[Mesa-dev] [PATCH 02/13] i965: Allow passing target_bo=NULL to brw_emit_reloc()

[Chris Wilson]

Quoting Chris Wilson (2017-07-20 15:15:02)
> Quoting Kenneth Graunke (2017-07-19 21:08:23)
> > On Wednesday, July 19, 2017 3:09:10 AM PDT Chris Wilson wrote:
> > > Sometimes we want to emit a relocation to a NULL surface when the
> > > constructing the batch. If we push the NULL handling into the common
> > > brw_emit_reloc() we can make the batch construction itself more
> > > readable.
> > 
> > I don't like this...
> > 
> > There is no such thing as a "relocation to a NULL surface".  No relocation
> > is emittted in this case.  It either means the field is relative to a base
> > address, and is simply an offset, or the address is unused and we're setting
> > a NULL pointer combined with other bits packed into the same DWord.
> 
> There's actually no such thing as a relocation ;) I only put it out
> because there were so many duplicated checks.

The difference is that in the always use brw_emit_reloc patch end up
with 

@@ -661,18 +662,17 @@ brw_emit_buffer_surface_state(struct brw_context *brw,
                                   out_offset);
 
    isl_buffer_fill_state(&brw->isl_dev, dw,
-                         .address = (bo ? bo->offset64 : 0) + buffer_offset,
+                         .address = (bo ?
+                                     brw_emit_reloc(&brw->batch,
+                                                    *out_offset + brw->isl_dev.ss.addr_offset,
+                                                    bo, buffer_offset,
+                                                    I915_GEM_DOMAIN_SAMPLER,
+                                                    (rw ? I915_GEM_DOMAIN_SAMPLER : 0)) :
+                                     buffer_offset),
                          .size = buffer_size,
                          .format = surface_format,
                          .stride = pitch,
                          .mocs = tex_mocs[brw->gen]);

which was a bit too much of an eyesore for me.
-Chris