From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([209.51.188.92]:49526) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1gnoEY-0007pW-89 for qemu-devel@nongnu.org; Sun, 27 Jan 2019 12:28:38 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1gnoC7-0003FV-89 for qemu-devel@nongnu.org; Sun, 27 Jan 2019 12:26:07 -0500 Received: from mail-pf1-x42f.google.com ([2607:f8b0:4864:20::42f]:35085) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1gnoC7-0003Ds-1m for qemu-devel@nongnu.org; Sun, 27 Jan 2019 12:26:07 -0500 Received: by mail-pf1-x42f.google.com with SMTP id z9so6940680pfi.2 for ; Sun, 27 Jan 2019 09:26:06 -0800 (PST) References: <20190127090306.30826-1-mark.cave-ayland@ilande.co.uk> <20190127090306.30826-3-mark.cave-ayland@ilande.co.uk> <3dc12858-4254-9da1-7eb2-309948d0d376@ilande.co.uk> From: Richard Henderson Message-ID: <5ea37d08-91f6-33cc-b220-f1a96796d794@linaro.org> Date: Sun, 27 Jan 2019 09:26:02 -0800 MIME-Version: 1.0 In-Reply-To: <3dc12858-4254-9da1-7eb2-309948d0d376@ilande.co.uk> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [Qemu-ppc] [PATCH v3 2/8] target/ppc: rework vmrg{l, h}{b, h, w} instructions to use Vsr* macros List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Mark Cave-Ayland , BALATON Zoltan Cc: qemu-ppc@nongnu.org, qemu-devel@nongnu.org, david@gibson.dropbear.id.au On 1/27/19 7:19 AM, Mark Cave-Ayland wrote: > Could this make the loop slower? I certainly haven't noticed any obvious > performance difference during testing (OS X uses merge quite a bit for > display rendering), and I'd hope that with a good compiler and modern branch > prediction then any effect here would be negligible. I would expect the i < n/2 loop to be faster, because the assignments are unconditional. FWIW. r~