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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug target/104440] nvptx: FAIL: gcc.c-torture/execute/pr53465.c 
 execution test
Date: Tue, 08 Feb 2022 09:25:26 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D104440

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2022-02-08
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW

--- Comment #6 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #5)
> (In reply to Tom de Vries from comment #4)
> > (In reply to Andrew Pinski from comment #2)
> > > I thought there was another bug that reported a similar issue.
> >=20
> > You mean related to nvptx, or in general?
>=20
> It was in general. PR 21111 is related but not the same issue.
>=20
>=20
> PR 61810 is the one pointing out the problems with init-regs and talking
> about removing it.

I think there's a bug that ifcombine produces the situation and that
valgrind complains about uninitialized uses.

Note that indeed the init-regs pass should go away.

It's somewhat unfeasible to compute a must-initialized regs so the issue
is really hard to avoid.  But nobody tried yet (it would also come at a cost
of course).  It would definitely inhibit all early short-circuiting on
GENERIC (a good thing, but with a lot of fallout I think).

That said, --param logical-op-non-short-circuit=3D0 is only a workaround un=
til
you hit ifcombine doing similar transforms.

LOGICAL_OP_NON_SHORT_CIRCUIT is a target macro btw, so you could arrange it
to be zero for nvptx (but that's of course too late since the hosts
LOGICAL_OP_NON_SHORT_CIRCUIT value will be used).=