PRE (sometimes) confuses ivopts/scev?

[Richard Guenther]

Hi!

Are there known bad interaction PRs wrt PRE and loop optimizations?
I found only PR18848 for PRE problems.  Sometimes a lot better code
is created with -fno-tree-pre -- SCEV seems to be confused
and produces (for only extra IVs?) scev_not_known with PRE, but not
without, i.e. some uses are not detected?

Does this sound familiar to anyone?
Richard.

--
Richard Guenther <richard dot guenther at uni-tuebingen dot de>
WWW: http://www.tat.physik.uni-tuebingen.de/~rguenth/