[PATCH 3/8] sparc: Rewrite everything

[Richard Henderson]

On 10/29/2014 01:10 PM, David Miller wrote:
> From: Richard Henderson <rth@twiddle.net>
> Date: Wed, 29 Oct 2014 13:01:45 -0700
> 
>> On 10/29/2014 11:10 AM, David Miller wrote:
>>> Maybe I'm missing something?
>>
>> The two limits are in fact different.  In gcc, see sparc_return_in_memory and
>> sparc_pass_by_reference.
> 
> My bad, thanks for clarifying.
> 
> That's the only thing that caught my eye.  I think for most v9 chips a
> 'return' is slightly more expensive than a 'ret/restore'.  'return' is
> good for saving an instruction when you can put something in that
> delay slot, but if you can't then you might as well do 'ret/restore'.

Ah right, thanks.

The one other microarchitecture question I had was wrt call/ret paring.

I was assuming that, for predition purposes, "ret" vs "jmp" must be based on
the register used -- %i7 or %o7.  Thus my call ... jmp %o7+const hopefully
keeps any call/return prediction stack in sync?


r~