https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82447
--- Comment #4 from amker at gcc dot gnu.org --- (In reply to Jakub Jelinek from comment #2) > Indeed. But when the body is: > sum += a[size - 1 - i]; > while base 128U with step -1U is considered, it isn't found as the cheapest > for some reason either. On 64-bit targets, candidate [128, -1] is added in unsigned int type, while address IV has pointer type. IVOPTs simply skips the candidate because it has smaller precision than the IV use. On 32-bit targets, I increased cost in case of invariant expression on purpose in order to avoid generating too many invariant expressions. So I think this strategy works better for large cases but not for the simplest cases. Probably we should special case simple case with only one address type IV.
