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

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);
@@ -125,9 +128,11 @@ private:
 	std::mutex                           m_mutex; // Fault-visible Memory state and m_memories.
 	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_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;