[llvm] r176868 - Don't reserve R2 on Darwin/PPC

[Peter Bergner]

On Tue, 2013-03-12 at 15:18 +0000, Hal Finkel wrote:
> Darwin can use R0 as a spare register in any case where the
> System V ABI uses it (R0 is special architecturally, and so
> is reserved under all common ABIs).

To be pedantic, r0 is special architecturally, but I know the
Linux ABIs (ppc32 and ppc64) do not reserve it and it is used
by the GCC register allocater like any other volatile register,
with the caveat that it cannot be used as a base register in
load/store insns, etc.  Does LLVM really disallow its use
during RA?

Peter