From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 10583 invoked by alias); 22 Jun 2016 20:34:26 -0000 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 Received: (qmail 10497 invoked by uid 89); 22 Jun 2016 20:34:25 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-3.3 required=5.0 tests=BAYES_00,RP_MATCHES_RCVD,SPF_HELO_PASS autolearn=ham version=3.3.2 spammy=jeffs, meets X-HELO: mx1.redhat.com Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES256-GCM-SHA384 encrypted) ESMTPS; Wed, 22 Jun 2016 20:34:23 +0000 Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 4664464387; Wed, 22 Jun 2016 20:34:22 +0000 (UTC) Received: from localhost.localdomain (ovpn-116-33.rdu2.redhat.com [10.10.116.33]) by int-mx10.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u5MKYKYt011192; Wed, 22 Jun 2016 16:34:21 -0400 Subject: Re: [PATCH 1/2][v3] Drop excess size used for run time allocated stack variables. To: vogt@linux.vnet.ibm.com, gcc-patches@gcc.gnu.org, Andreas Krebbel References: <20160429221242.GA2205@linux.vnet.ibm.com> <20160503141753.GA17351@linux.vnet.ibm.com> <20160525133054.GA6938@linux.vnet.ibm.com> From: Jeff Law Message-ID: <3dfd1aca-3733-4c50-1921-832f11c30a19@redhat.com> Date: Wed, 22 Jun 2016 20:34:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.1.1 MIME-Version: 1.0 In-Reply-To: <20160525133054.GA6938@linux.vnet.ibm.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-IsSubscribed: yes X-SW-Source: 2016-06/txt/msg01647.txt.bz2 On 05/25/2016 07:30 AM, Dominik Vogt wrote: > On Tue, May 03, 2016 at 03:17:53PM +0100, Dominik Vogt wrote: >> > Version two of the patch including a test case. >> > >> > On Mon, May 02, 2016 at 09:10:25AM -0600, Jeff Law wrote: >>> > > On 04/29/2016 04:12 PM, Dominik Vogt wrote: >>>> > > >The attached patch removes excess stack space allocation with >>>> > > >alloca in some situations. Plese check the commit message in the >>>> > > >patch for details. >> > >>> > > However, I would strongly recommend some tests, even if they are >>> > > target specific. You can always copy pr36728-1 into the s390x >>> > > directory and look at size of the generated stack. Simliarly for >>> > > pr50938 for x86. >> > >> > However, x86 uses the "else" branch in round_push, i.e. it uses >> > "virtual_preferred_stack_boundary_rtx" to calculate the number of >> > bytes to add for stack alignment. That value is unknown at the >> > time round_push is called, so the test case fails on such targets, >> > and I've no idea how to fix this properly. > Third version of the patch with the suggested cleanup in the first > patch and the functional stuff in the second one. The first patch > is based on Jeff's draft with the change suggested by Eric and > more cleanup added by me. > > Tested and bootstrapped on s390x biarch (but did not look for > performance regressions as the change should be a no-op). > > Ciao > > Dominik ^_^ ^_^ > > -- Dominik Vogt IBM Germany > > > 0001-ChangeLog > > > gcc/ChangeLog0 > > * explow.c (allocate_dynamic_stack_space): Simplify knowing that > MUST_ALIGN was always true and extra_align ist always BITS_PER_UNIT. I think this meets the spirit of Eric's request to save the comment. So OK for the trunk. I realize this is kind of self-approving since the original cleanup was mine, but Eric signaled he was OK with the cleanup as long as the comment was saved. jeff