Performance optimizations in Vulkan backend

5 files changed, 37 insertions, 20 deletions

diff --git a/Graphics/GraphicsEngineVulkan/include/PipelineLayout.h b/Graphics/GraphicsEngineVulkan/include/PipelineLayout.h
index a0810ab7..947f27dc 100644
--- a/Graphics/GraphicsEngineVulkan/include/PipelineLayout.h
+++ b/Graphics/GraphicsEngineVulkan/include/PipelineLayout.h
@@ -87,20 +87,26 @@ public:
         std::vector<uint32_t>        DynamicOffsets;
         ShaderResourceCacheVk*       pResourceCache = nullptr;
         VkPipelineBindPoint          BindPoint      = VK_PIPELINE_BIND_POINT_MAX_ENUM;
-
+        Uint32                       SetCout            = 0;
+        Uint32                       DynamicOffsetCount = 0;
 #ifdef _DEBUG
         const PipelineLayout *pDbgPipelineLayout = nullptr;
 #endif
-        DescriptorSetBindInfo()
+        DescriptorSetBindInfo() : 
+            vkSets(2),
+            DynamicOffsets(64)
         {
-            vkSets.reserve(2);
-            DynamicOffsets.reserve(64);
         }
 
         void Reset()
         {
+            SetCout            = 0;
+            DynamicOffsetCount = 0;
+#ifdef _DEBUG
+            // In release mode, do not clear vectors as this causes unnecessary work
             vkSets.clear();
             DynamicOffsets.clear();
+#endif
             pResourceCache = nullptr;
             BindPoint = VK_PIPELINE_BIND_POINT_MAX_ENUM;
 #ifdef _DEBUG
diff --git a/Graphics/GraphicsEngineVulkan/include/ShaderResourceCacheVk.h b/Graphics/GraphicsEngineVulkan/include/ShaderResourceCacheVk.h
index 92f01236..5bd7eebc 100644
--- a/Graphics/GraphicsEngineVulkan/include/ShaderResourceCacheVk.h
+++ b/Graphics/GraphicsEngineVulkan/include/ShaderResourceCacheVk.h
@@ -173,7 +173,7 @@ public:
     template<bool VerifyOnly>
     void TransitionResources(DeviceContextVkImpl *pCtxVkImpl);
 
-    void GetDynamicBufferOffsets(Uint32 CtxId, std::vector<uint32_t>& Offsets)const;
+    Uint32 GetDynamicBufferOffsets(Uint32 CtxId, std::vector<uint32_t>& Offsets)const;
 
 private:
 
diff --git a/Graphics/GraphicsEngineVulkan/src/DeviceContextVkImpl.cpp b/Graphics/GraphicsEngineVulkan/src/DeviceContextVkImpl.cpp
index 7709a821..d1f88d0d 100644
--- a/Graphics/GraphicsEngineVulkan/src/DeviceContextVkImpl.cpp
+++ b/Graphics/GraphicsEngineVulkan/src/DeviceContextVkImpl.cpp
@@ -444,7 +444,7 @@ namespace Diligent
         else
             CommitVkVertexBuffers();
 
-        if(!m_DesrSetBindInfo.DynamicOffsets.empty())
+        if(m_DesrSetBindInfo.DynamicOffsetCount != 0)
             pPipelineStateVk->BindDescriptorSetsWithDynamicOffsets(this, m_DesrSetBindInfo);
 #if 0
 #ifdef _DEBUG
diff --git a/Graphics/GraphicsEngineVulkan/src/PipelineLayout.cpp b/Graphics/GraphicsEngineVulkan/src/PipelineLayout.cpp
index 8c746f5d..e3d88771 100644
--- a/Graphics/GraphicsEngineVulkan/src/PipelineLayout.cpp
+++ b/Graphics/GraphicsEngineVulkan/src/PipelineLayout.cpp
@@ -430,18 +430,25 @@ void PipelineLayout::PrepareDescriptorSets(DeviceContextVkImpl*    pCtxVkImpl,
                                            ShaderResourceCacheVk&  ResourceCache,
                                            DescriptorSetBindInfo&  BindInfo)const
 {
+#ifdef _DEBUG
     BindInfo.vkSets.clear();
+#endif
+
+    // Do not use vector::resize for BindInfo.vkSets and BindInfo.DynamicOffsets as this 
+    // causes unnecessary work to zero-initialize new elements
 
     VERIFY(m_LayoutMgr.GetDescriptorSet(SHADER_VARIABLE_TYPE_STATIC).SetIndex == m_LayoutMgr.GetDescriptorSet(SHADER_VARIABLE_TYPE_MUTABLE).SetIndex, 
            "Static and mutable variables are expected to share the same descriptor set");
     Uint32 TotalDynamicDescriptors = 0;
+    BindInfo.SetCout = 0;
     for(SHADER_VARIABLE_TYPE VarType = SHADER_VARIABLE_TYPE_MUTABLE; VarType <= SHADER_VARIABLE_TYPE_DYNAMIC; VarType = static_cast<SHADER_VARIABLE_TYPE>(VarType+1))
     {
         const auto &Set = m_LayoutMgr.GetDescriptorSet(VarType);
         if(Set.SetIndex >= 0)
         {
-            if(Set.SetIndex >= BindInfo.vkSets.size())
-                BindInfo.vkSets.resize(Set.SetIndex + 1);
+            BindInfo.SetCout = std::max(BindInfo.SetCout, static_cast<Uint32>(Set.SetIndex + 1));
+            if(BindInfo.SetCout > BindInfo.vkSets.size())
+                BindInfo.vkSets.resize(BindInfo.SetCout);
             VERIFY_EXPR(BindInfo.vkSets[Set.SetIndex] == VK_NULL_HANDLE);
             BindInfo.vkSets[Set.SetIndex] = ResourceCache.GetDescriptorSet(Set.SetIndex).GetVkDescriptorSet();
             VERIFY(BindInfo.vkSets[Set.SetIndex] != VK_NULL_HANDLE, "Descriptor set must not be null");
@@ -454,7 +461,9 @@ void PipelineLayout::PrepareDescriptorSets(DeviceContextVkImpl*    pCtxVkImpl,
         VERIFY(set != VK_NULL_HANDLE, "Descriptor set must not be null");
 #endif
 
-    BindInfo.DynamicOffsets.resize(TotalDynamicDescriptors);
+    BindInfo.DynamicOffsetCount = TotalDynamicDescriptors;
+    if(TotalDynamicDescriptors > BindInfo.DynamicOffsets.size())
+        BindInfo.DynamicOffsets.resize(TotalDynamicDescriptors);
     BindInfo.BindPoint = IsCompute ? VK_PIPELINE_BIND_POINT_COMPUTE : VK_PIPELINE_BIND_POINT_GRAPHICS;
     BindInfo.pResourceCache = &ResourceCache;
 #ifdef _DEBUG
@@ -468,8 +477,8 @@ void PipelineLayout::PrepareDescriptorSets(DeviceContextVkImpl*    pCtxVkImpl,
         CmdBuffer.BindDescriptorSets(BindInfo.BindPoint,
                                      m_LayoutMgr.GetVkPipelineLayout(), 
                                      0, // First set
-                                     static_cast<uint32_t>(BindInfo.vkSets.size()),
-                                     !BindInfo.vkSets.empty() ? BindInfo.vkSets.data() : nullptr,
+                                     BindInfo.SetCout,
+                                     BindInfo.vkSets.data(), // BindInfo.vkSets is never empty
                                      0, 
                                      nullptr);
     }
@@ -480,7 +489,7 @@ void PipelineLayout::BindDescriptorSetsWithDynamicOffsets(DeviceContextVkImpl*
 {
     VERIFY(BindInfo.pDbgPipelineLayout != nullptr, "Pipeline layout is not initialized, which most likely means that CommitShaderResources() has never been called");
     VERIFY(BindInfo.pDbgPipelineLayout->IsSameAs(*this), "Inconsistent pipeline layout");
-    VERIFY(!BindInfo.DynamicOffsets.empty(), "This function should only be called for pipelines that contain dynamic descriptors");
+    VERIFY(BindInfo.DynamicOffsetCount > 0, "This function should only be called for pipelines that contain dynamic descriptors");
 
     VERIFY_EXPR(BindInfo.pResourceCache != nullptr);
 #ifdef _DEBUG
@@ -490,10 +499,12 @@ void PipelineLayout::BindDescriptorSetsWithDynamicOffsets(DeviceContextVkImpl*
         const auto &Set = m_LayoutMgr.GetDescriptorSet(VarType);
         TotalDynamicDescriptors += Set.NumDynamicDescriptors;
     }
-    VERIFY(BindInfo.DynamicOffsets.size() == TotalDynamicDescriptors, "Incosistent dynamic buffer size");
+    VERIFY(BindInfo.DynamicOffsetCount == TotalDynamicDescriptors, "Incosistent dynamic buffer size");
+    VERIFY_EXPR(BindInfo.DynamicOffsets.size() >= BindInfo.DynamicOffsetCount);
 #endif
 
-    BindInfo.pResourceCache->GetDynamicBufferOffsets(pCtxVkImpl->GetContextId(), BindInfo.DynamicOffsets);
+    auto NumOffsetsWritten = BindInfo.pResourceCache->GetDynamicBufferOffsets(pCtxVkImpl->GetContextId(), BindInfo.DynamicOffsets);
+    VERIFY_EXPR(NumOffsetsWritten == BindInfo.DynamicOffsetCount);
 
     auto& CmdBuffer = pCtxVkImpl->GetCommandBuffer();
     // vkCmdBindDescriptorSets causes the sets numbered [firstSet .. firstSet+descriptorSetCount-1] to use the 
@@ -503,11 +514,11 @@ void PipelineLayout::BindDescriptorSetsWithDynamicOffsets(DeviceContextVkImpl*
     CmdBuffer.BindDescriptorSets(BindInfo.BindPoint,
                                  m_LayoutMgr.GetVkPipelineLayout(), 
                                  0, // First set
-                                 static_cast<uint32_t>(BindInfo.vkSets.size()),
-                                 !BindInfo.vkSets.empty() ? BindInfo.vkSets.data() : nullptr,
+                                 BindInfo.SetCout,
+                                 BindInfo.vkSets.data(), // BindInfo.vkSets is never empty
                                  // dynamicOffsetCount must equal the total number of dynamic descriptors in the sets being bound (13.2.5)
-                                 static_cast<uint32_t>(BindInfo.DynamicOffsets.size()),
-                                 !BindInfo.DynamicOffsets.empty() ? BindInfo.DynamicOffsets.data() : nullptr);
+                                 BindInfo.DynamicOffsetCount,
+                                 BindInfo.DynamicOffsets.data());
 }
 
 }
diff --git a/Graphics/GraphicsEngineVulkan/src/ShaderResourceCacheVk.cpp b/Graphics/GraphicsEngineVulkan/src/ShaderResourceCacheVk.cpp
index 4b16539e..f282426e 100644
--- a/Graphics/GraphicsEngineVulkan/src/ShaderResourceCacheVk.cpp
+++ b/Graphics/GraphicsEngineVulkan/src/ShaderResourceCacheVk.cpp
@@ -284,7 +284,7 @@ VkDescriptorImageInfo ShaderResourceCacheVk::Resource::GetSamplerDescriptorWrite
     return DescrImgInfo;
 }
 
-void ShaderResourceCacheVk::GetDynamicBufferOffsets(Uint32 CtxId, std::vector<uint32_t>& Offsets)const
+Uint32 ShaderResourceCacheVk::GetDynamicBufferOffsets(Uint32 CtxId, std::vector<uint32_t>& Offsets)const
 {
     // If any of the sets being bound include dynamic uniform or storage buffers, then 
     // pDynamicOffsets includes one element for each array element in each dynamic descriptor 
@@ -337,7 +337,7 @@ void ShaderResourceCacheVk::GetDynamicBufferOffsets(Uint32 CtxId, std::vector<ui
         }
 #endif
     }
-    VERIFY(OffsetInd == Offsets.size(), "Incorrect number of dynamic offsets written");
+    return OffsetInd;
 }
 
 }