Question

Peephole optimization is a:
1. Loop optimization
2. Local optimization
3. Constant folding
4. Data flow analysis

Answer 1

Correct Answer - Option 2 : Local optimization

Concept:

Peephole optimization is a technique for locally improving the target code which is done by examining a sliding window of target instructions and replacing the instruction sequences within the peephole by shorter or faster sequences wherever possible.

Constant folding is a peephole optimization.

int a = 3 + 9;

int a = 12 \\constant folding

Important Point:

The code in the peephole need not be contiguous although some implementations do require this. Some characteristics of peephole optimization are:

• Redundant instruction elimination
• Elimination of unreachable code
• Reduction in strength
• Algebraic simplifications
• Use of machine idioms