3dnow, mmx, k6-2 optimizing?

[Puna Tannehill]

I've been looking for possible flags, optimizations, really anything 
that would help me setup my laptop to use mmx and 3dnow.  I've updated 
/etc/make.conf to -march to the drum of a k6-2, but I'm not even sure 
if mmx and 3dnow are being taken into consideration for compiling and 
such, especially for Xorg.

I did some googling and found people who used CFLAGS like -mmmx and 
-m3dnow, but when I run with those options, they fail and said to be 
invalid.  they don't appear in 'man gcc' which should have been the 
first place i looked.  I'm not finding anything in terms of compiling 
or configuring Xorg to use 3dnow or mmx, or even how to check to see 
if they are automatically detected and used.

Any thoughts?

Puna