[Mesa-dev] [PATCH 1/4] i965: Don't emit saturates for instructions without destinations.

[Matt Turner]

On Thu, Feb 19, 2015 at 3:31 PM, Ian Romanick <idr at freedesktop.org> wrote:
> On 02/10/2015 11:09 AM, Matt Turner wrote:
>> We were special casing OPCODE_END but no other instructions that have no
>> destination, like OPCODE_KIL, leading us to emitting MOVs with null
>> destinations.
>
> Should we (or do we somehow already) handle instructions with null
> destinations?   So...
>
>         ADD.sat.nz      null, g38, g22
>
> Or is that just impossible?

I don't think that's possible. The cases I saw were because we were
emitting MOV.SAT to copy results of instructions that don't have
destinations. :)

After I made this change, I grepped all of the output of shader-db and
found no more MOVs (without conditional mod) with null destinations.