Bug in loop optimize (invalid postinc to preinc transformation)

[Robert Dewar]

<<Overflow of unsigned integers has defined behaviour -- they wrap.  The
question is, what rule applies to pointer comparisons?
>>

This is a malformed question. Any pointer increment is constrained 
to require that the resulting pointer be valid. Wrapping is simply
not an issue.

If p points to a valid address in an allocated array, then P+1 is also
valid, and there is no question of wrap. But P+2 may be beyond the
array and therefore ill-defined, and this has nothing to do with wrapping.