=== Register allocation example ===

Rules:
  * t <- num
    * mov t,num
  * t <- var (if var can be stored in reg)
    * mov t,t_var
  * t <- Exp1 + Exp2
    * t1 <- Exp1
    * t2 <- Exp2
    * mov t,t1
    * add t,t2
  * var := Exp (if var can be in reg)
    * t_var <- Exp

Example: y := y+1; x := x + 2 - y; 
  * mov t1,ty  ;t1 ty
  * mov t2,1   ;t1 ty t2
  * mov ty,t1  ;t1 ty t2
  * add ty,t2  ;   ty t2
  * mov t3,tx  ;   ty    tx t3
  * mov t4,2   ;   ty    tx t3 t4
  * mov t5,t3  ;   ty    tx t3 t4
  * add t5,t4  ;   ty    tx    t4 t5
  * mov t6,ty  ;   ty    tx       t5 t6
  * mov t7,t5  ;         tx          t6 t7
  * sub t7,t6  ;         tx          t6 t7
  * mov tx,t7  ;         tx             t7

{{mscfordprog:regalloc.png}}