[dxvk] Compact vertex buffer bindings

This way, we can always update all vertex buffer bindings with one
single API call, without having to deal with any gaps in binding IDs.

The previous optimization triggers a bug in some drivers when no
vertex buffer is ever bound to a given binding point, and may also
trigger inefficient behaviour if the binding range is assumed to
be contiguous.

src/dxvk/dxvk_context.cpp

@@ -3672,46 +3672,35 @@ namespace dxvk {
   void DxvkContext::updateVertexBufferBindings() {
     if (m_flags.test(DxvkContextFlag::GpDirtyVertexBuffers)) {
       m_flags.clr(DxvkContextFlag::GpDirtyVertexBuffers);
+
+      if (unlikely(!m_state.gp.state.ilBindingCount))
+        return;
       
       std::array<VkBuffer,     MaxNumVertexBindings> buffers;
       std::array<VkDeviceSize, MaxNumVertexBindings> offsets;
       
       // Set buffer handles and offsets for active bindings
-      uint32_t bindingMask = 0;
-      
       for (uint32_t i = 0; i < m_state.gp.state.ilBindingCount; i++) {
         uint32_t binding = m_state.gp.state.ilBindings[i].binding;
-        bindingMask |= 1u << binding;
         
         if (likely(m_state.vi.vertexBuffers[binding].defined())) {
           auto vbo = m_state.vi.vertexBuffers[binding].getDescriptor();
           
-          buffers[binding] = vbo.buffer.buffer;
+          buffers[i] = vbo.buffer.buffer;
-          offsets[binding] = vbo.buffer.offset;
+          offsets[i] = vbo.buffer.offset;
           
           m_cmd->trackResource(m_state.vi.vertexBuffers[binding].buffer());
         } else {
-          buffers[binding] = m_device->dummyBufferHandle();
+          buffers[i] = m_device->dummyBufferHandle();
-          offsets[binding] = 0;
+          offsets[i] = 0;
         }
       }
       
-      // Actually bind all the vertex buffers.
+      // Vertex bindigs get remapped when compiling the
-      uint32_t bindingIndex = 0;
+      // pipeline, so this actually does the right thing
-      
+      m_cmd->cmdBindVertexBuffers(
-      while (bindingMask) {
+        0, m_state.gp.state.ilBindingCount,
-        uint32_t shift = bit::tzcnt(bindingMask);
+        buffers.data(), offsets.data());
-        uint32_t count = bit::tzcnt(~bindingMask >> shift);
-        uint32_t index = bindingIndex + shift;
-
-        m_cmd->cmdBindVertexBuffers(
-          index, count,
-          &buffers[index],
-          &offsets[index]);
-        
-        bindingIndex += shift + count;
-        bindingMask >>= shift + count;
-      }
     }
   }
   

src/dxvk/dxvk_graphics.cpp

@@ -258,6 +258,22 @@ namespace dxvk {
     int32_t rasterizedStream = m_gs != nullptr
       ? m_gs->shaderOptions().rasterizedStream
       : 0;
+    
+    // Compact vertex bindings so that we can more easily update vertex buffers
+    std::array<VkVertexInputAttributeDescription, MaxNumVertexAttributes> viAttribs;
+    std::array<VkVertexInputBindingDescription,   MaxNumVertexBindings>   viBindings;
+    std::array<uint32_t,                          MaxNumVertexBindings>   viBindingMap = { };
+
+    for (uint32_t i = 0; i < state.ilBindingCount; i++) {
+      viBindings[i] = state.ilBindings[i];
+      viBindings[i].binding = i;
+      viBindingMap[state.ilBindings[i].binding] = i;
+    }
+
+    for (uint32_t i = 0; i < state.ilAttributeCount; i++) {
+      viAttribs[i] = state.ilAttributes[i];
+      viAttribs[i].binding = viBindingMap[state.ilAttributes[i].binding];
+    }
 
     VkPipelineVertexInputDivisorStateCreateInfoEXT viDivisorInfo;
     viDivisorInfo.sType                     = VK_STRUCTURE_TYPE_PIPELINE_VERTEX_INPUT_DIVISOR_STATE_CREATE_INFO_EXT;
@@ -270,9 +286,9 @@ namespace dxvk {
     viInfo.pNext                            = &viDivisorInfo;
     viInfo.flags                            = 0;
     viInfo.vertexBindingDescriptionCount    = state.ilBindingCount;
-    viInfo.pVertexBindingDescriptions       = state.ilBindings;
+    viInfo.pVertexBindingDescriptions       = viBindings.data();
     viInfo.vertexAttributeDescriptionCount  = state.ilAttributeCount;
-    viInfo.pVertexAttributeDescriptions     = state.ilAttributes;
+    viInfo.pVertexAttributeDescriptions     = viAttribs.data();
     
     if (viDivisorCount == 0)
       viInfo.pNext = viDivisorInfo.pNext;