From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: David Kastrup Newsgroups: gmane.emacs.devel Subject: Re: Compiling Elisp to a native code with a GCC plugin Date: Fri, 17 Sep 2010 15:31:26 +0200 Organization: Organization?!? Message-ID: <87sk18bioh.fsf@lola.goethe.zz> References: <87bp805ecr.fsf@gmail.com> <87iq26z97e.fsf@uwakimon.sk.tsukuba.ac.jp> <87y6b0yi8o.fsf@uwakimon.sk.tsukuba.ac.jp> NNTP-Posting-Host: lo.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: dough.gmane.org 1284730316 7477 80.91.229.12 (17 Sep 2010 13:31:56 GMT) X-Complaints-To: usenet@dough.gmane.org NNTP-Posting-Date: Fri, 17 Sep 2010 13:31:56 +0000 (UTC) To: emacs-devel@gnu.org Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Fri Sep 17 15:31:54 2010 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([199.232.76.165]) by lo.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1Owb2f-0006DK-KZ for ged-emacs-devel@m.gmane.org; Fri, 17 Sep 2010 15:31:53 +0200 Original-Received: from localhost ([127.0.0.1]:47800 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Owb2e-0000Gx-QH for ged-emacs-devel@m.gmane.org; Fri, 17 Sep 2010 09:31:52 -0400 Original-Received: from [140.186.70.92] (port=46576 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Owb2P-0000B4-L2 for emacs-devel@gnu.org; Fri, 17 Sep 2010 09:31:41 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1Owb2N-0006SV-MU for emacs-devel@gnu.org; Fri, 17 Sep 2010 09:31:37 -0400 Original-Received: from lo.gmane.org ([80.91.229.12]:39320) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1Owb2N-0006SL-8o for emacs-devel@gnu.org; Fri, 17 Sep 2010 09:31:35 -0400 Original-Received: from list by lo.gmane.org with local (Exim 4.69) (envelope-from ) id 1Owb2M-00060A-GR for emacs-devel@gnu.org; Fri, 17 Sep 2010 15:31:34 +0200 Original-Received: from p508ea523.dip.t-dialin.net ([80.142.165.35]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Fri, 17 Sep 2010 15:31:34 +0200 Original-Received: from dak by p508ea523.dip.t-dialin.net with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Fri, 17 Sep 2010 15:31:34 +0200 X-Injected-Via-Gmane: http://gmane.org/ Original-Lines: 43 Original-X-Complaints-To: usenet@dough.gmane.org X-Gmane-NNTP-Posting-Host: p508ea523.dip.t-dialin.net X-Face: 2FEFf>]>q>2iw=B6, xrUubRI>pR&Ml9=ao@P@i)L:\urd*t9M~y1^:+Y]'C0~{mAl`oQuAl \!3KEIp?*w`|bL5qr,H)LFO6Q=qx~iH4DN; i"; /yuIsqbLLCh/!U#X[S~(5eZ41to5f%E@'ELIi$t^ Vc\LWP@J5p^rst0+('>Er0=^1{]M9!p?&:\z]|;&=NP3AhB!B_bi^]Pfkw User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.0.50 (gnu/linux) Cancel-Lock: sha1:7OvNDboQJvj8+4GA0FpkIhqYoV4= X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.6 (newer, 3) X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.devel:130301 Archived-At: Lars Magne Ingebrigtsen writes: > "Stephen J. Turnbull" writes: > >> > Does everything have to be slow? :-) >> >> Wrong polarity. The question here is "does everything have to be >> fast?", and the answer is "no -- I mean, HELL NO!" >> >> Make your case that this function needs to be faster than a pure elisp >> implementation. > > I think that's a rather ... stunning approach, but might explain many > things about XEmacs. > > I've presented a use case, and I've demonstrated how all the alternative > implementations are 50-150% slower than my suggested new implementation, > and I've done the implementation, which turned out to be totally > trivial. Not really sure about that. + looking_at_literally (Lisp_Object string) + { + int start_byte = CHAR_TO_BYTE (PT); + int end_byte, end = PT + SCHARS (string); PT + SCHARS (string) can overflow here. Better check first rather than later whether ZV - PT < SCHARS (string). Yes, I know that most-positive-fixnum <= MAX_INT/2, but just on principle. + end_byte = CHAR_TO_BYTE (end); + + if (! memcmp (SDATA (string), BYTE_POS_ADDR (start_byte), + end_byte - start_byte)) That is assuming that both string and buffer are identically encoded (nowadays that likely means both have the same multibyteness). -- David Kastrup