/*
 * Copyright © 2015 Intel Corporation
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice (including the next
 * paragraph) shall be included in all copies or substantial portions of the
 * Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
 * IN THE SOFTWARE.
 */

#include <assert.h>
#include <stdbool.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>

#include "anv_private.h"

#include "vk_format_info.h"

/**
 * Exactly one bit must be set in \a aspect.
 */
static isl_surf_usage_flags_t
choose_isl_surf_usage(VkImageUsageFlags vk_usage,
                      VkImageAspectFlags aspect)
{
   isl_surf_usage_flags_t isl_usage = 0;

   /* FINISHME: Support aux surfaces */
   isl_usage |= ISL_SURF_USAGE_DISABLE_AUX_BIT;

   if (vk_usage & VK_IMAGE_USAGE_SAMPLED_BIT)
      isl_usage |= ISL_SURF_USAGE_TEXTURE_BIT;

   if (vk_usage & VK_IMAGE_USAGE_INPUT_ATTACHMENT_BIT)
      isl_usage |= ISL_SURF_USAGE_TEXTURE_BIT;

   if (vk_usage & VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT)
      isl_usage |= ISL_SURF_USAGE_RENDER_TARGET_BIT;

   if (vk_usage & VK_IMAGE_CREATE_CUBE_COMPATIBLE_BIT)
      isl_usage |= ISL_SURF_USAGE_CUBE_BIT;

   if (vk_usage & VK_IMAGE_USAGE_DEPTH_STENCIL_ATTACHMENT_BIT) {
      switch (aspect) {
      default:
         unreachable("bad VkImageAspect");
      case VK_IMAGE_ASPECT_DEPTH_BIT:
         isl_usage |= ISL_SURF_USAGE_DEPTH_BIT;
         break;
      case VK_IMAGE_ASPECT_STENCIL_BIT:
         isl_usage |= ISL_SURF_USAGE_STENCIL_BIT;
         break;
      }
   }

   if (vk_usage & VK_IMAGE_USAGE_TRANSFER_SRC_BIT) {
      /* Meta implements transfers by sampling from the source image. */
      isl_usage |= ISL_SURF_USAGE_TEXTURE_BIT;
   }

   if (vk_usage & VK_IMAGE_USAGE_TRANSFER_DST_BIT) {
      /* Meta implements transfers by rendering into the destination image. */
      isl_usage |= ISL_SURF_USAGE_RENDER_TARGET_BIT;
   }

   return isl_usage;
}

/**
 * Exactly one bit must be set in \a aspect.
 */
static struct anv_surface *
get_surface(struct anv_image *image, VkImageAspectFlags aspect)
{
   switch (aspect) {
   default:
      unreachable("bad VkImageAspect");
   case VK_IMAGE_ASPECT_COLOR_BIT:
      return &image->color_surface;
   case VK_IMAGE_ASPECT_DEPTH_BIT:
      return &image->depth_surface;
   case VK_IMAGE_ASPECT_STENCIL_BIT:
      return &image->stencil_surface;
   }
}

/**
 * Initialize the anv_image::*_surface selected by \a aspect. Then update the
 * image's memory requirements (that is, the image's size and alignment).
 *
 * Exactly one bit must be set in \a aspect.
 */
static VkResult
make_surface(const struct anv_device *dev,
             struct anv_image *image,
             const struct anv_image_create_info *anv_info,
             VkImageAspectFlags aspect)
{
   const VkImageCreateInfo *vk_info = anv_info->vk_info;
   bool ok UNUSED;

   static const enum isl_surf_dim vk_to_isl_surf_dim[] = {
      [VK_IMAGE_TYPE_1D] = ISL_SURF_DIM_1D,
      [VK_IMAGE_TYPE_2D] = ISL_SURF_DIM_2D,
      [VK_IMAGE_TYPE_3D] = ISL_SURF_DIM_3D,
   };

   isl_tiling_flags_t tiling_flags = anv_info->isl_tiling_flags;
   if (vk_info->tiling == VK_IMAGE_TILING_LINEAR)
      tiling_flags = ISL_TILING_LINEAR_BIT;

   struct anv_surface *anv_surf = get_surface(image, aspect);

   image->extent = anv_sanitize_image_extent(vk_info->imageType,
                                             vk_info->extent);

   ok = isl_surf_init(&dev->isl_dev, &anv_surf->isl,
      .dim = vk_to_isl_surf_dim[vk_info->imageType],
      .format = anv_get_isl_format(&dev->info, vk_info->format,
                                   aspect, vk_info->tiling),
      .width = image->extent.width,
      .height = image->extent.height,
      .depth = image->extent.depth,
      .levels = vk_info->mipLevels,
      .array_len = vk_info->arrayLayers,
      .samples = vk_info->samples,
      .min_alignment = 0,
      .min_pitch = anv_info->stride,
      .usage = choose_isl_surf_usage(image->usage, aspect),
      .tiling_flags = tiling_flags);

   /* isl_surf_init() will fail only if provided invalid input. Invalid input
    * is illegal in Vulkan.
    */
   assert(ok);

   anv_surf->offset = align_u32(image->size, anv_surf->isl.alignment);
   image->size = anv_surf->offset + anv_surf->isl.size;
   image->alignment = MAX(image->alignment, anv_surf->isl.alignment);

   return VK_SUCCESS;
}

/**
 * Parameter @a format is required and overrides VkImageCreateInfo::format.
 */
static VkImageUsageFlags
anv_image_get_full_usage(const VkImageCreateInfo *info,
                         VkImageAspectFlags aspects)
{
   VkImageUsageFlags usage = info->usage;

   if (info->samples > 1 &&
       (usage & VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT)) {
      /* Meta will resolve the image by binding it as a texture. */
      usage |= VK_IMAGE_USAGE_SAMPLED_BIT;
   }

   if (usage & VK_IMAGE_USAGE_TRANSFER_SRC_BIT) {
      /* Meta will transfer from the image by binding it as a texture. */
      usage |= VK_IMAGE_USAGE_SAMPLED_BIT;
   }

   if (usage & VK_IMAGE_USAGE_TRANSFER_DST_BIT) {
      /* For non-clear transfer operations, meta will transfer to the image by
       * binding it as a color attachment, even if the image format is not
       * a color format.
       */
      usage |= VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT;

      if (aspects & (VK_IMAGE_ASPECT_DEPTH_BIT | VK_IMAGE_ASPECT_STENCIL_BIT)) {
         /* vkCmdClearDepthStencilImage() only requires that
          * VK_IMAGE_USAGE_TRANSFER_SRC_BIT be set. In particular, it does
          * not require VK_IMAGE_USAGE_DEPTH_STENCIL_ATTACHMENT_BIT. Meta
          * clears the image, though, by binding it as a depthstencil
          * attachment.
          */
         usage |= VK_IMAGE_USAGE_DEPTH_STENCIL_ATTACHMENT_BIT;
      }
   }

   return usage;
}

VkResult
anv_image_create(VkDevice _device,
                 const struct anv_image_create_info *create_info,
                 const VkAllocationCallbacks* alloc,
                 VkImage *pImage)
{
   ANV_FROM_HANDLE(anv_device, device, _device);
   const VkImageCreateInfo *pCreateInfo = create_info->vk_info;
   struct anv_image *image = NULL;
   VkResult r;

   assert(pCreateInfo->sType == VK_STRUCTURE_TYPE_IMAGE_CREATE_INFO);

   anv_assert(pCreateInfo->mipLevels > 0);
   anv_assert(pCreateInfo->arrayLayers > 0);
   anv_assert(pCreateInfo->samples > 0);
   anv_assert(pCreateInfo->extent.width > 0);
   anv_assert(pCreateInfo->extent.height > 0);
   anv_assert(pCreateInfo->extent.depth > 0);

   image = anv_alloc2(&device->alloc, alloc, sizeof(*image), 8,
                      VK_SYSTEM_ALLOCATION_SCOPE_OBJECT);
   if (!image)
      return vk_error(VK_ERROR_OUT_OF_HOST_MEMORY);

   memset(image, 0, sizeof(*image));
   image->type = pCreateInfo->imageType;
   image->extent = pCreateInfo->extent;
   image->vk_format = pCreateInfo->format;
   image->aspects = vk_format_aspects(image->vk_format);
   image->levels = pCreateInfo->mipLevels;
   image->array_size = pCreateInfo->arrayLayers;
   image->samples = pCreateInfo->samples;
   image->usage = anv_image_get_full_usage(pCreateInfo, image->aspects);
   image->tiling = pCreateInfo->tiling;

   uint32_t b;
   for_each_bit(b, image->aspects) {
      r = make_surface(device, image, create_info, (1 << b));
      if (r != VK_SUCCESS)
         goto fail;
   }

   *pImage = anv_image_to_handle(image);

   return VK_SUCCESS;

fail:
   if (image)
      anv_free2(&device->alloc, alloc, image);

   return r;
}

VkResult
anv_CreateImage(VkDevice device,
                const VkImageCreateInfo *pCreateInfo,
                const VkAllocationCallbacks *pAllocator,
                VkImage *pImage)
{
   return anv_image_create(device,
      &(struct anv_image_create_info) {
         .vk_info = pCreateInfo,
         .isl_tiling_flags = ISL_TILING_ANY_MASK,
      },
      pAllocator,
      pImage);
}

void
anv_DestroyImage(VkDevice _device, VkImage _image,
                 const VkAllocationCallbacks *pAllocator)
{
   ANV_FROM_HANDLE(anv_device, device, _device);

   anv_free2(&device->alloc, pAllocator, anv_image_from_handle(_image));
}

static void
anv_surface_get_subresource_layout(struct anv_image *image,
                                   struct anv_surface *surface,
                                   const VkImageSubresource *subresource,
                                   VkSubresourceLayout *layout)
{
   /* If we are on a non-zero mip level or array slice, we need to
    * calculate a real offset.
    */
   anv_assert(subresource->mipLevel == 0);
   anv_assert(subresource->arrayLayer == 0);

   layout->offset = surface->offset;
   layout->rowPitch = surface->isl.row_pitch;
   layout->depthPitch = isl_surf_get_array_pitch(&surface->isl);
   layout->arrayPitch = isl_surf_get_array_pitch(&surface->isl);
   layout->size = surface->isl.size;
}

void anv_GetImageSubresourceLayout(
    VkDevice                                    device,
    VkImage                                     _image,
    const VkImageSubresource*                   pSubresource,
    VkSubresourceLayout*                        pLayout)
{
   ANV_FROM_HANDLE(anv_image, image, _image);

   assert(__builtin_popcount(pSubresource->aspectMask) == 1);

   switch (pSubresource->aspectMask) {
   case VK_IMAGE_ASPECT_COLOR_BIT:
      anv_surface_get_subresource_layout(image, &image->color_surface,
                                         pSubresource, pLayout);
      break;
   case VK_IMAGE_ASPECT_DEPTH_BIT:
      anv_surface_get_subresource_layout(image, &image->depth_surface,
                                         pSubresource, pLayout);
      break;
   case VK_IMAGE_ASPECT_STENCIL_BIT:
      anv_surface_get_subresource_layout(image, &image->stencil_surface,
                                         pSubresource, pLayout);
      break;
   default:
      assert(!"Invalid image aspect");
   }
}

static struct anv_state
alloc_surface_state(struct anv_device *device,
                    struct anv_cmd_buffer *cmd_buffer)
{
      if (cmd_buffer) {
         return anv_cmd_buffer_alloc_surface_state(cmd_buffer);
      } else {
         return anv_state_pool_alloc(&device->surface_state_pool, 64, 64);
      }
}

static enum isl_channel_select
remap_swizzle(VkComponentSwizzle swizzle, VkComponentSwizzle component,
              struct anv_format_swizzle format_swizzle)
{
   if (swizzle == VK_COMPONENT_SWIZZLE_IDENTITY)
      swizzle = component;

   switch (swizzle) {
   case VK_COMPONENT_SWIZZLE_ZERO:  return ISL_CHANNEL_SELECT_ZERO;
   case VK_COMPONENT_SWIZZLE_ONE:   return ISL_CHANNEL_SELECT_ONE;
   case VK_COMPONENT_SWIZZLE_R:     return format_swizzle.r;
   case VK_COMPONENT_SWIZZLE_G:     return format_swizzle.g;
   case VK_COMPONENT_SWIZZLE_B:     return format_swizzle.b;
   case VK_COMPONENT_SWIZZLE_A:     return format_swizzle.a;
   default:
      unreachable("Invalid swizzle");
   }
}

void
anv_image_view_init(struct anv_image_view *iview,
                    struct anv_device *device,
                    const VkImageViewCreateInfo* pCreateInfo,
                    struct anv_cmd_buffer *cmd_buffer,
                    VkImageUsageFlags usage_mask)
{
   ANV_FROM_HANDLE(anv_image, image, pCreateInfo->image);
   const VkImageSubresourceRange *range = &pCreateInfo->subresourceRange;

   assert(range->layerCount > 0);
   assert(range->baseMipLevel < image->levels);
   assert(image->usage & (VK_IMAGE_USAGE_SAMPLED_BIT |
                          VK_IMAGE_USAGE_STORAGE_BIT |
                          VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT |
                          VK_IMAGE_USAGE_DEPTH_STENCIL_ATTACHMENT_BIT));

   switch (image->type) {
   default:
      unreachable("bad VkImageType");
   case VK_IMAGE_TYPE_1D:
   case VK_IMAGE_TYPE_2D:
      assert(range->baseArrayLayer + anv_get_layerCount(image, range) - 1 <= image->array_size);
      break;
   case VK_IMAGE_TYPE_3D:
      assert(range->baseArrayLayer + anv_get_layerCount(image, range) - 1
             <= anv_minify(image->extent.depth, range->baseMipLevel));
      break;
   }

   struct anv_surface *surface =
      anv_image_get_surface_for_aspect_mask(image, range->aspectMask);

   iview->image = image;
   iview->bo = image->bo;
   iview->offset = image->offset + surface->offset;

   iview->aspect_mask = pCreateInfo->subresourceRange.aspectMask;
   iview->vk_format = pCreateInfo->format;

   struct anv_format format = anv_get_format(&device->info, pCreateInfo->format,
                                             range->aspectMask, image->tiling);

   iview->base_layer = range->baseArrayLayer;
   iview->base_mip = range->baseMipLevel;

   struct isl_view isl_view = {
      .format = format.isl_format,
      .base_level = range->baseMipLevel,
      .levels = anv_get_levelCount(image, range),
      .base_array_layer = range->baseArrayLayer,
      .array_len = anv_get_layerCount(image, range),
      .channel_select = {
         remap_swizzle(pCreateInfo->components.r,
                       VK_COMPONENT_SWIZZLE_R, format.swizzle),
         remap_swizzle(pCreateInfo->components.g,
                       VK_COMPONENT_SWIZZLE_G, format.swizzle),
         remap_swizzle(pCreateInfo->components.b,
                       VK_COMPONENT_SWIZZLE_B, format.swizzle),
         remap_swizzle(pCreateInfo->components.a,
                       VK_COMPONENT_SWIZZLE_A, format.swizzle),
      },
   };

   iview->extent = (VkExtent3D) {
      .width  = anv_minify(image->extent.width , range->baseMipLevel),
      .height = anv_minify(image->extent.height, range->baseMipLevel),
      .depth  = anv_minify(image->extent.depth , range->baseMipLevel),
   };

   isl_surf_usage_flags_t cube_usage;
   if (pCreateInfo->viewType == VK_IMAGE_VIEW_TYPE_CUBE ||
       pCreateInfo->viewType == VK_IMAGE_VIEW_TYPE_CUBE_ARRAY) {
      cube_usage = ISL_SURF_USAGE_CUBE_BIT;
   } else {
      cube_usage = 0;
   }

   if (image->usage & usage_mask & VK_IMAGE_USAGE_SAMPLED_BIT) {
      iview->sampler_surface_state = alloc_surface_state(device, cmd_buffer);

      isl_view.usage = cube_usage | ISL_SURF_USAGE_TEXTURE_BIT;
      isl_surf_fill_state(&device->isl_dev,
                          iview->sampler_surface_state.map,
                          .surf = &surface->isl,
                          .view = &isl_view,
                          .mocs = device->default_mocs);

      if (!device->info.has_llc)
         anv_state_clflush(iview->sampler_surface_state);
   } else {
      iview->sampler_surface_state.alloc_size = 0;
   }

   if (image->usage & usage_mask & VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT) {
      iview->color_rt_surface_state = alloc_surface_state(device, cmd_buffer);

      isl_view.usage = cube_usage | ISL_SURF_USAGE_RENDER_TARGET_BIT;
      isl_surf_fill_state(&device->isl_dev,
                          iview->color_rt_surface_state.map,
                          .surf = &surface->isl,
                          .view = &isl_view,
                          .mocs = device->default_mocs);

      if (!device->info.has_llc)
         anv_state_clflush(iview->color_rt_surface_state);
   } else {
      iview->color_rt_surface_state.alloc_size = 0;
   }

   /* NOTE: This one needs to go last since it may stomp isl_view.format */
   if (image->usage & usage_mask & VK_IMAGE_USAGE_STORAGE_BIT) {
      iview->storage_surface_state = alloc_surface_state(device, cmd_buffer);

      if (isl_has_matching_typed_storage_image_format(&device->info,
                                                      format.isl_format)) {
         isl_view.usage = cube_usage | ISL_SURF_USAGE_STORAGE_BIT;
         isl_view.format = isl_lower_storage_image_format(&device->info,
                                                          isl_view.format);
         isl_surf_fill_state(&device->isl_dev,
                             iview->storage_surface_state.map,
                             .surf = &surface->isl,
                             .view = &isl_view,
                             .mocs = device->default_mocs);
      } else {
         anv_fill_buffer_surface_state(device, iview->storage_surface_state,
                                       ISL_FORMAT_RAW,
                                       iview->offset,
                                       iview->bo->size - iview->offset, 1);
      }

      isl_surf_fill_image_param(&device->isl_dev,
                                &iview->storage_image_param,
                                &surface->isl, &isl_view);

      if (!device->info.has_llc)
         anv_state_clflush(iview->storage_surface_state);
   } else {
      iview->storage_surface_state.alloc_size = 0;
   }
}

VkResult
anv_CreateImageView(VkDevice _device,
                    const VkImageViewCreateInfo *pCreateInfo,
                    const VkAllocationCallbacks *pAllocator,
                    VkImageView *pView)
{
   ANV_FROM_HANDLE(anv_device, device, _device);
   struct anv_image_view *view;

   view = anv_alloc2(&device->alloc, pAllocator, sizeof(*view), 8,
                     VK_SYSTEM_ALLOCATION_SCOPE_OBJECT);
   if (view == NULL)
      return vk_error(VK_ERROR_OUT_OF_HOST_MEMORY);

   anv_image_view_init(view, device, pCreateInfo, NULL, ~0);

   *pView = anv_image_view_to_handle(view);

   return VK_SUCCESS;
}

void
anv_DestroyImageView(VkDevice _device, VkImageView _iview,
                     const VkAllocationCallbacks *pAllocator)
{
   ANV_FROM_HANDLE(anv_device, device, _device);
   ANV_FROM_HANDLE(anv_image_view, iview, _iview);

   if (iview->color_rt_surface_state.alloc_size > 0) {
      anv_state_pool_free(&device->surface_state_pool,
                          iview->color_rt_surface_state);
   }

   if (iview->sampler_surface_state.alloc_size > 0) {
      anv_state_pool_free(&device->surface_state_pool,
                          iview->sampler_surface_state);
   }

   if (iview->storage_surface_state.alloc_size > 0) {
      anv_state_pool_free(&device->surface_state_pool,
                          iview->storage_surface_state);
   }

   anv_free2(&device->alloc, pAllocator, iview);
}


void anv_buffer_view_init(struct anv_buffer_view *view,
                          struct anv_device *device,
                          const VkBufferViewCreateInfo* pCreateInfo,
                          struct anv_cmd_buffer *cmd_buffer)
{
   ANV_FROM_HANDLE(anv_buffer, buffer, pCreateInfo->buffer);

   /* TODO: Handle the format swizzle? */

   view->format = anv_get_isl_format(&device->info, pCreateInfo->format,
                                     VK_IMAGE_ASPECT_COLOR_BIT,
                                     VK_IMAGE_TILING_LINEAR);
   const uint32_t format_bs = isl_format_get_layout(view->format)->bs;
   view->bo = buffer->bo;
   view->offset = buffer->offset + pCreateInfo->offset;
   view->range = pCreateInfo->range == VK_WHOLE_SIZE ?
                 buffer->size - pCreateInfo->offset : pCreateInfo->range;
   view->range = align_down_npot_u32(view->range, format_bs);

   if (buffer->usage & VK_BUFFER_USAGE_UNIFORM_TEXEL_BUFFER_BIT) {
      view->surface_state = alloc_surface_state(device, cmd_buffer);

      anv_fill_buffer_surface_state(device, view->surface_state,
                                    view->format,
                                    view->offset, view->range, format_bs);
   } else {
      view->surface_state = (struct anv_state){ 0 };
   }

   if (buffer->usage & VK_BUFFER_USAGE_STORAGE_TEXEL_BUFFER_BIT) {
      view->storage_surface_state = alloc_surface_state(device, cmd_buffer);

      enum isl_format storage_format =
         isl_has_matching_typed_storage_image_format(&device->info,
                                                     view->format) ?
         isl_lower_storage_image_format(&device->info, view->format) :
         ISL_FORMAT_RAW;

      anv_fill_buffer_surface_state(device, view->storage_surface_state,
                                    storage_format,
                                    view->offset, view->range,
                                    (storage_format == ISL_FORMAT_RAW ? 1 :
                                     isl_format_get_layout(storage_format)->bs));

      isl_buffer_fill_image_param(&device->isl_dev,
                                  &view->storage_image_param,
                                  view->format, view->range);
   } else {
      view->storage_surface_state = (struct anv_state){ 0 };
   }
}

VkResult
anv_CreateBufferView(VkDevice _device,
                     const VkBufferViewCreateInfo *pCreateInfo,
                     const VkAllocationCallbacks *pAllocator,
                     VkBufferView *pView)
{
   ANV_FROM_HANDLE(anv_device, device, _device);
   struct anv_buffer_view *view;

   view = anv_alloc2(&device->alloc, pAllocator, sizeof(*view), 8,
                     VK_SYSTEM_ALLOCATION_SCOPE_OBJECT);
   if (!view)
      return vk_error(VK_ERROR_OUT_OF_HOST_MEMORY);

   anv_buffer_view_init(view, device, pCreateInfo, NULL);

   *pView = anv_buffer_view_to_handle(view);

   return VK_SUCCESS;
}

void
anv_DestroyBufferView(VkDevice _device, VkBufferView bufferView,
                      const VkAllocationCallbacks *pAllocator)
{
   ANV_FROM_HANDLE(anv_device, device, _device);
   ANV_FROM_HANDLE(anv_buffer_view, view, bufferView);

   if (view->surface_state.alloc_size > 0)
      anv_state_pool_free(&device->surface_state_pool,
                          view->surface_state);

   if (view->storage_surface_state.alloc_size > 0)
      anv_state_pool_free(&device->surface_state_pool,
                          view->storage_surface_state);

   anv_free2(&device->alloc, pAllocator, view);
}

struct anv_surface *
anv_image_get_surface_for_aspect_mask(struct anv_image *image, VkImageAspectFlags aspect_mask)
{
   switch (aspect_mask) {
   case VK_IMAGE_ASPECT_COLOR_BIT:
      /* Dragons will eat you.
       *
       * Meta attaches all destination surfaces as color render targets. Guess
       * what surface the Meta Dragons really want.
       */
      if (image->aspects & VK_IMAGE_ASPECT_DEPTH_BIT) {
         return &image->depth_surface;
      } else if (image->aspects & VK_IMAGE_ASPECT_STENCIL_BIT) {
         return &image->stencil_surface;
      } else {
         assert(image->aspects == VK_IMAGE_ASPECT_COLOR_BIT);
         return &image->color_surface;
      }
      break;
   case VK_IMAGE_ASPECT_DEPTH_BIT:
      assert(image->aspects & VK_IMAGE_ASPECT_DEPTH_BIT);
      return &image->depth_surface;
   case VK_IMAGE_ASPECT_STENCIL_BIT:
      assert(image->aspects & VK_IMAGE_ASPECT_STENCIL_BIT);
      return &image->stencil_surface;
   case VK_IMAGE_ASPECT_DEPTH_BIT | VK_IMAGE_ASPECT_STENCIL_BIT:
      /* FINISHME: The Vulkan spec (git a511ba2) requires support for
       * combined depth stencil formats. Specifically, it states:
       *
       *    At least one of ename:VK_FORMAT_D24_UNORM_S8_UINT or
       *    ename:VK_FORMAT_D32_SFLOAT_S8_UINT must be supported.
       *
       * Image views with both depth and stencil aspects are only valid for
       * render target attachments, in which case
       * cmd_buffer_emit_depth_stencil() will pick out both the depth and
       * stencil surfaces from the underlying surface.
       */
      if (image->aspects & VK_IMAGE_ASPECT_DEPTH_BIT) {
         return &image->depth_surface;
      } else {
         assert(image->aspects == VK_IMAGE_ASPECT_STENCIL_BIT);
         return &image->stencil_surface;
      }
    default:
       unreachable("image does not have aspect");
       return NULL;
   }
}
