v3d: avoid submit of supertile coordinates on jobs without rasterization

If all draw calls of a job were submitted with GL_RASTERIZER_DISCARD
enabled we can avoid all the rasterization by not submitting the
supertile coordinates in the CLE.

There is a performance improvement in scenarios where only running the
geometry stages is needed like using TF. Altought the load/stores were
already avoided. Before this patch, the FS was still being executed for
each tile.

It helps on manhattan benchmarks.

fps_avg  helped:  gl_manhattan.trace:   12.71 -> 13.16 (3.54%)
fps_avg  helped:  gl_manhattan31.trace:  7.86 ->  8.02 (2.03%)

total fps_avg in affected (through threshold) runs: 20.57 -> 21.18 (2.96%)

Reviewed-by: Iago Toral Quiroga <itoral@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/35739>

src/gallium/drivers/v3d/v3d_blit.c

@@ -405,7 +405,8 @@ v3d_tlb_blit_fast(struct pipe_context *pctx, struct pipe_blit_info *info)
         if (info->dst.box.x != 0 || info->dst.box.width != dst_width ||
             info->dst.box.y != 0 || info->dst.box.height != dst_height ||
             job->draw_min_x != 0 || job->draw_min_y != 0 ||
-            job->draw_max_x != dst_width || job->draw_max_y != dst_height) {
+            job->draw_max_x != dst_width || job->draw_max_y != dst_height ||
+            !job->does_rasterization) {
                 return;
         }
 
@@ -551,6 +552,7 @@ v3d_tlb_blit(struct pipe_context *pctx, struct pipe_blit_info *info)
         job->draw_max_x = info->dst.box.x + info->dst.box.width;
         job->draw_max_y = info->dst.box.y + info->dst.box.height;
         job->scissor.disabled = false;
+        job->does_rasterization = true;
 
         /* The simulator complains if we do a TLB load from a source with a
          * stride that is smaller than the destination's, so we program the

src/gallium/drivers/v3d/v3d_context.h

@@ -537,6 +537,12 @@ struct v3d_job {
          */
         bool early_zs_clear;
 
+        /**
+         * Tracks if at least one of the draws/clears submitted to the
+         * job was submitted with GL_RASTERIZER_DISCARD disabled.
+         */
+        bool does_rasterization;
+
         /**
          * Number of draw calls (not counting full buffer clears) queued in
          * the current job.

src/gallium/drivers/v3d/v3dx_draw.c

@@ -1062,6 +1062,7 @@ v3d_update_job_tlb_load_store(struct v3d_job *job) {
 
         if (v3d->rasterizer->base.rasterizer_discard)
                return;
+        job->does_rasterization = true;
 
         uint32_t no_load_mask =
                 job->clear_tlb | job->clear_draw | job->invalidated_load;
@@ -1798,6 +1799,12 @@ v3d_clear(struct pipe_context *pctx, unsigned buffers, const struct pipe_scissor
         struct v3d_context *v3d = v3d_context(pctx);
         struct v3d_job *job = v3d_get_job_for_fbo(v3d);
 
+        /* If the clear call reaches the drives implies that rasterizer
+         * discard is always disabled. The state tracker is already ignoring
+         * clear calls if rasterization discard is enabled.
+         */
+        job->does_rasterization = true;
+
         buffers &= ~v3d_tlb_clear(job, buffers, color, depth, stencil);
 
         if (!buffers || !v3d_render_condition_check(v3d))

src/gallium/drivers/v3d/v3dx_rcl.c

@@ -642,6 +642,14 @@ emit_render_layer(struct v3d_job *job, uint32_t layer)
 
         v3d_rcl_emit_generic_per_tile_list(job, layer);
 
+        /* If rasterization has been disabled for all the draws/clears of the
+         * job we can avoid the submission of the Supertile Coordinates.
+         * This disables the execution of the fragment shader for each of the
+         * tiles.
+         */
+        if (!job->does_rasterization)
+               return;
+
         /* XXX perf: We should expose GL_MESA_tile_raster_order to
          * improve X11 performance, but we should use Morton order
          * otherwise to improve cache locality.
@@ -678,10 +686,12 @@ v3dX(emit_rcl)(struct v3d_job *job)
         /* The RCL list should be empty. */
         assert(!job->rcl.bo);
         struct v3d_device_info *devinfo = &job->v3d->screen->devinfo;
-
-        v3d_cl_ensure_space_with_branch(&job->rcl, 200 +
-                                        MAX2(job->num_layers, 1) * 256 *
-                                        cl_packet_length(SUPERTILE_COORDINATES));
+        uint32_t cl_supertile_coordinates_size = 0;
+        if (job->does_rasterization) {
+                cl_supertile_coordinates_size = MAX2(job->num_layers, 1) *
+                        256 * cl_packet_length(SUPERTILE_COORDINATES);
+        }
+        v3d_cl_ensure_space_with_branch(&job->rcl, 200 + cl_supertile_coordinates_size);
         job->submit.rcl_start = job->rcl.bo->offset;
         v3d_job_add_bo(job, job->rcl.bo);