What should be in a symbol table?

All information is derived from syntax tree

• symbol table is interconnected with syntax tree
• in old one-pass compilers there was only symbol table
• today it gives faster, easier access to parts of syntax tree

Goal: efficiently supporting phases of compiler

Semantic check phases:

• finding which identifier refers to which definition
• we store definitions

What can we define?

• variables (globals, fields, parameters, locals)
  • need to know types
  • later: memory layout
  • sometimes need to make more information explicit
    • whether variable is declared local or global
    • in tree we would know it by position
• methods and functions
• classes