[dxvk] Implement read/write tracking in lifetime tracker

This way we will be able to more accurately determine how a
resource is going to be used by the GPU, and we can also cut
unnecessary atomic operations for non-resource objects.

src/dxvk/dxvk_cmdlist.h

@@ -147,7 +147,7 @@ namespace dxvk {
      * completed.
      */
     void trackResource(Rc<DxvkResource> rc) {
-      m_resources.trackResource(std::move(rc));
+      m_resources.trackResource<DxvkAccess::Write>(std::move(rc));
     }
     
     /**

src/dxvk/dxvk_lifetime.cpp

@@ -8,7 +8,7 @@ namespace dxvk {
   
   void DxvkLifetimeTracker::reset() {
     for (const auto& resource : m_resources)
-      resource->release();
+      resource.first->release(resource.second);
     m_resources.clear();
   }
   

src/dxvk/dxvk_lifetime.h

@@ -25,9 +25,10 @@ namespace dxvk {
      * \brief Adds a resource to track
      * \param [in] rc The resource to track
      */
+    template<DxvkAccess Access>
     void trackResource(Rc<DxvkResource>&& rc) {
-      rc->acquire();
-      m_resources.emplace_back(std::move(rc));
+      rc->acquire(Access);
+      m_resources.emplace_back(std::move(rc), Access);
     }
     
     /**
@@ -40,7 +41,7 @@ namespace dxvk {
     
   private:
     
-    std::vector<Rc<DxvkResource>> m_resources;
+    std::vector<std::pair<Rc<DxvkResource>, DxvkAccess>> m_resources;
     
   };
   

src/dxvk/dxvk_resource.h

@@ -7,6 +7,7 @@ namespace dxvk {
   enum class DxvkAccess {
     Read    = 0,
     Write   = 1,
+    None    = 2,
   };
   
   using DxvkAccessFlags = Flags<DxvkAccess>;
@@ -19,22 +20,63 @@ namespace dxvk {
    * is recorded, it will be marked as 'in use'.
    */
   class DxvkResource : public RcObject {
-    
+    constexpr static uint32_t UseCountIncrementW = 1 << 18;
+    constexpr static uint32_t UseCountIncrementR = 1;
+    constexpr static uint32_t UseCountMaskW      = ~(UseCountIncrementW - 1);
+    constexpr static uint32_t UseCountMaskR      = ~(UseCountIncrementR - 1);
   public:
     
     virtual ~DxvkResource();
     
-    bool isInUse() const {
-      return m_useCount.load() != 0;
+    /**
+     * \brief Checks whether resource is in use
+     * 
+     * Returns \c true if there are pending accesses to
+     * the resource by the GPU matching the given access
+     * type. Note that checking for reads will also return
+     * \c true if the resource is being written to.
+     * \param [in] access Access type to check for
+     * \returns \c true if the resource is in use
+     */
+    bool isInUse(DxvkAccess access = DxvkAccess::Read) const {
+      uint32_t mask = access == DxvkAccess::Write
+        ? UseCountMaskW
+        : UseCountMaskR;
+      return m_useCount.load() & mask;
     }
     
-    void acquire() { m_useCount += 1; }
-    void release() { m_useCount -= 1; }
+    /**
+     * \brief Acquires resource
+     * 
+     * Increments use count for the given access type.
+     * \param Access Resource access type
+     */
+    void acquire(DxvkAccess access) {
+      if (access != DxvkAccess::None)
+        m_useCount += getIncrement(access);
+    }
+
+    /**
+     * \brief Releases resource
+     * 
+     * Decrements use count for the given access type.
+     * \param Access Resource access type
+     */
+    void release(DxvkAccess access) {
+      if (access != DxvkAccess::None)
+        m_useCount -= getIncrement(access);
+    }
     
   private:
     
     std::atomic<uint32_t> m_useCount = { 0u };
-    
+
+    static constexpr uint32_t getIncrement(DxvkAccess access) {
+      return access == DxvkAccess::Write
+        ? UseCountIncrementW
+        : UseCountIncrementR;
+    }
+
   };
   
 }