From mboxrd@z Thu Jan 1 00:00:00 1970 From: "David R. Conrad" To: egcs@cygnus.com Subject: Built egcs-1.1b on i586-pc-linux-gnulibc1, -fgcse slowdowns Date: Mon, 21 Sep 1998 07:32:00 -0000 Message-id: X-SW-Source: 1998-09/msg01190.html -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 I have successfully built egcs-1.1b on darwin, my linux 2.1.119 system: Linux darwin 2.1.119 #5 Sat Sep 5 13:45:37 EDT 1998 i586 unknown A Pentium 166Mhz non-MMX machine with 32 Meg ram. One odd thing: I have a cpu-bound program I'd written which took about 6 minutes to run to completion when compiled with gcc-2.7.2.1. It took about 5m47s when compiled with gcc from egcs-1.0.3 with -O6 -fomit-frame-pointer -mpentium - -funroll-loops. I tried --enable-haifa (does this make sense on a pentium?) and got 6m13s so I recompiled egcs-1.1b with --disable-haifa and it went up a bit. I've been playing with various options, and I found that egcs-1.1b gets the time down to 5m40s *IF I GIVE THE -fno-gcse SWITCH*! Should I be surprised that gcse pessimizes my code? Should I generally compile things with -fno-gcse, or is it likely to be a quirk with this particular program? Would you like a copy of the program (480 bytes) that I'm trying all this with? I'm hesitant to recompile my kernel with this compiler; any thoughts on how I can tell what optimization options get the best results there? All in all, though, I'm impressed by the egcs project. Cheers, David R. Conrad, drc@adni.net Nota Bene, India and Pakistan: "If you go on with this nuclear arms race, all you are going to do is make the rubble bounce." -- Winston Churchill -----BEGIN PGP SIGNATURE----- Version: PGPfreeware 5.0i for non-commercial use Charset: noconv iQA/AwUBNgZJIIPOYu8Zk+GuEQINGgCgrC+bO7j5z4Nzmlh+uWWtxagPogEAn2Ah aTqeqf2VxFQ01gMAZ2XTsEWD =UbCX -----END PGP SIGNATURE-----