Zilog Z80380 - Manual (Page 28)

Sample Session Introduction
1–16 UM004001-COR1103
• The Level 2 optimization option performs:
– constant propagation
– copy propagation
– dead code elimination
– common sub expression elimination
– jump to jump optimization
– loop invariant code motion
– constant condition evaluation and other condition evaluation optimizations
– constant evaluation and expression simplification
– all the optimizations in level 1
• The Level 3 optimization option performs Level 2 optimizations twice, and replaces
any redirection of read-only nonvolatile global or static data with a copy of the initial
expression.
• The Level 4 optimization option performs Level 2 optimizations three times, and
eliminates common sub-expressions by transforming expression trees.