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Constant Folding

Constant folding is performing operations on constants at compile time:

x = angle * 3.1415926 / 180.0

y = sqrt(2.0)

z = a[3]

The savings from doing this on programmer expressions is minor. However, there can be major savings by optimizing:

  1. Subscript expressions generated by the compiler.

  2. Messages in an object-oriented language.

Constant folding should not allow the programmer to ``break'' the compiler by writing a bad expression: sqrt(-1.0).