<sub>Unfortunately, the original "answer" was deleted and it contained a good bit of valuable discussion...here's the condensed version...</sub>

After various attempts at getting GCC to perform loop unswitching, it appears (so far) that **the best solution is the use of a magic number** if portability is required, or resort to inline assembly otherwise.

Attempted alternate portable solutions, which do not work on GCC 4.6.3, included:

* Marking `k_local` `const` and `register` (no effect)
* Changing `k_local` to unsigned and using a simpler one-sided check on the upper bound (no effect)
* Making a trivial change to one side of the branch to prevent elimination of the conditional (no effect)