[dxvk] Implement transform feedback

Begins transform feedback when rendering with an xfb-enabled
pipeline bound, and ends transform feedback as needed, while
writing back the counters supplied by the app. This does not
yet support transform feedback queries or the draw command.

src/dxvk/dxvk_buffer.h

@@ -273,7 +273,9 @@ namespace dxvk {
      * \returns The physical buffer slice
      */
     DxvkPhysicalBufferSlice physicalSlice() const {
-      return m_buffer->subSlice(m_offset, m_length);
+      return m_buffer != nullptr
+        ? m_buffer->subSlice(m_offset, m_length)
+        : DxvkPhysicalBufferSlice();
     }
 
     /**
@@ -301,7 +303,9 @@ namespace dxvk {
      * \returns Pointer into mapped buffer memory
      */
     void* mapPtr(VkDeviceSize offset) const  {
-      return m_buffer->mapPtr(m_offset + offset);
+      return m_buffer != nullptr
+        ? m_buffer->mapPtr(m_offset + offset)
+        : nullptr;
     }
     
     /**

src/dxvk/dxvk_buffer_res.h

@@ -134,7 +134,9 @@ namespace dxvk {
      * \returns Buffer handle
      */
     VkBuffer handle() const {
-      return m_buffer->handle();
+      return m_buffer != nullptr
+        ? m_buffer->handle()
+        : VK_NULL_HANDLE;
     }
     
     /**

src/dxvk/dxvk_context.cpp

@@ -36,6 +36,7 @@ namespace dxvk {
     // before any draw or dispatch command is recorded.
     m_flags.clr(
       DxvkContextFlag::GpRenderPassBound,
+      DxvkContextFlag::GpXfbActive,
       DxvkContextFlag::GpClearRenderTargets);
     
     m_flags.set(
@@ -44,6 +45,7 @@ namespace dxvk {
       DxvkContextFlag::GpDirtyResources,
       DxvkContextFlag::GpDirtyVertexBuffers,
       DxvkContextFlag::GpDirtyIndexBuffer,
+      DxvkContextFlag::GpDirtyXfbBuffers,
       DxvkContextFlag::CpDirtyPipeline,
       DxvkContextFlag::CpDirtyPipelineState,
       DxvkContextFlag::CpDirtyResources,
@@ -222,6 +224,8 @@ namespace dxvk {
           uint32_t              binding,
     const DxvkBufferSlice&      buffer,
     const DxvkBufferSlice&      counter) {
+    this->spillRenderPass();
+
     m_state.xfb.buffers [binding] = buffer;
     m_state.xfb.counters[binding] = counter;
     
@@ -1151,6 +1155,9 @@ namespace dxvk {
     if (usage & VK_BUFFER_USAGE_VERTEX_BUFFER_BIT)
       m_flags.set(DxvkContextFlag::GpDirtyVertexBuffers);
     
+    if (usage & VK_BUFFER_USAGE_TRANSFORM_FEEDBACK_BUFFER_BIT_EXT)
+      m_flags.set(DxvkContextFlag::GpDirtyXfbBuffers);
+    
     if (usage & (VK_BUFFER_USAGE_UNIFORM_TEXEL_BUFFER_BIT
                | VK_BUFFER_USAGE_STORAGE_TEXEL_BUFFER_BIT)) {
       m_flags.set(DxvkContextFlag::GpDirtyResources,
@@ -2163,6 +2170,8 @@ namespace dxvk {
     if (m_flags.test(DxvkContextFlag::GpRenderPassBound)) {
       m_flags.clr(DxvkContextFlag::GpRenderPassBound);
 
+      this->pauseTransformFeedback();
+      
       m_queries.endQueries(m_cmd, VK_QUERY_TYPE_OCCLUSION);
       m_queries.endQueries(m_cmd, VK_QUERY_TYPE_PIPELINE_STATISTICS);
       
@@ -2243,6 +2252,52 @@ namespace dxvk {
   }
   
   
+  void DxvkContext::startTransformFeedback() {
+    if (!m_flags.test(DxvkContextFlag::GpXfbActive)) {
+      m_flags.set(DxvkContextFlag::GpXfbActive);
+
+      VkBuffer     ctrBuffers[MaxNumXfbBuffers];
+      VkDeviceSize ctrOffsets[MaxNumXfbBuffers];
+
+      for (uint32_t i = 0; i < MaxNumXfbBuffers; i++) {
+        auto physSlice = m_state.xfb.counters[i].physicalSlice();
+
+        ctrBuffers[i] = physSlice.handle();
+        ctrOffsets[i] = physSlice.offset();
+
+        if (physSlice.handle() != VK_NULL_HANDLE)
+          m_cmd->trackResource(physSlice.resource());
+      }
+      
+      m_cmd->cmdBeginTransformFeedback(
+        0, MaxNumXfbBuffers, ctrBuffers, ctrOffsets);
+    }
+  }
+
+
+  void DxvkContext::pauseTransformFeedback() {
+    if (m_flags.test(DxvkContextFlag::GpXfbActive)) {
+      m_flags.clr(DxvkContextFlag::GpXfbActive);
+      
+      VkBuffer     ctrBuffers[MaxNumXfbBuffers];
+      VkDeviceSize ctrOffsets[MaxNumXfbBuffers];
+
+      for (uint32_t i = 0; i < MaxNumXfbBuffers; i++) {
+        auto physSlice = m_state.xfb.counters[i].physicalSlice();
+
+        ctrBuffers[i] = physSlice.handle();
+        ctrOffsets[i] = physSlice.offset();
+
+        if (physSlice.handle() != VK_NULL_HANDLE)
+          m_cmd->trackResource(physSlice.resource());
+      }
+
+      m_cmd->cmdEndTransformFeedback(
+        0, MaxNumXfbBuffers, ctrBuffers, ctrOffsets);
+    }
+  }
+
+
   void DxvkContext::unbindComputePipeline() {
     m_flags.set(
       DxvkContextFlag::CpDirtyPipeline,
@@ -2289,7 +2344,8 @@ namespace dxvk {
       DxvkContextFlag::GpDirtyPipelineState,
       DxvkContextFlag::GpDirtyResources,
       DxvkContextFlag::GpDirtyVertexBuffers,
-      DxvkContextFlag::GpDirtyIndexBuffer);
+      DxvkContextFlag::GpDirtyIndexBuffer,
+      DxvkContextFlag::GpDirtyXfbBuffers);
     
     m_gpActivePipeline = VK_NULL_HANDLE;
   }
@@ -2315,6 +2371,8 @@ namespace dxvk {
     if (m_flags.test(DxvkContextFlag::GpDirtyPipelineState)) {
       m_flags.clr(DxvkContextFlag::GpDirtyPipelineState);
       
+      this->pauseTransformFeedback();
+
       for (uint32_t i = 0; i < m_state.gp.state.ilBindingCount; i++) {
         const uint32_t binding = m_state.gp.state.ilBindings[i].binding;
         
@@ -2679,6 +2737,50 @@ namespace dxvk {
   }
   
   
+  void DxvkContext::updateTransformFeedbackBuffers() {
+    VkBuffer     xfbBuffers[MaxNumXfbBuffers];
+    VkDeviceSize xfbOffsets[MaxNumXfbBuffers];
+    VkDeviceSize xfbLengths[MaxNumXfbBuffers];
+
+    for (size_t i = 0; i < MaxNumXfbBuffers; i++) {
+      auto physSlice = m_state.xfb.buffers[i].physicalSlice();
+      
+      xfbBuffers[i] = physSlice.handle();
+      xfbOffsets[i] = physSlice.offset();
+      xfbLengths[i] = physSlice.length();
+
+      if (physSlice.handle() == VK_NULL_HANDLE)
+        xfbBuffers[i] = m_device->dummyBufferHandle();
+      
+      if (physSlice.handle() != VK_NULL_HANDLE)
+        m_cmd->trackResource(physSlice.resource());
+    }
+
+    m_cmd->cmdBindTransformFeedbackBuffers(
+      0, MaxNumXfbBuffers,
+      xfbBuffers, xfbOffsets, xfbLengths);
+  }
+
+
+  void DxvkContext::updateTransformFeedbackState() {
+    bool hasTransformFeedback =
+         m_state.gp.pipeline != nullptr
+      && m_state.gp.pipeline->flags().test(DxvkGraphicsPipelineFlag::HasTransformFeedback);
+    
+    if (!hasTransformFeedback)
+      return;
+    
+    if (m_flags.test(DxvkContextFlag::GpDirtyXfbBuffers)) {
+      m_flags.clr(DxvkContextFlag::GpDirtyXfbBuffers);
+
+      this->pauseTransformFeedback();
+      this->updateTransformFeedbackBuffers();
+    }
+
+    this->startTransformFeedback();
+  }
+
+  
   void DxvkContext::updateDynamicState() {
     if (m_gpActivePipeline == VK_NULL_HANDLE)
       return;
@@ -2743,6 +2845,7 @@ namespace dxvk {
     this->updateVertexBufferBindings();
     this->updateGraphicsShaderResources();
     this->updateGraphicsPipelineState();
+    this->updateTransformFeedbackState();
     this->updateGraphicsShaderDescriptors();
     this->updateDynamicState();
   }

src/dxvk/dxvk_context.h

@@ -788,6 +788,9 @@ namespace dxvk {
       const DxvkRenderTargets&    renderTargets,
             DxvkRenderPassOps&    renderPassOps);
     
+    void startTransformFeedback();
+    void pauseTransformFeedback();
+    
     void unbindComputePipeline();
     void updateComputePipeline();
     void updateComputePipelineState();
@@ -821,6 +824,9 @@ namespace dxvk {
     void updateIndexBufferBinding();
     void updateVertexBufferBindings();
     
+    void updateTransformFeedbackBuffers();
+    void updateTransformFeedbackState();
+
     void updateDynamicState();
     
     bool validateComputeState();

src/dxvk/dxvk_renderpass.cpp

@@ -135,6 +135,8 @@ namespace dxvk {
         VK_PIPELINE_STAGE_ALL_COMMANDS_BIT,
         VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT          |
         VK_ACCESS_DEPTH_STENCIL_ATTACHMENT_WRITE_BIT  |
+        VK_ACCESS_TRANSFORM_FEEDBACK_WRITE_BIT_EXT    |
+        VK_ACCESS_TRANSFORM_FEEDBACK_COUNTER_WRITE_BIT_EXT |
         VK_ACCESS_SHADER_WRITE_BIT,
         VK_ACCESS_COLOR_ATTACHMENT_READ_BIT           |
         VK_ACCESS_DEPTH_STENCIL_ATTACHMENT_READ_BIT   |
@@ -144,7 +146,8 @@ namespace dxvk {
         VK_ACCESS_SHADER_READ_BIT                     |
         VK_ACCESS_TRANSFER_READ_BIT                   |
         VK_ACCESS_UNIFORM_READ_BIT                    |
-        VK_ACCESS_VERTEX_ATTRIBUTE_READ_BIT, 0 },
+        VK_ACCESS_VERTEX_ATTRIBUTE_READ_BIT           |
+        VK_ACCESS_TRANSFORM_FEEDBACK_COUNTER_READ_BIT_EXT, 0 },
     }};
     
     VkRenderPassCreateInfo info;