From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 27527 invoked by alias); 9 Jul 2010 00:06:49 -0000 Received: (qmail 27343 invoked by uid 48); 9 Jul 2010 00:06:34 -0000 Date: Fri, 09 Jul 2010 00:06:00 -0000 Message-ID: <20100709000634.27342.qmail@sourceware.org> X-Bugzilla-Reason: CC References: Subject: [Bug target/44883] Combine separate shift and add instructions into a single one In-Reply-To: Reply-To: gcc-bugzilla@gcc.gnu.org To: gcc-bugs@gcc.gnu.org From: "pinskia at gcc dot gnu dot org" 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: 2010-07/txt/msg00949.txt.bz2 ------- Comment #3 from pinskia at gcc dot gnu dot org 2010-07-09 00:06 ------- (In reply to comment #2) > Give it a single register, the cost is 6. Give it the rtx (plus (reg 144) (reg > 143)), the cost is 4. So a single register is more expensive than a plus > expression, not reasonable. And that causes forwprop to do what it does; it is a lower total cost according to the cost function :). -- pinskia at gcc dot gnu dot org changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |NEW Ever Confirmed|0 |1 Keywords| |missed-optimization Last reconfirmed|0000-00-00 00:00:00 |2010-07-09 00:06:33 date| | http://gcc.gnu.org/bugzilla/show_bug.cgi?id=44883