Suppose that k (the number of temporary registers) in Figure 15.6 is 4 (this is an artificially small number for modern machines). Give an example of an expression that will lead to register spilling under our naive register allocation algorithm.

Figure 15.6:

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program (7) call for (8) 0.0 (4) null (10) 1 (7) call null (9) call null (6) Index Symbol Туре Scope (8) 1 void type (5) null 2 int (8) float type type func: (1) (2) func: (1) – (3) func: (3) – (1) 3 real (8) (9) 4 getint (7) getreal putreal 7 2 1 8 sum 3 1 9 3 1 10 i 2 2