From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:40792) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TIkve-0008Ic-Bo for qemu-devel@nongnu.org; Mon, 01 Oct 2012 14:41:25 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1TIkvV-0002iB-Eu for qemu-devel@nongnu.org; Mon, 01 Oct 2012 14:41:18 -0400 Received: from mail-pb0-f45.google.com ([209.85.160.45]:55312) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1TIkvV-0002hg-9t for qemu-devel@nongnu.org; Mon, 01 Oct 2012 14:41:09 -0400 Received: by pbbrp2 with SMTP id rp2so8097424pbb.4 for ; Mon, 01 Oct 2012 11:41:08 -0700 (PDT) Sender: Richard Henderson Message-ID: <5069E3CF.6080606@twiddle.net> Date: Mon, 01 Oct 2012 11:41:19 -0700 From: Richard Henderson MIME-Version: 1.0 References: <1348766397-20731-1-git-send-email-rth@twiddle.net> <1348766397-20731-3-git-send-email-rth@twiddle.net> <20120927232015.GN23819@ohm.aurel32.net> <5064E12F.5040308@twiddle.net> <20121001174644.GA4623@ohm.aurel32.net> In-Reply-To: <20121001174644.GA4623@ohm.aurel32.net> Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 2/7] tcg: Optimize add2 + sub2 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Aurelien Jarno Cc: qemu-devel@nongnu.org On 2012-10-01 10:46, Aurelien Jarno wrote: > For the first add2 that seemed to have work correctly, this patch > optimized 0.2% of them. I am not sure it worth it as is. You're probably right. > I think optimizing add2, and in general all *2 ops is a good idea, but > we should be able to do more agressive optimization. Maybe, a bit like > Blue was suggesting, add2 should always be followed by a nop, so we can > do more optimizations? Adding an extra nop sounds like a better idea than add2_part[12]. And it's probably easier than adding mov2 opcodes -- one little assert inside the optimizer and we're golden. r~