IA-64 compile flags for gcc

Many times when using gcc, I use certain flags to optimize the compilation, for example with Solaris8 and a sparc IIe v9 cpu, I would use something like...

CC=gcc CFLAGS="-O4 -mcpu=v8"; export CC CFLAGS

There are others as well. Also many times when doing a configure there is an
option for something like --prefix=/foo/bar --hosth6 to optimize the code for
my specific hardware.

Does anyone know what the "optimal" flags are for an IA-64 in gcc? I realize you
can't always use the ones you want, but if you could...?

I have gone through a lot of the gcc documentation, but there is so much, and
what I have seen so far doesn't cover this. Can anyone point me in the right
direction?

Ray