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From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/111489] Incorrect "-Wmaybe-uninitialized"
 warning from GCC 13.2.0
Date: Wed, 20 Sep 2023 06:34:26 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D111489

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2023-09-20
     Ever confirmed|0                           |1

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #1)
> 159 -> 58: one_pred =3D NOT (iftmp.32_490 !=3D 0)
> 	((NOT (iftmp.32_490 !=3D 0)))
> After normalization [USE]:
> 	_419 =3D (int) pg_version_168;
>   is conditional on:
> 	((NOT (iftmp.32_490 !=3D 0)))
>=20
>=20
> While the define was:
> After normalization [DEF]:
> 	pg_version_168 =3D PHI <pg_version_263(D)(39), iftmp.13_391(36),
> iftmp.13_491(35)>
>   is conditional on:
> 	((flags_262(D) =3D=3D 2))

The issue is really

MAX_CHAIN_LEN exceeded: 6
init_use_preds: dep_chain incomplete, using conservative approximation
init_from_control_deps [USE] {{}}:
        TRUE (empty)

at -O2.  At -O3 we manage to get a slightly less complex CFG but still run
into this limit.  Raising MAX_CHAIN_LEN to 8 (up from 5) avoids the diagnos=
tic.=