From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cockroach.ash.relay.mailchannels.net (cockroach.ash.relay.mailchannels.net [23.83.222.37]) by sourceware.org (Postfix) with ESMTPS id BC6213A7705C for ; Wed, 28 Apr 2021 15:45:35 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org BC6213A7705C X-Sender-Id: dreamhost|x-authsender|tuliom@ascii.art.br Received: from relay.mailchannels.net (localhost [127.0.0.1]) by relay.mailchannels.net (Postfix) with ESMTP id 3A03B342A38; Wed, 28 Apr 2021 15:45:32 +0000 (UTC) Received: from pdx1-sub0-mail-a91.g.dreamhost.com (100-96-17-237.trex.outbound.svc.cluster.local [100.96.17.237]) (Authenticated sender: dreamhost) by relay.mailchannels.net (Postfix) with ESMTPA id E0095342AE7; Wed, 28 Apr 2021 15:45:29 +0000 (UTC) X-Sender-Id: dreamhost|x-authsender|tuliom@ascii.art.br Received: from pdx1-sub0-mail-a91.g.dreamhost.com (pop.dreamhost.com [64.90.62.162]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384) by 100.96.17.237 (trex/6.2.1); Wed, 28 Apr 2021 15:45:32 +0000 X-MC-Relay: Neutral X-MailChannels-SenderId: dreamhost|x-authsender|tuliom@ascii.art.br X-MailChannels-Auth-Id: dreamhost X-Thread-Turn: 498151ec594821f0_1619624732018_825385326 X-MC-Loop-Signature: 1619624732018:3661823329 X-MC-Ingress-Time: 1619624732018 Received: from pdx1-sub0-mail-a91.g.dreamhost.com (localhost [127.0.0.1]) by pdx1-sub0-mail-a91.g.dreamhost.com (Postfix) with ESMTP id 9BFA37E3A5; Wed, 28 Apr 2021 08:45:29 -0700 (PDT) Received: from ascii.art.br (unknown [168.195.64.210]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) (Authenticated sender: tuliom@ascii.art.br) by pdx1-sub0-mail-a91.g.dreamhost.com (Postfix) with ESMTPSA id 058E97E376; Wed, 28 Apr 2021 08:45:26 -0700 (PDT) X-DH-BACKEND: pdx1-sub0-mail-a91 From: Tulio Magno Quites Machado Filho To: Paul Zimmermann Cc: fweimer@redhat.com, libc-alpha@sourceware.org Subject: Re: use of fma In-Reply-To: References: <87sg3ake7i.fsf@oldenburg.str.redhat.com> <87im46zc6q.fsf@linux.ibm.com> User-Agent: Notmuch/0.31.3 (http://notmuchmail.org) Emacs/27.1 (x86_64-redhat-linux-gnu) Date: Wed, 28 Apr 2021 12:45:24 -0300 Message-ID: <87fszaza3v.fsf@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain X-Spam-Status: No, score=-3.0 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, RCVD_IN_DNSWL_NONE, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 28 Apr 2021 15:45:38 -0000 Paul Zimmermann writes: >> Side note: single and double-precision multiply-add have been available since >> the PPC ISA and POWER1 ISA respectively. >> So, they're also available by default on powerpc64 and powerpc builds >> supporting hw fpu. > > thank you Tulio Magno. By the way, does anyone know of any hardware with > extended double and/or quadruple precision multiply-add? That's a good example of FMA that is not available by default on any of the ABIs because it has been added to the POWER ISA 3.0 (e.g. POWER9). :-D You need a new enough compiler (GCC >= 7.4), but you can use gcc135 (POWER9) from the GCC Compile Farm project: [tuliom@gcc135 ~]$ /opt/at12.0/bin/gcc -O2 -mcpu=power9 -g -dM -E -xc /dev/null | grep __FP_FAST_FMA #define __FP_FAST_FMAF128 1 #define __FP_FAST_FMAF 1 #define __FP_FAST_FMAF64x 1 #define __FP_FAST_FMAF32 1 #define __FP_FAST_FMAF64 1 #define __FP_FAST_FMAF32x 1 #define __FP_FAST_FMA 1 Notice I used -mcpu instead of -march. -- Tulio Magno