[Mesa-dev] [PATCH 14/14] anv/cmd_buffer: Avoid unnecessary transitions before fast clears

[Jason Ekstrand]

Previously, we would always apply the layout transition at the beginning
of the subpass and then do the clear whether fast or slow.  This meant
that there were some cases, specifically when the initial layout is
VK_IMAGE_LAYOUT_UNDEFINED, where we would end up doing a fast-clear or
ambiguate followed immediately by a fast-clear.  This probably isn't
terribly expensive, but it is a waste that we can avoid easily enough
now that we're doing everything at the same time in begin_subpass.
---
 src/intel/vulkan/genX_cmd_buffer.c | 57 ++++++++++++++++++++++----------------
 1 file changed, 33 insertions(+), 24 deletions(-)

diff --git a/src/intel/vulkan/genX_cmd_buffer.c b/src/intel/vulkan/genX_cmd_buffer.c
index 2732ef3..819bd36 100644
--- a/src/intel/vulkan/genX_cmd_buffer.c
+++ b/src/intel/vulkan/genX_cmd_buffer.c
@@ -3326,39 +3326,25 @@ cmd_buffer_begin_subpass(struct anv_cmd_buffer *cmd_buffer,
          target_layout = subpass->attachments[i].layout;
       }
 
-      if (image->aspects & VK_IMAGE_ASPECT_ANY_COLOR_BIT_ANV) {
-         assert(image->aspects == VK_IMAGE_ASPECT_COLOR_BIT);
-         transition_color_buffer(cmd_buffer, image, VK_IMAGE_ASPECT_COLOR_BIT,
-                                 iview->planes[0].isl.base_level, 1,
-                                 iview->planes[0].isl.base_array_layer,
-                                 iview->planes[0].isl.array_len,
-                                 att_state->current_layout, target_layout);
-      } else if (image->aspects & VK_IMAGE_ASPECT_DEPTH_BIT) {
-         transition_depth_buffer(cmd_buffer, image,
-                                 att_state->current_layout, target_layout);
-         att_state->aux_usage =
-            anv_layout_to_aux_usage(&cmd_buffer->device->info, image,
-                                    VK_IMAGE_ASPECT_DEPTH_BIT, target_layout);
-      }
-      att_state->current_layout = target_layout;
+      uint32_t base_layer = iview->planes[0].isl.base_array_layer;
+      uint32_t layer_count = fb->layers;
 
-      if (att_state->pending_clear_aspects & VK_IMAGE_ASPECT_COLOR_BIT) {
-         assert(att_state->pending_clear_aspects == VK_IMAGE_ASPECT_COLOR_BIT);
-
-         /* Multi-planar images are not supported as attachments */
+      if (image->aspects & VK_IMAGE_ASPECT_ANY_COLOR_BIT_ANV) {
          assert(image->aspects == VK_IMAGE_ASPECT_COLOR_BIT);
-         assert(image->n_planes == 1);
-
-         uint32_t base_layer = iview->planes[0].isl.base_array_layer;
-         uint32_t layer_count = fb->layers;
 
-         if (att_state->fast_clear) {
+         if ((att_state->pending_clear_aspects & VK_IMAGE_ASPECT_COLOR_BIT) &&
+             att_state->fast_clear) {
             /* We only support fast-clears on the first layer */
             assert(iview->planes[0].isl.base_level == 0);
             assert(iview->planes[0].isl.base_array_layer == 0);
 
             anv_image_ccs_op(cmd_buffer, image, VK_IMAGE_ASPECT_COLOR_BIT,
                              0, 0, 1, ISL_AUX_OP_FAST_CLEAR, false);
+
+            /* Performing a fast clear takes care of all our transition needs
+             * for the first slice.  Increment the base layer and layer count
+             * so that later transitions and clears don't touch layer 0.
+             */
             base_layer++;
             layer_count--;
 
@@ -3383,6 +3369,29 @@ cmd_buffer_begin_subpass(struct anv_cmd_buffer *cmd_buffer,
          }
 
          if (layer_count > 0) {
+            transition_color_buffer(cmd_buffer, image,
+                                    VK_IMAGE_ASPECT_COLOR_BIT,
+                                    iview->planes[0].isl.base_level, 1,
+                                    base_layer, layer_count,
+                                    att_state->current_layout, target_layout);
+         }
+      } else if (image->aspects & VK_IMAGE_ASPECT_DEPTH_BIT) {
+         transition_depth_buffer(cmd_buffer, image,
+                                 att_state->current_layout, target_layout);
+         att_state->aux_usage =
+            anv_layout_to_aux_usage(&cmd_buffer->device->info, image,
+                                    VK_IMAGE_ASPECT_DEPTH_BIT, target_layout);
+      }
+      att_state->current_layout = target_layout;
+
+      if (att_state->pending_clear_aspects & VK_IMAGE_ASPECT_COLOR_BIT) {
+         assert(att_state->pending_clear_aspects == VK_IMAGE_ASPECT_COLOR_BIT);
+
+         /* Multi-planar images are not supported as attachments */
+         assert(image->aspects == VK_IMAGE_ASPECT_COLOR_BIT);
+         assert(image->n_planes == 1);
+
+         if (layer_count > 0) {
             assert(image->n_planes == 1);
             anv_image_clear_color(cmd_buffer, image, VK_IMAGE_ASPECT_COLOR_BIT,
                                   att_state->aux_usage,
-- 
2.5.0.400.gff86faf