https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88405
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
Last reconfirmed| |2018-12-10
CC| |hubicka at gcc dot gnu.org,
| |matz at gcc dot gnu.org,
| |rguenth at gcc dot gnu.org
Ever confirmed|0 |1
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
Confirmed.
But in general a prerequesite to eliminate Section A is
fusion of both loop nests and then CSEing the loads from a and b and finally
eliminate the stores as dead because a and b are only written to.
For the testcase we eliminate Section B because 'c' is discovered as writeonly.
But we do not update the writeonly flag of a or b when removing uses (and
IMHO we cannot easily). Note we perform this "DSE" in fixup_cfg.
