Mesa (master): draw: fix no position output in non-llvm pipeline.

[Roland Scheidegger]

Module: Mesa
Branch: master
Commit: ea8b2ae8a50432a8dd51f144f4b981c592254de8
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=ea8b2ae8a50432a8dd51f144f4b981c592254de8

Author: Roland Scheidegger <sroland at vmware.com>
Date:   Sat Mar  2 02:49:28 2013 +0100

draw: fix no position output in non-llvm pipeline.

It seems easiest (and best) if we simply skip all the later stages
(after stream output).
(This is different to the llvm case at least for now where we will
simply try to render garbage, though both behaviors should be correct.)
Fixes piglit glsl-1.40-tf-no-position with softpipe.

Reviewed-by: Brian Paul <brianp at vmware.com>

---

 .../auxiliary/draw/draw_pt_fetch_shade_pipeline.c  |   38 ++++++++++----------
 1 files changed, 19 insertions(+), 19 deletions(-)

diff --git a/src/gallium/auxiliary/draw/draw_pt_fetch_shade_pipeline.c b/src/gallium/auxiliary/draw/draw_pt_fetch_shade_pipeline.c
index 2fc8220..45d964d 100644
--- a/src/gallium/auxiliary/draw/draw_pt_fetch_shade_pipeline.c
+++ b/src/gallium/auxiliary/draw/draw_pt_fetch_shade_pipeline.c
@@ -284,27 +284,27 @@ static void fetch_pipeline_generic( struct draw_pt_middle_end *middle,
     * XXX: Stream output surely needs to respect the prim_info->elt
     *      lists.
     */
-   draw_pt_so_emit( fpme->so_emit,
-                    vert_info,
-                    prim_info );
-
-   if (draw_pt_post_vs_run( fpme->post_vs,
-                            vert_info ))
-   {
-      opt |= PT_PIPELINE;
-   }
+   draw_pt_so_emit( fpme->so_emit, vert_info, prim_info );
 
-   /* Do we need to run the pipeline?
+   /*
+    * if there's no position, need to stop now, or the latter stages
+    * will try to access non-existent position output.
     */
-   if (opt & PT_PIPELINE) {
-      pipeline( fpme,
-                vert_info,
-                prim_info );
-   }
-   else {
-      emit( fpme->emit,
-            vert_info,
-            prim_info );
+   if (draw_current_shader_position_output(draw) != -1) {
+
+      if (draw_pt_post_vs_run( fpme->post_vs, vert_info ))
+      {
+         opt |= PT_PIPELINE;
+      }
+
+      /* Do we need to run the pipeline?
+       */
+      if (opt & PT_PIPELINE) {
+         pipeline( fpme, vert_info, prim_info );
+      }
+      else {
+         emit( fpme->emit, vert_info, prim_info );
+      }
    }
    FREE(vert_info->verts);
 }