Peephole optimization

1. NADAR SARASWATHI COLLEGE OF
ARTS AND SCIENCE
DEPARTMENT OF COMPUTER SCIENCE
PEEPHOLE OPTIMIZATION
BY
M.VIDHYA
1.MSC(CS)

2. CONTENTS:
 What is an optimization
 Introduction
 Working flow of peephole optimization
 Replacement rules
 functioning of peephole optimization&example
conclusion

3. WHAT IS OPTIMIZATION??
Process of transformation a piece of code to
make it more efficient(either in terms of time or
space)without changing its output or side-
effects.
 Tries to minimize or maximize some attributes
of an executable computer program.

5. INTRODUCTION:
Optimization performed over a very small set
of instruction in a segment of generated code.
Works by recognizing sets of instruction that
can be replaced by shorter or faster sets of
instructions.

6. GOALS :
Improve performance
Reduce code size
Reduce memory footprint

7. WORKING FLOW OF PEEPHOLE OPTIMIZATION

8. REPLACEMENT RULES:
 Constant folding
-Evaluate constant sub-expression in
advance
 Strength reduction
-Replace slow operations with faster
eqivalents
 Null sequences
-Delete useless operations

9. FUNCTIONING OF PEEPHOLE
OPTIMIZATION
 Replacing slow instructions with faster
ones
 Removing redundant code
 Removing redundant stack instructions

10. Functioning (contd…)
 Replacing slow instructions with faster ones
……
load1
load1
mul
…..
Can be replaced by
…..
load 1
dup
mul
……

11. CONCLUSION:
Peephole optimization remains viable
-Post allocation improvements
-Cleans up rough edges
 Peephole technology works for selection
-Description driven matchers
-Used in several important systems
All of this work equally well in binary-to-binary
translation.

12. THANK YOU