gpu: keep reused smaller image tables resident and drop them a frame after their last draw

src/graphics/host_gpu/renderer/pipeline/imageHeap.cpp

@@ -20,7 +20,7 @@ namespace {
 
 namespace IR = ShaderRecompiler::IR;
 
-// Smaller tables are cheap to materialize on each draw and are often transient.
+// Smaller tables are often written for one draw, so they enter on a second draw of a frame.
 constexpr uint64_t MinTableBytes = 64ull * 1024ull;
 constexpr uint32_t ElementMask   = (1u << IR::ImageHeapKindShift) - 1u;
 
@@ -133,12 +133,16 @@ ImageHeap::~ImageHeap() {
 bool ImageHeap::Acquire(const IR::ImageHeapRequest& request, IR::ImageHeapView& result) {
 	KYTY_PROFILER_FUNCTION();
 	const auto size = request.size & ~uint64_t {3};
-	if (size < MinTableBytes || request.count == 0u || request.step == 0u ||
+	if (request.count == 0u || request.step == 0u ||
 	    ((request.base | request.first | request.step) & 3u) != 0u) {
 		return false;
 	}
 	auto memory = std::ranges::find_if(
 	    m_memories, [&](const auto& candidate) { return candidate->base == request.base; });
+	if (memory == m_memories.end() && size < MinTableBytes &&
+	    m_sightings.try_emplace(request.base, m_draw).first->second == m_draw) {
+		return false;
+	}
 	// A table follows its descriptor's size, as the first program of a draw acquires it.
 	if (memory == m_memories.end() || ((*memory)->size != size && (*memory)->draw != m_draw)) {
 		if (!m_context.IsMapped(request.base, size)) return false;
@@ -593,14 +597,32 @@ void ImageHeap::UnmapMemory(uint64_t address, uint64_t size) {
 	} else {
 		m_unmapped.push_back({address, size});
 	}
-	auto&           scheduler = m_context.GetCommandScheduler();
 	std::scoped_lock lock {m_mutex};
 	std::erase_if(m_memories, [&](const std::unique_ptr<Memory>& memory) {
 		if (address >= memory->base + memory->size || memory->base >= address + size) {
 			return false;
 		}
-		Unwatch(*memory);
+		Drop(*memory);
-		for (auto& view: memory->views) {
+		return true;
+	});
+}
+
+void ImageHeap::RunGarbageCollector() {
+	// A smaller table rebuilt each frame moves to a new base. Larger ones keep their dead words.
+	std::scoped_lock lock {m_mutex};
+	std::erase_if(m_memories, [&](const std::unique_ptr<Memory>& memory) {
+		if (memory->size >= MinTableBytes || memory->draw > m_suspend_draw) return false;
+		Drop(*memory);
+		return true;
+	});
+	m_suspend_draw = m_draw;
+	m_sightings.clear();
+}
+
+void ImageHeap::Drop(Memory& memory) {
+	auto& scheduler = m_context.GetCommandScheduler();
+	Unwatch(memory);
+	for (auto& view: memory.views) {
 		std::erase(m_active, view.get());
 		for (const auto& [value, index]: view->elements) {
 			Unreference(m_elements[index]);
@@ -611,8 +633,6 @@ void ImageHeap::UnmapMemory(uint64_t address, uint64_t size) {
 			scheduler.DeferOperation([buffer = std::move(view->buffer)] {});
 		}
 	}
-		return true;
-	});
 }
 
 } // namespace Libs::Graphics

src/graphics/host_gpu/renderer/pipeline/imageHeap.h

@@ -26,7 +26,7 @@ struct ImageHeapTestAccess;
 // of a table owns device slot words, one per table dword, that select an array element. CPU
 // writes to a table fault in its snapshot, which each draw refreshes once; a view takes the
 // changes when a draw first acquires it. Changes to the images behind elements bump
-// Image::heap_epoch.
+// Image::heap_epoch. A smaller table leaves at a suspend point if the frame did not acquire it.
 class ImageHeap final: public ShaderRecompiler::IR::ImageHeapSource {
 public:
 	ImageHeap(RenderContext& context, PageManager& page_manager);
@@ -47,6 +47,8 @@ public:
 	// CPU write fault, on any thread.
 	void InvalidateMemory(uint64_t address, uint64_t size);
 	void UnmapMemory(uint64_t address, uint64_t size);
+	// At a suspend point.
+	void RunGarbageCollector();
 
 private:
 	using DescriptorValue = ShaderRecompiler::IR::DescriptorValue;
@@ -107,6 +109,7 @@ private:
 	template <bool track>
 	void     Watch(const Memory& memory, size_t begin, size_t end);
 	void     Unwatch(const Memory& memory);
+	void     Drop(Memory& memory);
 	void     UpdateProbes(View& view, uint64_t begin, uint64_t end);
 	void     UpdateProbe(View& view, uint64_t probe);
 	void     Assign(View& view, size_t slot, uint32_t entry);
@@ -126,8 +129,10 @@ private:
 	std::vector<std::unique_ptr<Memory>> m_memories;
 	std::vector<View*>                   m_active; // Acquired since the last commit.
 	uint64_t                             m_draw         = 1;
+	uint64_t                             m_suspend_draw = 0; // m_draw at the last suspend point.
 	std::vector<Element>                 m_elements;
 	std::vector<uint32_t>                m_free;
+	std::unordered_map<uint64_t, uint64_t>    m_sightings; // Smaller tables: base, first draw.
 	std::deque<std::pair<uint64_t, uint32_t>> m_retired; // Tick, element.
 	std::vector<std::pair<size_t, size_t>>    m_runs;
 	std::vector<uint32_t>                     m_scratch;

src/graphics/host_gpu/renderer/renderContext.cpp

@@ -147,6 +147,7 @@ void RenderContext::RunGarbageCollector() {
 		m_fault_process_pending = false;
 		m_buffer_cache.ProcessFaultBuffer();
 	}
+	m_image_heap.RunGarbageCollector();
 	m_texture_cache.ProcessDownloadImages();
 	m_texture_cache.RunGarbageCollector();
 	m_buffer_cache.RunGarbageCollector();

tests/ShaderRecompilerComputeTests.cpp

@@ -5684,6 +5684,25 @@ public:
               ImageHeapTestAccess::MemoryCount(heap) == 0u &&
                   textures.GetImage(resident).heap_refs.load() == 0u,
               "unmapping the table kept its images pinned");
+      // A smaller table enters once a second draw acquires it and leaves at the suspend point
+      // after a frame that did not acquire it. Larger tables stay.
+      const IR::ImageHeapRequest small{table, table_size / 2u, 32u, 0u, table_size / 64u, &sampled};
+      Require(name, "first small draw",
+              acquire(sampled, idle_table) && !heap.Acquire(small, view) &&
+                  !heap.Acquire(small, view),
+              "a smaller table entered on its first draw");
+      draw();
+      Require(name, "second small draw", heap.Acquire(small, view),
+              "a smaller table was declined on its second draw");
+      context.RunGarbageCollector();
+      Require(name, "acquired frame", ImageHeapTestAccess::MemoryCount(heap) == 2u,
+              "a table left at the suspend point of a frame that acquired it");
+      draw();
+      context.RunGarbageCollector();
+      Require(name, "idle frame",
+              ImageHeapTestAccess::MemoryCount(heap) == 1u &&
+                  textures.GetImage(resident).heap_refs.load() == 0u,
+              "a suspend point kept an idle smaller table pinned or dropped a larger one");
       // The idle table stays watched; destroying the heap must unwatch it before the page
       // manager fails on live watches.
       Require(name, "idle table",