v3d: skip tlb loads when emitting clears with a draw call

We skip loading the tile buffer from memory if the job has flagged
a clear (job->clears) for the buffer, however, this only tracks
clears emitted via the TLB. In some cases we may need to fallback
to clearing with a draw call, in which case we also want to skip
the load.

Reviewed-by: Jose Maria Casanova Crespo <jmcasanova@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/30205>

src/gallium/drivers/v3d/v3d_context.h

@@ -432,6 +432,11 @@ struct v3d_job {
          * first rendering.
          */
         uint32_t clear;
+        /* Bitmask of PIPE_CLEAR_* of buffers that were cleared using a draw
+         * call (not necessarily before the first rendering) instead of a TLB
+         * clear.
+         */
+        uint32_t clear_draw;
         /* Bitmask of PIPE_CLEAR_* of buffers that have been read by a draw
          * call without having been cleared first.
          */

src/gallium/drivers/v3d/v3dx_draw.c

@@ -1357,11 +1357,11 @@ v3d_draw_vbo(struct pipe_context *pctx, const struct pipe_draw_info *info,
                                 u_stream_outputs_for_vertices(info->mode, draws[0].count);
         }
 
+        uint32_t clear_mask = job->clear | job->clear_draw;
         if (v3d->zsa && job->zsbuf && v3d->zsa->base.depth_enabled) {
                 struct v3d_resource *rsc = v3d_resource(job->zsbuf->texture);
                 v3d_job_add_bo(job, rsc->bo);
-
+                job->load |= PIPE_CLEAR_DEPTH & ~clear_mask;
-                job->load |= PIPE_CLEAR_DEPTH & ~job->clear;
                 if (v3d->zsa->base.depth_writemask)
                         job->store |= PIPE_CLEAR_DEPTH;
                 rsc->initialized_buffers = PIPE_CLEAR_DEPTH;
@@ -1374,7 +1374,7 @@ v3d_draw_vbo(struct pipe_context *pctx, const struct pipe_draw_info *info,
 
                 v3d_job_add_bo(job, rsc->bo);
 
-                job->load |= PIPE_CLEAR_STENCIL & ~job->clear;
+                job->load |= PIPE_CLEAR_STENCIL & ~clear_mask;
                 if (v3d->zsa->base.stencil[0].writemask ||
                     v3d->zsa->base.stencil[1].writemask) {
                         job->store |= PIPE_CLEAR_STENCIL;
@@ -1390,7 +1390,7 @@ v3d_draw_vbo(struct pipe_context *pctx, const struct pipe_draw_info *info,
                         continue;
                 struct v3d_resource *rsc = v3d_resource(job->cbufs[i]->texture);
 
-                job->load |= bit & ~job->clear;
+                job->load |= bit & ~clear_mask;
                 if (v3d->blend->base.rt[blend_rt].colormask)
                         job->store |= bit;
                 v3d_job_add_bo(job, rsc->bo);
@@ -1619,10 +1619,18 @@ v3d_launch_grid(struct pipe_context *pctx, const struct pipe_grid_info *info)
  */
 static void
 v3d_draw_clear(struct v3d_context *v3d,
+               struct v3d_job *job,
                unsigned buffers,
                const union pipe_color_union *color,
                double depth, unsigned stencil)
 {
+        /* Flag we are clearing these buffers with a draw call so we can
+         * skip loads for them. Notice that if we had emitted any draw calls
+         * before this clear the loads will still happen, since those previous
+         * draw calls would have flagged them.
+         */
+        job->clear_draw |= buffers;
+
         v3d_blitter_save(v3d, false, true);
         util_blitter_clear(v3d->blitter,
                            v3d->framebuffer.width,
@@ -1770,7 +1778,7 @@ v3d_clear(struct pipe_context *pctx, unsigned buffers, const struct pipe_scissor
         if (!buffers || !v3d_render_condition_check(v3d))
                 return;
 
-        v3d_draw_clear(v3d, buffers, color, depth, stencil);
+        v3d_draw_clear(v3d, job, buffers, color, depth, stencil);
 }
 
 static void