From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([209.51.188.92]:42954) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hGK59-0001fc-DV for qemu-devel@nongnu.org; Tue, 16 Apr 2019 05:08:48 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hGK57-00025X-Np for qemu-devel@nongnu.org; Tue, 16 Apr 2019 05:08:46 -0400 Sender: Richard Henderson References: <20190411100836.646-1-david@redhat.com> <20190411100836.646-10-david@redhat.com> <71ce854d-da00-565e-0b36-9458a7bc9183@linaro.org> From: Richard Henderson Message-ID: <7e9ca895-031e-9843-8617-491e72a330e7@twiddle.net> Date: Mon, 15 Apr 2019 23:08:32 -1000 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v1 09/41] s390x/tcg: Implement VECTOR CHECKSUM List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: David Hildenbrand , Richard Henderson , qemu-devel@nongnu.org Cc: qemu-s390x@nongnu.org, Cornelia Huck , Thomas Huth On 4/15/19 10:58 PM, David Hildenbrand wrote: >> You could use >> >> tcg_gen_add2_i32(sum, tmp, sum, zero, tmp, zero); >> tcg_gen_add_i32(sum, sum, tmp); > That makes perfect sense, I will use that for now, thanks! > Here's a funny one. We can do this in one operation: tcg_gen_add2_i32(tmp, sum, sum, sum, tmp, tmp); The lower (sum+tmp) carries into the upper (sum+tmp). We take the upper result and discard the lower. r~