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

[Kenneth Graunke]

Module: Mesa
Branch: master
Commit: 8fc5443a2b39aaa8292984f7225a2c7968d568ae
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=8fc5443a2b39aaa8292984f7225a2c7968d568ae

Author: Kenneth Graunke <kenneth at whitecape.org>
Date:   Mon Dec 19 11:21:27 2016 -0800

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

---

 src/mesa/drivers/dri/i965/gen8_draw_upload.c | 34 ++++++++++++++--------------
 1 file changed, 17 insertions(+), 17 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/gen8_draw_upload.c b/src/mesa/drivers/dri/i965/gen8_draw_upload.c
index 69ba8e9..3177f9a 100644
--- 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.
     */