Smashers - Compiler Design Gate

Replacing expressions that evaluate to a constant at compile time with the actual value (e.g., replacing x = 3 + 5 with x = 8 ).

Contains only synthesized attributes. Semantic actions are placed exclusively at the very end of production right-hand sides. They are naturally evaluated during bottom-up parsing.

The final code generation step must effectively manage hardware constraints:

Happy Learning and Good Luck with your GATE Preparation! 🎯 compiler design gate smashers

Counting tokens. This is a classic GATE question. Smasher Trick for Counting Tokens:

Now, there are zero branches. The control flow is linear. While this increases code size (a trade-off), it eliminates the branch prediction overhead entirely.

Uses four explicit fields: (operator, argument_1, argument_2, result) . Replacing expressions that evaluate to a constant at

Recognizing variables inside a loop that maintain a locked linear relationship to substitute costly multiplications with cheap additions.

To score maximum marks in this section, structuring your study method is crucial.

Can contain both synthesized and inherited attributes. However, its inherited attributes are restricted: a node can only inherit values from its parent or its left siblings . This constraint ensures dependencies flow predictably from left to right, making it compatible with top-down parsing. 6. Intermediate Code Generation (ICG) They are naturally evaluated during bottom-up parsing

The lexical analyzer acts as the first line of defense. It evaluates the source text linearly to identify tokens, which are the atomic building blocks of a programming language.

| Topic | Weight (approx) | Important Subtopics | | :--- | :--- | :--- | | | 4–5 marks | LR(0) DFA, Shift-reduce conflicts, FOLLOW sets for SLR | | First & Follow + LL(1) | 2–3 marks | Predictive parsing table, First/Follow calculation | | Intermediate Code | 2 marks | TAC generation, Quadruples, Triples | | Syntax Directed Translation | 2 marks | SDT for expressions, declarations | | Runtime Environment | 1–2 marks | Activation record, stack vs heap | | Lexical Analysis | 1–2 marks | DFA minimization, Token count |

Context-Free Grammars (CFG) and Pushdown Automata (PDA). Phase 3: Semantic Analysis

Strength Reduction: Replacing computationally heavy operations with cheaper ones (e.g., replacing x * 2 with x + x or x << 1 ). 🛠️ Phase 6: Code Generation & Runtime Environments