Sparc issue in GCC 2.95.2

[Josh Fryman <fryman at cc dot gatech dot edu>]

Hi,

I didn't see someplace more appropriate to send this, so here goes.  Please
don't flame me, if there's someplace better put it on the GCC web pages!

This isn't a bug so much a performance issue.  I have a very simple C program
that computes an infinite impulse response.  When I use the Sun "cc" compiler
with no special flags, I get pretty good performance.  When I use gcc with
flags to get better performance, I get performance that's
_substantially_ worse.  As in, more than an order of magnitude.

I've looked at the assembly output, and the best guess I have is that the sun
"cc" compiler really knows how to schedule and unroll the source code, whereas
gcc is just doing a good guess.

I found it most annoying that when I told gcc to generate ultrasparc code, it
had _worse_ performance than without the flags!

Are there any special compiler flags beyond the obvious ones that might improve
the results from gcc?  I browsed the manual for a while, and could only come up
with these two as most important: -mflat -mcpu=ultrasparc.

Would anyone like a copy of the source code?  Is anyone actively investigating
issues like this?

Disclaimer: I like gcc and would prefer to use it always, this is not
criticism!  I'm just trying to find out if this is an on-going area of effort
or if this is "just the way it is" for now.

Regards,

Josh Fryman