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[Bug tree-optimization/68576] scev failed for loop auto parallelize
- From: "rguenth at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Fri, 27 Nov 2015 10:00:08 +0000
- Subject: [Bug tree-optimization/68576] scev failed for loop auto parallelize
- Auto-submitted: auto-generated
- References: <bug-68576-4 at http dot gcc dot gnu dot org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68576
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |missed-optimization
Status|UNCONFIRMED |NEW
Last reconfirmed| |2015-11-27
CC| |spop at gcc dot gnu.org
Ever confirmed|0 |1
--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> ---
I think the issue is that with respect to loop 4 the evolution is
_76 = { 1 + _373, + , 1 }_4
but with all the casting we end up with
(set_scalar_evolution
instantiated_below = 5
(scalar = _470)
(scalar_evolution = {(unsigned long) stride.92_29 + (unsigned long)
offset.93_35, +, (unsigned long) stride.92_29}_1))
)
and instantiate_scev for the SCEV above fails. Likewise for instantiate
below 10, only below 15 succeeds in the end.