Compiler Design

Choose the correct answer of the following:
Quadruple is a record structure of
(i) three fields
(ii) four fields
(iii) one field
(iv) none of these

Choose the correct answer of the following:
Right side of three-address code has how many numbers of operator at most?
(i) 1
(ii) 2
(iii) 4
(iv) 3

Choose the correct option / answer the following:
Which of the following phase of the compiler is optional?
(i) Syntax Analysis
(ii) Intermediate Code Generation
(iii) Semantic Analysis
(iv) Code Optimization

Choose the correct answer of the following:
In compilers, generation of intermediate code based on an abstract machine model is useful because
(i) syntax-directed translations can be written for intermediate code generation
(ii) to generate code for real machines directly from high-level language program is not possible
(iii) portability of the front end of the compiler is enhanced
(iv) implementation of lexical and syntax analyses is easier

Choose the correct option / answer the following:
Which optimization technique focuses on reducing code in small sequences?
(i) Peephole optimization
(ii) Strength reduction
(iii) Loop optimization
(iv) Code hoisting

Which optimization removes repeated computations?

(i) Dead code elimination
(ii) Common sub-expression elimination
(iii) Loop optimization
(iv) Register allocation

Choose the correct answer of the following:
The method which merges the bodies of two loops is
(i) loop rolling
(ii) loop jamming
(iii) constant folding
(iv) None of the above

Choose the correct answer of the following:
By which of the following, bodies of two loops merges to form a single loop?
(i) Loop Unrolling
(ii) Strength Reduction
(iii) Loop Concatenation
(iv) Loop Fusion

A three-address code uses

(i) One operand
(ii) Two operands
(iii) Three operands
(iv) No operands

Construct the DAG for the following basic block:
$d = b * c$
$e = a + b$
$b = b * c$
$a = e - d$

Discuss peephole optimization with suitable example.

Translate the following expression into quadruples and triples representation.
$A = -b * (c + d)/e$

Find the three-address codes of the following program. There are four bytes per word:

Sum = 0;
for (i = 1; i<=20; i++)
Sum = Sum + a[i] + b[i];

Write down Three Address Code for the following expression:

$$(a \times b) + (c + d) - (a + b + c + d)$$

Explain peephole optimization with examples and its benefits.

Explain how type checking and error reporting are performed in compiler. Draw syntax tree and DAG for the statement:
$a = (a * b + c) \wedge (b + c) * b + c$

Explain various targets for code optimization with examples.

Translate the arithmetic expression $a + - (b + c)$ into:
(a) Syntax tree
(b) Quadruples
(c) Triples
(d) Indirect Triples

Write down the process for identifying basic blocks.

How are CPU registers allocated while creating machine code?

Consider the following code:
(i) i = 12
(ii) j = 1
(iii) t1 = 10 * i
(iv) t2 = t1 + j
(v) t3 = 8 * t2
(vi) t4 = t3 - 88
(vii) a [ t4 ] = 0.0
(viii) j = j + 1
(ix) if j <= 10 goto (iii)
(x) i = i + 1
(xi) if i <= 10 goto (ii)
(xii) i = 1
(xiii) t5 = i - 1
(xiv) t6 = 88 * t5
(xv) a [ t6 ] = 1.0
(xvi) i = i + 1
(xvii) if i <= 10 goto (xiii)

find out the basic block and draw the flow graph for the above code.

Explain the process of translating an arithmetic expression into intermediate code using three-address code (TAC). Translate the expression $a * -b + (c - d) * e$ into TAC and show the corresponding syntax tree and code.

Discuss code motion and copy propagation as machine - independent code optimization techniques.

Discuss the different types of code optimization techniques in compilers.

Explain local and global optimization techniques.

What is basic block in the graph representation of intermediate codes. Construct DAG for the basic block given below. Also optimize the three address code, assuming only $a$ is live on exit from the block.
$d = b * c$
$e = a + b$
$b = b * c$
$a = e - d$

Explain how instruction scheduling helps in pipeline optimization. Discuss how rearranging instructions improves performance and reduces stalls in pipelined architectures. Illustrate with an example.

Explain three of the targets for code optimization with examples.

What is register allocation in code generation? Explain the role of graph coloring in register allocation and describe how it improves the efficiency of target code.

Explain any two of the following :
(i) Lexical phase error
(ii) Code generation using dynamic programming
(iii) Syntax tree

Write short notes on: Peephole optimization