Add minimal traceback table and prefetch to rs6000.

[Aldy Hernandez]

>>>>> "Dale" == Dale Johannesen <dalej@apple.com> writes:

> Altivec load/store has this restriction also.  It's handled by checks
 > in LEGITIMATE_OFFSET_ADDRESS_P and LEGITIMATE_LO_SUM_ADDRESS_P, and code in
 > rs6000_legitimize_address and rs6000_legitimize_reload_address.  See the
 > Darwin branch (most of this goes back to Motorola and has copyright

the LEGIT* macros i modified restrict things into [reg+reg].

Perhaps this might explain why Stan's more recent FSF tree is failing
some altivec tests, and it works for me.

Dale, if you find LEGIT* macros that are not correct, please fix.  I
thought they were correct.

Cheers.
Aldy