GATE · Compiler Design · Brazil

Compiler Design for the GATE Exam — Brazilian candidates

5% of the GATE test plan. Lexical analysis, syntax-directed translation, parsing (LL/LR), intermediate code generation, and code optimisation — approximately 5% of GATE CS. Calibrated for Brazilian candidates.

High-stakes exams reward two skills equally: knowledge and test-craft. This page focuses on both for one of the most failure-prone areas. Compiler Design sits at roughly 5% of the Graduate Aptitude Test in Engineering content distribution — Compiler Design is a lower-weightage but high-difficulty topic in GATE CS. Questions test LL(1) and LR(0)/SLR/LALR parser construction, FIRST and FOLLOW sets, and three-address code generation. Candidates who invest time here pick up marks that many competitors miss. Pass rates for the GATE are published annually by the awarding body and vary by cohort and locale. For Brazilian candidates preparing for GATE, the calibration of study to local context matters: ENEM is Brazil's national entrance exam. For international study, IELTS and TOEFL dominate; CDL US licensure is a growing cross-border opportunity.

Pass rates for GATE (Brazil) are published periodically by the awarding body.

Common failure modes

These are the patterns that cause most candidates to lose marks on this topic. Recognising them in advance is half the work.

!Computing FIRST sets incorrectly when a production has nullable symbols
!Building FOLLOW sets without including the eof ($) marker for the start symbol
!Misclassifying parsing conflicts: shift-reduce vs reduce-reduce in an LR parsing table
!Confusing LL(1) conflict conditions with LR(0) conflict conditions
!Generating incorrect three-address code by misordering temporaries in expressions

Study tips

1Practise FIRST and FOLLOW set computation on at least 10 different grammars — errors here cascade into parser table construction.
2For LL(1) parsing, verify the LL(1) condition: no two rows for the same non-terminal have the same terminal in their selection sets.
3Build the canonical LR(0) item sets and SLR parsing table for a small grammar (4–5 productions) from scratch.
4Memorise the precedence of common code optimisation techniques: constant folding → dead-code elimination → common-subexpression elimination → loop invariant code motion.
5Practice syntax-directed translation: attribute grammars, S-attributed vs L-attributed, and evaluating inherited vs synthesised attributes.
6Brazilian candidates preparing for GATE should account for visa-processing timelines if testing abroad — most U.S. test centres require a B1/B2 visa appointment scheduled 90+ days in advance.

Sample GATE Compiler Design questions

These sample items mirror the format and difficulty of real GATE questions. Practice with thousands more on the free Koydo question bank.

1
For the grammar S → aAb | b and A → aA | ε, FIRST(S) is:
- A{a}
- B{a, b}Correct
- C{a, b, ε}
- D{a, ε}
Why this answer?
(GATE CS style) From S → aAb: FIRST starts with 'a'. From S → b: FIRST includes 'b'. S cannot derive ε, so ε ∉ FIRST(S). Therefore FIRST(S) = {a, b}.
2
Which of the following is a shift-reduce conflict in an LR parser?
- ATwo items want to reduce by different productions on the same lookahead
- BOne item wants to shift and another wants to reduce on the same lookaheadCorrect
- CTwo items want to shift on the same lookahead
- DAn item set has no actions defined for a terminal
Why this answer?
(GATE CS style) A shift-reduce conflict occurs when, for the same lookahead symbol, the parser can either shift the symbol onto the stack or reduce by a production. This makes the grammar ambiguous for LR(0)/SLR parsing without additional lookahead.

Frequently asked questions

Is Compiler Design worth studying thoroughly for GATE?

Yes, but proportionally. At 5% weightage, 2–3 focused weeks of study targeting FIRST/FOLLOW sets, LL(1) parsing, and three-address code generation is sufficient. Deep LR parsing table construction is lower-yield than the other topics.

What is the difference between LL and LR parsers for GATE purposes?

LL parsers are top-down and read input left-to-right constructing a leftmost derivation. LR parsers are bottom-up and construct a rightmost derivation in reverse. LR parsers handle a larger class of grammars. GATE tests LL(1) table construction and LR(0)/SLR item-set construction separately.

What is the GATE pass rate for Brazilian candidates?

Pass rates for GATE candidates in Brazil are published periodically by the awarding body. Practice questions, full-length simulations, and weak-area drills are the highest-impact way to improve your odds.

How long should Brazilian candidates study Compiler Design for the GATE?

For most candidates, focused mastery of Compiler Design requires 20–40 hours of deliberate practice — drilling sample questions, reviewing failure modes, and timing yourself against exam conditions. ENEM is Brazil's national entrance exam. For international study, IELTS and TOEFL dominate; CDL US licensure is a growing cross-border opportunity. Combine Compiler Design study with full-length mock exams in the final two weeks before your test date.

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Related study guides

Regulatory citation: GATE 2024 CS Syllabus — Compiler Design (Lexical Analysis, Parsing, Syntax-Directed Translation, Runtime Environments, Code Generation, Optimisation).