How to detect whether we're inside of a loop??

[Robert Dewar]

> The average you cite above for loops means that the loop-body is still
> executed more often than code which is not in a loop, just not by as
> much as I'd hoped.  And if-then clauses have execution probability of
> less than one for each clause so code in there is even less likely to
> be executed than loop bodies.

Normal assumptions are that inner loops are executed more often than
outer loops. The figure of 1.5 is wildly wrong for inner loops