Common Subexpression Elimination. An optimization that removes common
subexpression compuation. For example ``(a+b)*(a+b)`` has two subexpressions
that are the same: ``(a+b)``. This optimization would perform the addition
- only once and then perform the multiply (but only if it's compulationally
+ only once and then perform the multiply (but only if it's computationally
correct/safe).
D