anv/cmd_buffer: consider multiview masks for tracking pending clear aspects

When multiview is active a subpass clear may only clear a subset of the
attachment layers. Other subpasses in the same render pass may also
clear too and we want to honor those clears as well, however, we need to
ensure that we only clear a layer once, on the first subpass that uses
a particular layer (view) of a given attachment.

This means that when we check if a subpass attachment needs to be cleared
we need to check if all the layers used by that subpass (as indicated by
its view_mask) have already been cleared in previous subpasses or not, in
which case, we must clear any pending layers used by the subpass, and only
those pending.

v2:
  - track pending clear views in the attachment state (Jason)
  - rebased on top of fast-clear rework.

v3:
  - rebased on top of subpass rework.

v4: rebased.

v5 (Caio):
 - Rebased.
 - Initialize pending clear views to only have bits set for layers
   that exist.
 - Reset pending clear views in one go rather one bit at a time.
 - Put "last subpass for this attachment" condition in a separate
   function to simplify the conditional that resets pending_clear_aspects.

Fixes:
dEQP-VK.multiview.readback_implicit_clear.*

Reviewed-by: Jason Ekstrand <[email protected]>

2 files changed, 96 insertions, 3 deletions

diff --git a/src/intel/vulkan/anv_private.h b/src/intel/vulkan/anv_private.h
index ee533581ab4..0e209e1769f 100644
--- a/src/intel/vulkan/anv_private.h
+++ b/src/intel/vulkan/anv_private.h
@@ -1724,6 +1724,14 @@ struct anv_attachment_state {
    VkClearValue                                 clear_value;
    bool                                         clear_color_is_zero_one;
    bool                                         clear_color_is_zero;
+
+   /* When multiview is active, attachments with a renderpass clear
+    * operation have their respective layers cleared on the first
+    * subpass that uses them, and only in that subpass. We keep track
+    * of this using a bitfield to indicate which layers of an attachment
+    * have not been cleared yet when multiview is active.
+    */
+   uint32_t                                     pending_clear_views;
 };
 
 /** State tracking for particular pipeline bind point
diff --git a/src/intel/vulkan/genX_cmd_buffer.c b/src/intel/vulkan/genX_cmd_buffer.c
index b5741fb8dc1..3c55cd964c6 100644
--- a/src/intel/vulkan/genX_cmd_buffer.c
+++ b/src/intel/vulkan/genX_cmd_buffer.c
@@ -1250,6 +1250,9 @@ genX(cmd_buffer_setup_attachments)(struct anv_cmd_buffer *cmd_buffer,
          anv_assert(iview->vk_format == att->format);
          anv_assert(iview->n_planes == 1);
 
+         const uint32_t num_layers = iview->planes[0].isl.array_len;
+         state->attachments[i].pending_clear_views = (1 << num_layers) - 1;
+
          union isl_color_value clear_color = { .u32 = { 0, } };
          if (att_aspects & VK_IMAGE_ASPECT_ANY_COLOR_BIT_ANV) {
             assert(att_aspects == VK_IMAGE_ASPECT_COLOR_BIT);
@@ -3414,6 +3417,42 @@ cmd_buffer_emit_depth_stencil(struct anv_cmd_buffer *cmd_buffer)
    cmd_buffer->state.hiz_enabled = info.hiz_usage == ISL_AUX_USAGE_HIZ;
 }
 
+/**
+ * This ANDs the view mask of the current subpass with the pending clear
+ * views in the attachment to get the mask of views active in the subpass
+ * that still need to be cleared.
+ */
+static inline uint32_t
+get_multiview_subpass_clear_mask(const struct anv_cmd_state *cmd_state,
+                                 const struct anv_attachment_state *att_state)
+{
+   return cmd_state->subpass->view_mask & att_state->pending_clear_views;
+}
+
+static inline bool
+do_first_layer_clear(const struct anv_cmd_state *cmd_state,
+                     const struct anv_attachment_state *att_state)
+{
+   if (!cmd_state->subpass->view_mask)
+      return true;
+
+   uint32_t pending_clear_mask =
+      get_multiview_subpass_clear_mask(cmd_state, att_state);
+
+   return pending_clear_mask & 1;
+}
+
+static inline bool
+current_subpass_is_last_for_attachment(const struct anv_cmd_state *cmd_state,
+                                       uint32_t att_idx)
+{
+   const uint32_t last_subpass_idx =
+      cmd_state->pass->attachments[att_idx].last_subpass_idx;
+   const struct anv_subpass *last_subpass =
+      &cmd_state->pass->subpasses[last_subpass_idx];
+   return last_subpass == cmd_state->subpass;
+}
+
 static void
 cmd_buffer_begin_subpass(struct anv_cmd_buffer *cmd_buffer,
                          uint32_t subpass_id)
@@ -3452,6 +3491,8 @@ cmd_buffer_begin_subpass(struct anv_cmd_buffer *cmd_buffer,
    VkRect2D render_area = cmd_buffer->state.render_area;
    struct anv_framebuffer *fb = cmd_buffer->state.framebuffer;
 
+   bool is_multiview = subpass->view_mask != 0;
+
    for (uint32_t i = 0; i < subpass->attachment_count; ++i) {
       const uint32_t a = subpass->attachments[i].attachment;
       if (a == VK_ATTACHMENT_UNUSED)
@@ -3519,7 +3560,8 @@ cmd_buffer_begin_subpass(struct anv_cmd_buffer *cmd_buffer,
          uint32_t base_clear_layer = iview->planes[0].isl.base_array_layer;
          uint32_t clear_layer_count = fb->layers;
 
-         if (att_state->fast_clear) {
+         if (att_state->fast_clear &&
+             do_first_layer_clear(cmd_state, att_state)) {
             /* 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);
@@ -3533,6 +3575,8 @@ cmd_buffer_begin_subpass(struct anv_cmd_buffer *cmd_buffer,
             }
             base_clear_layer++;
             clear_layer_count--;
+            if (is_multiview)
+               att_state->pending_clear_views &= ~1;
 
             genX(copy_fast_clear_dwords)(cmd_buffer, att_state->color.state,
                                          image, VK_IMAGE_ASPECT_COLOR_BIT,
@@ -3554,7 +3598,39 @@ cmd_buffer_begin_subpass(struct anv_cmd_buffer *cmd_buffer,
             }
          }
 
-         if (clear_layer_count > 0) {
+         /* From the VkFramebufferCreateInfo spec:
+          *
+          * "If the render pass uses multiview, then layers must be one and each
+          *  attachment requires a number of layers that is greater than the
+          *  maximum bit index set in the view mask in the subpasses in which it
+          *  is used."
+          *
+          * So if multiview is active we ignore the number of layers in the
+          * framebuffer and instead we honor the view mask from the subpass.
+          */
+         if (is_multiview) {
+            assert(image->n_planes == 1);
+            uint32_t pending_clear_mask =
+               get_multiview_subpass_clear_mask(cmd_state, att_state);
+
+            uint32_t layer_idx;
+            for_each_bit(layer_idx, pending_clear_mask) {
+               uint32_t layer =
+                  iview->planes[0].isl.base_array_layer + layer_idx;
+
+               anv_image_clear_color(cmd_buffer, image,
+                                     VK_IMAGE_ASPECT_COLOR_BIT,
+                                     att_state->aux_usage,
+                                     iview->planes[0].isl.format,
+                                     iview->planes[0].isl.swizzle,
+                                     iview->planes[0].isl.base_level,
+                                     layer, 1,
+                                     render_area,
+                                     vk_to_isl_color(att_state->clear_value.color));
+            }
+
+            att_state->pending_clear_views &= ~pending_clear_mask;
+         } else if (clear_layer_count > 0) {
             assert(image->n_planes == 1);
             anv_image_clear_color(cmd_buffer, image, VK_IMAGE_ASPECT_COLOR_BIT,
                                   att_state->aux_usage,
@@ -3656,7 +3732,16 @@ cmd_buffer_begin_subpass(struct anv_cmd_buffer *cmd_buffer,
          }
       }
 
-      att_state->pending_clear_aspects = 0;
+      /* If multiview is enabled, then we are only done clearing when we no
+       * longer have pending layers to clear, or when we have processed the
+       * last subpass that uses this attachment.
+       */
+      if (!is_multiview ||
+          att_state->pending_clear_views == 0 ||
+          current_subpass_is_last_for_attachment(cmd_state, a)) {
+         att_state->pending_clear_aspects = 0;
+      }
+
       att_state->pending_load_aspects = 0;
    }