[Bug middle-end/52701] [4.8 Regression] 416.gamess in SPEC CPU 2006 failed to build

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=52701

--- Comment #5 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-03-26 11:44:55 UTC ---
During analysis we have {c_50, +, pretmp.51_172}_4 as access function.  This
is analyzed to be unknown:

9: Unknown def-use cycle pattern.

but we still vectorize this loop, as the induction (with unknown step,
thus not detected as such) is irrelevant, only the final value after
the loop (thus, a missed SCEV "const"-prop).

Which means we should simply always set STMT_VINFO_LOOP_PHI_EVOLUTION_PART.

I have a patch.