Compiler Phases

Main Compiler Phases

• Compiler Phases
1. Lexical Analysis
2. Syntactic Analysis (ie Parsing)
3. Intermediate Code Generation (and semantic analysis)
4. Optimization (optional)
5. Code Generation
• Data structure: Symbol table
• Used to communicate information between phases
• See figure 1.3 in Sebesta

Compiler Structure

• Compiler phases
1. Lexical analysis (aka scanner): seq of characters -> seq of tokens
2. Syntactic analysis (aka parser): seq of tokens -> parse tree
3. Intermediate code generation
4. Code generation
• Optimization (optional)
• Symbol table involved in several phases
• See Figure 1.3 in text



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Grammars and Compiler Structure

• The structure of the productions for identifiers and numbers is much simpler than that of program


• Programs have hierarchical structure


• Identifiers and numbers have little structure


• This difference in structure is reflected in the grammars


• This difference in structure and grammar is reflected in how compilers are written, as we will see later.



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Truth in Advertising Alert

• Actually, the lexical analyzer produces a single tokens each time it is called by the parser
• Parse trees are not always produced