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 ECBC43858D32; Fri,  5 Jan 2024 17:21:13 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org ECBC43858D32
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1704475273;
	bh=4bNUN0M8KWHqZmBG7WWcCMeuum6mhBwdM4mdAyfJ0SE=;
	h=From:To:Subject:Date:In-Reply-To:References:From;
	b=c7qF9wDDmmyJQoO4sil/CIsbhRjIdtXLzuX3MFichtIUDMoWKzzm6oxcSlIDzXime
	 6p36zgzAl0y49xsp1ftEtbYScjDGTEXrpRORPzkzj2n059wI77geTrSUMKtn+Jc58F
	 M7DHLBT8Pb1Aki/6Iviqwh6aNOrBsIT4UO+jH/qA=
From: "avieira at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/113229] [14 Regression] gcc.dg/torture/pr70083.c ICEs
 when compiled with -march=armv9-a+sve2
Date: Fri, 05 Jan 2024 17:21:13 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: target
X-Bugzilla-Version: 14.0
X-Bugzilla-Keywords: ice-on-valid-code, testsuite-fail
X-Bugzilla-Severity: normal
X-Bugzilla-Who: avieira at gcc dot gnu.org
X-Bugzilla-Status: NEW
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: 14.0
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: cf_reconfirmed_on everconfirmed bug_status
Message-ID: <bug-113229-4-pCB7obJd4r@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-113229-4@http.gcc.gnu.org/bugzilla/>
References: <bug-113229-4@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=3D113229

avieira at gcc dot gnu.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2024-01-05
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW

--- Comment #4 from avieira at gcc dot gnu.org ---
So I can confirm this ICE and it was exposed rather than caused by my patch.

The problem arises because it seems we have never tried to simplify a:
(subreg:<poly-sized mode> (subreg:<...> (<non-poly-sized-mode>) N) M)

This makes simplify_subreg neter the if (GET_CODE (op) =3D=3D SUBREG) which=
 calls:
'paradoxical_subreg_p (VNx4SImode, OImode)'
Which seems to assume these are ordered with an assert.

I am not sure what the right fix is here, I did check and changing
paradoxical_subreg_p to return false if the mode sizes are not ordered lead=
s to
some bizarre fail, it looks like simplify_gen_subreg then just returns 0 ...
rather than the original nested subregs.

Before I dig deeper I'll get richi and Richard S to comment.=