From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 28600 invoked by alias); 16 Aug 2007 10:36:03 -0000 Received: (qmail 28585 invoked by uid 22791); 16 Aug 2007 10:36:02 -0000 X-Spam-Check-By: sourceware.org Received: from pfepa.post.tele.dk (HELO pfepa.post.tele.dk) (195.41.46.235) by sourceware.org (qpsmtpd/0.31) with ESMTP; Thu, 16 Aug 2007 10:35:52 +0000 Received: from x1-6-00-0f-9f-c6-3e-90 (x1-6-00-0f-9f-c6-3e-90.k75.webspeed.dk [80.197.1.215]) by pfepa.post.tele.dk (Postfix) with ESMTP id 40DCAFAC037; Thu, 16 Aug 2007 12:35:49 +0200 (CEST) Received: from x1-6-00-0f-9f-c6-3e-90 (localhost.localdomain [127.0.0.1]) by x1-6-00-0f-9f-c6-3e-90 (8.14.0/8.14.0) with ESMTP id l7GAZn00032446; Thu, 16 Aug 2007 12:35:49 +0200 Received: (from rask@localhost) by x1-6-00-0f-9f-c6-3e-90 (8.14.0/8.14.0/Submit) id l7GAZm8A032445; Thu, 16 Aug 2007 12:35:48 +0200 Date: Thu, 16 Aug 2007 10:36:00 -0000 From: Rask Ingemann Lambertsen To: Zack Weinberg Cc: gcc-patches@gcc.gnu.org Subject: Re: Arch-independent double-word clz expansion and a few other tweaks for bitscanning Message-ID: <20070816103548.GK25795@sygehus.dk> References: <46BD5B0D.403@codesourcery.com> <20070811090549.GW25795@sygehus.dk> <46BDF82E.80202@codesourcery.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <46BDF82E.80202@codesourcery.com> User-Agent: Mutt/1.5.14 (2007-02-12) Mailing-List: contact gcc-patches-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-patches-owner@gcc.gnu.org X-SW-Source: 2007-08/txt/msg00997.txt.bz2 On Sat, Aug 11, 2007 at 10:55:58AM -0700, Zack Weinberg wrote: > I'm happy to change it around, but empirically, it doesn't seem to make > any difference: initial RTL generation produces > > (insn 7 6 8 test.c:2 (parallel [ > (set (reg:CCZ 17 flags) > (compare:CCZ (reg/v:DI 59 [ x ]) > (const_int 0 [0x0]))) > (set (reg:DI 61) > (ctz:DI (reg/v:DI 59 [ x ]))) > ]) -1 (nil)) > > despite that I wrote it the other way around in the insn pattern. That's odd. But in any case, it only matters when combine tries find such an instruction. -- Rask Ingemann Lambertsen