Content

1. Basic Blocks
   1. Local Optimizations
   2. Register Allocation
   3. Object Code Optimizations

Basic Blocks

A segment of code that must enter at beginning and exits only at end.

• Local optimizations
• Optimizations accross BBs

Local Optimizations

• Constant folding
• Constant propagation
• Algebraic simplification & reassociation
• Operator strength reduction
• Copy propagation
• Dead code elimination/remove unreachable code
• Common subexpression elimination
• Code motion: move statements evaluating to the same value in every iteration outside of loop
• Remove redundant jumps
• Branch chaining

Register Allocation

k-coloring graph problem.

Object Code Optimizations

• Instruction scheduling
• Redundant load & stores