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From: "aldyh at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug tree-optimization/99919] [9/10/11/12 Regression] bogus
 -Wmaybe-uninitialized with a _Bool bit-field
Date: Tue, 30 Nov 2021 14:22:06 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D99919

--- Comment #5 from Aldy Hernandez <aldyh at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #4)
> (In reply to Aldy Hernandez from comment #3)
> > The warning on the above IL seems legit.
> >=20
> > x_5 is initialized from b$i_11 when b & 1 =3D=3D 0, but the read from x=
_5
> > happens when b & 2 !=3D 0.  So the set and the read are predicated on t=
wo
> > different things.
> >=20
> > Maybe I'm missing some subtle bit field thing.  Does setting b.j somehow
> > alter b.i?
> b.j is (b&2)<<1.
>=20
> If lower bit field acceses it is fixed (but also becomes more obvious what
> the of b.j is:
>   _20 =3D VIEW_CONVERT_EXPR<unsigned char>(b);
>   _21 =3D BIT_INSERT_EXPR <_20, b$j_15, 1 (1 bits)>;
>   VIEW_CONVERT_EXPR<unsigned char>(b) =3D _21;
>   _3 =3D VIEW_CONVERT_EXPR<unsigned char>(b);
>   _4 =3D _3 & 2;
>=20
> So Mine for GCC 13.

You're a rockstar.  Thanks.=