Q38

MCQ2 marks, −0.67

For a statement $S$ in a program, in the context of liveness analysis, the following sets are defined: $\text{USE}(S)$ : the set of variables used in $S$ $\text{IN}(S)$ : the set of variables that are live at the entry of $S$ $\text{OUT}(S)$ : the set of variables that are live at the exit of $S$ Consider a basic block that consists of two statements, $S_1$ followed by $S_2$ . Which one of the following statements is correct?

(A)

$\text{OUT($ S_1 $)} = \text{IN ($ S_2 $)}$

(B)

$\text{OUT ($ S_1 $)} = \text{IN ($ S_1 $)} \cup \text{ USE ($ S_1 $)}$

(C)

$\text{OUT ($ S_1 $)} = \text{IN ($ S_2 $) }\cup \text{ OUT ($ S_2 $)}$

(D)

$\text{OUT ($ S_1 $)} = \text{USE ($ S_1 $)} \cup \text{IN ($ S_2 $)}$

Loading…