Optimization tries to transform a program to use less time or memory while keeping its external results identical. GATE questions here generally focus on identifying the specific technique applied to a code snippet. Compile-Time Evaluation
The raw sequence of characters matching a pattern (e.g., int , total , 3.14 ).
To succeed in Compiler Design on the GATE exam, focus your study on high-yield problem types and practice them consistently.
Consider grammar: E → E + T | T T → T * F | F F → id compiler design gate smashers
Follow the : “Concepts clear karo, bas phir GATE crack hai” (Clear your concepts, and GATE is cracked).
Their “One Shot” videos (1.5–2 hours) are great for last-minute GATE prep.
The compiler stops working on source code and starts working on IR. Optimization tries to transform a program to use
In 3AC, instructions have at most three memory references: two inputs and one output. Statement: x = a + b * c 3AC Equivalent: t1 = b * c t2 = a + t1 x = t2 Use code with caution. 3AC Data Structures
for (int i = 0; i < 4; i++) sum += array[i];
| Phase | Input | Output | Key Concept (as per Gate Smashers) | | :--- | :--- | :--- | :--- | | | Source code | Tokens | "Scanner – removes comments, whitespace, expands macros." | | 2. Syntax Analyzer | Tokens | Parse Tree | "Checks grammar – like English grammar check, but for code." | | 3. Semantic Analyzer | Parse Tree | Annotated Tree | "Type checking – int x = "hello" → error." | | 4. Intermediate Code Gen. | Annotated Tree | 3-address code | "T1 = a + b" (machine independent). | | 5. Code Optimizer | 3-address code | Optimized 3-address code | "Constant folding, dead code removal." | | 6. Code Generator | Optimized code | Target assembly | "Register allocation, instruction selection." | To succeed in Compiler Design on the GATE
(led by Dr. Varun Singla ) is a go-to resource for Computer Science students preparing for GATE, UGC NET, and college exams. Their teaching style focuses on:
This phase checks the parse tree for semantic errors and ensures structural validity. It gathers type information and checks for data type compatibility (type checking), labels, and identifier declarations.
Explain the differences between with examples.