PipelineLayoutVk: only store push constant info when needed

Author: TheMostDiligent

Graphics/GraphicsEngineVulkan/include/PipelineLayoutVk.hpp

@@ -31,6 +31,7 @@
 /// Declaration of Diligent::PipelineLayoutVk class
 
 #include <array>
+#include <memory>
 
 #include "VulkanUtilities/ObjectWrappers.hpp"
 
@@ -63,17 +64,21 @@ class PipelineLayoutVk
 
     struct PushConstantInfo
     {
-        Uint32             Size           = 0;
-        VkShaderStageFlags StageFlags     = 0;
-        Uint32             SignatureIndex = ~0u;
-        Uint32             ResourceIndex  = ~0u;
+        VkPushConstantRange vkRange = {};
 
-        constexpr explicit operator bool() const { return Size != 0; }
+        Uint32 SignatureIndex = ~0u;
+        Uint32 ResourceIndex  = ~0u;
+
+        constexpr explicit operator bool() const { return vkRange.size != 0; }
     };
     static PushConstantInfo GetPushConstantInfo(const RefCntAutoPtr<PipelineResourceSignatureVkImpl>* ppSignatures,
                                                 Uint32                                                SignatureCount);
 
-    const PushConstantInfo& GetPushConstantInfo() const { return m_PushConstantInfo; }
+    const PushConstantInfo& GetPushConstantInfo() const
+    {
+        static const PushConstantInfo NullPCInfo;
+        return m_PushConstantInfo ? *m_PushConstantInfo : NullPCInfo;
+    }
 
 private:
     VulkanUtilities::PipelineLayoutWrapper m_VkPipelineLayout;
@@ -86,7 +91,7 @@ class PipelineLayoutVk
     // (Maximum is MAX_RESOURCE_SIGNATURES * 2)
     Uint8 m_DescrSetCount = 0;
 
-    PushConstantInfo m_PushConstantInfo;
+    std::unique_ptr<PushConstantInfo> m_PushConstantInfo;
 
 #ifdef DILIGENT_DEBUG
     Uint32 m_DbgMaxBindIndex = 0;

Graphics/GraphicsEngineVulkan/src/PipelineLayoutVk.cpp

@@ -83,10 +83,13 @@ PipelineLayoutVk::PushConstantInfo PipelineLayoutVk::GetPushConstantInfo(
                 {
                     VERIFY_EXPR(ResDesc.ArraySize > 0);
                     // For inline constants, ArraySize contains the number of 32-bit constants.
-                    PCInfo.Size           = ResDesc.ArraySize * sizeof(Uint32);
-                    PCInfo.StageFlags     = ShaderTypesToVkShaderStageFlags(ResDesc.ShaderStages);
+                    PCInfo.vkRange.size       = ResDesc.ArraySize * sizeof(Uint32);
+                    PCInfo.vkRange.offset     = 0;
+                    PCInfo.vkRange.stageFlags = ShaderTypesToVkShaderStageFlags(ResDesc.ShaderStages);
+
                     PCInfo.SignatureIndex = BindInd;
                     PCInfo.ResourceIndex  = r;
+
                     break;
                 }
             }
@@ -156,22 +159,15 @@ void PipelineLayoutVk::Create(RenderDeviceVkImpl*                             pD
                             ") used by the pipeline layout exceeds device limit (", Limits.maxDescriptorSetStorageBuffersDynamic, ")");
     }
 
-    m_PushConstantInfo = GetPushConstantInfo(ppSignatures, SignatureCount);
-
-    // Set up push constant range if present
-    VkPushConstantRange PushConstantRange{};
-    if (m_PushConstantInfo)
+    if (PushConstantInfo PCInfo = GetPushConstantInfo(ppSignatures, SignatureCount))
     {
         // Validate push constant size against device limits
-        if (m_PushConstantInfo.Size > Limits.maxPushConstantsSize)
+        if (PCInfo.vkRange.size > Limits.maxPushConstantsSize)
         {
-            LOG_ERROR_AND_THROW("Push constant size (", m_PushConstantInfo.Size,
+            LOG_ERROR_AND_THROW("Push constant size (", PCInfo.vkRange.size,
                                 " bytes) exceeds device limit (", Limits.maxPushConstantsSize, " bytes)");
         }
-
-        PushConstantRange.stageFlags = m_PushConstantInfo.StageFlags;
-        PushConstantRange.offset     = 0;
-        PushConstantRange.size       = m_PushConstantInfo.Size;
+        m_PushConstantInfo = std::make_unique<PushConstantInfo>(std::move(PCInfo));
     }
 
     VkPipelineLayoutCreateInfo PipelineLayoutCI{};
@@ -181,7 +177,7 @@ void PipelineLayoutVk::Create(RenderDeviceVkImpl*                             pD
     PipelineLayoutCI.setLayoutCount         = DescSetLayoutCount;
     PipelineLayoutCI.pSetLayouts            = DescSetLayoutCount ? DescSetLayouts.data() : nullptr;
     PipelineLayoutCI.pushConstantRangeCount = m_PushConstantInfo ? 1 : 0;
-    PipelineLayoutCI.pPushConstantRanges    = m_PushConstantInfo ? &PushConstantRange : nullptr;
+    PipelineLayoutCI.pPushConstantRanges    = m_PushConstantInfo ? &m_PushConstantInfo->vkRange : nullptr;
 
     m_VkPipelineLayout = pDeviceVk->GetLogicalDevice().CreatePipelineLayout(PipelineLayoutCI);