last
    code.children.slice! -1
  end

  if captures = ForInMatcher.match(node)
    case captures[:iterator]
    when :next_name
      type = :for_in
    when :next_value
      type = :for_each_in
    else
      return
    end

    index_node = object_node = nil

    loop_index = parent.children.index(enclosure)
    parent.children[0..loop_index].reverse_each do |parent_node|
      if ForInIndexMatcher.match(parent_node, captures)
        index_node  = parent_node
      elsif ForInObjectMatcher.match(parent_node, captures)
        object_node = parent_node
      end

      break if index_node && object_node
    end

    return unless index_node && object_node

    index_node.update(:remove)
    object_node.update(:remove) if type != :for_each_in

    node.update(type, [
      captures[:value_reg],
      captures[:value_type],
      captures[:object_reg],
      AST::Node.new(:begin, captures[:body])
    ])
  end
end

#remove_useless_return ⇒ Object 



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# File 'lib/furnace-avm2/transform/nf_normalize.rb', line 15

def remove_useless_return
  if @nf.children.last.type == :return_void
    @nf.children.slice! -1
  end
end

#transform(nf) ⇒ Object 



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# File 'lib/furnace-avm2/transform/nf_normalize.rb', line 6

def transform(nf)
  @nf = nf.normalize_hierarchy!

  remove_useless_return
  visit @nf

  @nf
end