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

[Joseph S. Myers]

On Wed, 24 Jul 2013, H.J. Lu wrote:

> > Afaik avx 512 doubles the amount of xmm registers. Can we get them 
> > callee saved please?
> 
> Make them callee saved means we need to change ld.so to
> preserve them and we need to change unwind library to
> support them.  It is certainly doable.

And setjmp/longjmp (with consequent versioning implications if there isn't 
enough space in jmp_buf).  Avoiding the need for such library changes in 
order to use new instruction set features is why it's usual to make new 
registers (or new bits of existing registers) call-clobbered.

-- 
Joseph S. Myers
joseph@codesourcery.com