[Mesa-dev] [PATCH 1/7] gallium: add CONSTBUF type to tgsi_file_type

[Nicolai Hähnle]

On 22.08.2017 16:56, Ilia Mirkin wrote:
> On Tue, Aug 22, 2017 at 10:51 AM, Roland Scheidegger <sroland at vmware.com> wrote:
>> I am probably missing something here, but why do you need a new register
>> file? Since you couldn't use LOAD with TGSI_FILE_CONSTANT before, can't
>> you just allow LOAD with TGSI_FILE_CONSTANT and achieve the same thing?
>> Or do you need to know how it's going to be accessed in advance?
> 
> With bindless, LOAD can take a CONST I believe [which contains the
> value of the bindless id]. I think it's nice to keep those concepts
> separate... having CONST sometimes mean the value and other times mean
> the address is a bit weird. This way CONSTBUF[0] is the address of the
> 0th constbuf.

I'm still not quite convinced. The levels of indirection should clarify 
the meaning, shouldn't they?

You get

   LOAD dst, CONST[0][0], IMM[0]

when loading from offset IMM[0] of a bindless buffer whose handle is at 
the beginning of the buffer CONST[0].

You get

   LOAD dst, CONST[0], IMM[0]

when loading from offset IMM[0] of non-bindless buffer 0.

Is there ever really a situation where the two could be confused?

Cheers,
Nicolai


> 
>    -ilia
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