From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 12701 invoked by alias); 27 Jul 2011 16:40:31 -0000 Received: (qmail 12691 invoked by uid 22791); 27 Jul 2011 16:40:30 -0000 X-SWARE-Spam-Status: No, hits=-2.9 required=5.0 tests=ALL_TRUSTED,AWL,BAYES_00 X-Spam-Check-By: sourceware.org Received: from localhost (HELO gcc.gnu.org) (127.0.0.1) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Wed, 27 Jul 2011 16:40:17 +0000 From: "ramana at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug target/48789] missed ARM optimization: use LDMIA X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: target X-Bugzilla-Keywords: missed-optimization X-Bugzilla-Severity: normal X-Bugzilla-Who: ramana at gcc dot gnu.org X-Bugzilla-Status: UNCONFIRMED X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: --- X-Bugzilla-Changed-Fields: CC Message-ID: In-Reply-To: References: X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/ Auto-Submitted: auto-generated Content-Type: text/plain; charset="UTF-8" MIME-Version: 1.0 Date: Wed, 27 Jul 2011 16:40:00 -0000 Mailing-List: contact gcc-bugs-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-bugs-owner@gcc.gnu.org X-SW-Source: 2011-07/txt/msg02360.txt.bz2 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48789 Ramana Radhakrishnan changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |ramana at gcc dot gnu.org --- Comment #4 from Ramana Radhakrishnan 2011-07-27 16:40:09 UTC --- There are a number of problems and not all of them are related to the backend. - ldm / stm aren't really first class citizens as far as GCC is concerned . There is no way today of getting the register allocator to forcefully use increasing addresses as a metric of choosing where to do what. - I suspect the performance issues you are seeing are with the number of spills and fills that are being generated in this case. If you tried -fsched-pressure life becomes much better and in fact the amount of stack space used is 0 . I haven't run any benchmarks to see if in this particular case you get better performance .