Overview of Code Generation

We will take a hierarchical approach to code generation:

• genc(code) generates code for a statement. There are only a few kinds of statements. genc is easy to do given genarith.

• genarith(expr) generates code for an arithmetic expression. genarith is a classical postorder tree-recursive program, with a simple basic form (but many special cases). genarith is not hard given getreg.

• getreg(kind) gets a register from a pool of available registers. It also handles returning unused registers with unused(reg).

• While register management can be complex, a simple implementation of getreg() works pretty well. We will discuss some improvements.