question on how to experiment with register pressure

[Joe Landman <landman at scalableinformatics dot com>]

Hi Folks:

  I am doing some (simple minded) research on the effect of register
pressure on code run time.  I want to have a somewhat finer grain of
control over the register allocator if possible (to place "artificial"
register pressure on a machine with many registers).  Specific items I
can think of would be turning off or on the sse/sse2 system, and the
frame pointer.  At higher optimization levels, the frame pointer is shut
off and that register is left for use in the general optimization.  For
my tests, I would like to exclude that register if possible from the
allocator.  Can this be done?

This is on an x86 platform, looking more specifically at Opteron.  I
have access to gcc 3.3.1, 3.3.2, 3.4-20040128, and 3.2.3.  I am hoping
for a finer grain control that I get from -m32/-m64.  

Thanks!

-- 
Joe Landman
landman@scalableinformatics.com