[d3d11] Map default constant buffers to host memory

Improves performance in applications that use UpdateSubresources
to frequently update constant buffers, such as Unigine Heaven,
Unigine Valley and Homefront.

src/d3d11/d3d11_buffer.cpp

@@ -120,7 +120,23 @@ namespace dxvk {
     }
     
     return m_device->GetDXVKDevice()->createBuffer(
-      info, GetMemoryFlagsForUsage(pDesc->Usage));
+      info, GetMemoryFlags(pDesc));
+  }
+  
+  
+  VkMemoryPropertyFlags D3D11Buffer::GetMemoryFlags(
+    const D3D11_BUFFER_DESC* pDesc) const {
+    // Default constant buffers may get updated frequently with calls
+    // to D3D11DeviceContext::UpdateSubresource, so we'll map them to
+    // host memory in order to allow direct access to the buffer
+    if ((pDesc->Usage == D3D11_USAGE_DEFAULT)
+     && (pDesc->BindFlags & D3D11_BIND_CONSTANT_BUFFER)) {
+      return VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT
+           | VK_MEMORY_PROPERTY_HOST_COHERENT_BIT;
+    }
+    
+    // Use default memory flags for the intended use
+    return GetMemoryFlagsForUsage(pDesc->Usage);
   }
   
 }

src/d3d11/d3d11_buffer.h

@@ -59,6 +59,9 @@ namespace dxvk {
     Rc<DxvkBuffer> CreateBuffer(
       const D3D11_BUFFER_DESC* pDesc) const;
     
+    VkMemoryPropertyFlags GetMemoryFlags(
+      const D3D11_BUFFER_DESC* pDesc) const;
+    
   };
   
 }

src/d3d11/d3d11_context.cpp

@@ -213,7 +213,7 @@ namespace dxvk {
       const D3D11Buffer* resource = static_cast<D3D11Buffer*>(pResource);
       const Rc<DxvkBuffer> buffer = resource->GetBufferSlice().buffer();
       
-      if (buffer->mapPtr(0) == nullptr) {
+      if (!(buffer->memFlags() & VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT)) {
         Logger::err("D3D11: Cannot map a device-local buffer");
         return E_INVALIDARG;
       }
@@ -680,7 +680,14 @@ namespace dxvk {
         return;
       }
       
-      if (size != 0) {
+      if (size == 0)
+        return;
+      
+      if (((size == bufferSlice.length())
+       && (bufferSlice.memFlags() & VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT))) {
+        m_context->invalidateBuffer(bufferSlice.buffer());
+        std::memcpy(bufferSlice.mapPtr(0), pSrcData, size);
+      } else {
         m_context->updateBuffer(
           bufferSlice.buffer(),
           bufferSlice.offset() + offset,

src/dxvk/dxvk_buffer.h

@@ -102,6 +102,17 @@ namespace dxvk {
       return m_info;
     }
     
+    /**
+     * \brief Memory type flags
+     * 
+     * Use this to determine whether a
+     * buffer is mapped to host memory.
+     * \returns Vulkan memory flags
+     */
+    VkMemoryPropertyFlags memFlags() const {
+      return m_memFlags;
+    }
+    
     /**
      * \brief Buffer handle
      * \returns Buffer handle
@@ -260,6 +271,12 @@ namespace dxvk {
       return m_buffer->resource();
     }
     
+    VkMemoryPropertyFlags memFlags() const {
+      return m_buffer != nullptr
+        ? m_buffer->memFlags()
+        : 0;
+    }
+    
     VkBuffer handle() const {
       return m_buffer != nullptr
         ? m_buffer->handle()