[dxvk] Add global specialization constant data structures

Implements a unified way of defining specialization constants
for graphics and compute pipelines which can be easily extended
in the future.

src/dxvk/dxvk_shader.h

@@ -11,6 +11,22 @@ namespace dxvk {
   
   class DxvkShader;
   
+  /**
+   * \brief Built-in specialization constants
+   * 
+   * These specialization constants allow the SPIR-V
+   * shaders to access some pipeline state like D3D
+   * shaders do. They need to be filled in by the
+   * implementation at pipeline compilation time.
+   */
+  enum class DxvkSpecConstantId : uint32_t {
+    RasterizerSampleCount       = 0x10000,
+    
+    SpecConstantIdMin           = RasterizerSampleCount,
+    SpecConstantIdMax           = RasterizerSampleCount,
+  };
+  
+  
   /**
    * \brief Shader interface slots
    * 

src/dxvk/dxvk_spec_const.cpp

@@ -0,0 +1,43 @@
+#include "dxvk_spec_const.h"
+
+#include <iostream>
+
+#define SET_CONSTANT_ENTRY(specId, member)  \
+  this->setConstantEntry(specId,            \
+    offsetof(DxvkSpecConstantData, member), \
+    sizeof(DxvkSpecConstantData::member))
+
+namespace dxvk {
+  
+  DxvkSpecConstantMap g_specConstantMap;
+  
+  DxvkSpecConstantMap::DxvkSpecConstantMap() {
+    SET_CONSTANT_ENTRY(DxvkSpecConstantId::RasterizerSampleCount, rasterizerSampleCount);
+    
+    for (uint32_t i = 0; i < MaxNumActiveBindings; i++)
+      this->setBindingEntry(i);
+  }
+  
+  
+  void DxvkSpecConstantMap::setConstantEntry(
+          DxvkSpecConstantId  specId,
+          uint32_t            offset,
+          uint32_t            size) {
+    VkSpecializationMapEntry entry;
+    entry.constantID = uint32_t(specId);
+    entry.offset     = offset;
+    entry.size       = size;
+    m_mapEntries[uint32_t(specId) - uint32_t(DxvkSpecConstantId::SpecConstantIdMin)] = entry;
+  }
+  
+  
+  void DxvkSpecConstantMap::setBindingEntry(
+          uint32_t            binding) {
+    VkSpecializationMapEntry entry;
+    entry.constantID = binding;
+    entry.offset     = sizeof(VkBool32) * binding + offsetof(DxvkSpecConstantData, activeBindings);
+    entry.size       = sizeof(VkBool32);
+    m_mapEntries[MaxNumSpecConstants + binding] = entry;
+  }
+  
+}

src/dxvk/dxvk_spec_const.h

@@ -0,0 +1,72 @@
+#pragma once
+
+#include "dxvk_limits.h"
+#include "dxvk_shader.h"
+
+namespace dxvk {
+  
+  constexpr uint32_t MaxNumSpecConstants = 1
+    + uint32_t(DxvkSpecConstantId::SpecConstantIdMax)
+    - uint32_t(DxvkSpecConstantId::SpecConstantIdMin);
+  
+  /**
+   * \brief Spec costant data
+   * 
+   * The values are derived from the pipeline
+   * state vector so that they can be used by
+   * the shaders.
+   */
+  struct DxvkSpecConstantData {
+    uint32_t rasterizerSampleCount;
+    VkBool32 activeBindings[MaxNumActiveBindings];
+  };
+  
+  
+  /**
+   * \brief Spec constant map
+   * 
+   * Stores the specialization constant map.
+   * This can be passed to Vulkan when compiling
+   * both graphics and compute pipelines.
+   */
+  class DxvkSpecConstantMap {
+    
+  public:
+    
+    DxvkSpecConstantMap();
+    
+    /**
+     * \brief Map entry count
+     * 
+     * \param [in] bindingCount Number of active bindings
+     * \returns The number of map entries to read
+     */
+    uint32_t mapEntryCount() const {
+      return m_mapEntries.size();
+    }
+    
+    /**
+     * \brief Map entry data
+     * \returns Map entries
+     */
+    const VkSpecializationMapEntry* mapEntryData() const {
+      return m_mapEntries.data();
+    }
+    
+  private:
+    
+    std::array<VkSpecializationMapEntry, MaxNumSpecConstants + MaxNumActiveBindings> m_mapEntries;
+    
+    void setConstantEntry(
+            DxvkSpecConstantId  specId,
+            uint32_t            offset,
+            uint32_t            size);
+    
+    void setBindingEntry(
+            uint32_t            binding);
+    
+  };
+  
+  extern DxvkSpecConstantMap g_specConstantMap;
+  
+}

src/dxvk/meson.build

@@ -61,6 +61,7 @@ dxvk_src = files([
   'dxvk_resource.cpp',
   'dxvk_sampler.cpp',
   'dxvk_shader.cpp',
+  'dxvk_spec_const.cpp',
   'dxvk_staging.cpp',
   'dxvk_stats.cpp',
   'dxvk_surface.cpp',