[Mesa-dev] [PATCH 0/9] Skip automatic execsize for instructions with a width of 4

[Pohjolainen, Topi]

On Mon, Mar 07, 2016 at 10:48:49AM +0100, Samuel Iglesias Gons?lvez wrote:
> Hello,
> 
> There is only one patch from this series that has been reviewed (patch
> 1).
> 
> Our plans is to start sending patches for adding fp64 support to i965
> driver in the coming weeks but they depend on these patches.
> 
> Can someone take a look at them? ;)
> 
> Sam
> 
> 
> On Thu, 2015-12-17 at 14:44 +0100, Samuel Iglesias Gonsálvez wrote:
> > Hello,
> > 
> > This patch series is a updated version of the one Iago sent last
> > week [0] that includes patches for gen6 too, as suggested by Jason.
> > 
> > We checked the gen9 code paths that work with a horizontal width of 4
> > and we think there won't be any regression on gen9... but we don't
> > have any gen9 machine to run piglit with these patches. Can someone
> > check it?
> > 
> > Please read the original cover letter [0] for more information.
> > 
> > Sam
> > 
> > [0] http://lists.freedesktop.org/archives/mesa-dev/2015-December/1027
> > 46.html
> > 
> > Iago Toral Quiroga (5):
> >   i965/eu: set correct execution size in brw_NOP
> >   i965/fs: set execution size for SEND messages in
> >     generate_uniform_pull_constant_load_gen7

I don't have the series in my mailbox anymore, so I'll comment here. There is:

       brw_set_dest(p, send, dst);
@@ -1279,6 +1280,7 @@ fs_generator::generate_uniform_pull_constant_load_gen7(fs_inst *inst,
       /* dst = send(payload, a0.0 | <descriptor>) */
       brw_inst *insn = brw_send_indirect_message(
          p, BRW_SFID_SAMPLER, dst, src, addr);
+      brw_inst_set_exec_size(devinfo, insn, dst.width);

I wonder if we should modify brw_send_indirect_message() instead? It already
calls brw_inst_set_exec_size() itself:

   if (dst.width < BRW_EXECUTE_8)
      brw_inst_set_exec_size(devinfo, send, dst.width);

This would then also serve generate_varying_pull_constant_load_gen7() later on
when we add support for double varyings, right? (It has similar logic
involving brw_send_indirect_message()).


In general, currently we set execution width both in brw_fs_generator.cpp
and in brw_eu_emit.c. I wonder if we should isolate it more. This is me
just thinking aloud for now. I studied this bit some time ago but can't
remember all the details...