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

Matt Turner mattst88 at gmail.com
Thu Feb 19 15:38:24 PST 2015

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.

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