From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 11666 invoked by alias); 18 Jun 2014 14:21:29 -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 Received: (qmail 11592 invoked by uid 48); 18 Jun 2014 14:21:19 -0000 From: "bpringlemeir at gmail dot com" To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/60172] [4.9/4.10 Regression] ARM performance regression from trunk@207239 Date: Wed, 18 Jun 2014 14:21:00 -0000 X-Bugzilla-Reason: CC X-Bugzilla-Type: changed X-Bugzilla-Watch-Reason: None X-Bugzilla-Product: gcc X-Bugzilla-Component: tree-optimization X-Bugzilla-Version: 4.9.0 X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: bpringlemeir at gmail dot com X-Bugzilla-Status: WAITING X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org X-Bugzilla-Target-Milestone: 4.9.1 X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: cc Message-ID: In-Reply-To: References: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/ Auto-Submitted: auto-generated MIME-Version: 1.0 X-SW-Source: 2014-06/txt/msg01571.txt.bz2 https://gcc.gnu.org/bugzilla/show_bug.cgi?id=60172 Bill Pringlemeir changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |bpringlemeir at gmail dot com --- Comment #22 from Bill Pringlemeir --- The good ARM assembler uses the 'mla' instruction which is a 'multiply and accumulate'. Since this is not recognized, the multiply result needs a temporary register to do the add with and I think this cause the extra registers. I believe you should look to see why the 'mla' is not matched. I don't know if the x86 has an op-code like this.