Code Generation and Optimization

Question 31

Which of the following class of statement usually produces no executable code when compiled?

• declaration
• assignment statements
• input and output statements
• structural statements

Question 32

Which of the following comparisons between static and dynamic type checking is incorrect?

• Dynamic type checking slows down the execution
• Dynamic type checking offers more flexibility to the programmers
• In contrast to Static type checking, dynamic type checking may cause failure in runtime due to type errors
• Unlike static type checking, dynamic type checking is done during compilation

Question 33

Which of the following comment about peep-hole optimization is true?

• It is applied to small part of the code and applied repeatedly
• It can be used to optimize intermediate code
• It can be applied to a portion of the code that is not contiguous
• It is applied in symbol table to optimize the memory requirements.

Question 34

In multi-programmed systems, it is advantageous if some programs such as editors and compilers can be shared by several users. Which of the following must be true of multi-programmed systems in order that a single copy of a program can be shared by several users? I. The program is a macro II. The program is recursive III. The program is reentrant

• I only
• II only
• Ill only
• I, II and III

Question 35

Consider the following C code segment:

a = b + c;
e = a + 1;
d = b + c;
f = d + 1;
g = e + f; 

In a compiler, this code segment is represented internally as a directed acyclic graph (DAG). The number of nodes in the DAG is _____________ .

• 6
• 12
• 7
• 10

Question 36

In the context of compilers, which of the following is/are NOT an intermediate representation of the source program?

• Three address code
• Abstract Syntax Tree (AST)
• Control Flow Graph (CFG)
• Symbol table

Question 37

For a statement S in a program, in the context of liveness analysis, the following sets are defined:

• USE(S) : the set of variables used in S
• IN(S) : the set of variables that are live at the entry of S
• OUT(S) : the set of variables that are live at the exit of S

Consider a basic block that consists of two statements, S1 followed by S2. Which one of the following statements is correct?

• OUT(S1) = IN (S2)
• OUT (S1) = IN (S1) ∪ USE (S1)
• OUT (S1) = IN (S2) ∪ OUT (S2)
• OUT (S1) = USE (S1) ∪ IN (S2)

Question 38

Match the description of several parts of a classic optimizing compiler in List - I, with the names of those parts in List - II:

• (1)

• (2)

• (3)

• (4)