Looks like all the arith->shift attribute changes from the patch you
posted are already in mainline, so all you really need to add r10000
support is a pipeline model. All the MIPSen were converted from the
old pipeline description (i.e. "define_function_unit") to the new one
(i.e. "define_insn_reservation" and friends) in a big patch posted
last year: http://gcc.gnu.org/ml/gcc-patches/2004-07/msg01065.html.
Maybe you can find in the trhead surrounding that message some ideas
on how to convert your r10000 pipeline model.
HTH,
Gr.
Steven