From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 2796 invoked by alias); 16 Aug 2011 02:05:21 -0000 Received: (qmail 2686 invoked by uid 22791); 16 Aug 2011 02:05:20 -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; Tue, 16 Aug 2011 02:05:07 +0000 From: "vmakarov at redhat dot com" To: gcc-bugs@gcc.gnu.org Subject: [Bug rtl-optimization/49936] [4.7 Regression] IRA handles CANNOT_CHANGE_MODE_CLASS poorly, + spills to memory on 4.7 Date: Tue, 16 Aug 2011 02:10:00 -0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: rtl-optimization X-Bugzilla-Keywords: missed-optimization, ra X-Bugzilla-Severity: normal X-Bugzilla-Who: vmakarov at redhat dot com X-Bugzilla-Status: UNCONFIRMED X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: 4.7.0 X-Bugzilla-Changed-Fields: 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 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: 2011-08/txt/msg01395.txt.bz2 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49936 --- Comment #2 from Vladimir Makarov 2011-08-16 02:05:02 UTC --- After thorough investigation of the problem I came to a conclusion that fixing it in IRA requires to form regions on pseudo mode usage too (besides just register pressure). Allocnos for the pseudo in question should get a different classes (FP class inside loop and INT outside). The problem is that IRA were written on assumption that register class of all allocnos for a pseudo is the same. It needs a lot of changes besides a new code for forming regions on the mode base. I'll try to do this but it will take long time. If it does not work, I could try to restore 4.6 behaviour (assigning INT class instead of memory).