A sample algorithm for inter-procedural analysis using PCG 

Repeat
        loop for each p in PCG
	    repeat
	         loop for each node N in CFG
		     if N is a call, calling procedure r
			  compute OutN using r.Exit and InN
		      else
	                  OutN = genN + (InN - KillN)
                 end loop
            until, for each node N in CFG, InN and OutN converge
            
            update p.Exit
            for each procedure r called by p
               update r.Entry using InN       
        end loop
Until,  for each p in PCG,  p.Entry and p.Exit converge