From 7936dd7386acfae8e2d7ae4886a4bb6692fd716a Mon Sep 17 00:00:00 2001
From: Vladislav Mikhalin <mikhalinvlad@gmail.com>
Date: Sun, 24 Nov 2024 12:55:30 +0300
Subject: [PATCH] track potentially dirty images and hash them

---
 src/video_core/texture_cache/image.h          |  6 +++--
 .../texture_cache/texture_cache.cpp           | 25 ++++++++++++++++++-
 2 files changed, 28 insertions(+), 3 deletions(-)

diff --git a/src/video_core/texture_cache/image.h b/src/video_core/texture_cache/image.h
index 8d84277d8..fdf536fd7 100644
--- a/src/video_core/texture_cache/image.h
+++ b/src/video_core/texture_cache/image.h
@@ -22,9 +22,10 @@ VK_DEFINE_HANDLE(VmaAllocator)
 namespace VideoCore {
 
 enum ImageFlagBits : u32 {
-    CpuDirty = 1 << 1, ///< Contents have been modified from the CPU
+    MaybeCpuDirty = 1 << 0, ///< The page this image is in was touched before the image address
+    CpuDirty = 1 << 1,      ///< Contents have been modified from the CPU
     GpuDirty = 1 << 2, ///< Contents have been modified from the GPU (valid data in buffer cache)
-    Dirty = CpuDirty | GpuDirty,
+    Dirty = CpuDirty | GpuDirty | MaybeCpuDirty,
     GpuModified = 1 << 3,    ///< Contents have been modified from the GPU
     Tracked = 1 << 4,        ///< Writes and reads are being hooked from the CPU
     Registered = 1 << 6,     ///< True when the image is registered
@@ -130,6 +131,7 @@ struct Image {
     std::vector<State> subresource_states{};
     boost::container::small_vector<u64, 14> mip_hashes{};
     u64 tick_accessed_last{0};
+    u64 hash{0};
 
     struct {
         union {
diff --git a/src/video_core/texture_cache/texture_cache.cpp b/src/video_core/texture_cache/texture_cache.cpp
index 81d1d6b7d..129c1af8c 100644
--- a/src/video_core/texture_cache/texture_cache.cpp
+++ b/src/video_core/texture_cache/texture_cache.cpp
@@ -47,7 +47,17 @@ void TextureCache::InvalidateMemory(VAddr addr, VAddr addr_aligned, size_t size)
     std::scoped_lock lock{mutex};
     ForEachImageInRegion(addr_aligned, size, [&](ImageId image_id, Image& image) {
         const auto image_end = image.info.guest_address + image.info.guest_size_bytes;
-        if (addr < image_end) {
+        const auto page_end = addr_aligned + size;
+        if (addr < image.info.guest_address) {
+            // This page access may or may not modify the image.
+            // We should not mark it as dirty now, if it really was modified,
+            // it will receive more invalidations on subsequent pages.
+            if (image_end < page_end) {
+                // Image ends on this page so it can not receive any more invalidations.
+                // We will check it's hash later to see if it really was modified.
+                image.flags |= ImageFlagBits::MaybeCpuDirty;
+            }
+        } else if (addr < image_end) {
             // Ensure image is reuploaded when accessed again.
             image.flags |= ImageFlagBits::CpuDirty;
         }
@@ -418,6 +428,19 @@ void TextureCache::RefreshImage(Image& image, Vulkan::Scheduler* custom_schedule
         return;
     }
 
+    if (True(image.flags & ImageFlagBits::MaybeCpuDirty) &&
+        False(image.flags & ImageFlagBits::CpuDirty)) {
+        // The image size should be less than page size to be considered MaybeCpuDirty
+        // So this calculation should be very uncommon and reasonably fast
+        ASSERT(image.info.guest_size_bytes <= 4_KB);
+        const u8* addr = std::bit_cast<u8*>(image.info.guest_address);
+        const u64 hash = XXH3_64bits(addr, image.info.guest_size_bytes);
+        if (image.hash == hash) {
+            return;
+        }
+        image.hash = hash;
+    }
+
     const auto& num_layers = image.info.resources.layers;
     const auto& num_mips = image.info.resources.levels;
     ASSERT(num_mips == image.info.mips_layout.size());