# A PhiFunction is a kind of Variable used in SSA-construction,
# it is placed at the beginning of a BasicBlock with many incoming blocks
class PhiFunction
	super Variable

	# The dependences of this variable for SSA-Algorithm
	var dependences = new Array[Couple[Variable, BasicBlock]]

	# The position in the AST of the phi-function
	var block: BasicBlock

	# Set the dependences for the phi-function
	# *`block` BasicBlock in which we go through the dominance-frontier
	# *`v` The variable to looking for
	fun add_dependences(block: BasicBlock, v: Variable)
	do
		# Look in which blocks of DF(block) `v` has been assigned
		for b in block.predecessors do
			if v.assignment_blocks.has(b) then
				var dep = new Couple[Variable, BasicBlock](v, b)
				dependences.add(dep)
			end
		end
	end

	# Print the PhiFunction with all its dependences
	redef fun to_s: String
	do
		var s = ""
		s += " dependences = [ "
		for d in dependences do
			s += d.first.to_s + " "
		end
		s += "]"

		return s
	end
end