iris: Rework iris_update_draw_parameters to be more efficient

This improves a couple of things:

1. We now only update anything if the shader actually cares.

   Previously, is_indexed_draw was causing us to flag dirty vertex
   buffers, elements, and SGVs every time the shader switched between
   indexed and non-indexed draws.  This is a very common situation,
   but we only need that information if the shader uses gl_BaseVertex.

   We were also flagging things when switching between indirect/direct
   draws as well, and now we only bother if it matters.

2. We upload new draw parameters only when necessary.

   When we detect that the draw parameters have changed, we upload a
   new copy, and use that.  Previously we were uploading it every time
   the vertex buffers were dirty (for possibly unrelated reasons) and
   the shader needed that info.  Tying these together also makes the
   code a bit easier to follow.

In Civilization VI's benchmark, this code was flagging dirty state
many times per frame (49 average, 16 median, 614 maximum).  Now it
occurs exactly once for the entire run.

3 files changed, 56 insertions, 40 deletions

diff --git a/src/gallium/drivers/iris/iris_context.h b/src/gallium/drivers/iris/iris_context.h
index ed814ee6824..970c5688e95 100644
--- a/src/gallium/drivers/iris/iris_context.h
+++ b/src/gallium/drivers/iris/iris_context.h
@@ -551,6 +551,13 @@ struct iris_context {
       } params;
 
       /**
+       * Are the above values the ones stored in the draw_params buffer?
+       * If so, we can compare them against new values to see if anything
+       * changed.  If not, we need to assume they changed.
+       */
+      bool params_valid;
+
+      /**
        * Resource and offset that stores draw_parameters from the indirect
        * buffer or to the buffer that stures the previous values for non
        * indirect draws.
@@ -577,8 +584,6 @@ struct iris_context {
        * drawid and is_indexed_draw. They will go in their own vertex element.
        */
       struct iris_state_ref derived_draw_params;
-
-      bool is_indirect;
    } draw;
 
    struct {
diff --git a/src/gallium/drivers/iris/iris_draw.c b/src/gallium/drivers/iris/iris_draw.c
index 005da3f7a6d..9cdf1a2dd0e 100644
--- a/src/gallium/drivers/iris/iris_draw.c
+++ b/src/gallium/drivers/iris/iris_draw.c
@@ -113,35 +113,56 @@ static void
 iris_update_draw_parameters(struct iris_context *ice,
                             const struct pipe_draw_info *info)
 {
-   if (info->indirect) {
-      pipe_resource_reference(&ice->draw.draw_params.res,
-                              info->indirect->buffer);
-      ice->draw.draw_params.offset = info->indirect->offset +
-                                     (info->index_size ? 12 : 8);
-      ice->draw.params.firstvertex = 0;
-      ice->draw.params.baseinstance = 0;
-      ice->state.dirty |= IRIS_DIRTY_VERTEX_BUFFERS |
-                          IRIS_DIRTY_VERTEX_ELEMENTS |
-                          IRIS_DIRTY_VF_SGVS;
-   } else if (ice->draw.is_indirect ||
-              ice->draw.params.firstvertex !=
-              (info->index_size ? info->index_bias : info->start) ||
-              (ice->draw.params.baseinstance != info->start_instance)) {
-      pipe_resource_reference(&ice->draw.draw_params.res, NULL);
-      ice->draw.draw_params.offset = 0;
-      ice->draw.params.firstvertex =
-         info->index_size ? info->index_bias : info->start;
-      ice->draw.params.baseinstance = info->start_instance;
-      ice->state.dirty |= IRIS_DIRTY_VERTEX_BUFFERS |
-                          IRIS_DIRTY_VERTEX_ELEMENTS |
-                          IRIS_DIRTY_VF_SGVS;
+   bool changed = false;
+
+   if (ice->state.vs_uses_draw_params) {
+      struct iris_state_ref *draw_params = &ice->draw.draw_params;
+
+      if (info->indirect) {
+         pipe_resource_reference(&draw_params->res, info->indirect->buffer);
+         draw_params->offset =
+            info->indirect->offset + (info->index_size ? 12 : 8);
+
+         changed = true;
+         ice->draw.params_valid = false;
+      } else {
+         int firstvertex = info->index_size ? info->index_bias : info->start;
+
+         if (!ice->draw.params_valid ||
+             ice->draw.params.firstvertex != firstvertex ||
+             ice->draw.params.baseinstance != info->start_instance) {
+
+            changed = true;
+            ice->draw.params.firstvertex = firstvertex;
+            ice->draw.params.baseinstance = info->start_instance;
+            ice->draw.params_valid = true;
+
+            u_upload_data(ice->ctx.stream_uploader, 0,
+                          sizeof(ice->draw.params), 4, &ice->draw.params,
+                          &draw_params->offset, &draw_params->res);
+         }
+      }
+   }
+
+   if (ice->state.vs_uses_derived_draw_params) {
+      struct iris_state_ref *derived_params = &ice->draw.derived_draw_params;
+      int is_indexed_draw = info->index_size ? -1 : 0;
+
+      if (ice->draw.derived_params.drawid != info->drawid ||
+          ice->draw.derived_params.is_indexed_draw != is_indexed_draw) {
+
+         changed = true;
+         ice->draw.derived_params.drawid = info->drawid;
+         ice->draw.derived_params.is_indexed_draw = is_indexed_draw;
+
+         u_upload_data(ice->ctx.stream_uploader, 0,
+                       sizeof(ice->draw.derived_params), 4,
+                       &ice->draw.derived_params,
+                       &derived_params->offset, &derived_params->res);
+      }
    }
-   ice->draw.is_indirect = info->indirect;
 
-   if (ice->draw.derived_params.drawid != info->drawid ||
-       ice->draw.derived_params.is_indexed_draw != (info->index_size ? ~0 : 0)) {
-      ice->draw.derived_params.drawid = info->drawid;
-      ice->draw.derived_params.is_indexed_draw = info->index_size ? ~0 : 0;
+   if (changed) {
       ice->state.dirty |= IRIS_DIRTY_VERTEX_BUFFERS |
                           IRIS_DIRTY_VERTEX_ELEMENTS |
                           IRIS_DIRTY_VF_SGVS;
diff --git a/src/gallium/drivers/iris/iris_state.c b/src/gallium/drivers/iris/iris_state.c
index 609115bce60..370dc52df38 100644
--- a/src/gallium/drivers/iris/iris_state.c
+++ b/src/gallium/drivers/iris/iris_state.c
@@ -5293,11 +5293,6 @@ iris_upload_dirty_render_state(struct iris_context *ice,
       int dynamic_bound = ice->state.bound_vertex_buffers;
 
       if (ice->state.vs_uses_draw_params) {
-         if (ice->draw.draw_params.offset == 0) {
-            u_upload_data(ice->ctx.stream_uploader, 0, sizeof(ice->draw.params),
-                          4, &ice->draw.params, &ice->draw.draw_params.offset,
-                          &ice->draw.draw_params.res);
-         }
          assert(ice->draw.draw_params.res);
 
          struct iris_vertex_buffer_state *state =
@@ -5320,12 +5315,6 @@ iris_upload_dirty_render_state(struct iris_context *ice,
       }
 
       if (ice->state.vs_uses_derived_draw_params) {
-         u_upload_data(ice->ctx.stream_uploader, 0,
-                       sizeof(ice->draw.derived_params), 4,
-                       &ice->draw.derived_params,
-                       &ice->draw.derived_draw_params.offset,
-                       &ice->draw.derived_draw_params.res);
-
          struct iris_vertex_buffer_state *state =
             &(ice->state.genx->vertex_buffers[count]);
          pipe_resource_reference(&state->resource,
@@ -6983,6 +6972,7 @@ genX(init_state)(struct iris_context *ice)
    ice->state.num_viewports = 1;
    ice->state.prim_mode = PIPE_PRIM_MAX;
    ice->state.genx = calloc(1, sizeof(struct iris_genx_state));
+   ice->draw.derived_params.drawid = -1;
 
    /* Make a 1x1x1 null surface for unbound textures */
    void *null_surf_map =