video_core: preserve coherence across aliased images

CMakeLists.txt

@@ -1122,6 +1122,8 @@ set(VIDEO_CORE src/video_core/amdgpu/cb_db_extent.h
                src/video_core/renderer_vulkan/host_passes/fsr_pass.h
                src/video_core/renderer_vulkan/host_passes/pp_pass.cpp
                src/video_core/renderer_vulkan/host_passes/pp_pass.h
+               src/video_core/texture_cache/aliasing.cpp
+               src/video_core/texture_cache/aliasing.h
                src/video_core/texture_cache/blit_helper.cpp
                src/video_core/texture_cache/blit_helper.h
                src/video_core/texture_cache/host_compatibility.cpp

src/video_core/buffer_cache/buffer.cpp

@@ -160,6 +160,13 @@ void Buffer::Fill(u64 offset, u32 num_bytes, u32 value) {
     });
 }
 
+void Buffer::Invalidate(u64 offset, u64 size) {
+    ASSERT(offset + size <= size_bytes);
+    if (!is_coherent && usage == MemoryUsage::Download) {
+        vmaInvalidateAllocation(instance->GetAllocator(), buffer.allocation, offset, size);
+    }
+}
+
 constexpr u64 WATCHES_INITIAL_RESERVE = 0x4000;
 constexpr u64 WATCHES_RESERVE_CHUNK = 0x1000;
 

src/video_core/buffer_cache/buffer.h

@@ -150,6 +150,9 @@ class Buffer {
 
     void Fill(u64 offset, u32 num_bytes, u32 value);
 
+    /// Makes a completed download range visible to the CPU.
+    void Invalidate(u64 offset, u64 size);
+
 public:
     VAddr cpu_addr = 0;
     bool is_picked{};

src/video_core/texture_cache/aliasing.cpp

@@ -0,0 +1,49 @@
+// SPDX-FileCopyrightText: Copyright 2026 shadPS4 Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#include <algorithm>
+#include <optional>
+
+#include "video_core/texture_cache/aliasing.h"
+#include "video_core/texture_cache/host_compatibility.h"
+#include "video_core/texture_cache/image_info.h"
+#include "video_core/texture_cache/types.h"
+
+namespace VideoCore {
+
+std::optional<Extent3D> GetAliasCopyExtent(const ImageInfo& src, const ImageInfo& dst) {
+    const bool same_layout =
+        src.guest_address == dst.guest_address && src.num_bits == dst.num_bits &&
+        src.num_samples == dst.num_samples && !src.props.is_depth && !dst.props.is_depth &&
+        src.props.is_block == dst.props.is_block && src.props.is_pow2 == dst.props.is_pow2 &&
+        src.type == dst.type && src.pitch == dst.pitch && src.tile_mode == dst.tile_mode &&
+        src.array_mode == dst.array_mode && src.bank_swizzle == dst.bank_swizzle &&
+        src.alt_tile == dst.alt_tile;
+    if (!same_layout) {
+        return std::nullopt;
+    }
+
+    if (src.pixel_format == dst.pixel_format && src.resources.levels == 1 &&
+        dst.resources.levels == 1 && src.resources.layers >= dst.resources.layers &&
+        src.size.width >= dst.size.width && src.size.height >= dst.size.height &&
+        src.size.depth >= dst.size.depth) {
+        return dst.size;
+    }
+
+    const bool can_copy_intersection = !src.props.is_block && src.resources.levels == 1 &&
+                                       dst.resources.levels == 1 && src.resources.layers == 1 &&
+                                       dst.resources.layers == 1 && src.size.depth == 1 &&
+                                       dst.size.depth == 1 && src.size.width == dst.size.width &&
+                                       IsVulkanFormatCompatible(src.pixel_format, dst.pixel_format);
+    if (!can_copy_intersection) {
+        return std::nullopt;
+    }
+
+    return Extent3D{
+        .width = src.size.width,
+        .height = std::min(src.size.height, dst.size.height),
+        .depth = 1,
+    };
+}
+
+} // namespace VideoCore

src/video_core/texture_cache/aliasing.h

@@ -0,0 +1,17 @@
+// SPDX-FileCopyrightText: Copyright 2026 shadPS4 Emulator Project
+// SPDX-License-Identifier: GPL-2.0-or-later
+
+#pragma once
+
+#include <optional>
+
+#include "video_core/texture_cache/types.h"
+
+namespace VideoCore {
+
+struct ImageInfo;
+
+[[nodiscard]] std::optional<Extent3D> GetAliasCopyExtent(const ImageInfo& src,
+                                                         const ImageInfo& dst);
+
+} // namespace VideoCore

src/video_core/texture_cache/image.h

@@ -32,6 +32,7 @@ enum ImageFlagBits : u32 {
     GpuDirty = 1 << 2, ///< Contents have been modified from the GPU (valid data in buffer cache)
     Dirty = MaybeCpuDirty | CpuDirty | GpuDirty,
     GpuModified = 1 << 3, ///< Contents have been modified from the GPU
+    Aliased = 1 << 4,     ///< Image shares its guest storage with another compatible image
     Registered = 1 << 6,  ///< True when the image is registered
     Picked = 1 << 7,      ///< Temporary flag to mark the image as picked
 };
@@ -176,6 +177,7 @@ struct Image {
     BackingImage* backing{};
     boost::container::static_vector<u64, 16> mip_hashes{};
     u64 image_uid{};
+    u64 alias_generation{};
     u64 lru_id{};
     u64 tick_accessed_last{};
     u64 hash{};