12.2.3 Semantic Analysis

Semantic analysis is the bridge between parsing and code generation. The levels and number of intermediate representations depend upon the goals of the compiler. Trees are simplest; graphs may be required for serious optimizations.

For small and fast, it is desirable to minimize the number of visits to each node; for example Sethi-Ullman numbering may be done as the abstract syntax tree is generated. Perhaps the object code may be emitted directly, although this will result in poorer quality code.