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# File 'lib/furnace-avm2/transform/cfg_build.rb', line 4
def transform(ast, body, finallies)
@jumps = Set.new
@exceptions = {}
@cfg = CFG::Graph.new
body.exceptions.each_with_index do |exc, index|
if finallies.find { |f| f[:first_catch] == exc }
next
end
unless exc_block = @exceptions[exc.range]
exc_block = CFG::Node.new(@cfg, "exc_#{index}")
dispatch_node = AST::Node.new(:exception_dispatch, [], keep: true)
exc_block.insns << dispatch_node
exc_block.cti = dispatch_node
@exceptions[exc.range] = exc_block
end
exc_block.target_labels << exc.target_offset
if finallies.find { |f| f[:second_catch] == exc }
exc_block.cti.children <<
AST::Node.new(:finally,
[ exc.target_offset ])
else
exc_block.cti.children <<
AST::Node.new(:catch,
[ (exc.exception.to_astlet if exc.exception),
exc.variable.to_astlet,
exc.target_offset ])
end
end
@pending_label = nil
@pending_exc_block = nil
@pending_exc_range = nil
@pending_queue = []
ast.children.each_with_index do |node, index|
unless @pending_label
@pending_label = node.metadata[:label]
exception_block_for(@pending_label) do |block, range|
@pending_exc_block = block
@pending_exc_range = range
end
end
@pending_queue << node if ![:nop, :jump, :label].include? node.type
next_node = ast.children[index + 1]
next_label = next_node.metadata[:label] if next_node
case node.type
when :return_value, :return_void, :throw
cutoff(nil, [nil])
when :jump
@jumps.add(node.children[0])
cutoff(nil, [ node.children.delete_at(0) ])
when :jump_if
@jumps.add(node.children[1])
cutoff(node, [ node.children.delete_at(1), next_label ])
when :lookup_switch
jumps_to = [ node.children[0] ] + node.children[1]
@jumps.merge(jumps_to)
cutoff(node, jumps_to)
else
*, next_exception_block = exception_block_for(next_label)
if @jumps.include?(next_label) || (next_node && next_node.type == :label)
cutoff(nil, [next_label])
elsif body.exceptions.find { |ex| ex.target_offset == next_label }
cutoff(nil, [next_label])
elsif @pending_exc_block != next_exception_block
cutoff(nil, [next_label])
end
end
end
exit_node = CFG::Node.new(@cfg)
@cfg.nodes.add exit_node
@cfg.exit = exit_node
@exceptions.values.each do |exc_node|
@cfg.nodes.add exc_node
end
@cfg.eliminate_unreachable!
@cfg.merge_redundant!
@cfg
end
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