From mboxrd@z Thu Jan  1 00:00:00 1970
Return-path: <libre-riscv-dev-bounces@lists.libre-riscv.org>
Envelope-to: publicinbox@libre-riscv.org
Delivery-date: Sat, 16 May 2020 10:47:30 +0100
Received: from localhost ([::1] helo=libre-riscv.org)
	by libre-soc.org with esmtp (Exim 4.89)
	(envelope-from <libre-riscv-dev-bounces@lists.libre-riscv.org>)
	id 1jZtPl-0005pq-Qi; Sat, 16 May 2020 10:47:29 +0100
Received: from vps2.stafverhaegen.be ([85.10.201.15])
 by libre-soc.org with esmtp (Exim 4.89)
 (envelope-from <staf@fibraservi.eu>) id 1jZtPk-0005pk-Bd
 for libre-riscv-dev@lists.libre-riscv.org; Sat, 16 May 2020 10:47:28 +0100
Received: from hpdc7800 (hpdc7800 [10.0.0.1])
 by vps2.stafverhaegen.be (Postfix) with ESMTP id 063D111C04FF
 for <libre-riscv-dev@lists.libre-riscv.org>;
 Sat, 16 May 2020 11:47:27 +0200 (CEST)
Message-ID: <ff622773af59baea76786e85e28649a3941e69e5.camel@fibraservi.eu>
From: Staf Verhaegen <staf@fibraservi.eu>
To: libre-riscv-dev@lists.libre-riscv.org
Date: Sat, 16 May 2020 11:47:27 +0200
In-Reply-To: <CAEoCstS+xz_K6AYNkq-nXB=e7B4FqdC5nzdOXRaNyiqNOuCC7w@mail.gmail.com>
References: <CAEoCstQz36UuDJ+ZUgLRJNeQkA=pTfYuzCr+XgF-FJY9+yJsvA@mail.gmail.com>
 <747F8870-06C6-46A0-AFD9-D55289D4C41A@gatech.edu>
 <CAEoCstRUXkB_LxXXubx4A0dhLGvFqq6EPL+GzukDQORpHopaiw@mail.gmail.com>
 <4BDA96A5-9063-42A6-9548-CAE3CBEBEBAC@gatech.edu>
 <CAPweEDyZQEBsh8uZ4VkzzALPcoiTgs0AvTmTwS6B0Dc+jy+mfw@mail.gmail.com>
 <CAEoCstTERH=Z84je148ffL7_yiBYFj_Zet2VfOzkbe86MVmyQQ@mail.gmail.com>
 <CAPweEDyHrrQqPaNy7OqCsPUgR0yrELuRENqZTw_qr-tBVHVg+g@mail.gmail.com>
 <CAEoCstT7yZObkbS9GhWDRE7rm3p=Y5CzAJgYYj_3THCuRy=MCQ@mail.gmail.com>
 <CAPweEDzObJ1RXD51Y1D1WDJqsmsiNJKL1j-jDQqy0OwKLs6fdQ@mail.gmail.com>
 <CAEoCstS+xz_K6AYNkq-nXB=e7B4FqdC5nzdOXRaNyiqNOuCC7w@mail.gmail.com>
Organization: FibraServi bvba
X-Mailer: Evolution 3.28.5 (3.28.5-8.el7) 
Mime-Version: 1.0
X-Content-Filtered-By: Mailman/MimeDel 2.1.23
Subject: Re: [libre-riscv-dev] Introduction and Questions
X-BeenThere: libre-riscv-dev@lists.libre-riscv.org
X-Mailman-Version: 2.1.23
Precedence: list
List-Id: Libre-RISCV General Development
 <libre-riscv-dev.lists.libre-riscv.org>
List-Unsubscribe: <http://lists.libre-riscv.org/mailman/options/libre-riscv-dev>, 
 <mailto:libre-riscv-dev-request@lists.libre-riscv.org?subject=unsubscribe>
List-Archive: <http://lists.libre-riscv.org/pipermail/libre-riscv-dev/>
List-Post: <mailto:libre-riscv-dev@lists.libre-riscv.org>
List-Help: <mailto:libre-riscv-dev-request@lists.libre-riscv.org?subject=help>
List-Subscribe: <http://lists.libre-riscv.org/mailman/listinfo/libre-riscv-dev>, 
 <mailto:libre-riscv-dev-request@lists.libre-riscv.org?subject=subscribe>
Reply-To: Libre-RISCV General Development
 <libre-riscv-dev@lists.libre-riscv.org>
Content-Type: multipart/mixed; boundary="===============6853962972487324962=="
Errors-To: libre-riscv-dev-bounces@lists.libre-riscv.org
Sender: "libre-riscv-dev" <libre-riscv-dev-bounces@lists.libre-riscv.org>
Archived-At: <https://inbox.libre-soc.org/libre-riscv-dev/ff622773af59baea76786e85e28649a3941e69e5.camel@fibraservi.eu/>
List-Archive: <https://inbox.libre-soc.org/libre-riscv-dev/>


--===============6853962972487324962==
Content-Type: multipart/signed; micalg="pgp-sha1"; protocol="application/pgp-signature";
	boundary="=-aNfOkJazDJL9i8Rts+Jp"


--=-aNfOkJazDJL9i8Rts+Jp
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

Jeremy Singher schreef op vr 15-05-2020 om 16:49 [-0700]:
>=20
> >=20
> > sigh over a year ago i understood this enough to be able to answer.
> > what we will have to do is simply ignore the optimisation opportunity.
>=20
>=20
> Hmmm, ignoring WAW will significantly limit the ability of the core to
> exploit ILP, which is one of the fundamental reasons for going OOO.

I've wondered about this myself. Can you give concrete example of where
not supporting a WAW hazard blocks ILP ?
I am asking because just a WAW hazard could be easily avoided by a good
peep hole optimizer in software because it would see that the output of
the first write is never used.

greets,
Staf.


--=-aNfOkJazDJL9i8Rts+Jp--



--===============6853962972487324962==
Content-Type: text/plain; charset="utf-8"
MIME-Version: 1.0
Content-Transfer-Encoding: base64
Content-Disposition: inline

X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18KbGlicmUtcmlz
Y3YtZGV2IG1haWxpbmcgbGlzdApsaWJyZS1yaXNjdi1kZXZAbGlzdHMubGlicmUtcmlzY3Yub3Jn
Cmh0dHA6Ly9saXN0cy5saWJyZS1yaXNjdi5vcmcvbWFpbG1hbi9saXN0aW5mby9saWJyZS1yaXNj
di1kZXYK

--===============6853962972487324962==--