i965: Swap the order of the vertex ID and edge flag attributes

The edge flag data on Gen6+ is passed through the fixed function hardware as
an extra attribute. According to the PRM it must be the last valid
VERTEX_ELEMENT structure. However if the vertex ID is also used then another
extra element is added to source the VID. This made it so the vertex ID is in
the wrong register in the vertex shader and the edge attribute is no longer in
the last element.

v2: Also implement for BDW+

v3 [by Ben]: Remove 10.5 tag. Too late.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=84677
Cc: <mesa-stable@lists.freedesktop.org>
Reviewed-by: Kristian Høgsberg <krh@bitplanet.net>
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Tested-by: Ben Widawsky <ben@bwidawsk.net>
Tested-by: Mark Janes <mark.a.janes@intel.com>

1 files changed, 42 insertions, 14 deletions

diff --git a/src/mesa/drivers/dri/i965/gen8_draw_upload.c b/src/mesa/drivers/dri/i965/gen8_draw_upload.c
index f7d9952..2bac5ff 100644
--- a/src/mesa/drivers/dri/i965/gen8_draw_upload.c
+++ b/src/mesa/drivers/dri/i965/gen8_draw_upload.c
@@ -40,16 +40,25 @@ gen8_emit_vertices(struct brw_context *brw)
 {
    struct gl_context *ctx = &brw->ctx;
    uint32_t mocs_wb = brw->gen >= 9 ? SKL_MOCS_WB : BDW_MOCS_WB;
+   bool uses_edge_flag;
 
    brw_prepare_vertices(brw);
    brw_prepare_shader_draw_parameters(brw);
 
+   uses_edge_flag = (ctx->Polygon.FrontMode != GL_FILL ||
+                     ctx->Polygon.BackMode != GL_FILL);
+
    if (brw->vs.prog_data->uses_vertexid || brw->vs.prog_data->uses_instanceid) {
       unsigned vue = brw->vb.nr_enabled;
 
-      WARN_ONCE(brw->vs.prog_data->inputs_read & VERT_BIT_EDGEFLAG,
-                "Using VID/IID with edgeflags, need to reorder the "
-                "vertex attributes");
+      /* The element for the edge flags must always be last, so we have to
+       * insert the SGVS before it in that case.
+       */
+      if (uses_edge_flag) {
+         assert(vue > 0);
+         vue--;
+      }
+
       WARN_ONCE(vue >= 33,
                 "Trying to insert VID/IID past 33rd vertex element, "
                 "need to reorder the vertex attrbutes.");
@@ -138,7 +147,18 @@ gen8_emit_vertices(struct brw_context *brw)
       ADVANCE_BATCH();
    }
 
-   unsigned nr_elements = brw->vb.nr_enabled + brw->vs.prog_data->uses_vertexid;
+   /* Normally we don't need an element for the SGVS attribute because the
+    * 3DSTATE_VF_SGVS instruction lets you store the generated attribute in an
+    * element that is past the list in 3DSTATE_VERTEX_ELEMENTS. However if the
+    * vertex ID is used then it needs an element for the base vertex buffer.
+    * Additionally if there is an edge flag element then the SGVS can't be
+    * inserted past that so we need a dummy element to ensure that the edge
+    * flag is the last one.
+    */
+   bool needs_sgvs_element = (brw->vs.prog_data->uses_vertexid ||
+                              (brw->vs.prog_data->uses_instanceid &&
+                               uses_edge_flag));
+   unsigned nr_elements = brw->vb.nr_enabled + needs_sgvs_element;
 
    /* The hardware allows one more VERTEX_ELEMENTS than VERTEX_BUFFERS,
     * presumably for VertexID/InstanceID.
@@ -192,6 +212,24 @@ gen8_emit_vertices(struct brw_context *brw)
                 (comp3 << BRW_VE1_COMPONENT_3_SHIFT));
    }
 
+   if (needs_sgvs_element) {
+      if (brw->vs.prog_data->uses_vertexid) {
+         OUT_BATCH(GEN6_VE0_VALID |
+                   brw->vb.nr_buffers << GEN6_VE0_INDEX_SHIFT |
+                   BRW_SURFACEFORMAT_R32_UINT << BRW_VE0_FORMAT_SHIFT);
+         OUT_BATCH((BRW_VE1_COMPONENT_STORE_SRC << BRW_VE1_COMPONENT_0_SHIFT) |
+                   (BRW_VE1_COMPONENT_STORE_0 << BRW_VE1_COMPONENT_1_SHIFT) |
+                   (BRW_VE1_COMPONENT_STORE_0 << BRW_VE1_COMPONENT_2_SHIFT) |
+                   (BRW_VE1_COMPONENT_STORE_0 << BRW_VE1_COMPONENT_3_SHIFT));
+      } else {
+         OUT_BATCH(GEN6_VE0_VALID);
+         OUT_BATCH((BRW_VE1_COMPONENT_STORE_0 << BRW_VE1_COMPONENT_0_SHIFT) |
+                   (BRW_VE1_COMPONENT_STORE_0 << BRW_VE1_COMPONENT_1_SHIFT) |
+                   (BRW_VE1_COMPONENT_STORE_0 << BRW_VE1_COMPONENT_2_SHIFT) |
+                   (BRW_VE1_COMPONENT_STORE_0 << BRW_VE1_COMPONENT_3_SHIFT));
+      }
+   }
+
    if (gen6_edgeflag_input) {
       uint32_t format =
          brw_get_vertex_surface_type(brw, gen6_edgeflag_input->glarray);
@@ -206,16 +244,6 @@ gen8_emit_vertices(struct brw_context *brw)
                 (BRW_VE1_COMPONENT_STORE_0 << BRW_VE1_COMPONENT_2_SHIFT) |
                 (BRW_VE1_COMPONENT_STORE_0 << BRW_VE1_COMPONENT_3_SHIFT));
    }
-
-   if (brw->vs.prog_data->uses_vertexid) {
-      OUT_BATCH(GEN6_VE0_VALID |
-                brw->vb.nr_buffers << GEN6_VE0_INDEX_SHIFT |
-                BRW_SURFACEFORMAT_R32_UINT << BRW_VE0_FORMAT_SHIFT);
-      OUT_BATCH((BRW_VE1_COMPONENT_STORE_SRC << BRW_VE1_COMPONENT_0_SHIFT) |
-                (BRW_VE1_COMPONENT_STORE_0 << BRW_VE1_COMPONENT_1_SHIFT) |
-                (BRW_VE1_COMPONENT_STORE_0 << BRW_VE1_COMPONENT_2_SHIFT) |
-                (BRW_VE1_COMPONENT_STORE_0 << BRW_VE1_COMPONENT_3_SHIFT));
-   }
    ADVANCE_BATCH();
 
    for (unsigned i = 0; i < brw->vb.nr_enabled; i++) {