From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 31845 invoked by alias); 7 May 2007 01:36:21 -0000 Received: (qmail 31804 invoked by uid 48); 7 May 2007 01:36:11 -0000 Date: Mon, 07 May 2007 01:36:00 -0000 Message-ID: <20070507013611.31803.qmail@sourceware.org> X-Bugzilla-Reason: CC References: Subject: [Bug rtl-optimization/31849] Code size regression caused by fix to PR 31360 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: 2007-05/txt/msg00540.txt.bz2 ------- Comment #2 from pinskia at gcc dot gnu dot org 2007-05-07 02:36 ------- > 1) Hoists a register containing 0 out of the loop The correct thing to do. >2) Uses that *only* as a copy into another register (mov reg, #0 costs exactly the same as mov reg, reg) Interesting, but this is also true on ppc where I reported the original problem. > 3) By doing the above, somehow prevents the post-increment sequence from being found. This might be the true issue. But is this a regression from 4.1 where loop.c would actually move this invariant? -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31849