CSE415 : Compiler Design End Question Paper Question Paper | CSE 415 | Lpu Question Paper

A compiler is computer software that transforms computer code written in one programming language into another computer language.

1. what do you understand by longest pattern matching rule in LEX tool?

2. define a token

3. what do you understand by backtracking of a compiler. discuss in context with left factoring

4. what is left factoring and how left factoring is eliminated from the grammar?

5. what are the different conflicts that occur during shift-reduce parsing

6. give example of l-atributed definition

7. describe dependency graph in SDT

8. what are the various methods of implementing three address statements ?

9. what are the triplets prrferred over quadraples as intermediate code?

10. what are activation records?

 PART-B

2 a) write short notes on i)buffer pairs ii)sentinentals

 or

 b) i)give an example of lexical error. how lexical errors are handled

 ii)briefly explain about compiler construction tools

3 a)i)consider the g

a)what do you men by an ambigious grammar?consider the following grammar.

E-->E+E|E*E|1.

Check whether the grammar is ambigious for the input string:1+1*1.

Give an appropriate to rewrite the grammar to remove ambiguity.

 OR

b)(i)Consider the context free grammar.

S-->SS+|SS*|a

and the string aa+a*.

a)Give a leftmost derivation for the string.

b)give the rightmost deivation for the string.

c)give the parse tree for the string.

d)is the grammar ambigious or unambigious ?justify.

(ii)Define a context free grammar with the help of an example.

Q4. a)consider the grammar with the folllowing translation rules and E as the start symbol.

E-->E*T (TE value =E value *T value).

 IF (Evalue =t value).

T-->T&F (T value=T value+F.value).

 IF (T value=F value).

F-->num(F.value=num.value).

Compute E.value for the root of the parse tree for expression:2#3&5#6&4.

b)(i)For the given syntax directed definitions draw the annotated parse trees for the expression

1*2*3*(4+5)n

PRODUCTIONS SEMANTIC RULES.

L->En L val=E.val

E->E1+T E.val=E1.val++T.val

E->T E.val=T.val

T->T1*F T.val=T1.val*F.val.

T->F T.val=F.val>

F->(E) F.val=E.val

F->digit F.val=digit*lexval.

(ii) for the given syntax directed definition draw the annotated parse trees for the expression : float

w,x,y

PRODUCTIONS SEMANTIC RULES

D->TL L.inh=T.type

T->int T.type=integer

T->float t.type=float

L->L1,id L1.inh=L.inh;addtype(id.entry,L.inh)

L->id addtype(id.entry,L.inh)

5 a)write three adress code,quadraple , triples, syntax tree and DAG for the the following

expressions:(consider operator procedure as per ANSIC)

i. a=b*-c+b*-c ii. -(a+b)*(c+d)+(a+b+c)

 or

b)(i) write the three adress code for the following statement:

 int a[10],b[10],d,i;

d=0;

for(i=0;i<10;i++)d+=a[i]*b[i];

ii)write the three adress code for the following code:

 int fact(int n)

{

if n==0) return1;

else return (n*fact(n-1));

}

6 a)consider quicksort example pseudocoe,show downward-growing stack of activation record and

activation tree for quicksort example

 quicksort(A,p,r){

 if(p<r){

q<-partition(A,p,r)

quick sort(A,p,r)

quick sort (A,q+1,r)

}

}

partition(A,p,r){

a<-A[p]

i<-p-1

j<- r+1

while(true){

repeat

j<- j-1

until (a[j]<=x)

repeat

i<-i+1

until (A[i]>=x)

if(i<j)

swap(A[i],A[j])

else

return(j)

}

}

 or

b i)consider following code:

int fib(n){

if(n==0) return 1;

if (n==1) return 1;

return fib(n-1)+fib(n-2);

}

draw the activation tree for n=5

ii) write short notes on following

i)activation trees ii)activation record