From mboxrd@z Thu Jan 1 00:00:00 1970 From: Leo Famulari Subject: bug#24703: Store references in 8-byte chunks in compiled code Date: Sat, 5 Nov 2016 14:36:50 -0400 Message-ID: <20161105183650.GA21301@jasmine> References: <8737jwnb1c.fsf@netris.org> <87r37gstf6.fsf_-_@netris.org> <87d1j0sl1l.fsf@netris.org> <87a8e4glot.fsf@gnu.org> <8f2024ad-13c1-d4b1-1541-c2a5bddcb403@etorok.net> <87h98bdvng.fsf@gnu.org> <87k2d6qqee.fsf@netris.org> <20161024194022.GA1772@jasmine> <87insh1oxz.fsf@gnu.org> <87a8de7s6q.fsf@inria.fr> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Return-path: Received: from eggs.gnu.org ([2001:4830:134:3::10]:41021) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1c35pv-0007gr-IV for bug-guix@gnu.org; Sat, 05 Nov 2016 14:37:06 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1c35pu-0006lB-Oz for bug-guix@gnu.org; Sat, 05 Nov 2016 14:37:03 -0400 Received: from debbugs.gnu.org ([208.118.235.43]:58954) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1c35pu-0006ku-Kn for bug-guix@gnu.org; Sat, 05 Nov 2016 14:37:02 -0400 Sender: "Debbugs-submit" Resent-Message-ID: Content-Disposition: inline In-Reply-To: <87a8de7s6q.fsf@inria.fr> List-Id: Bug reports for GNU Guix List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: bug-guix-bounces+gcggb-bug-guix=m.gmane.org@gnu.org Sender: "bug-Guix" To: Ludovic =?UTF-8?Q?Court=C3=A8s?= Cc: 24703@debbugs.gnu.org On Sat, Nov 05, 2016 at 12:15:25AM +0100, Ludovic Courtès wrote: > I’ve fiddled a bit with GCC and read some code. No success yet, but > here’s a status update. Thanks for writing this out! > Instead, the knobs we have are (1) global flag to enable/disable each > built-in function (like -fno-builtin-… does), and (2) an x86-specific > knob to determine whether to use ‘movabs’ or not (‘-mmemcpy-strategy’ > supposedly controls that, but ‘-mmemcpy-strategy=libcall:-1:noalign’ > doesn’t seem to have any effect for instance.) Please correct me if I paraphrase the choices incorrectly: (1) Completely disable the strcpy optimization for all architectures (2) Ostensibly change how strcpy is optimized on x86, except the knob seems to have no effect > These knobs are not great because that would lead us to disable the > optimization wholesale, which is not desirable. What are the costs of (1)? Should we report (2) upstream?