[Bug middle-end/80399] Premature optimization with unsigned

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80399

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2017-04-12
     Ever confirmed|0                           |1

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Huh, sth folds (t + 4294967295) * 16 to (t + 268435455) * 16.

Certainly "interesting".  I suppose we're trying to make constants cheaper
but that's sth quite premature in this particular case.

Looks like it's iterating extract_muldiv doing t * 16 + 4294967295 * 16 and
fold_plusminus_mult_expr undoing it until it arrives at a point where
extract_muldiv iteration gives up.