[Mesa-dev] [PATCH] i965/fs: Replace subreg_offset with brw_reg's subnr.

[Matt Turner]

On Thu, Feb 11, 2016 at 7:31 PM, Francisco Jerez <currojerez at riseup.net> wrote:
> Matt Turner <mattst88 at gmail.com> writes:
>
>> On Thu, Feb 11, 2016 at 3:33 PM, Francisco Jerez <currojerez at riseup.net> wrote:
>>> Would be really nice if we could also get rid of reg_offset as we're at
>>> it.  reg and subreg_offset basically represent the same thing but with
>>> different units, couldn't we just have a single offset field in bytes?
>>> Should it be part of brw_reg or backend_reg?  I think I would lean
>>> towards backend_reg.  In that case does it make sense to move this into
>>> brw_reg now only to move it back to backend_reg later on?
>>
>> That would be nice.
>>
>> I'm just not sure how to do it. brw_reg has to have the subnr field,
>> and it's nice if that's the field the higher levels use too.
>>
> I guess at this point brw_reg is just an implementation detail of
> backend_reg, if some of it doesn't make sense at the IR level
> (e.g. because the IR wants more than 5 bits of sub-(V)GRF offset)
> there's no need to keep the IR tied up to the lower-level brw_reg
> representation.

Do you have an example of where we might want a subreg_offset >= 32?

I think using brw_reg is nice... it pretty simply contains the bits
that are common to the IR and the hardware. I'm not finding this limiting.