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 5C0F93886C53; Fri, 30 Apr 2021 22:02:27 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 5C0F93886C53
From: "torvalds@linux-foundation.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/100363] gcc generating wider load/store than
 warranted at -O3
Date: Fri, 30 Apr 2021 22:02:27 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: middle-end
X-Bugzilla-Version: 10.2.0
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: torvalds@linux-foundation.org
X-Bugzilla-Status: WAITING
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: cc
Message-ID: <bug-100363-4-7ogwvHgAkN@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-100363-4@http.gcc.gnu.org/bugzilla/>
References: <bug-100363-4@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: Fri, 30 Apr 2021 22:02:27 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D100363

Linus Torvalds <torvalds@linux-foundation.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |torvalds@linux-foundation.o
                   |                            |rg

--- Comment #4 from Linus Torvalds <torvalds@linux-foundation.org> ---
(In reply to Andrew Pinski from comment #1)
> The loop gets vectorized, I don't see the problem really.


See

=20=20=20
https://github.com/foss-for-synopsys-dwc-arc-processors/toolchain/issues/372

and in particular the comment

   "In the first 8-byte copy, src and dst overlap"

so apparently gcc has decided that they can't overlap, despite the two poin=
ters
being literally generated from the same base pointer.

But I don't real arc assembly, so I'll have to take Vineet's word for it.

Vineet, have you been able to generate a smaller test-case?=