[Mesa-dev] [PATCH v3 02/18] anv: Be more careful about fast-clear colors

[Jason Ekstrand]

Previously, we just used all the channels regardless of the format.
This is less than ideal because some channels may have undefined values
and this should be ok from the client's perspective.  Even though the
driver should do the correct thing regardless of what is in the
undefined value, it makes things less deterministic.  In particular, the
driver may choose to fast-clear or not based on undefined values.  This
level of nondeterminism is bad.

Cc: mesa-stable at lists.freedesktop.org
---
 src/intel/vulkan/genX_cmd_buffer.c | 46 ++++++++++++++++----------------------
 1 file changed, 19 insertions(+), 27 deletions(-)

diff --git a/src/intel/vulkan/genX_cmd_buffer.c b/src/intel/vulkan/genX_cmd_buffer.c
index ce47b8a..8b1816a 100644
--- a/src/intel/vulkan/genX_cmd_buffer.c
+++ b/src/intel/vulkan/genX_cmd_buffer.c
@@ -202,24 +202,6 @@ add_image_view_relocs(struct anv_cmd_buffer *cmd_buffer,
    }
 }
 
-static bool
-color_is_zero_one(VkClearColorValue value, enum isl_format format)
-{
-   if (isl_format_has_int_channel(format)) {
-      for (unsigned i = 0; i < 4; i++) {
-         if (value.int32[i] != 0 && value.int32[i] != 1)
-            return false;
-      }
-   } else {
-      for (unsigned i = 0; i < 4; i++) {
-         if (value.float32[i] != 0.0f && value.float32[i] != 1.0f)
-            return false;
-      }
-   }
-
-   return true;
-}
-
 static void
 color_attachment_compute_aux_usage(struct anv_device * device,
                                    struct anv_cmd_state * cmd_state,
@@ -283,13 +265,25 @@ color_attachment_compute_aux_usage(struct anv_device * device,
 
    assert(iview->image->planes[0].aux_surface.isl.usage & ISL_SURF_USAGE_CCS_BIT);
 
+   const struct isl_format_layout *view_fmtl =
+      isl_format_get_layout(iview->planes[0].isl.format);
+   union isl_color_value clear_color = {};
+
+#define COPY_CLEAR_COLOR_CHANNEL(c, i) \
+   if (view_fmtl->channels.c.bits) \
+      clear_color.u32[i] = att_state->clear_value.color.uint32[i]
+
+   COPY_CLEAR_COLOR_CHANNEL(r, 0);
+   COPY_CLEAR_COLOR_CHANNEL(g, 1);
+   COPY_CLEAR_COLOR_CHANNEL(b, 2);
+   COPY_CLEAR_COLOR_CHANNEL(a, 3);
+
+#undef COPY_CLEAR_COLOR_CHANNEL
+
    att_state->clear_color_is_zero_one =
-      color_is_zero_one(att_state->clear_value.color, iview->planes[0].isl.format);
+      isl_color_value_is_zero_one(clear_color, iview->planes[0].isl.format);
    att_state->clear_color_is_zero =
-      att_state->clear_value.color.uint32[0] == 0 &&
-      att_state->clear_value.color.uint32[1] == 0 &&
-      att_state->clear_value.color.uint32[2] == 0 &&
-      att_state->clear_value.color.uint32[3] == 0;
+      isl_color_value_is_zero(clear_color, iview->planes[0].isl.format);
 
    if (att_state->pending_clear_aspects == VK_IMAGE_ASPECT_COLOR_BIT) {
       /* Start off assuming fast clears are possible */
@@ -341,10 +335,8 @@ color_attachment_compute_aux_usage(struct anv_device * device,
                        "LOAD_OP_CLEAR.  Only fast-clearing the first slice");
       }
 
-      if (att_state->fast_clear) {
-         memcpy(fast_clear_color->u32, att_state->clear_value.color.uint32,
-                sizeof(fast_clear_color->u32));
-      }
+      if (att_state->fast_clear)
+         *fast_clear_color = clear_color;
    } else {
       att_state->fast_clear = false;
    }
-- 
2.5.0.400.gff86faf