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 750233858292; Mon, 18 Dec 2023 07:14:30 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 750233858292
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1702883670;
	bh=3bM3yU4fDbKejJLyMw7xguftL272fiCX/YvzoL6Z6cw=;
	h=From:To:Subject:Date:In-Reply-To:References:From;
	b=xyeW692ZdNASJFrMQw/Fb6xviUnlqE0NUeRUCMyoQsa+el2YhlxAEYDdbRb7WQ1rU
	 Wjl+tT6cL71421YavHVG7qmxYYcq8buBxyHg9mu5XnoaW+e2+PCf7MhOF5ANcMk9ut
	 NcC2Kinv8QOLxwK8eyDq8lyCoBvVmZRQ2UjbjPuk=
From: "rguenther at suse dot de" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/113026] Bogus -Wstringop-overflow warning on
 simple memcpy type loop
Date: Mon, 18 Dec 2023 07:14:29 +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: 14.0
X-Bugzilla-Keywords: diagnostic, missed-optimization
X-Bugzilla-Severity: normal
X-Bugzilla-Who: rguenther at suse dot de
X-Bugzilla-Status: ASSIGNED
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: rguenth at gcc dot gnu.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: 
Message-ID: <bug-113026-4-vQZbDKcKip@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-113026-4@http.gcc.gnu.org/bugzilla/>
References: <bug-113026-4@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
List-Id: <gcc-bugs.sourceware.org>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D113026

--- Comment #5 from rguenther at suse dot de <rguenther at suse dot de> ---
On Fri, 15 Dec 2023, avieira at gcc dot gnu.org wrote:

> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D113026
>=20
> --- Comment #4 from avieira at gcc dot gnu.org ---
> Drive by comments as it's been a while since I looked at this. I'm also
> surprised we didn't adjust the bounds. But why do we only subtract VF? Li=
ke you
> say, if there's no loop around edge, can't we guarantee the epilogue will=
 only
> need to iterate at most VF-1?  This is assuming we didn't take an early e=
xit,
> if we do then we can't assume anything as the iterations 'reset'.

Subtracting can bring down epilogue iterations max to 1 while yes,
we should also apply a max of VF-1 but in addition to the subtraction.=