CC PRELIM SET B

Q1.Multiple Choice Questions                                                                                 

1 Backpatching occurs due to _________________

            a) Procedure calls          b) Jump statement       c) Assignment statement        d) None

2 Dotted lines used in activation trees indicates ________________

            a) Execution of procedure is completed     b) Execution of procedure is yet not completed  

c) Procedure is in execution                   d) none

3 Which of the following is not addressing mode?

            a) Register                     b) Absolute      c) Indirect absolute    d) indirect indexed

4 Which of the following is needed to locate data needed by the called procedure but found elsewhere?

            a) Control lonk              b) Access link            c) Temporaries d) Saved machine status

5 Which of the following is false?

            a) Instruction involving register operands are slower than those involving memory operands

            b) Graph coloring is used for register allocation

c) Run time stack is used to keep track of live procedure activations

6 The most powerful parser is

            a) SLR             b) LALR         c) canonical LR                       d) LL(1)

7 Which of the following is phase of compilation process?

a) Lexical analysis                                                       b) code generation

c) Static analysis                                                         d) both a & b

8 The grammar S-> a sa|bs|c is

            a) LL(1) but not LR(1)                                   b) LR(1) but not LL(1)          

c) Both LL(1) and LR(1)                    d) Neither  LL(1) nor LR(1)

9 An ideal compiler should

            a) detect error                                                              b) detect and repair error

c) detect repair & correct error                                                d)  none of these

10 Which is the permanent database in the general model of the compiler?

            a) Literal table   b) Identifier table         c) Terminal table                    d) Reductions

11 A bottom up parser generates

            a)Left most derivation                                    b)Right most derivation 

c)Right most derivation in reverse      d)Left  most derivation in reverse

12 The grammar E-> E + E | E*E | a  is

            a) Ambiguous                                                                         b) Unambiguous 

            c) Ambiguous or not depends on given sentence                   d) None

13 For which of the following situations, inherited attribute is a natural choice

            a) Evaluation of a arithmetic expression          b) keeping track of variable declaration

c) Checking for correct use of L values and R values            d) b) & c)

14 A syntax tree

            a) is another name for a parse tree                                b) is a condensed form of parse tree

c) Should not have keywords as leaves                      d) All above

15 Which of the following symbol table implementation makes efficient use of memory?

            a) List                b) Search tree                          c) Hash table d) self organizing list

16Which is not part of run time memory subdivision?

            a) Stack                         b) Static data               c) Control link                       d) Heap

d) DAG is used to identify common sub expressions in the basic block

17 The most powerful parser is

            a) SLR             b) LALR         c) canonical LR                       d) LL(1)

18 Implicit allocation stands for _______________

            a) Allocation does by user                              b)Allocation does by programmer                  c)Allocation does by runtime support package                d) None 

19 For each available register, which of the following is used to keep track of the variable names whose current value in that register?

            a) Address descriptor              b) Register descriptor    c) Variable descriptor            d) None

20 What is the cost of following target code?

            Ld R1, a

            Add R1, b

            ST C, R1

            a) 5                                b) 4                               c) 6                           d) 3

 

2          Attempt any four:                                                                                       (5x4=20 Marks)

1. What is compiler? Draw diagram for phases of compiler. And explain any three in                                                                    detail.                                                                                               

2. What is scanning? Show diagrammatically translation of

X= a – b * 50; and explain.                                                                         

3. What is parse tree? How it is used to prove that grammar is ambiguous? Explain with suitable example.                                                                                

4. For what we use subset construction algorithm? Write & explain in detail the scheme.           

5. How to eliminate left recursion from a translation scheme? Explain with example.

3          Attempt any one:                                                                                                    10 Marks

a) Focus on non recursive predictive parsing by giving suitable model. Write predictive parsing program. And explain how to generate parsing table with suitable example.           

b) When to say syntax directed definition is L attributed? Give the basic requirements those are required for translation scheme. Give the ways to implement these requirements. Write & explain the algorithm for construction of a predictive syntax directed translator.

4          Explain the predictive parsing for LL(1) grammar with the help of suitable example.                 

                                                                                                                                         10Marks       

5          Attempt any four:                                                                                       (5x4=20 Marks)

a) Explain the syntax directed translation of case statement.                       

b) Explain stack and heap allocation strategy with example.                      

c) Explain code generation using DAG.                                                      

d) What is optimization? Write characteristics of peephole optimization        

e) Discuss issues in the design of code generator.               

6          Attempt any one:                                                                                                     10Marks

a) List and explain intermediate languages in detail.                       

b) Explain sources of optimization in detail. 

7          Explain basic block with example and write down algorithm for partitioning a 3-address statement in to basic block with example.                                                              10Marks