From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 9756 invoked by alias); 21 Dec 2002 11:16:03 -0000 Mailing-List: contact gcc-prs-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Archive: List-Post: List-Help: Sender: gcc-prs-owner@gcc.gnu.org Received: (qmail 9727 invoked by uid 71); 21 Dec 2002 11:16:02 -0000 Date: Sat, 21 Dec 2002 03:16:00 -0000 Message-ID: <20021221111602.9726.qmail@sources.redhat.com> To: nobody@gcc.gnu.org Cc: gcc-prs@gcc.gnu.org, From: Jan Hubicka Subject: Re: optimization/8492: [3.3 regression] GCC spins forever compiling loop Reply-To: Jan Hubicka X-SW-Source: 2002-12/txt/msg01168.txt.bz2 List-Id: The following reply was made to PR optimization/8492; it has been noted by GNATS. From: Jan Hubicka To: Eric Botcazou Cc: janis187@us.ibm.com, gcc-gnats@gcc.gnu.org, gcc-prs@gcc.gnu.org, gcc-bugs@gcc.gnu.org, nobody@gcc.gnu.org, thorpej@shagadelic.org, jh@suse.cz Subject: Re: optimization/8492: [3.3 regression] GCC spins forever compiling loop Date: Sat, 21 Dec 2002 12:14:29 +0100 > > The mainline regression reported in PR optimization/8492 > > (an infinite loop in the compiler) showed up starting with > > this patch: > > > > Sun Jul 21 00:54:54 CEST 2002 Jan Hubicka > > > > * gcse.c: Include cselib.h > > (constptop_register): Break out from ... > > (cprop_insn): ... here; kill basic_block argument. > > (do_local_cprop, local_cprop_pass): New functions. > > (one_cprop_pass): Call local_cprop_pass. > > > > Ha! I understand now... see the analysis: > http://gcc.gnu.org/ml/gcc/2002-12/msg00039.html > > I think the CFG should be cleaned up between the local cprop pass and the > global cprop pass, but I guess doing so won't particularly speed up the > compiler, to say the least. I think deleting unreachable blocks is cheap enought to do in the case conditional jump was eliminated. Alternatively we may prevent first local cprop pass from modifying CFG. I will try to get into this tonight. Thanks! Honza > > -- > Eric Botcazou