From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 539 invoked by alias); 2 Mar 2012 08:29:29 -0000 Received: (qmail 529 invoked by uid 22791); 2 Mar 2012 08:29:27 -0000 X-SWARE-Spam-Status: No, hits=-2.7 required=5.0 tests=ALL_TRUSTED,AWL,BAYES_00,TW_DD,TW_VZ,TW_ZB 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; Fri, 02 Mar 2012 08:29:15 +0000 From: "jakub at gcc dot gnu.org" To: gcc-bugs@gcc.gnu.org Subject: [Bug target/50182] Performance degradation from gcc 4.1 (x86_64) Date: Fri, 02 Mar 2012 08:29:00 -0000 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: jakub at gcc dot gnu.org X-Bugzilla-Status: NEW X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: --- 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: 2012-03/txt/msg00194.txt.bz2 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50182 --- Comment #32 from Jakub Jelinek 2012-03-02 08:28:34 UTC --- For me, 4.1 is equally fast to 4.6 on my CPU and on the reduced testcase I've attached (not clear if it models what the original benchmark did right or not), and on the trunk regressed with http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=176072 Before that the inner loop looked like: .L12: addl $10, %edx addb 0(%rbp,%rcx), %dl addq $1, %rcx cmpl %ecx, %ebx jg .L12 and now it looks like: .L12: movzbl 0(%rbp,%rdx), %r8d addq $1, %rdx cmpl %edx, %ebx leal 10(%rcx,%r8), %ecx jg .L12