Built egcs-1.1b on i586-pc-linux-gnulibc1, -fgcse slowdowns

["David R. Conrad" <drc at adni dot net>]

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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

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