gallium: better flush logic in draw module

This is the other half of Keith's draw/flush patch.

There are now 5 flush flags to control what's flushed (post-xform vertex
cache, prim cache, vbuf, etc).

The gears slow-down in this part of the patch was due to the cull stage not
getting invoked.  It was unconditional before, but is now gated by 'need_det'.
But it also needs to be gated by draw->rasterizer->cull_mode.  Gears uses
back-face culling.

1 files changed, 21 insertions, 11 deletions

diff --git a/src/mesa/pipe/draw/draw_validate.c b/src/mesa/pipe/draw/draw_validate.c
index a626fb1fba..86d5a5f814 100644
--- a/src/mesa/pipe/draw/draw_validate.c
+++ b/src/mesa/pipe/draw/draw_validate.c
@@ -43,6 +43,13 @@ static struct draw_stage *validate_pipeline( struct draw_stage *stage )
 {
    struct draw_context *draw = stage->draw;
    struct draw_stage *next = draw->pipeline.rasterize;
+   int need_det = 0;
+   int precalc_flat = 0;
+
+   /* Set the validate's next stage to the rasterize stage, so that it
+    * can be found later if needed for flushing.
+    */
+   stage->next = next;
 
    /*
     * NOTE: we build up the pipeline in end-to-start order.
@@ -61,29 +68,38 @@ static struct draw_stage *validate_pipeline( struct draw_stage *stage )
    if (draw->rasterizer->line_stipple_enable) {
       draw->pipeline.stipple->next = next;
       next = draw->pipeline.stipple;
+      precalc_flat = 1;		/* only needed for lines really */
    }
 
    if (draw->rasterizer->fill_cw != PIPE_POLYGON_MODE_FILL ||
        draw->rasterizer->fill_ccw != PIPE_POLYGON_MODE_FILL) {
       draw->pipeline.unfilled->next = next;
       next = draw->pipeline.unfilled;
+      precalc_flat = 1;		/* only needed for triangles really */
+      need_det = 1;
    }
 	 
    if (draw->rasterizer->offset_cw ||
        draw->rasterizer->offset_ccw) {
       draw->pipeline.offset->next = next;
       next = draw->pipeline.offset;
+      need_det = 1;
    }
 
    if (draw->rasterizer->light_twoside) {
       draw->pipeline.twoside->next = next;
       next = draw->pipeline.twoside;
+      need_det = 1;
    }
 
    /* Always run the cull stage as we calculate determinant there
-    * also.  Fix this..
+    * also.  
+    *
+    * This can actually be a win as culling out the triangles can lead
+    * to less work emitting vertices, smaller vertex buffers, etc.
+    * It's difficult to say whether this will be true in general.
     */
-   {
+   if (need_det || draw->rasterizer->cull_mode) {
       draw->pipeline.cull->next = next;
       next = draw->pipeline.cull;
    }
@@ -94,23 +110,18 @@ static struct draw_stage *validate_pipeline( struct draw_stage *stage )
    {
       draw->pipeline.clip->next = next;
       next = draw->pipeline.clip;
+      precalc_flat = 1;		/* XXX: FIX ME! Only needed for clipped prims */
    }
 
-   /* Do software flatshading prior to clipping.  XXX: should only do
-    * this for clipped primitives, ie it is a part of the clip
-    * routine.
-    */
-   if (draw->rasterizer->flatshade) {
+   if (draw->rasterizer->flatshade && precalc_flat) {
       draw->pipeline.flatshade->next = next;
       next = draw->pipeline.flatshade;
    }
-
+   
    draw->pipeline.first = next;
-   //BP draw->pipeline.first->begin( draw->pipeline.first );
    return next;
 }
 
-
 static void validate_tri( struct draw_stage *stage, 
 			  struct prim_header *header )
 {
@@ -162,7 +173,6 @@ struct draw_stage *draw_validate_stage( struct draw_context *draw )
    struct draw_stage *stage = CALLOC_STRUCT(draw_stage);
 
    stage->draw = draw;
-
    stage->next = NULL;
    stage->point = validate_point;
    stage->line = validate_line;