anv/image: Add anv_layout_to_aux_usage()

This function supersedes layout_to_hiz_usage().

v2:
- Don't find the optimal buffer for layout transitions (Jason Ekstrand).
- Pass the devinfo instead of the gen (Jason Ekstrand)
- Update the function documentation.

Signed-off-by: Nanley Chery <nanley.g.chery@intel.com>
Reviewed-by: Jason Ekstrand <jason@jlekstrand.net>

src/intel/vulkan/anv_image.c

@@ -432,6 +432,140 @@ void anv_GetImageSubresourceLayout(
    }
 }
 
+/**
+ * This function determines the optimal buffer to use for device
+ * accesses given a VkImageLayout and other pieces of information needed to
+ * make that determination. This does not determine the optimal buffer to
+ * use during a resolve operation.
+ *
+ * NOTE: Some layouts do not support device access.
+ *
+ * @param devinfo The device information of the Intel GPU.
+ * @param image The image that may contain a collection of buffers.
+ * @param aspects The aspect(s) of the image to be accessed.
+ * @param layout The current layout of the image aspect(s).
+ *
+ * @return The primary buffer that should be used for the given layout.
+ */
+enum isl_aux_usage
+anv_layout_to_aux_usage(const struct gen_device_info * const devinfo,
+                        const struct anv_image * const image,
+                        const VkImageAspectFlags aspects,
+                        const VkImageLayout layout)
+{
+   /* Validate the inputs. */
+
+   /* The devinfo is needed as the optimal buffer varies across generations. */
+   assert(devinfo != NULL);
+
+   /* The layout of a NULL image is not properly defined. */
+   assert(image != NULL);
+
+   /* The aspects must be a subset of the image aspects. */
+   assert(aspects & image->aspects && aspects <= image->aspects);
+
+   /* Determine the optimal buffer. */
+
+   /* If there is no auxiliary surface allocated, we must use the one and only
+    * main buffer.
+    */
+   if (image->aux_surface.isl.size == 0)
+      return ISL_AUX_USAGE_NONE;
+
+   /* All images that use an auxiliary surface are required to be tiled. */
+   assert(image->tiling == VK_IMAGE_TILING_OPTIMAL);
+
+   /* On BDW+, when clearing the stencil aspect of a depth stencil image,
+    * the HiZ buffer allows us to record the clear with a relatively small
+    * number of packets. Prior to BDW, the HiZ buffer provides no known benefit
+    * to the stencil aspect.
+    */
+   if (devinfo->gen < 8 && aspects == VK_IMAGE_ASPECT_STENCIL_BIT)
+      return ISL_AUX_USAGE_NONE;
+
+   const bool has_depth = aspects & VK_IMAGE_ASPECT_DEPTH_BIT;
+   const bool color_aspect = aspects == VK_IMAGE_ASPECT_COLOR_BIT;
+
+   /* The following switch currently only handles depth stencil aspects.
+    * TODO: Handle the color aspect.
+    */
+   if (color_aspect)
+      return image->aux_usage;
+
+   switch (layout) {
+
+   /* Invalid Layouts */
+
+   /* According to the Vulkan Spec, the following layouts are valid only as
+    * initial layouts in a layout transition and don't support device access.
+    */
+   case VK_IMAGE_LAYOUT_UNDEFINED:
+   case VK_IMAGE_LAYOUT_PREINITIALIZED:
+   case VK_IMAGE_LAYOUT_RANGE_SIZE:
+   case VK_IMAGE_LAYOUT_MAX_ENUM:
+      unreachable("Invalid image layout for device access.");
+
+
+   /* Transfer Layouts
+    *
+    * This buffer could be a depth buffer used in a transfer operation. BLORP
+    * currently doesn't use HiZ for transfer operations so we must use the main
+    * buffer for this layout. TODO: Enable HiZ in BLORP.
+    */
+   case VK_IMAGE_LAYOUT_GENERAL:
+   case VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL:
+   case VK_IMAGE_LAYOUT_TRANSFER_SRC_OPTIMAL:
+      return ISL_AUX_USAGE_NONE;
+
+
+   /* Sampling Layouts */
+   case VK_IMAGE_LAYOUT_DEPTH_STENCIL_READ_ONLY_OPTIMAL:
+      assert(!color_aspect);
+      /* Fall-through */
+   case VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL:
+      if (has_depth && anv_can_sample_with_hiz(devinfo->gen, image->samples))
+         return ISL_AUX_USAGE_HIZ;
+      else
+         return ISL_AUX_USAGE_NONE;
+
+   case VK_IMAGE_LAYOUT_PRESENT_SRC_KHR:
+      assert(color_aspect);
+
+      /* On SKL+, the render buffer can be decompressed by the presentation
+       * engine. Support for this feature has not yet landed in the wider
+       * ecosystem. TODO: Update this code when support lands.
+       *
+       * From the BDW PRM, Vol 7, Render Target Resolve:
+       *
+       *    If the MCS is enabled on a non-multisampled render target, the
+       *    render target must be resolved before being used for other
+       *    purposes (display, texture, CPU lock) The clear value from
+       *    SURFACE_STATE is written into pixels in the render target
+       *    indicated as clear in the MCS.
+       *
+       * Pre-SKL, the render buffer must be resolved before being used for
+       * presentation. We can infer that the auxiliary buffer is not used.
+       */
+      return ISL_AUX_USAGE_NONE;
+
+
+   /* Rendering Layouts */
+   case VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL:
+      assert(color_aspect);
+      unreachable("Color images are not yet supported.");
+
+   case VK_IMAGE_LAYOUT_DEPTH_STENCIL_ATTACHMENT_OPTIMAL:
+      assert(!color_aspect);
+      return ISL_AUX_USAGE_HIZ;
+   }
+
+   /* If the layout isn't recognized in the exhaustive switch above, the
+    * VkImageLayout value is not defined in vulkan.h.
+    */
+   unreachable("layout is not a VkImageLayout enumeration member.");
+}
+
+
 static struct anv_state
 alloc_surface_state(struct anv_device *device)
 {

src/intel/vulkan/anv_private.h

@@ -1777,6 +1777,11 @@ anv_gen8_hiz_op_resolve(struct anv_cmd_buffer *cmd_buffer,
                         const struct anv_image *image,
                         enum blorp_hiz_op op);
 
+enum isl_aux_usage
+anv_layout_to_aux_usage(const struct gen_device_info * const devinfo,
+                        const struct anv_image *image,
+                        const VkImageAspectFlags aspects,
+                        const VkImageLayout layout);
 static inline uint32_t
 anv_get_layerCount(const struct anv_image *image,
                    const VkImageSubresourceRange *range)