GATE CSE 2021 Set 2 | Question: 13

Question

In the context of compilers, which of the following is/are $\text{NOT}$ an intermediate representation of the source program?

• A. Three address code
• B. Abstract Syntax Tree $\text{(AST)}$
• C. Control Flow Graph $\text{(CFG)}$
• D. Symbol table

Comments

Is it an MSQ?

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Kanwae Kan Yes

Answer 1

Correct Answer: D

Symbol table is a data structure created and maintained by compilers in order to store info about occurrences of various entities like variable names, function names, objects, classes and interface.

Various forms of intermediate representation of code include Postfix Notation, Three address code ( x = y op z), Syntax Tree, DAG.
Abstract Syntax Tree is a condensed version of syntax tree/parse tree more to with program than the compiler.

Parse Tree and Syntax Tree:

Control Flow Graph is used in optimization phase of compiler,each basic block consists of linear code, the next block to access is determined by the last instruction of the current block.

An Example,

     goto L2
L1:
     t0 := 3 >> x
     t1 := y / t0
     x := t1
     if y == 0 goto L3
     t2 := x - 3
     print t2
L3:
L2:
     t4 := 4 * y
     x := t4 < t5
     if t5 != 0 goto L1

See:

1. https://cs.lmu.edu/~ray/notes/ir/
2. https://www2.cs.arizona.edu/~collberg/Teaching/453/2009/Handouts/Handout-15.pdf
3. http://pages.cs.wisc.edu/~fischer/cs536.s06/course.hold/html/NOTES/4.SYNTAX-DIRECTED-TRANSLATION.html

Answer 2

Symbol table is not an intermediate representation

Comments

https://www.rose-hulman.edu/class/csse/csse404/schedule/day24/IntermediateRepresentations.pdf (page 8)

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This question was of how many marks ?

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I also think , the answer was C and D.

Answer 3

As it is given in the Ullman

8.4 Basic Blocks and Flow Graphs

This section introduces a graph representation of intermediate code.

so OPTION D is correct.

Comments

As stated above, the answer should be C and D

Answer 4

https://testbook.com/question-answer/in-the-context-of-compilers-which-of-the-followin--6037bd1220b00eabf4667b67#:~:text=Control%20Flow%20Graph%3A%20Control%20flow,terms%20of%20some%20variable%20notation.

may be helpful.