i965: Don't bail on vertex element processing if we need draw params.

BaseVertex, BaseInstance, DrawID, and some edge flag conditions need
vertex buffer and elements structs.  We can't bail early in this case.

Gen4-7 already do this properly.  Gen8+ did not.

Thanks to Ilia Mirkin for helping track this down.

Cc: mesa-stable@lists.freedesktop.org
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=99144
Reported-by: Pierre-Eric Pelloux-Prayer <pelloux@gmail.com>
Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>

diff --git a/src/mesa/drivers/dri/i965/gen8_draw_upload.c b/src/mesa/drivers/dri/i965/gen8_draw_upload.c
index 69ba8e923e77284b04cd2459bd7dac1a5ef20649..3177f9a8c7fa43144e83df12e1a5e2feb150430c 100644 (file)
--- a/src/mesa/drivers/dri/i965/gen8_draw_upload.c
+++ b/src/mesa/drivers/dri/i965/gen8_draw_upload.c
@@ -110,6 +110,22 @@ gen8_emit_vertices(struct brw_context *brw)
       ADVANCE_BATCH();
    }
 
+   /* 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
+    * we're using draw parameters then we need an element for the those
+    * values.  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.
+    */
+   const bool needs_sgvs_element = (vs_prog_data->uses_basevertex ||
+                                    vs_prog_data->uses_baseinstance ||
+                                    ((vs_prog_data->uses_instanceid ||
+                                      vs_prog_data->uses_vertexid) &&
+                                     uses_edge_flag));
+   const unsigned nr_elements =
+      brw->vb.nr_enabled + needs_sgvs_element + vs_prog_data->uses_drawid;
+
    /* If the VS doesn't read any inputs (calculating vertex position from
     * a state variable for some reason, for example), emit a single pad
     * VERTEX_ELEMENT struct and bail.
@@ -117,7 +133,7 @@ gen8_emit_vertices(struct brw_context *brw)
     * The stale VB state stays in place, but they don't do anything unless
     * a VE loads from them.
     */
-   if (brw->vb.nr_enabled == 0) {
+   if (nr_elements == 0) {
       BEGIN_BATCH(3);
       OUT_BATCH((_3DSTATE_VERTEX_ELEMENTS << 16) | (3 - 2));
       OUT_BATCH((0 << GEN6_VE0_INDEX_SHIFT) |
@@ -172,22 +188,6 @@ gen8_emit_vertices(struct brw_context *brw)
       ADVANCE_BATCH();
    }
 
-   /* 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
-    * we're using draw parameters then we need an element for the those
-    * values.  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.
-    */
-   const bool needs_sgvs_element = (vs_prog_data->uses_basevertex ||
-                                    vs_prog_data->uses_baseinstance ||
-                                    ((vs_prog_data->uses_instanceid ||
-                                      vs_prog_data->uses_vertexid) &&
-                                     uses_edge_flag));
-   const unsigned nr_elements =
-      brw->vb.nr_enabled + needs_sgvs_element + vs_prog_data->uses_drawid;
-
    /* The hardware allows one more VERTEX_ELEMENTS than VERTEX_BUFFERS,
     * presumably for VertexID/InstanceID.
     */