Code No: 07A71902

R07

Set No. 2

IV B.Tech I Semester Examinations,December 2011 AUTOMATA AND COMPILER DESIGN Electronics And Computer Engineering Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ????? 1. (a) Write the algorithm to test structural equivalence of two type expressions s and t. (b) Write about type graph.

[8+8]

2. (a) Explain scope and lifetime of variable with some suitable examples. (b) What is meant by dangling references? Explain.

[8+8]

3. (a) What is a Syntax Directed Definition? Give an example. (b) Explain the Dependency Graph with an example.

[6+10]

4. (a) Explain briefly about data- flow analysis. (b) Explain various function-preserving Transformations. 5. Describe the entire bottom up parsing techniques.

[8+8] [16]

6. (a) Explain Regular Expressions with suitable examples. (b) Design a DFA that accepts the language over Σ = {a, b} of all strings that contain the sub-string either aa or bb. [6+10] 7. Write and Explain Heuristic Ordering algorithm for DAG with one example. [16] 8. Write a Context Free Grammar(CFG) for the while statement in ‘C’ language. [16] ?????

1

Code No: 07A71902

R07

Set No. 4

IV B.Tech I Semester Examinations,December 2011 AUTOMATA AND COMPILER DESIGN Electronics And Computer Engineering Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ????? 1. (a) Compare Inherited attributes and Synthesized attributes with an example. (b) Construct triples of an expression: a * - (b + c).

[8+8]

2. (a) Define Alphabets, Strings, and Languages. Give two examples of each. (b) Consider the line number 4 of the following ‘C’ program: int main() /* Line 1 */ { /* Line 2 */ int i, n; /* Line 3 */ for(i=0, i
What is the compiler’s response about this line while creating the object module? Explain. [9+7] 3. (a) Explain the concept of type graph in view of cycles existing in that graph. (b) What are Coercions?

[8+8]

4. Explain about Generic code generation algorithm.

[16]

5. Construct the canonical collection of LR(1) items for the following grammar: E → E + T |T T → T ∗ F |F [16] F → (E) |a.

6. (a) What are self-organizing lists? How can this be used to organize a symbol table? Explain with an example. (b) Write about storage Organization.

[10+6]

7. Construct a Context Free Grammar(CFG) that generates all even integers up to 998. [16] 8. Write about the following Algorithms (a) Detection of Loop Invariant Computation (b) Code Motion.

[8+8]

?????

2

Code No: 07A71902

R07

Set No. 1

IV B.Tech I Semester Examinations,December 2011 AUTOMATA AND COMPILER DESIGN Electronics And Computer Engineering Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ????? 1. Explain the following: (a) Copy Propagation (b) Dead-Code Elimination (c) Code Motion (d) Reduction in Strength.

[4×4]

2. Write and explain Unification algorithm.

[16]

3. Construct the predictive parse table for the following grammar: S →FR R → ∗ S |∈ F→i.

[16]

4. Consider the following Syntax Directed Translation Schema: E→E + E { print ‘+’} E → E*E { print ‘*’} E → (E) { . } E →i { print ‘id.name’} An LR parser executes the actions specified within braces immediately after reducing with the corresponding production. Draw the decorated parse tree and find the translation of a string: (a + b) * (c + d) into another string using Syntax Directed Translation Schemes. [8+8] 5. Design a DFA whose states are the canonical collection of LR(1) items for the following: S → SA |Ba A → Ab |∈ [16] B → aA |c. 6. (a) Prove the Regular Expression Identity: ∈ + 1* (011)* (1* (011)* )* = (1 + 011)* (b) Construct an NFA that accepts all strings such that the fifth symbol from the left end is zero over an alphabet Σ = {0, 1}. [8+8] 7. (a) Write a notes on the static storage allocation strategy with example and discuss its limitations. (b) Discuss about the stack allocation strategy of runtime environment with an example. [8+8] 3

Code No: 07A71902

R07

8. Generate three address code for the following C program Main( ) { int i; int a[10]; while ( i <= 10 ) a[i] = 0; } ?????

4

Set No. 1 [16]

Code No: 07A71902

R07

Set No. 3

IV B.Tech I Semester Examinations,December 2011 AUTOMATA AND COMPILER DESIGN Electronics And Computer Engineering Time: 3 hours Max Marks: 80 Answer any FIVE Questions All Questions carry equal marks ????? 1. Write and Explain about algorithm for construction of equivalence trees in FORTRAN. [16] 2. (a) Draw the parse tree for the production grammar: S → (S) |S ⊃ S| ∼ S |i| j, generating the symbolic formula ( ∼ ∼ i ⊃ (i ⊃ ∼ ∼ j)). (b) Find the language generated by the following grammar: i. S → aS |bA ii. A → d |ccA.

[8+8]

3. Write and explain about equivalence of Type Expressions.

[16]

4. (a) Explain the concept of calculating cost of instructions. (b) Consider below addressing codes along with associated costs Mode Added Cost absolute 1 register 0 indexed 1 indirect register 0 indirect indexed 1 Compute cost of following set of statements i. mov b, R0 Add c , R0 Mov R0,a ii. add R2, R1 Mov R1,a iii. Mov b , a Add c , a.

[8+8]

5. (a) Draw an NFA and DFA to recognize the regular expression: (a + b)*abb. (b) Find the regular expression recognized by the DFA as shown in figure 5b. [8+8]

5

Code No: 07A71902

R07

Set No. 3

Figure 5b 6. Build the SLR(1) parsing table for the following grammar: E → E + T |T T → TF |F F → F∗ |a| b. 7. Explain about Iterative solution of Data-Flow Equations. 8. Generate the three-address code for the following ‘C’ program fragment: switch( i + j). { case 1: x = y + z; default: c = c - 1; case 2: u = v + w; } ?????

6

[16] [16] [16]