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 C5ED83858C39; Thu, 29 Feb 2024 07:19:35 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org C5ED83858C39
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1709191175;
	bh=nch7G3F0TVhS7yJbY1On18Hl67qRVMBORsJGm/in6SQ=;
	h=From:To:Subject:Date:In-Reply-To:References:From;
	b=UbNbjeBm1xuNbTHX7HR1vG4kQh2MLoei7WDZX/8JRPglSs21Uqt3Oe7RlilLl9K8O
	 +/Gdp0mtKaRYh6eE+OFugPxC+09eHeIoyOMULWdBiJxVFAUZtW8PvIDEIj82p972xa
	 nFXWW8mfhf4F6WDMzTsHmDzkUf/tIGVfoH/JZd4U=
From: "rguenther at suse dot de" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/114151] [14 Regression] weird and inefficient
 codegen and addressing modes since g:a0b1798042d033fd2cc2c806afbb77875dd2909b
Date: Thu, 29 Feb 2024 07:19:35 +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: missed-optimization
X-Bugzilla-Severity: normal
X-Bugzilla-Who: rguenther at suse dot de
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: 
Message-ID: <bug-114151-4-bZs86lq86R@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-114151-4@http.gcc.gnu.org/bugzilla/>
References: <bug-114151-4@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=3D114151

--- Comment #4 from rguenther at suse dot de <rguenther at suse dot de> ---
On Wed, 28 Feb 2024, tnfchris at gcc dot gnu.org wrote:

> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D114151
>=20
> --- Comment #3 from Tamar Christina <tnfchris at gcc dot gnu.org> ---
> >=20
> > This was a correctness fix btw, so I'm not sure we can easily recover -=
 we
> > could try using niter information for CHREC_VARIABLE but then there's
> > variable niter here so I don't see a chance.
> >=20
>=20
> It looks like it's mostly SVE suffering here. Adv. SIMD an scalar codegen=
 seems
> to have vastly improved with it. we see ~10% improvements due to better
> addressing for scalar.
>=20
> It also only happens at -O3 but -O2 is fine, which is weird as I was expe=
cted
> IVopts to be enabled at -O2 too.

Note the underlying issue, analyzing { a, +, b } * c differently and
thus eventually dependent CHRECs failing to analyze should be independent
on the architecture.

What was definitely missing is consideration of POLY_INT_CSTs (and
variable polys, as I think there's no range info for those).

We do eventually want to improve how ranger behaves here.  I'm not sure
why when we do not provide a context 'stmt' it can't see to compute
a range valid at the SSA names point of definition?  (so basically
compute the global range)

Maybe there's another API to do that.  But I thought it was convenient
to use range_of_expr as that also handles GENERIC expression trees
to some extent and those are common within SCEV.=