From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=34685 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1PPXHG-00016A-27 for qemu-devel@nongnu.org; Mon, 06 Dec 2010 04:22:34 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1PPXHF-0005ai-BJ for qemu-devel@nongnu.org; Mon, 06 Dec 2010 04:22:33 -0500 Received: from mail.codesourcery.com ([38.113.113.100]:51475) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1PPXHF-0005Vr-3q for qemu-devel@nongnu.org; Mon, 06 Dec 2010 04:22:33 -0500 From: Paul Brook Subject: Re: [Qemu-devel] implementation of Vmul instruction in QEMU that seems to be illogical Date: Mon, 6 Dec 2010 09:22:19 +0000 References: In-Reply-To: MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-15" Content-Transfer-Encoding: 7bit Message-Id: <201012060922.20190.paul@codesourcery.com> List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: vandung.tran@vn.panasonic.com > Logically, implementation of Vmull.s32 and vmul.u32 is just similar to the > 8 and 16 bit cases. For example: > case 4: gen_helper_neon_mull_s32(dest, a, b); break; > case 5: gen_helper_neon_mull_u32(dest, a, b); break; > I implemented in this way and tested. It is OK. So I can't understand why > Vmull.s32 and vmul.u32 were implemented like this in QEMU 0.12.5. Please > explain for me ! I think you're asking the wrong question. Instead ask yourself why should we add a new helper when we already know how to do 32x32->64 multiplies. Paul