Re: 19980707 built on win95/i686-pc-cygwin32

[N8TM at aol dot com]

In a message dated 7/10/98 3:57:03 PM Pacific Daylight Time,
amylaar@cygnus.co.uk writes:

>  it the code is larger, you might see some slowdown due to
>  more code fetches from L2 cache into icache.
>  
>  Did you try egcs with -fno-gcse ?

I wasn't aware of that option.  It certainly accentuates the differences in
performance between egcs/g77 and g77-0.5.23 on Linux/P II.  Livermore Kernel
(double precision) loops vary from 50% faster for egcs with this option to 50%
faster for g77-0.5.23.  On win95, however, the effects of -fno-gcse seem to be
all favorable, bringing the performance of egcs on win95 almost up to where it
is on Linux, and well above g77-0.5.23 on win95.  win95 must be poisoning the
cache, if I take your suggestion.

On my CFD benchmark (all single precision), the one subroutine which spends
most of its time copying data, with a relatively low cache hit rate, runs 20%
faster with egcs -fno-gcse, while all the other subroutines which spend
significant time are faster with g77-0.5.23.