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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug target/106187] armhf: Miscompilation at O2 level (O0 / O1 are
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Date: Tue, 19 Jul 2022 09:13:21 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D106187

--- Comment #30 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Richard Earnshaw from comment #29)
> Thanks for having a look, yes, I was at a loss to understand how that cha=
nge
> (which is before the problematic hunk would be the cause of the problem. =
 It
> looks like we can rule that change out as a real fix.
>=20
> > The code at RTL expansion time looks reasonable (also from an aliasing =
POV),
> > if -fno-strict-aliasing fixes it, does -fno-schedule-insn{,2} also?
>=20
> Yes, disabling scheduling also solves the issue.

There are several sched* debug counters, so maybe bisecting to the wrong
schedule via -fdbg-cnt=3Dsched_insn might work.  I think the above strongly
hints at either RTL/target messing up alias info somewhere or scheduling not
properly computing dependences.=