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Compiler Design Expert

Before Starting

1. Which compilation phase?
2. New language or existing compiler modification?
3. Optimization or correctness focus?

Core Expertise Areas

Lexical Analysis

Tokens: atomic units — keywords, identifiers, literals, operators. Regular expressions: define token patterns. Finite automata: DFA and NFA implement lexers. Lexer generators: Lex, Flex, ANTLR — generate lexer from token rules.

Parsing

Context-free grammars: productions defining language syntax. Top-down: recursive descent, LL parsers — predictive, left-to-right. Bottom-up: LR parsers — shift-reduce, more powerful, handles more grammars. Parser generators: Yacc, Bison, ANTLR — generate parser from grammar. Parse tree vs AST: AST removes redundant nodes, better for analysis.

Semantic Analysis

Type checking: static vs dynamic typing, type inference. Symbol table: scope management, variable binding, type lookup. Attribute grammars: synthesized and inherited attributes on parse tree. Name resolution: binding identifiers to declarations.

Intermediate Representation

Three-address code: at most three operands per instruction. SSA form: single static assignment, each variable defined exactly once. LLVM IR: typed, SSA-based, platform-independent, widely used. Control flow graph: basic blocks connected by edges.

Optimization

Constant folding: evaluate constant expressions at compile time. Dead code elimination: remove unreachable or unused code. Common subexpression elimination: compute repeated expressions once. Loop optimizations: unrolling, invariant code motion, vectorization. Inlining: replace function call with function body.

Code Generation

Instruction selection: map IR to target instructions. Register allocation: map variables to physical registers, spill to stack. Instruction scheduling: reorder instructions to minimize pipeline stalls.

Best Practices

• Separate phases clearly for maintainability
• Use SSA form for most optimization passes
• Test with both valid and invalid input programs
• Profile optimization passes on real workloads

Common Pitfalls

Related Skills

• compiler-expert
• algorithms-cs-expert
• computer-architecture-expert