[dxbc] Implement sampleinfo instruction for rasterizer

src/dxbc/dxbc_compiler.cpp

@@ -41,6 +41,13 @@ namespace dxvk {
       m_oRegs.at(i) = 0;
     }
     
+    // Clear spec constants
+    for (uint32_t i = 0; i < m_specConstants.size(); i++) {
+      m_specConstants.at(i) = DxbcRegisterValue {
+        DxbcVectorType { DxbcScalarType::Uint32, 0 },
+        0 };
+    }
+    
     this->emitInit();
   }
   
@@ -4557,15 +4564,21 @@ namespace dxvk {
   
   DxbcRegisterValue DxbcCompiler::emitQueryTextureSamples(
     const DxbcRegister&           resource) {
-    const DxbcBufferInfo info = getBufferInfo(resource);
-    
-    DxbcRegisterValue result;
-    result.type.ctype  = DxbcScalarType::Uint32;
-    result.type.ccount = 1;
-    result.id = m_module.opImageQuerySamples(
-      getVectorTypeId(result.type),
-      m_module.opLoad(info.typeId, info.varId));
-    return result;
+    if (resource.type == DxbcOperandType::Rasterizer) {
+      // SPIR-V has no gl_NumSamples equivalent, so we have
+      // to work around it using a specialization constant
+      return getSpecConstant(DxvkSpecConstantId::RasterizerSampleCount);
+    } else {
+      DxbcBufferInfo info = getBufferInfo(resource);
+      
+      DxbcRegisterValue result;
+      result.type.ctype  = DxbcScalarType::Uint32;
+      result.type.ccount = 1;
+      result.id = m_module.opImageQuerySamples(
+        getVectorTypeId(result.type),
+        m_module.opLoad(info.typeId, info.varId));
+      return result;
+    }
   }
   
   
@@ -4778,6 +4791,43 @@ namespace dxvk {
   }
   
   
+  DxbcRegisterValue DxbcCompiler::getSpecConstant(DxvkSpecConstantId specId) {
+    const uint32_t specIdOffset = uint32_t(specId) - uint32_t(DxvkSpecConstantId::SpecConstantIdMin);
+    
+    // Look up spec constant in the array
+    DxbcRegisterValue value = m_specConstants.at(specIdOffset);
+    
+    if (value.id != 0)
+      return value;
+    
+    // Declare a new specialization constant if needed
+    DxbcSpecConstant info = getSpecConstantProperties(specId);
+    
+    value.type.ctype  = info.ctype;
+    value.type.ccount = info.ccount;
+    value.id = m_module.specConst32(
+      getVectorTypeId(value.type),
+      info.value);
+    
+    m_module.decorateSpecId(value.id, uint32_t(specId));
+    m_module.setDebugName(value.id, info.name);
+    
+    m_specConstants.at(specIdOffset) = value;
+    return value;
+  }
+  
+  
+  DxbcSpecConstant DxbcCompiler::getSpecConstantProperties(DxvkSpecConstantId specId) {
+    static const std::array<DxbcSpecConstant,
+      uint32_t(DxvkSpecConstantId::SpecConstantIdMax) -
+      uint32_t(DxvkSpecConstantId::SpecConstantIdMin) + 1> s_specConstants = {{
+        { DxbcScalarType::Uint32,   1,   1, "RasterizerSampleCount" },
+    }};
+    
+    return s_specConstants.at(uint32_t(specId) - uint32_t(DxvkSpecConstantId::SpecConstantIdMin));
+  }
+  
+  
   void DxbcCompiler::emitInputSetup() {
     // Copy all defined v# registers into the input array
     const uint32_t vecTypeId = m_module.defVectorType(m_module.defFloatType(32), 4);

src/dxbc/dxbc_compiler.h

@@ -96,6 +96,20 @@ namespace dxvk {
   };
   
   
+  /**
+   * \brief Specialization constant properties
+   * 
+   * Stores the name, data type and initial
+   * value of a specialization constant.
+   */
+  struct DxbcSpecConstant {
+    DxbcScalarType  ctype;
+    uint32_t        ccount;
+    uint32_t        value;
+    const char*     name;
+  };
+  
+  
   /**
    * \brief Vertex shader-specific structure
    */
@@ -384,6 +398,13 @@ namespace dxvk {
     // currently active if-else blocks and loops.
     std::vector<DxbcCfgBlock> m_controlFlowBlocks;
     
+    ///////////////////////////////////////////////
+    // Specialization constants. These are defined
+    // as needed by the getSpecConstant method.
+    std::array<DxbcRegisterValue,
+      uint32_t(DxvkSpecConstantId::SpecConstantIdMax) -
+      uint32_t(DxvkSpecConstantId::SpecConstantIdMin) + 1> m_specConstants;
+    
     ///////////////////////////////////////////////////////////
     // Array of input values. Since v# registers are indexable
     // in DXBC, we need to copy them into an array first.
@@ -848,6 +869,14 @@ namespace dxvk {
       const DxbcRegister&           reg,
             DxbcRegisterValue       value);
     
+    ////////////////////////////////////////
+    // Spec constant declaration and access
+    DxbcRegisterValue getSpecConstant(
+            DxvkSpecConstantId      specId);
+    
+    DxbcSpecConstant getSpecConstantProperties(
+            DxvkSpecConstantId      specId);
+    
     ////////////////////////////
     // Input/output preparation
     void emitInputSetup();