[x86-64 psABI]: Extend x86-64 psABI to support AVX-512

[Peter Bergner]

On Wed, 2013-07-24 at 10:42 -0700, H.J. Lu wrote:
> Are there any other Linux targets with callee saved vector registers?

Yes, on POWER.  From our ABI:

  On processors with the VMX feature.
    v0-v1 Volatile scratch registers
    v2-v13 Volatile vector parameters registers
    v14-v19 Volatile scratch registers
    v20-v31 Non-volatile registers

I'll note that the new VSX register state we recently added with power7
were made volatile, but then we already had these non-volatile altivec
regs to use.

Peteer