Compiler Design: Lexical and Syntax Analysis

• Language processors translate source code into executable code
• Compilers are a type of language processor
• Compiler construction involves various scientific principles
• Understanding programming language basics is crucial for compiler design

Lexical Analysis

• Lexical analysis is the initial phase of a compiler
• It involves breaking down source code into a stream of tokens
• The lexical analyzer plays a crucial role in this process
• Input buffering optimizes the reading of the source program
• Token recognition identifies and categorizes tokens
• Lex is a lexical-analyzer generator
• Finite automata are used in lexical analysis for pattern recognition
• Regular expressions are converted to automata
• Lexical-analyzer generators are designed to automate lexical analysis
• DFA-based pattern matchers can be optimized for efficiency

Syntax Analysis

• Syntax analysis is the second phase of a compiler
• It checks the grammatical structure of the source code
• Context-free grammars define the syntax of a programming language
• Grammar writing involves creating rules for the language's syntax
• Top-down parsing constructs a parse tree from the root
• Recursive and non-recursive top-down parsers are two approaches
• Bottom-up parsing constructs a parse tree from the leaves
• LR parsing is a type of bottom-up parsing
• Simple LR (SLR) is a basic LR parser
• More powerful LR parsers exist for complex grammars
• Ambiguous grammars can be used with appropriate techniques
• Parser generators automate the creation of parsers

Syntax-Directed Translation

• Syntax-directed definitions (SDDs) associate attributes with grammar symbols
• SDD evaluation orders determine the order of attribute computation
• SDTs are utilized in various applications of syntax-directed translation
• Syntax-directed translation schemes (SDTs) integrate semantic actions into grammar rules
• Implementing L-attributed SDDs allows for efficient attribute evaluation

Intermediate-Code Generation

• Syntax trees are abstract representations of the source code
• Three-address code is a common intermediate representation
• Type declarations are processed during intermediate code generation
• Type checking ensures type correctness
• Control flow is represented in the intermediate code
• Backpatching is used to resolve forward references
• Switch statements are translated into intermediate code
• Procedures are represented in intermediate code

Run-Time Environments

• Storage organization manages memory during program execution
• Stack allocation is used for local variables
• Access to nonlocal data on the stack is handled carefully
• Heap management deals with dynamic memory allocation
• Garbage collection reclaims unused memory
• Trace-based collection is a garbage collection technique

Machine-Independent Optimizations

• Optimization aims to improve code efficiency
• Data-flow analysis is used for optimization
• Constant propagation replaces variables with constant values
• Partial-redundancy elimination removes redundant computations
• Loops in flow graphs are a target for optimization

Code Generation

• Code generation transforms intermediate code into machine code
• The target language influences code generation
• Addresses in the target code need to be managed
• Basic blocks and flow graphs are used in code generation
• Basic blocks can be optimized for efficiency
• Simple code generators can be developed

Machine-Dependent Optimizations

• Peephole optimization improves code locally
• Register allocation assigns variables to registers
• Dynamic programming can be used for code generation