Keep huge ASTC arrays from a lower mip on the host (title 1 terrain)

Title 1's terrain virtual textures are 8192x8192x68 ASTC 8x8 sRGB arrays with
12 levels: 1.5 GB in guest memory (fully backed) but 23 GB each as the RGBA8
Eden decodes ASTC to, so they were created unbacked and the near terrain
sampled black. A GPU-decoded ASTC 2D array over 1 GiB decoded now keeps only
the levels from the first one that fits in 512 MiB (here 3: 1024x1024, 380
MiB); host mip 0 is that guest level. Uploads read each layer's tail of the
mip chain into a compact buffer and decode only those levels, views shift
their level range, and these images are never downloaded. Normalized
coordinates and derivative LOD address the smaller image correctly; the
nearest terrain is lower resolution than on the console.

Also logs how unbacked images are used (views, render targets, blits, DMA).

1 files changed, 7 insertions, 0 deletions

diff --git a/src/video_core/texture_cache/util.cpp b/src/video_core/texture_cache/util.cpp
index 21070b2d25..aae2c7e4fd 100644
--- a/src/video_core/texture_cache/util.cpp
+++ b/src/video_core/texture_cache/util.cpp
@@ -1298,6 +1298,13 @@ void DeduceBlitImages(ImageInfo& dst_info, ImageInfo& src_info, const ImageBase*
 }
 
 u32 MapSizeBytes(const ImageBase& image) {
+    if (True(image.flags & ImageFlagBits::AcceleratedUpload) && image.host_level_offset != 0) {
+        // Each layer's mip chain from host_level_offset on (see UploadImageContents).
+        const auto uploads = FullUploadSwizzles(image.info);
+        const u32 tail = image.info.layer_stride -
+                         static_cast<u32>(uploads[image.host_level_offset].buffer_offset);
+        return tail * image.info.resources.layers;
+    }
     if (True(image.flags & ImageFlagBits::AcceleratedUpload)) {
         return image.guest_size_bytes;
     } else if (True(image.flags & ImageFlagBits::Converted)) {