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From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/107411] trivial-auto-var-init=zero invalid
 uninitialized variable warning
Date: Wed, 26 Oct 2022 17:52:50 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D107411

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2022-10-26

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed. reduced testcase:
int t();
void f(int);

void j()
{
        const int& e =3D t();
        f(e);
}

Someone who understands the uininit pass should look into this but the IR at
that point we get is (with -fno-exceptions due to extra clobbers otherwise
which don't make a difference):
  _1 =3D .DEFERRED_INIT (4, 2, &"D.2374"[0]);
  D.2374 =3D _1;
  e_6 =3D .DEFERRED_INIT (8, 2, &"e"[0]);
  _2 =3D t ();
  D.2374 =3D _2;
  e_9 =3D &D.2374;
  _3 =3D *e_9;
  f (_3);
  D.2374 =3D{v} {CLOBBER(eol)};

There is no read from D.2374 in the call to t at all and then we do a full
write after the call.=