[Mesa-dev] [PATCH v3 000/104] nir: Move to using instructions for derefs

[Caio Marcelo de Oliveira Filho]

Hi,

Given the fixes you already made based on my comments. Patches 1-20,
22-27, 29-43, and 61 (multiview!) are

Reviewed-by: Caio Marcelo de Oliveira Filho <caio.oliveira at intel.com>

Patches 46-47 and 49 seem to be valid regardless the rest of the code,
so I'd consider getting them in independently. They are also R-b'ed.

I've skipped 21 and 28 because I wanted to give a deeper look at the
originals.

>From the perspective of someone that is living with deref_vars for
just a short time, I like the idea of removing one special
construction (derefs) and rely on instructions instead.

Which made me wonder: was there a special factor that led NIR to start
with the "old-school derefs" in the first place? Other day Curro asked
about one of the "selling points" of NIR being it did not have all
those nodes representing dereferences. I digged up an old comment to
what I think he was referring to

    https://lists.freedesktop.org/archives/mesa-dev/2014-February/053477.html

    - All the ir_dereference chains blow up the memory usage, and the
    constant pointer chasing in the recursive algorithms needed to handle
    them is not just cache-unfriendly but "cache-mean."

How does deref_instructions avoid being "cache-mean" as their
"predecessors"? Was the blow up more a result of how the instructions
were structured than the fact it had those dereferences nodes?


Thanks,
Caio