[Mesa-dev] [PATCH 10/32] i965/fs: Remove logic to keep track of MRF metadata in lower_load_payload().

[Jason Ekstrand]

On Thu, Feb 19, 2015 at 12:13 PM, Francisco Jerez <currojerez at riseup.net>
wrote:

> Jason Ekstrand <jason at jlekstrand.net> writes:
>
> > On Fri, Feb 6, 2015 at 4:01 PM, Francisco Jerez <currojerez at riseup.net>
> > wrote:
> >
> >> Hey Matt,
> >>
> >> Matt Turner <mattst88 at gmail.com> writes:
> >>
> >> > On Fri, Feb 6, 2015 at 6:42 AM, Francisco Jerez <
> currojerez at riseup.net>
> >> wrote:
> >> >> MRFs cannot be read from anyway so they cannot possibly be a valid
> >> >> source of LOAD_PAYLOAD.
> >> >> ---
> >> >
> >> > The function only seems to test inst->dst.file == MRF. I don't see any
> >> > code for handling MRF sources. What am I missing?
> >>
> >> That test is for "handling" MRF sources -- More precisely, it's
> >> collecting the writemask and half flags for MRF writes, which can only
> >> possibly be useful if we're going to use them later on to read something
> >> out of an MRF into a payload, which we shouldn't be doing in the first
> >> place.
> >>
> >> Aside from simplifying the function somewhat, that allows us to drop the
> >> 16 register gap reserved for MRFs at register offset zero, what will
> >> allow us to drop the vgrf_to_reg[] offset calculation completely (also
> >> in split_virtual_grfs()) in a future patch (not sent for review yet).
> >>
> >
> > No, we do read from MRF's sort-of...  Send messages have an implicit
> "read"
> > from an MRF.
>
> Heh, and that's pretty much the only way you "read" from it.
>
> > This was written precicely so that we could use LOAD_PAYLOAD
> > to build MRF payloads.  We do on pre-GEN6.
> >
> I'm aware, but you don't need any of this meta-data to LOAD_PAYLOAD
> *into* an MRF, and LOAD_PAYLOAD with an MRF as source should be illegal
> anyway.
>

And no one is using it that way.  All of the metadata checks you are
deleting are checks on the *destination*.


> >
> >> _______________________________________________
> >> mesa-dev mailing list
> >> mesa-dev at lists.freedesktop.org
> >> http://lists.freedesktop.org/mailman/listinfo/mesa-dev
> >>
> >>
>
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