From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugzilla@gcc.gnu.org>
Received: by sourceware.org (Postfix, from userid 48)
 id 743C5385843F; Wed, 16 Feb 2022 14:05:23 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 743C5385843F
From: "amacleod at redhat dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/104526] [12 Regression] Dead Code Elimination
 Regression at -O3 (trunk vs. 11.2.0)
Date: Wed, 16 Feb 2022 14:05:23 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: tree-optimization
X-Bugzilla-Version: 12.0
X-Bugzilla-Keywords: missed-optimization
X-Bugzilla-Severity: normal
X-Bugzilla-Who: amacleod at redhat dot com
X-Bugzilla-Status: RESOLVED
X-Bugzilla-Resolution: FIXED
X-Bugzilla-Priority: P1
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: 12.0
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: 
Message-ID: <bug-104526-4-Gtw3jMbLLE@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-104526-4@http.gcc.gnu.org/bugzilla/>
References: <bug-104526-4@http.gcc.gnu.org/bugzilla/>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
MIME-Version: 1.0
X-BeenThere: gcc-bugs@gcc.gnu.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Gcc-bugs mailing list <gcc-bugs.gcc.gnu.org>
List-Unsubscribe: <https://gcc.gnu.org/mailman/options/gcc-bugs>,
 <mailto:gcc-bugs-request@gcc.gnu.org?subject=unsubscribe>
List-Archive: <https://gcc.gnu.org/pipermail/gcc-bugs/>
List-Post: <mailto:gcc-bugs@gcc.gnu.org>
List-Help: <mailto:gcc-bugs-request@gcc.gnu.org?subject=help>
List-Subscribe: <https://gcc.gnu.org/mailman/listinfo/gcc-bugs>,
 <mailto:gcc-bugs-request@gcc.gnu.org?subject=subscribe>
X-List-Received-Date: Wed, 16 Feb 2022 14:05:23 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D104526

--- Comment #7 from Andrew Macleod <amacleod at redhat dot com> ---
On 2/16/22 07:39, jakub at gcc dot gnu.org wrote:
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D104526
>
> --- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
> +  tree type =3D TREE_TYPE (TREE_OPERAND (cond, 0));
> +  if (type !=3D TREE_TYPE (TREE_OPERAND (cond, 1)))
> +    return false;
> looks unnecessarily restrictive.
> What tree-cfg.cc verification guarantees (and no need to check it in the
> ranger)
> is what verify_gimple_comparison verifies, i.e. that
>    /* For comparisons we do not have the operations type as the
>       effective type the comparison is carried out in.  Instead
>       we require that either the first operand is trivially
>       convertible into the second, or the other way around.  */
>    if (!useless_type_conversion_p (op0_type, op1_type)
>        && !useless_type_conversion_p (op1_type, op0_type))
> I think the ranger has to be prepared for non-pointer-equal type mismatch=
es as
> long as they are useless_type_conversion_p compatible, that can happen an=
ywhere
> in the IL, including even cases like different but useless_type_conversio=
n_p
> compatible types of binary operators like +, -, * etc.
> So I'd just remove the
>    if (type !=3D TREE_TYPE (TREE_OPERAND (cond, 1)))
>      return false;
> lines.

The rest of ranger isn't this restrictive.. it is satisfied by=20
range_compatable_p() which boils down to "same precision, same sign".

I added it here so to be super paranoid so I didn't get caught by=20
something unexpected later in the routine and cause an ICE in intersect=20
in the middle of building the kernel or something.=C2=A0 In hindsight, I=20
should have used range_compatible_p...

Are you OK with the following change?=C2=A0 I'll bootstrap and regression t=
est...

Andrew=