Try to merge image mip levels

src/video_core/texture_cache/texture_cache.h

@@ -1357,6 +1357,8 @@ ImageId TextureCache<P>::JoinImages(const ImageInfo& info, GPUVAddr gpu_addr, VA
     join_bad_overlap_ids.clear();
     join_copies_to_do.clear();
     join_alias_indices.clear();
+    boost::container::small_vector<ImageId, 8> merge_mips;
+    ImageId merge_with_existing_id{};
     const bool this_is_linear = info.type == ImageType::Linear;
     const auto region_check = [&](ImageId overlap_id, ImageBase& overlap) {
         if (True(overlap.flags & ImageFlagBits::Remapped)) {
@@ -1397,6 +1399,12 @@ ImageId TextureCache<P>::JoinImages(const ImageInfo& info, GPUVAddr gpu_addr, VA
             join_right_aliased_ids.push_back(overlap_id);
             overlap.flags |= ImageFlagBits::Alias;
             join_copies_to_do.emplace_back(JoinCopy{true, overlap_id});
+        } else if (IsSubLevel(new_image_base, overlap)) {
+            if (new_image_base.info.resources.levels > overlap.info.resources.levels) {
+                merge_mips.push_back(overlap_id);
+            } else {
+                merge_with_existing_id = overlap_id;
+            }
         } else {
             join_bad_overlap_ids.push_back(overlap_id);
         }
@@ -1439,6 +1447,10 @@ ImageId TextureCache<P>::JoinImages(const ImageInfo& info, GPUVAddr gpu_addr, VA
         }
     }
 
+    if (merge_with_existing_id) {
+        return merge_with_existing_id;
+    }
+
     const ImageId new_image_id = slot_images.insert(runtime, new_info, gpu_addr, cpu_addr);
     Image& new_image = slot_images[new_image_id];
 
@@ -1467,6 +1479,32 @@ ImageId TextureCache<P>::JoinImages(const ImageInfo& info, GPUVAddr gpu_addr, VA
         ScaleDown(new_image);
     }
 
+    const auto& resolution = Settings::values.resolution_info;
+    const u32 up_scale = can_rescale ? resolution.up_scale : 1;
+    const u32 down_shift = can_rescale ? resolution.down_shift : 0;
+
+    for (auto overlap_id : merge_mips) {
+        auto& overlap = slot_images[overlap_id];
+        if (True(overlap.flags & ImageFlagBits::GpuModified)) {
+            new_image.flags |= ImageFlagBits::GpuModified;
+            new_image.modification_tick = overlap.modification_tick;
+
+            const SubresourceBase base = new_image.TryFindBase(overlap.gpu_addr).value();
+            auto copies =
+                MakeShrinkImageCopies(new_image.info, overlap.info, base, up_scale, down_shift);
+            if (new_image.info.num_samples != overlap.info.num_samples) {
+                runtime.CopyImageMSAA(new_image, overlap, std::move(copies));
+            } else {
+                runtime.CopyImage(new_image, overlap, std::move(copies));
+            }
+        }
+        if (True(overlap.flags & ImageFlagBits::Tracked)) {
+            UntrackImage(overlap, overlap_id);
+        }
+        UnregisterImage(overlap_id);
+        DeleteImage(overlap_id);
+    }
+
     std::ranges::sort(join_copies_to_do, [this](const JoinCopy& lhs, const JoinCopy& rhs) {
         const ImageBase& lhs_image = slot_images[lhs.id];
         const ImageBase& rhs_image = slot_images[rhs.id];
@@ -1523,10 +1561,7 @@ ImageId TextureCache<P>::JoinImages(const ImageInfo& info, GPUVAddr gpu_addr, VA
         }
         if (True(overlap.flags & ImageFlagBits::GpuModified)) {
             new_image.flags |= ImageFlagBits::GpuModified;
-            const auto& resolution = Settings::values.resolution_info;
             const SubresourceBase base = new_image.TryFindBase(overlap.gpu_addr).value();
-            const u32 up_scale = can_rescale ? resolution.up_scale : 1;
-            const u32 down_shift = can_rescale ? resolution.down_shift : 0;
             auto copies = MakeShrinkImageCopies(new_info, overlap.info, base, up_scale, down_shift);
             if (overlap.info.num_samples != new_image.info.num_samples) {
                 runtime.CopyImageMSAA(new_image, overlap, std::move(copies));

src/video_core/texture_cache/util.cpp

@@ -1234,6 +1234,33 @@ bool IsSubresource(const ImageInfo& candidate, const ImageBase& image, GPUVAddr
         .has_value();
 }
 
+bool IsSubLevel(const ImageBase& image, const ImageBase& overlap) {
+    const std::optional<SubresourceBase> base = image.TryFindBase(overlap.gpu_addr);
+    if (!base) {
+        return false;
+    }
+    if (!IsViewCompatible(image.info.format, overlap.info.format, false, true)) {
+        return false;
+    }
+    if (AdjustMipSize(image.info.size, base->level) != overlap.info.size) {
+        return false;
+    }
+
+    const auto level_info = MakeLevelInfo(image.info);
+    auto level_sizes = CalculateLevelSizes(level_info, image.info.resources.levels);
+    auto total_size{0};
+    auto level = base->level;
+    while (level) {
+        total_size += level_sizes[level - 1];
+        level--;
+    }
+
+    if (overlap.gpu_addr - total_size != image.gpu_addr) {
+        return false;
+    }
+    return true;
+}
+
 bool IsSubCopy(const ImageInfo& candidate, const ImageBase& image, GPUVAddr candidate_addr) {
     const std::optional<SubresourceBase> base = image.TryFindBase(candidate_addr);
     if (!base) {

src/video_core/texture_cache/util.h

@@ -111,6 +111,8 @@ void SwizzleImage(Tegra::MemoryManager& gpu_memory, GPUVAddr gpu_addr, const Ima
                                  GPUVAddr candidate_addr, RelaxedOptions options, bool broken_views,
                                  bool native_bgr);
 
+[[nodiscard]] bool IsSubLevel(const ImageBase& image, const ImageBase& overlap);
+
 [[nodiscard]] bool IsSubCopy(const ImageInfo& candidate, const ImageBase& image,
                              GPUVAddr candidate_addr);