From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 20636 invoked by alias); 2 Jun 2007 14:20:33 -0000 Received: (qmail 20613 invoked by uid 48); 2 Jun 2007 14:20:24 -0000 Date: Sat, 02 Jun 2007 14:20:00 -0000 Message-ID: <20070602142024.20612.qmail@sourceware.org> X-Bugzilla-Reason: CC References: Subject: [Bug tree-optimization/32183] [4.3 Regression] reassoc2 can more extra calculations into a loop In-Reply-To: Reply-To: gcc-bugzilla@gcc.gnu.org To: gcc-bugs@gcc.gnu.org From: "hjl at lucon 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: 2007-06/txt/msg00100.txt.bz2 ------- Comment #16 from hjl at lucon dot org 2007-06-02 14:20 ------- Here are SPEC CPU 2K -O2 -ffast-math differences between revision 125029 and revision 125029 on Intel64 C2D: (r125030 - r125029)/r125029 164.gzip 0.0706714% 175.vpr -0.116077% 176.gcc -1.83805% 181.mcf 0.968263% 186.crafty 0.351975% 197.parser -0.15456% 252.eon -0.324675% 253.perlbmk -0.0394945% 254.gap -0.318471% 255.vortex 0.211775% 256.bzip2 0.300601% 300.twolf 0% Est. SPECint_base2000 -0.0983284% 168.wupwise 0.92511% 171.swim -0.0767165% 172.mgrid 0.179856% 173.applu -3.62731% 177.mesa 0.0398565% 178.galgel -4.55329% 179.art -1.38686% 183.equake 0.303819% 187.facerec -0.383583% 188.ammp -0.7768% 189.lucas -1.30465% 191.fma3d 1.38667% 200.sixtrack -0.135318% 301.apsi 0.0545256% Est. SPECfp_base2000 -0.660502% Here are SPEC CPU 2K -O2 -ffast-math differences between revision 125029 with DCE change disabled and revision 125029 on Intel64: (r125030 no DCE - r125029)/r125029 164.gzip 0.0706714% 175.vpr 0% 176.gcc 0% 181.mcf 0.484131% 186.crafty 0.195542% 197.parser -0.15456% 252.eon -0.202922% 253.perlbmk 0.35545% 254.gap 0.181984% 255.vortex 0.16942% 256.bzip2 -0.150301% 300.twolf 0.0389257% Est. SPECint_base2000 0.0983284% 168.wupwise 0.264317% 171.swim -0.0383583% 172.mgrid 0% 173.applu 0.0711238% 177.mesa 0% 178.galgel 0.123062% 179.art -3.16302% 183.equake 0.0434028% 187.facerec -0.115075% 188.ammp 0.0517866% 189.lucas 0.0705219% 191.fma3d 0% 200.sixtrack -0.135318% 301.apsi 0.163577% Est. SPECfp_base2000 -0.176134% Given the impact of DCE change, it isn't a real surprise. It not only may not optimize loop, but may make a loop to run slow. I will bet you will find the similar results on other architectures. -- http://gcc.gnu.org/bugzilla/show_bug.cgi?id=32183