Remove PIPELINE_RESOURCE_FLAG_VULKAN_PUSH_CONSTANT, implement deferred push constant selection.

Author: hzqst

Graphics/GraphicsAccessories/src/GraphicsAccessories.cpp

@@ -1637,7 +1637,7 @@ String GetPipelineResourceFlagsString(PIPELINE_RESOURCE_FLAGS Flags, bool GetFul
 
         PIPELINE_RESOURCE_FLAGS Flag = ExtractLSB(Flags);
 
-        static_assert(PIPELINE_RESOURCE_FLAG_LAST == (1u << 6), "Please update the switch below to handle the new pipeline resource flag.");
+        static_assert(PIPELINE_RESOURCE_FLAG_LAST == (1u << 5), "Please update the switch below to handle the new pipeline resource flag.");
         switch (Flag)
         {
             case PIPELINE_RESOURCE_FLAG_NO_DYNAMIC_BUFFERS:
@@ -1664,10 +1664,6 @@ String GetPipelineResourceFlagsString(PIPELINE_RESOURCE_FLAGS Flags, bool GetFul
                 Str.append(GetFullName ? "PIPELINE_RESOURCE_FLAG_GENERAL_INPUT_ATTACHMENT" : "GENERAL_INPUT_ATTACHMENT");
                 break;
 
-            case PIPELINE_RESOURCE_FLAG_VULKAN_PUSH_CONSTANT:
-                Str.append(GetFullName ? "PIPELINE_RESOURCE_FLAG_VULKAN_PUSH_CONSTANT" : "VULKAN_PUSH_CONSTANT");
-                break;
-
             default:
                 UNEXPECTED("Unexpected pipeline resource flag");
         }
@@ -1816,7 +1812,7 @@ PIPELINE_RESOURCE_FLAGS GetValidPipelineResourceFlags(SHADER_RESOURCE_TYPE Resou
     switch (ResourceType)
     {
         case SHADER_RESOURCE_TYPE_CONSTANT_BUFFER:
-            return PIPELINE_RESOURCE_FLAG_NO_DYNAMIC_BUFFERS | PIPELINE_RESOURCE_FLAG_RUNTIME_ARRAY | PIPELINE_RESOURCE_FLAG_INLINE_CONSTANTS | PIPELINE_RESOURCE_FLAG_VULKAN_PUSH_CONSTANT;
+            return PIPELINE_RESOURCE_FLAG_NO_DYNAMIC_BUFFERS | PIPELINE_RESOURCE_FLAG_RUNTIME_ARRAY | PIPELINE_RESOURCE_FLAG_INLINE_CONSTANTS;
 
         case SHADER_RESOURCE_TYPE_TEXTURE_SRV:
             return PIPELINE_RESOURCE_FLAG_COMBINED_SAMPLER | PIPELINE_RESOURCE_FLAG_RUNTIME_ARRAY;

Graphics/GraphicsEngine/interface/PipelineResourceSignature.h

@@ -148,18 +148,7 @@ DILIGENT_TYPED_ENUM(PIPELINE_RESOURCE_FLAGS, Uint8)
     /// \note This flag is only valid in Vulkan.
     PIPELINE_RESOURCE_FLAG_GENERAL_INPUT_ATTACHMENT = 1u << 5,
 
-    /// Indicates that this inline constant is a Vulkan push constant
-    /// (declared with push_constant storage class in SPIR-V).
-    /// This flag is must be explicitly set when creating PipelineResourceSignature
-    /// And must be used together with PIPELINE_RESOURCE_FLAG_INLINE_CONSTANTS
-    /// When this flag is set, the engine will use vkCmdPushConstants
-    /// instead of a dynamic uniform buffer to update the constants.
-    ///
-    /// \note This flag is only valid in Vulkan and is always combined with
-    ///       PIPELINE_RESOURCE_FLAG_INLINE_CONSTANTS.
-    PIPELINE_RESOURCE_FLAG_VULKAN_PUSH_CONSTANT = 1u << 6,
-
-    PIPELINE_RESOURCE_FLAG_LAST = PIPELINE_RESOURCE_FLAG_VULKAN_PUSH_CONSTANT
+    PIPELINE_RESOURCE_FLAG_LAST = PIPELINE_RESOURCE_FLAG_GENERAL_INPUT_ATTACHMENT
 };
 DEFINE_FLAG_ENUM_OPERATORS(PIPELINE_RESOURCE_FLAGS);
 

Graphics/GraphicsEngine/src/PipelineResourceSignatureBase.cpp

@@ -111,23 +111,8 @@ void ValidatePipelineResourceSignatureDesc(const PipelineResourceSignatureDesc&
                                     ": ", GetPipelineResourceFlagsString(AllowedResourceFlags, false, ", "), ".");
         }
 
-        if ((Res.Flags & PIPELINE_RESOURCE_FLAG_VULKAN_PUSH_CONSTANT) != 0)
-        {
-            if (Res.Flags != (PIPELINE_RESOURCE_FLAG_INLINE_CONSTANTS | PIPELINE_RESOURCE_FLAG_VULKAN_PUSH_CONSTANT))
-            {
-                LOG_PRS_ERROR_AND_THROW("Incorrect Desc.Resources[", i, "].Flags (", GetPipelineResourceFlagsString(Res.Flags),
-                                        "). VULKAN_PUSH_CONSTANT flags must be combined with INLINE_CONSTANTS.");
-            }
-        }
-
         if ((Res.Flags & PIPELINE_RESOURCE_FLAG_INLINE_CONSTANTS) != 0)
         {
-            if (Res.Flags != PIPELINE_RESOURCE_FLAG_INLINE_CONSTANTS && Res.Flags != (PIPELINE_RESOURCE_FLAG_INLINE_CONSTANTS | PIPELINE_RESOURCE_FLAG_VULKAN_PUSH_CONSTANT))
-            {
-                LOG_PRS_ERROR_AND_THROW("Incorrect Desc.Resources[", i, "].Flags (", GetPipelineResourceFlagsString(Res.Flags),
-                                        "). INLINE_CONSTANTS flag cannot be combined with flags other than VULKAN_PUSH_CONSTANT.");
-            }
-
             if (Res.ArraySize > 64)
             {
                 LOG_PRS_ERROR_AND_THROW("Desc.Resources[", i, "].ArraySize (", Res.ArraySize,

Graphics/GraphicsEngine/src/PipelineStateBase.cpp

@@ -849,15 +849,6 @@ void ValidatePipelineResourceCompatibility(const PipelineResourceDesc& ResDesc,
                             GetShaderResourceTypeLiteralName(ResDesc.ResourceType), "' specified in pipeline resource signature '", SignatureName, "'.");
     }
 
-    if ((ResourceFlags & PIPELINE_RESOURCE_FLAG_VULKAN_PUSH_CONSTANT) != (ResDesc.Flags & PIPELINE_RESOURCE_FLAG_VULKAN_PUSH_CONSTANT))
-    {
-        LOG_ERROR_AND_THROW("Shader '", ShaderName, "' contains resource '", ResDesc.Name,
-                            "' that is", ((ResourceFlags & PIPELINE_RESOURCE_FLAG_VULKAN_PUSH_CONSTANT) ? "" : " not"),
-                            " labeled as vulkan's push constant, while the same resource specified by the pipeline resource signature '",
-                            SignatureName, "' is", ((ResDesc.Flags & PIPELINE_RESOURCE_FLAG_VULKAN_PUSH_CONSTANT) ? "" : " not"),
-                            " labeled as such.");
-    }
-
     if ((ResourceFlags & PIPELINE_RESOURCE_FLAG_FORMATTED_BUFFER) != (ResDesc.Flags & PIPELINE_RESOURCE_FLAG_FORMATTED_BUFFER))
     {
         LOG_ERROR_AND_THROW("Shader '", ShaderName, "' contains resource '", ResDesc.Name,

Graphics/GraphicsEngineVulkan/include/PipelineLayoutVk.hpp

@@ -40,13 +40,17 @@ namespace Diligent
 class RenderDeviceVkImpl;
 class PipelineResourceSignatureVkImpl;
 
-/// Push constant information extracted from shaders
+/// Push constant information extracted from shaders or selected from inline constants
 struct PushConstantInfoVk
 {
-    VkShaderStageFlags StageFlags = 0;
-    Uint32             Size       = 0;
+    VkShaderStageFlags StageFlags      = 0;
+    Uint32             Size            = 0;
+    Uint32             SignatureIndex  = ~0u; // Index of the signature containing the push constant (~0u if none)
+    Uint32             ResourceIndex   = ~0u; // Resource index within the signature (~0u if none)
 };
 
+static constexpr Uint32 INVALID_PUSH_CONSTANT_INDEX = ~0u;
+
 /// Implementation of the Diligent::PipelineLayoutVk class
 class PipelineLayoutVk
 {
@@ -78,6 +82,14 @@ class PipelineLayoutVk
     // Returns the shader stage flags for push constants
     VkShaderStageFlags GetPushConstantStageFlags() const { return m_PushConstantStageFlags; }
 
+    // Returns the signature index containing the push constant resource
+    // Returns INVALID_PUSH_CONSTANT_INDEX if no push constant is selected
+    Uint32 GetPushConstantSignatureIndex() const { return m_PushConstantSignatureIndex; }
+
+    // Returns the resource index within the signature for push constant
+    // Returns INVALID_PUSH_CONSTANT_INDEX if no push constant is selected
+    Uint32 GetPushConstantResourceIndex() const { return m_PushConstantResourceIndex; }
+
 private:
     VulkanUtilities::PipelineLayoutWrapper m_VkPipelineLayout;
 
@@ -95,6 +107,12 @@ class PipelineLayoutVk
     // Shader stages that use push constants
     VkShaderStageFlags m_PushConstantStageFlags = 0;
 
+    // Index of the signature containing the push constant resource
+    Uint32 m_PushConstantSignatureIndex = INVALID_PUSH_CONSTANT_INDEX;
+
+    // Resource index within the signature for push constant
+    Uint32 m_PushConstantResourceIndex = INVALID_PUSH_CONSTANT_INDEX;
+
 #ifdef DILIGENT_DEBUG
     Uint32 m_DbgMaxBindIndex = 0;
 #endif

Graphics/GraphicsEngineVulkan/include/PipelineResourceAttribsVk.hpp

@@ -63,6 +63,8 @@ enum class DescriptorType : Uint8
 
 
 // sizeof(PipelineResourceAttribsVk) == 16, x64
+// Note: Push constant selection is deferred to PSO creation time.
+// At PRS level, all inline constants are treated uniformly with descriptor sets.
 struct PipelineResourceAttribsVk
 {
 private:
@@ -72,9 +74,9 @@ struct PipelineResourceAttribsVk
     static constexpr Uint32 _DescrTypeBits       = 5;
     static constexpr Uint32 _DescrSetBits        = 1;
     static constexpr Uint32 _SamplerAssignedBits = 1;
-    static constexpr Uint32 _IsPushConstantBits  = 1;
+    static constexpr Uint32 _ReservedBits        = 1; // Reserved for future use
 
-    static_assert((_BindingIndexBits + _ArraySizeBits + _SamplerIndBits + _DescrTypeBits + _DescrSetBits + _SamplerAssignedBits + _IsPushConstantBits) % 32 == 0, "Bits are not optimally packed");
+    static_assert((_BindingIndexBits + _ArraySizeBits + _SamplerIndBits + _DescrTypeBits + _DescrSetBits + _SamplerAssignedBits + _ReservedBits) % 32 == 0, "Bits are not optimally packed");
 
     // clang-format off
     static_assert((1u << _DescrTypeBits)    >  static_cast<Uint32>(DescriptorType::Count), "Not enough bits to store DescriptorType values");
@@ -89,11 +91,11 @@ struct PipelineResourceAttribsVk
     // clang-format off
     const Uint32  BindingIndex         : _BindingIndexBits;    // Binding in the descriptor set
     const Uint32  SamplerInd           : _SamplerIndBits;      // Index of the assigned sampler in m_Desc.Resources and m_pPipelineResourceAttribsVk
-    const Uint32  ArraySize            : _ArraySizeBits;       // Array size (for push constants, this is the number of 32-bit constants)
+    const Uint32  ArraySize            : _ArraySizeBits;       // Array size (for inline constants, this is the number of 32-bit constants)
     const Uint32  DescrType            : _DescrTypeBits;       // Descriptor type (DescriptorType)
     const Uint32  DescrSet             : _DescrSetBits;        // Descriptor set (0 or 1)
     const Uint32  ImtblSamplerAssigned : _SamplerAssignedBits; // Immutable sampler flag
-    const Uint32  IsPushConstant       : _IsPushConstantBits;  // True if this is a Vulkan push constant (not using descriptor sets)
+    const Uint32  Reserved             : _ReservedBits;        // Reserved for future use
 
     const Uint32  SRBCacheOffset;                              // Offset in the SRB resource cache
     const Uint32  StaticCacheOffset;                           // Offset in the static resource cache
@@ -105,7 +107,6 @@ struct PipelineResourceAttribsVk
                               DescriptorType _DescrType,
                               Uint32         _DescrSet,
                               bool           _ImtblSamplerAssigned,
-                              bool           _IsPushConstant,
                               Uint32         _SRBCacheOffset,
                               Uint32         _StaticCacheOffset) noexcept :
         // clang-format off
@@ -115,7 +116,7 @@ struct PipelineResourceAttribsVk
         DescrType            {static_cast<Uint32>(_DescrType)},
         DescrSet             {_DescrSet                      },
         ImtblSamplerAssigned {_ImtblSamplerAssigned ? 1u : 0u},
-        IsPushConstant       {_IsPushConstant ? 1u : 0u      },
+        Reserved             {0                              },
         SRBCacheOffset       {_SRBCacheOffset                },
         StaticCacheOffset    {_StaticCacheOffset             }
     // clang-format on
@@ -131,7 +132,7 @@ struct PipelineResourceAttribsVk
 
     // Only for serialization
     PipelineResourceAttribsVk() noexcept :
-        PipelineResourceAttribsVk{0, 0, 0, DescriptorType::Unknown, 0, false, false, 0, 0}
+        PipelineResourceAttribsVk{0, 0, 0, DescriptorType::Unknown, 0, false, 0, 0}
     {}
 
 
@@ -155,11 +156,6 @@ struct PipelineResourceAttribsVk
         return SamplerInd != InvalidSamplerInd;
     }
 
-    bool IsPushConstantBuffer() const
-    {
-        return IsPushConstant != 0;
-    }
-
     bool IsCompatibleWith(const PipelineResourceAttribsVk& rhs) const
     {
         // Ignore sampler index and cache offsets.
@@ -168,14 +164,13 @@ struct PipelineResourceAttribsVk
                ArraySize            == rhs.ArraySize    &&
                DescrType            == rhs.DescrType    &&
                DescrSet             == rhs.DescrSet     &&
-               ImtblSamplerAssigned == rhs.ImtblSamplerAssigned &&
-               IsPushConstant       == rhs.IsPushConstant;
+               ImtblSamplerAssigned == rhs.ImtblSamplerAssigned;
         // clang-format on
     }
 
     size_t GetHash() const
     {
-        return ComputeHash(BindingIndex, ArraySize, DescrType, DescrSet, ImtblSamplerAssigned, IsPushConstant);
+        return ComputeHash(BindingIndex, ArraySize, DescrType, DescrSet, ImtblSamplerAssigned);
     }
 };
 ASSERT_SIZEOF(PipelineResourceAttribsVk, 16, "The struct is used in serialization and must be tightly packed");

Graphics/GraphicsEngineVulkan/include/PipelineResourceSignatureVkImpl.hpp

@@ -60,28 +60,24 @@ struct ImmutableSamplerAttribsVk
 ASSERT_SIZEOF(ImmutableSamplerAttribsVk, 8, "The struct is used in serialization and must be tightly packed");
 
 /// Inline constant buffer attributes for Vulkan backend.
-/// Inline constants can be either:
-/// 1. True push constants (from SPIR-V push_constant storage class) - use vkCmdPushConstants
-/// 2. Emulated inline constants - use dynamic uniform buffers (similar to D3D11 backend)
+/// All inline constants are treated uniformly at PRS level - they all get:
+/// - DescriptorSet binding and cache allocation
+/// - Shared emulated buffer (created in the Signature, shared by all SRBs)
 ///
-/// For emulated inline constants (not push constants), the Buffer is created in the Signature
-/// and shared by all SRBs (similar to D3D11). Each SRB has its own CPU staging memory.
-/// For push constants, pPushConstantData points to the static cache's staging memory.
+/// Push constant selection is deferred to PSO creation time. At PSO creation,
+/// one inline constant may be selected to use vkCmdPushConstants based on:
+/// 1. SPIR-V reflection (ResourceType::PushConstant in shader)
+/// 2. First inline constant as fallback (converted via PatchShader)
 struct InlineConstantBufferAttribsVk
 {
-    Uint32 ResIndex       = 0;     // Resource index in the signature (used for matching)
-    Uint32 DescrSet       = 0;     // Descriptor set index (0 for push constants as placeholder)
-    Uint32 BindingIndex   = 0;     // Binding index within the descriptor set
-    Uint32 NumConstants   = 0;     // Number of 32-bit constants
-    bool   IsPushConstant = false; // True if this is a Vulkan push constant (not emulated)
+    Uint32 ResIndex     = 0; // Resource index in the signature (used for matching)
+    Uint32 DescrSet     = 0; // Descriptor set index
+    Uint32 BindingIndex = 0; // Binding index within the descriptor set
+    Uint32 NumConstants = 0; // Number of 32-bit constants
 
-    // For emulated inline constants: shared buffer created in the Signature (similar to D3D11)
+    // Shared buffer created in the Signature (similar to D3D11)
     // All SRBs reference this same buffer to reduce memory usage.
     RefCntAutoPtr<BufferVkImpl> pBuffer;
-
-    // For static push constants: pointer to data in the static resource cache
-    // This allows CopyStaticResources to copy the data to SRB caches.
-    void* pPushConstantData = nullptr;
 };
 
 struct PipelineResourceSignatureInternalDataVk : PipelineResourceSignatureInternalData<PipelineResourceAttribsVk, ImmutableSamplerAttribsVk>
@@ -161,9 +157,12 @@ class PipelineResourceSignatureVkImpl final : public PipelineResourceSignatureBa
                                 VkDescriptorSet              vkDynamicDescriptorSet) const;
 
     // Updates inline constant buffers by mapping the internal buffers and copying data from the resource cache
-    // ResourceCache must be valid - each SRB has its own copy of push constant data stored in the cache
+    // ResourceCache must be valid - each SRB has its own copy of inline constant data stored in the cache
+    // PushConstantResIndex: Resource index of the inline constant selected as push constant by PSO
+    //                       Pass ~0u if no push constant is selected from this signature
     void UpdateInlineConstantBuffers(const ShaderResourceCacheVk& ResourceCache,
-                                     DeviceContextVkImpl&         Ctx) const;
+                                     DeviceContextVkImpl&         Ctx,
+                                     Uint32                       PushConstantResIndex) const;
 
     // Returns the number of inline constant buffers
     Uint32 GetNumInlineConstantBufferAttribs() const { return m_NumInlineConstantBufferAttribs; }
@@ -236,10 +235,9 @@ class PipelineResourceSignatureVkImpl final : public PipelineResourceSignatureBa
     // Inline constant buffer attributes
     std::unique_ptr<InlineConstantBufferAttribsVk[]> m_InlineConstantBufferAttribs;
 
-    // Note: Static inline constant data (including push constants) is stored in m_pStaticResCache.
-    // For push constants, we use InitializePushConstantDataPtrs() and SetPushConstantDataPtr()
-    // in the static resource cache, similar to how SRB caches store push constant data.
-    // This ensures each SRB gets its own copy when CopyStaticResources() is called.
+    // Note: Static inline constant data is stored in m_pStaticResCache.
+    // Push constant selection is deferred to PSO creation time - the PRS treats
+    // all inline constants uniformly with emulated buffers.
 };
 
 template <> Uint32 PipelineResourceSignatureVkImpl::GetDescriptorSetIndex<PipelineResourceSignatureVkImpl::DESCRIPTOR_SET_ID_STATIC_MUTABLE>() const;

Graphics/GraphicsEngineVulkan/include/PipelineStateVkImpl.hpp

@@ -133,9 +133,11 @@ class PipelineStateVkImpl final : public PipelineStateBase<EngineVkImplTraits>
     void InitializePipeline(const ComputePipelineStateCreateInfo& CreateInfo);
     void InitializePipeline(const RayTracingPipelineStateCreateInfo& CreateInfo);
 
-    void InitPushConstantInfoFromSignatures(PushConstantInfoVk& PushConstant) const noexcept(false);
+    bool InitPushConstantInfoFromSignatures(PushConstantInfoVk& PushConstant,
+                                            TShaderStages&      ShaderStages) const noexcept(false);
 
-    void PatchShaderConvertUniformBufferToPushConstant(TShaderStages& ShaderStages) const noexcept(false);
+    void PatchShaderConvertUniformBufferToPushConstant(TShaderStages&            ShaderStages,
+                                                       const PushConstantInfoVk& PushConstant) const noexcept(false);
 
     // TPipelineStateBase::Construct needs access to InitializePipeline
     friend TPipelineStateBase;