From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B7C79C48BD9 for ; Thu, 27 Jun 2019 17:06:18 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 8AB1D214AF for ; Thu, 27 Jun 2019 17:06:18 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8AB1D214AF Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:52935 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hgXqj-00088e-IB for qemu-devel@archiver.kernel.org; Thu, 27 Jun 2019 13:06:17 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:52608) by lists.gnu.org with esmtp (Exim 4.86_2) (envelope-from ) id 1hgXWE-0006Vg-ED for qemu-devel@nongnu.org; Thu, 27 Jun 2019 12:45:08 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hgXWD-0004c3-FG for qemu-devel@nongnu.org; Thu, 27 Jun 2019 12:45:06 -0400 Received: from mx1.redhat.com ([209.132.183.28]:34100) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hgXWD-0004az-6o for qemu-devel@nongnu.org; Thu, 27 Jun 2019 12:45:05 -0400 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 72217308427C; Thu, 27 Jun 2019 16:45:04 +0000 (UTC) Received: from blackfin.pond.sub.org (ovpn-117-169.ams2.redhat.com [10.36.117.169]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3A5A21001DFD; Thu, 27 Jun 2019 16:45:04 +0000 (UTC) Received: by blackfin.pond.sub.org (Postfix, from userid 1000) id AB01211386A0; Thu, 27 Jun 2019 18:45:02 +0200 (CEST) From: Markus Armbruster To: Paolo Bonzini References: <87tvcbc9ul.fsf@dusky.pond.sub.org> <655a1ac0-bbd9-9798-4e44-478f94afb86f@redhat.com> Date: Thu, 27 Jun 2019 18:45:02 +0200 In-Reply-To: <655a1ac0-bbd9-9798-4e44-478f94afb86f@redhat.com> (Paolo Bonzini's message of "Thu, 27 Jun 2019 18:01:13 +0200") Message-ID: <87ftnvasfl.fsf@dusky.pond.sub.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.40]); Thu, 27 Jun 2019 16:45:04 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] Should configure --enable-debug add -Og to CFLAGS? X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Peter Maydell , "Daniel P. =?utf-8?Q?Berrang=C3=A9?=" , qemu-devel@nongnu.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Paolo Bonzini writes: > On 27/06/19 17:43, Markus Armbruster wrote: >> The fine manual advises: >> >> '-O0' >> Reduce compilation time and make debugging produce the expected >> results. This is the default. >> [...] >> '-Og' >> Optimize debugging experience. '-Og' should be the optimization >> level of choice for the standard edit-compile-debug cycle, offering >> a reasonable level of optimization while maintaining fast >> compilation and a good debugging experience. It is a better choice >> than '-O0' for producing debuggable code because some compiler >> passes that collect debug information are disabled at '-O0'. >> >> Our configure --enable-debug effectively picks -O0. Should it pick -Og >> instead? >> > > commit 48e56d503e18bd1e8a75463fd7cc1580bf7e7650 > Author: Paolo Bonzini > Date: Tue Mar 6 11:32:44 2018 +0100 > > Revert "build-sys: compile with -Og or -O1 when --enable-debug" > > This reverts commit 906548689e37ab6cca1e93b3f8d9327a4e17e8af. > Even with -Og, the debug experience is noticeably worse > because gdb shows a lot more "" variables and > function arguments. > > Signed-off-by: Paolo Bonzini > > :( Aha, GCC's documentation is more aspirational than factual here. Nevermind!