From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:47175) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bpU0l-0005h0-Ll for qemu-devel@nongnu.org; Thu, 29 Sep 2016 01:36:00 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bpU0j-0007s8-O7 for qemu-devel@nongnu.org; Thu, 29 Sep 2016 01:35:58 -0400 Date: Thu, 29 Sep 2016 14:24:48 +1000 From: David Gibson Message-ID: <20160929042448.GP8390@umbus.fritz.box> References: <1475041518-9757-1-git-send-email-raji@linux.vnet.ibm.com> <1475041518-9757-2-git-send-email-raji@linux.vnet.ibm.com> <20160929020745.GE8390@umbus.fritz.box> <6c666347-fa50-a824-b8bb-8a6f31f454e5@twiddle.net> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="rJ8inJ6ig7iY3YX9" Content-Disposition: inline In-Reply-To: <6c666347-fa50-a824-b8bb-8a6f31f454e5@twiddle.net> Subject: Re: [Qemu-devel] [Qemu-ppc] [PATCH 1/6] target-ppc: add vmul10[u, eu, cu, ecu]q instructions List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Richard Henderson Cc: Rajalakshmi Srinivasaraghavan , Vasant Hegde , qemu-ppc@nongnu.org, qemu-devel@nongnu.org --rJ8inJ6ig7iY3YX9 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Wed, Sep 28, 2016 at 09:00:51PM -0700, Richard Henderson wrote: > On 09/28/2016 07:07 PM, David Gibson wrote: > > > + tcg_gen_mulu2_i64(t0, t1, cpu_avrl[rA(ctx->opcode)], val); = \ > >=20 > > Do you really want to be using an actual mul op, rather than (in << 3) > > + (in << 1)? Obviously working out al the carries correctly will be a > > bit fiddly. >=20 > I think it's fine. Modern hardware will do the double-word multiply in 3= -5 > cycles, which is probably equal to what we could do by hand with > shifts. Fair enough. And it will make for less dicking around with the carry in and carry out. --=20 David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson --rJ8inJ6ig7iY3YX9 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAEBCAAGBQJX7JeQAAoJEGw4ysog2bOSDUgQAJsI5RxST4FDlCNckESkIIf3 RIxzOJ6YJZlhb0pn0DzD8lS+buIwY/UEj2dPTZ1GREcRTxO3mYKj8+O4fzTegyYf uMbz7aGtbdl+RkclVBdy0DSYVRnSAxjDycANX5CkTLfsCyvNgdqvvbfDmeyPbd3h ITaY2obC0aYIbEEqxYOI/XdNbGx1W8R+UCFO6wvS3RxgFe05SRPtQS1+i9pSwMh8 AXfZODiJYQ1XbkQB0Mh1dmxaN2Sl7h9slzDzFgYoM7Suh7gpAIjUsiwQZ0birLPW DHfqqTF9Py/rFRHTso5hbJVAZWX01dVZ0qkg94Q7Jh3cJnk+H7ygRQdQWe0qUoG+ cCHvDtzu+ViSWxEMmOToTcVk7GHQIXebYofrw72VZ/fxbvgsJHfQu2EgiFi+VYOA V+pZ+Op0IvzC2eYfAva18YX3J+kyAPl8nth770A37h1KNH3LVwHnBE3LehW7WlhC /ePdP2tixj6PZEyHZHfQLzSZgjIw/bMKgYPjaRctYeonc2mznb2KLlCx1w0ryega 7Sb19Ft9VE0/jH25ZVT6d6t4qFDNXZI1DgCBgx5zRka6jlBUbNhmjbJwJpnbzj47 mmPWIz3NzNReyW9KO/RFcQP/bX5onsoMLaDPYfxtBB5+limZHfYmOSKzT91CeVBJ dvjn3aOvl93zAuVg3QNt =BRHF -----END PGP SIGNATURE----- --rJ8inJ6ig7iY3YX9--