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Sixth Semester B.E. Degree Examination, Dec. 20l3lJan.2014 Time:3 hrs.
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Gomplier Design
Max. Marks:100
Note: Answer FIVE full questions, selecting utleast Tl,yO questions from each part. ,
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I a. b.
Explain the various phases of complier. Show the translations for an assignment statement. (12 Marks) Position: initial * rate + 60, clearly indicate the output of each phase. , Write thq.regular definition for an unsigned number. Also write the transition diagram.
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PART _ A
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What is printed by the following C code? # define a (x + l)
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Show that the following grammar,is ambiguous : E -+ E + E I E * E I (E) | id. Write an equivalent unambiguous grammar for the same.
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What are the key problem$'with top down parse? Write a recursive descent parser for the grarnmar : - --:;= )'r:F (08 Marks) S-+cAd A-+abla.
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Given the gramrner
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A-+cle B-+dfe
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Describe an algorithm used for eliminating the Ieft recursion. Eliminate left recursion from
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void b( ) {int x :l; printf("oZd ln", a)'} void c( ){printfl'"%d ln", a); } void main( ) {b( ) ; c( );}.
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Compute FIRST and FOLLOW sets Construct the predictive parsing table (10 Marks) ,, iii) Show the moves made by predictive parser on the input ; acdb. (05 Marks) Explain with a neat diagram, the model of a table driven predictive parser. * What is handle pruning? Give a bottom - up parse for the input : vsv v-t-t and grammar : (05 Marks) S-+SS+lSS*la.
a.
Given the grammar
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C-+cCld
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b. c.
Obtain the sets of canonical collection of sets of valid LR(0) items ii) Design SLR parsing table. Write an algorithm used to compute LR (1) sets of items. Write a note on the parser Generator - Yacc.
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(10 Marks) (06 Marks) (04 Marks)
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PART _ B
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Explain the concept of syntax - directed definition. The SDD to translate binary integer number into decimal is shown below Productions
BN-+L
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Semantic rules
L-+LrB
L+B
BN.val: L. val L. va :2 xLl.val + B. val L.va : B .val
B-+0 B-+1
B. va B. va
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Translate the arithmetiC.expression : a + - (b + c) into
b.
Give a semantic action i;",,S if (B) Sr etse Develop SDD to produce directed a cyclic grrpt for an expression. Show the steps for constructing the directedacyclic graph forthe expression : a-t a* (b-c) + (b-c) * d.
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triples and indirect triples.
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Construct the iarse tree and annotated parse tree for the input string : 1 1001 . (05 Marks) Give a SDT for desktop calculator and show its parser stack implementation. (10 Marks)
(08 Marks)
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a. b.
Describe the general structure of an aCtivation record. Explain the purpose of each field in the activation record. (08 Marks) A C - code to compute Fiborthcci numbers recursively is shown below :
int f(int n)
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<: 2) retum I s:f(n-l); t: fln -2) ; return (s,+ t);
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Draw the activation tree for the call : (5) W'hat is the largest number of activation records that ever appear together on the stack? ,,,,:, (06Marks) c, ' Explain the performance metrics to be considered while designing a garbage .oll..jg]._ _.. ' (06 Marks)
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a. b.
Discuss the issues in the design of a code generator.
(10 Marks)
Write the tree address code and construct the basic blocks for the following program segment.
sum: 0 ;
for(i:
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0; i 10 ; i ++; +a[i] sum: sum ; Give the code generation process for operations.
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(05 Marks) (05 Marks)
