Optimization

Program optimization can be defined as follows:

Given a program P, produce a program P' that produces the same output values as P for any given input, but has a lower cost.

Typical costs are execution time and program space. Most optimizations target time; fortunately, the two usually go together.

Optimization is an economic activity:

• Cost: a larger and sometimes slower compiler.

• Benefit:

  
    Amount saved by the code improvement
      * number of occurrences in code
      * number of repetitions in execution
      * number of uses of the compiled code