[Mesa-dev] [PATCH 6/7] i965/vec4/gs: Stop munging the ATTR containing gl_PointSize.

[Kenneth Graunke]

gl_PointSize is delivered in the .w component of the VUE header, while
the language expects it to be a float (and thus in the .x component).

Previously, we emitted MOVs to copy it over to the .x component.
But this is silly - we can just use a .wwww swizzle and access it
without copying anything or clobbering the value stored at .x
(which admittedly is useless).

Removes the last use of ATTR destinations.

Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
---
 src/mesa/drivers/dri/i965/brw_vec4_gs_nir.cpp     |  4 ++++
 src/mesa/drivers/dri/i965/brw_vec4_gs_visitor.cpp | 23 -----------------------
 2 files changed, 4 insertions(+), 23 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_vec4_gs_nir.cpp b/src/mesa/drivers/dri/i965/brw_vec4_gs_nir.cpp
index 6f66978..90aa54e 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4_gs_nir.cpp
+++ b/src/mesa/drivers/dri/i965/brw_vec4_gs_nir.cpp
@@ -73,6 +73,10 @@ vec4_gs_visitor::nir_emit_intrinsic(nir_intrinsic_instr *instr)
       src = src_reg(ATTR, BRW_VARYING_SLOT_COUNT * vertex->u[0] +
                           instr->const_index[0] + offset->u[0],
                     type);
+      /* gl_PointSize is passed in the .w component of the VUE header */
+      if (instr->const_index[0] == VARYING_SLOT_PSIZ)
+         src.swizzle = SWIZZLE_WWWW;
+
       dest = get_nir_dest(instr->dest, src.type);
       dest.writemask = brw_writemask_for_size(instr->num_components);
       emit(MOV(dest, src));
diff --git a/src/mesa/drivers/dri/i965/brw_vec4_gs_visitor.cpp b/src/mesa/drivers/dri/i965/brw_vec4_gs_visitor.cpp
index b13d36e..374b1a7 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4_gs_visitor.cpp
+++ b/src/mesa/drivers/dri/i965/brw_vec4_gs_visitor.cpp
@@ -182,29 +182,6 @@ vec4_gs_visitor::emit_prolog()
       }
    }
 
-   /* If the geometry shader uses the gl_PointSize input, we need to fix it up
-    * to account for the fact that the vertex shader stored it in the w
-    * component of VARYING_SLOT_PSIZ.
-    */
-   if (nir->info.inputs_read & VARYING_BIT_PSIZ) {
-      this->current_annotation = "swizzle gl_PointSize input";
-      for (int vertex = 0; vertex < (int)nir->info.gs.vertices_in; vertex++) {
-         dst_reg dst(ATTR,
-                     BRW_VARYING_SLOT_COUNT * vertex + VARYING_SLOT_PSIZ);
-         dst.type = BRW_REGISTER_TYPE_F;
-         src_reg src(dst);
-         dst.writemask = WRITEMASK_X;
-         src.swizzle = BRW_SWIZZLE_WWWW;
-         inst = emit(MOV(dst, src));
-
-         /* In dual instanced dispatch mode, dst has a width of 4, so we need
-          * to make sure the MOV happens regardless of which channels are
-          * enabled.
-          */
-         inst->force_writemask_all = true;
-      }
-   }
-
    this->current_annotation = NULL;
 }
 
-- 
2.7.0