//===--- DeclResultIdMapper.cpp - DeclResultIdMapper impl --------*- C++ -*-==//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#include "DeclResultIdMapper.h"

#include <sstream>

#include "dxc/DXIL/DxilConstants.h"
#include "dxc/DXIL/DxilTypeSystem.h"
#include "clang/AST/Expr.h"
#include "clang/AST/HlslTypes.h"
#include "clang/SPIRV/AstTypeProbe.h"
#include "llvm/ADT/SmallBitVector.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/StringSet.h"
#include "llvm/Support/Casting.h"

#include "AlignmentSizeCalculator.h"
#include "SpirvEmitter.h"

namespace clang {
namespace spirv {

namespace {

uint32_t getVkBindingAttrSet(const VKBindingAttr *attr, uint32_t defaultSet) {
  // If the [[vk::binding(x)]] attribute is provided without the descriptor set,
  // we should use the default descriptor set.
  if (attr->getSet() == INT_MIN) {
    return defaultSet;
  }
  return attr->getSet();
}

/// Returns the :packoffset() annotation on the given decl. Returns nullptr if
/// the decl does not have one.
hlsl::ConstantPacking *getPackOffset(const clang::NamedDecl *decl) {
  for (auto *annotation : decl->getUnusualAnnotations())
    if (auto *packing = llvm::dyn_cast<hlsl::ConstantPacking>(annotation))
      return packing;
  return nullptr;
}

QualType getUintTypeWithSourceComponents(const ASTContext &astContext,
                                         QualType sourceType) {
  if (isScalarType(sourceType)) {
    return astContext.UnsignedIntTy;
  }
  uint32_t elemCount = 0;
  if (isVectorType(sourceType, nullptr, &elemCount)) {
    return astContext.getExtVectorType(astContext.UnsignedIntTy, elemCount);
  }
  llvm_unreachable("only scalar and vector types are supported in "
                   "getUintTypeWithSourceComponents");
}

uint32_t getLocationCount(const ASTContext &astContext, QualType type) {
  // See Vulkan spec 14.1.4. Location Assignment for the complete set of rules.

  const auto canonicalType = type.getCanonicalType();
  if (canonicalType != type)
    return getLocationCount(astContext, canonicalType);

  // Inputs and outputs of the following types consume a single interface
  // location:
  // * 16-bit scalar and vector types, and
  // * 32-bit scalar and vector types, and
  // * 64-bit scalar and 2-component vector types.

  // 64-bit three- and four- component vectors consume two consecutive
  // locations.

  // Primitive types
  if (isScalarType(type))
    return 1;

  // Vector types
  {
    QualType elemType = {};
    uint32_t elemCount = {};
    if (isVectorType(type, &elemType, &elemCount)) {
      const auto *builtinType = elemType->getAs<BuiltinType>();
      switch (builtinType->getKind()) {
      case BuiltinType::Double:
      case BuiltinType::LongLong:
      case BuiltinType::ULongLong:
        if (elemCount >= 3)
          return 2;
      default:
        // Filter switch only interested in types occupying 2 locations.
        break;
      }
      return 1;
    }
  }

  // If the declared input or output is an n * m 16- , 32- or 64- bit matrix,
  // it will be assigned multiple locations starting with the location
  // specified. The number of locations assigned for each matrix will be the
  // same as for an n-element array of m-component vectors.

  // Matrix types
  {
    QualType elemType = {};
    uint32_t rowCount = 0, colCount = 0;
    if (isMxNMatrix(type, &elemType, &rowCount, &colCount))
      return getLocationCount(astContext,
                              astContext.getExtVectorType(elemType, colCount)) *
             rowCount;
  }

  // Typedefs
  if (const auto *typedefType = type->getAs<TypedefType>())
    return getLocationCount(astContext, typedefType->desugar());

  // Reference types
  if (const auto *refType = type->getAs<ReferenceType>())
    return getLocationCount(astContext, refType->getPointeeType());

  // Pointer types
  if (const auto *ptrType = type->getAs<PointerType>())
    return getLocationCount(astContext, ptrType->getPointeeType());

  // If a declared input or output is an array of size n and each element takes
  // m locations, it will be assigned m * n consecutive locations starting with
  // the location specified.

  // Array types
  if (const auto *arrayType = astContext.getAsConstantArrayType(type))
    return getLocationCount(astContext, arrayType->getElementType()) *
           static_cast<uint32_t>(arrayType->getSize().getZExtValue());

  // Struct type
  if (type->getAs<RecordType>()) {
    assert(false && "all structs should already be flattened");
    return 0;
  }

  llvm_unreachable(
      "calculating number of occupied locations for type unimplemented");
  return 0;
}

bool shouldSkipInStructLayout(const Decl *decl) {
  // Ignore implicit generated struct declarations/constructors/destructors
  if (decl->isImplicit())
    return true;
  // Ignore embedded type decls
  if (isa<TypeDecl>(decl))
    return true;
  // Ignore embeded function decls
  if (isa<FunctionDecl>(decl))
    return true;
  // Ignore empty decls
  if (isa<EmptyDecl>(decl))
    return true;

  // For the $Globals cbuffer, we only care about externally-visible
  // non-resource-type variables. The rest should be filtered out.

  const auto *declContext = decl->getDeclContext();

  // Special check for ConstantBuffer/TextureBuffer, whose DeclContext is a
  // HLSLBufferDecl. So that we need to check the HLSLBufferDecl's parent decl
  // to check whether this is a ConstantBuffer/TextureBuffer defined in the
  // global namespace.
  // Note that we should not be seeing ConstantBuffer/TextureBuffer for normal
  // cbuffer/tbuffer or push constant blocks. So this case should only happen
  // for $Globals cbuffer.
  if (isConstantTextureBuffer(decl) &&
      declContext->getLexicalParent()->isTranslationUnit())
    return true;

  // $Globals' "struct" is the TranslationUnit, so we should ignore resources
  // in the TranslationUnit "struct" and its child namespaces.
  if (declContext->isTranslationUnit() || declContext->isNamespace()) {
    // External visibility
    if (const auto *declDecl = dyn_cast<DeclaratorDecl>(decl))
      if (!declDecl->hasExternalFormalLinkage())
        return true;

    // cbuffer/tbuffer
    if (isa<HLSLBufferDecl>(decl))
      return true;

    // Other resource types
    if (const auto *valueDecl = dyn_cast<ValueDecl>(decl))
      if (isResourceType(valueDecl))
        return true;
  }

  return false;
}

void collectDeclsInField(const Decl *field,
                         llvm::SmallVector<const Decl *, 4> *decls) {

  // Case of nested namespaces.
  if (const auto *nsDecl = dyn_cast<NamespaceDecl>(field)) {
    for (const auto *decl : nsDecl->decls()) {
      collectDeclsInField(decl, decls);
    }
  }

  if (shouldSkipInStructLayout(field))
    return;

  if (!isa<DeclaratorDecl>(field)) {
    return;
  }

  decls->push_back(field);
}

llvm::SmallVector<const Decl *, 4>
collectDeclsInDeclContext(const DeclContext *declContext) {
  llvm::SmallVector<const Decl *, 4> decls;
  for (const auto *field : declContext->decls()) {
    collectDeclsInField(field, &decls);
  }
  return decls;
}

/// \brief Returns true if the given decl is a boolean stage I/O variable.
/// Returns false if the type is not boolean, or the decl is a built-in stage
/// variable.
bool isBooleanStageIOVar(const NamedDecl *decl, QualType type,
                         const hlsl::DXIL::SemanticKind semanticKind,
                         const hlsl::SigPoint::Kind sigPointKind) {
  // [[vk::builtin(...)]] makes the decl a built-in stage variable.
  // IsFrontFace (if used as PSIn) is the only known boolean built-in stage
  // variable.
  const bool isBooleanBuiltin =
      (decl->getAttr<VKBuiltInAttr>() != nullptr) ||
      (semanticKind == hlsl::Semantic::Kind::IsFrontFace &&
       sigPointKind == hlsl::SigPoint::Kind::PSIn);

  // TODO: support boolean matrix stage I/O variable if needed.
  QualType elemType = {};
  const bool isBooleanType =
      ((isScalarType(type, &elemType) || isVectorType(type, &elemType)) &&
       elemType->isBooleanType());

  return isBooleanType && !isBooleanBuiltin;
}

/// \brief Returns the stage variable's register assignment for the given Decl.
const hlsl::RegisterAssignment *getResourceBinding(const NamedDecl *decl) {
  for (auto *annotation : decl->getUnusualAnnotations()) {
    if (auto *reg = dyn_cast<hlsl::RegisterAssignment>(annotation)) {
      return reg;
    }
  }
  return nullptr;
}

/// \brief Returns the stage variable's 'register(c#) assignment for the given
/// Decl. Return nullptr if the given variable does not have such assignment.
const hlsl::RegisterAssignment *getRegisterCAssignment(const NamedDecl *decl) {
  const auto *regAssignment = getResourceBinding(decl);
  if (regAssignment)
    return regAssignment->RegisterType == 'c' ? regAssignment : nullptr;
  return nullptr;
}

/// \brief Returns true if the given declaration has a primitive type qualifier.
/// Returns false otherwise.
inline bool hasGSPrimitiveTypeQualifier(const Decl *decl) {
  return decl->hasAttr<HLSLTriangleAttr>() ||
         decl->hasAttr<HLSLTriangleAdjAttr>() ||
         decl->hasAttr<HLSLPointAttr>() || decl->hasAttr<HLSLLineAttr>() ||
         decl->hasAttr<HLSLLineAdjAttr>();
}

/// \brief Deduces the parameter qualifier for the given decl.
hlsl::DxilParamInputQual deduceParamQual(const DeclaratorDecl *decl,
                                         bool asInput) {
  const auto type = decl->getType();

  if (hlsl::IsHLSLInputPatchType(type))
    return hlsl::DxilParamInputQual::InputPatch;
  if (hlsl::IsHLSLOutputPatchType(type))
    return hlsl::DxilParamInputQual::OutputPatch;
  // TODO: Add support for multiple output streams.
  if (hlsl::IsHLSLStreamOutputType(type))
    return hlsl::DxilParamInputQual::OutStream0;

  // The inputs to the geometry shader that have a primitive type qualifier
  // must use 'InputPrimitive'.
  if (hasGSPrimitiveTypeQualifier(decl))
    return hlsl::DxilParamInputQual::InputPrimitive;

  if (decl->hasAttr<HLSLIndicesAttr>())
    return hlsl::DxilParamInputQual::OutIndices;
  if (decl->hasAttr<HLSLVerticesAttr>())
    return hlsl::DxilParamInputQual::OutVertices;
  if (decl->hasAttr<HLSLPrimitivesAttr>())
    return hlsl::DxilParamInputQual::OutPrimitives;
  if (decl->hasAttr<HLSLPayloadAttr>())
    return hlsl::DxilParamInputQual::InPayload;

  return asInput ? hlsl::DxilParamInputQual::In : hlsl::DxilParamInputQual::Out;
}

/// \brief Deduces the HLSL SigPoint for the given decl appearing in the given
/// shader model.
const hlsl::SigPoint *deduceSigPoint(const DeclaratorDecl *decl, bool asInput,
                                     const hlsl::ShaderModel::Kind kind,
                                     bool forPCF) {
  return hlsl::SigPoint::GetSigPoint(hlsl::SigPointFromInputQual(
      deduceParamQual(decl, asInput), kind, forPCF));
}

/// Returns the type of the given decl. If the given decl is a FunctionDecl,
/// returns its result type.
inline QualType getTypeOrFnRetType(const DeclaratorDecl *decl) {
  if (const auto *funcDecl = dyn_cast<FunctionDecl>(decl)) {
    return funcDecl->getReturnType();
  }
  return decl->getType();
}

/// Returns the number of base classes if this type is a derived class/struct.
/// Returns zero otherwise.
inline uint32_t getNumBaseClasses(QualType type) {
  if (const auto *cxxDecl = type->getAsCXXRecordDecl())
    return cxxDecl->getNumBases();
  return 0;
}
} // anonymous namespace

std::string StageVar::getSemanticStr() const {
  // A special case for zero index, which is equivalent to no index.
  // Use what is in the source code.
  // TODO: this looks like a hack to make the current tests happy.
  // Should consider remove it and fix all tests.
  if (semanticInfo.index == 0)
    return semanticInfo.str;

  std::ostringstream ss;
  ss << semanticInfo.name.str() << semanticInfo.index;
  return ss.str();
}

SpirvInstruction *CounterIdAliasPair::get(SpirvBuilder &builder,
                                          SpirvContext &spvContext) const {
  if (isAlias) {
    const auto *counterType = spvContext.getACSBufferCounterType();
    const auto *counterVarType =
        spvContext.getPointerType(counterType, spv::StorageClass::Uniform);
    return builder.createLoad(counterVarType, counterVar,
                              /* SourceLocation */ {});
  }
  return counterVar;
}

const CounterIdAliasPair *
CounterVarFields::get(const llvm::SmallVectorImpl<uint32_t> &indices) const {
  for (const auto &field : fields)
    if (field.indices == indices)
      return &field.counterVar;
  return nullptr;
}

bool CounterVarFields::assign(const CounterVarFields &srcFields,
                              SpirvBuilder &builder,
                              SpirvContext &context) const {
  for (const auto &field : fields) {
    const auto *srcField = srcFields.get(field.indices);
    if (!srcField)
      return false;

    field.counterVar.assign(*srcField, builder, context);
  }

  return true;
}

bool CounterVarFields::assign(const CounterVarFields &srcFields,
                              const llvm::SmallVector<uint32_t, 4> &dstPrefix,
                              const llvm::SmallVector<uint32_t, 4> &srcPrefix,
                              SpirvBuilder &builder,
                              SpirvContext &context) const {
  if (dstPrefix.empty() && srcPrefix.empty())
    return assign(srcFields, builder, context);

  llvm::SmallVector<uint32_t, 4> srcIndices = srcPrefix;

  // If whole has the given prefix, appends all elements after the prefix in
  // whole to srcIndices.
  const auto applyDiff =
      [&srcIndices](const llvm::SmallVector<uint32_t, 4> &whole,
                    const llvm::SmallVector<uint32_t, 4> &prefix) -> bool {
    uint32_t i = 0;
    for (; i < prefix.size(); ++i)
      if (whole[i] != prefix[i]) {
        break;
      }
    if (i == prefix.size()) {
      for (; i < whole.size(); ++i)
        srcIndices.push_back(whole[i]);
      return true;
    }
    return false;
  };

  for (const auto &field : fields)
    if (applyDiff(field.indices, dstPrefix)) {
      const auto *srcField = srcFields.get(srcIndices);
      if (!srcField)
        return false;

      field.counterVar.assign(*srcField, builder, context);
      for (uint32_t i = srcPrefix.size(); i < srcIndices.size(); ++i)
        srcIndices.pop_back();
    }

  return true;
}

SemanticInfo DeclResultIdMapper::getStageVarSemantic(const NamedDecl *decl) {
  for (auto *annotation : decl->getUnusualAnnotations()) {
    if (auto *sema = dyn_cast<hlsl::SemanticDecl>(annotation)) {
      llvm::StringRef semanticStr = sema->SemanticName;
      llvm::StringRef semanticName;
      uint32_t index = 0;
      hlsl::Semantic::DecomposeNameAndIndex(semanticStr, &semanticName, &index);
      const auto *semantic = hlsl::Semantic::GetByName(semanticName);
      return {semanticStr, semantic, semanticName, index, sema->Loc};
    }
  }
  return {};
}

bool DeclResultIdMapper::createStageOutputVar(const DeclaratorDecl *decl,
                                              SpirvInstruction *storedValue,
                                              bool forPCF) {
  QualType type = getTypeOrFnRetType(decl);
  uint32_t arraySize = 0;

  // Output stream types (PointStream, LineStream, TriangleStream) are
  // translated as their underlying struct types.
  if (hlsl::IsHLSLStreamOutputType(type))
    type = hlsl::GetHLSLResourceResultType(type);

  if (decl->hasAttr<HLSLIndicesAttr>() || decl->hasAttr<HLSLVerticesAttr>() ||
      decl->hasAttr<HLSLPrimitivesAttr>()) {
    const auto *typeDecl = astContext.getAsConstantArrayType(type);
    type = typeDecl->getElementType();
    arraySize = static_cast<uint32_t>(typeDecl->getSize().getZExtValue());
    if (decl->hasAttr<HLSLIndicesAttr>()) {
      // create SPIR-V builtin array PrimitiveIndicesNV of type
      // "uint [MaxPrimitiveCount * verticesPerPrim]"
      uint32_t verticesPerPrim = 1;
      if (!isVectorType(type, nullptr, &verticesPerPrim)) {
        assert(isScalarType(type));
      }
      arraySize = arraySize * verticesPerPrim;
      QualType arrayType = astContext.getConstantArrayType(
          astContext.UnsignedIntTy, llvm::APInt(32, arraySize),
          clang::ArrayType::Normal, 0);
      stageVarInstructions[cast<DeclaratorDecl>(decl)] = getBuiltinVar(
          spv::BuiltIn::PrimitiveIndicesNV, arrayType, decl->getLocation());
      return true;
    }
  }

  const auto *sigPoint = deduceSigPoint(
      decl, /*asInput=*/false, spvContext.getCurrentShaderModelKind(), forPCF);

  // HS output variables are created using the other overload. For the rest,
  // none of them should be created as arrays.
  assert(sigPoint->GetKind() != hlsl::DXIL::SigPointKind::HSCPOut);

  SemanticInfo inheritSemantic = {};

  // If storedValue is 0, it means this parameter in the original source code is
  // not used at all. Avoid writing back.
  //
  // Write back of stage output variables in GS is manually controlled by
  // .Append() intrinsic method, implemented in writeBackOutputStream(). So
  // ignoreValue should be set to true for GS.
  const bool noWriteBack =
      storedValue == nullptr || spvContext.isGS() || spvContext.isMS();

  return createStageVars(sigPoint, decl, /*asInput=*/false, type, arraySize,
                         "out.var", llvm::None, &storedValue, noWriteBack,
                         &inheritSemantic);
}

bool DeclResultIdMapper::createStageOutputVar(const DeclaratorDecl *decl,
                                              uint32_t arraySize,
                                              SpirvInstruction *invocationId,
                                              SpirvInstruction *storedValue) {
  assert(spvContext.isHS());

  QualType type = getTypeOrFnRetType(decl);

  const auto *sigPoint =
      hlsl::SigPoint::GetSigPoint(hlsl::DXIL::SigPointKind::HSCPOut);

  SemanticInfo inheritSemantic = {};

  return createStageVars(sigPoint, decl, /*asInput=*/false, type, arraySize,
                         "out.var", invocationId, &storedValue,
                         /*noWriteBack=*/false, &inheritSemantic);
}

bool DeclResultIdMapper::createStageInputVar(const ParmVarDecl *paramDecl,
                                             SpirvInstruction **loadedValue,
                                             bool forPCF) {
  uint32_t arraySize = 0;
  QualType type = paramDecl->getType();

  // Deprive the outermost arrayness for HS/DS/GS and use arraySize
  // to convey that information
  if (hlsl::IsHLSLInputPatchType(type)) {
    arraySize = hlsl::GetHLSLInputPatchCount(type);
    type = hlsl::GetHLSLInputPatchElementType(type);
  } else if (hlsl::IsHLSLOutputPatchType(type)) {
    arraySize = hlsl::GetHLSLOutputPatchCount(type);
    type = hlsl::GetHLSLOutputPatchElementType(type);
  }
  if (hasGSPrimitiveTypeQualifier(paramDecl)) {
    const auto *typeDecl = astContext.getAsConstantArrayType(type);
    arraySize = static_cast<uint32_t>(typeDecl->getSize().getZExtValue());
    type = typeDecl->getElementType();
  }

  const auto *sigPoint =
      deduceSigPoint(paramDecl, /*asInput=*/true,
                     spvContext.getCurrentShaderModelKind(), forPCF);

  SemanticInfo inheritSemantic = {};

  if (paramDecl->hasAttr<HLSLPayloadAttr>()) {
    spv::StorageClass sc = getStorageClassForSigPoint(sigPoint);
    return createPayloadStageVars(sigPoint, sc, paramDecl, /*asInput=*/true,
                                  type, "in.var", loadedValue);
  } else {
    return createStageVars(sigPoint, paramDecl, /*asInput=*/true, type,
                           arraySize, "in.var", llvm::None, loadedValue,
                           /*noWriteBack=*/false, &inheritSemantic);
  }
}

const DeclResultIdMapper::DeclSpirvInfo *
DeclResultIdMapper::getDeclSpirvInfo(const ValueDecl *decl) const {
  auto it = astDecls.find(decl);
  if (it != astDecls.end())
    return &it->second;

  return nullptr;
}

SpirvInstruction *DeclResultIdMapper::getDeclEvalInfo(const ValueDecl *decl,
                                                      SourceLocation loc) {
  if (const auto *info = getDeclSpirvInfo(decl)) {
    if (info->indexInCTBuffer >= 0) {
      // If this is a VarDecl inside a HLSLBufferDecl, we need to do an extra
      // OpAccessChain to get the pointer to the variable since we created
      // a single variable for the whole buffer object.

      // Should only have VarDecls in a HLSLBufferDecl.
      QualType valueType = cast<VarDecl>(decl)->getType();
      return spvBuilder.createAccessChain(
          valueType, info->instr,
          {spvBuilder.getConstantInt(
              astContext.IntTy, llvm::APInt(32, info->indexInCTBuffer, true))},
          loc);
    } else {
      return *info;
    }
  }

  emitFatalError("found unregistered decl", decl->getLocation())
      << decl->getName();
  emitNote("please file a bug report on "
           "https://github.com/Microsoft/DirectXShaderCompiler/issues with "
           "source code if possible",
           {});
  return 0;
}

SpirvFunctionParameter *
DeclResultIdMapper::createFnParam(const ParmVarDecl *param) {
  const auto type = getTypeOrFnRetType(param);
  const auto loc = param->getLocation();
  SpirvFunctionParameter *fnParamInstr = spvBuilder.addFnParam(
      type, param->hasAttr<HLSLPreciseAttr>(), loc, param->getName());

  bool isAlias = false;
  (void)getTypeAndCreateCounterForPotentialAliasVar(param, &isAlias);
  fnParamInstr->setContainsAliasComponent(isAlias);

  assert(astDecls[param].instr == nullptr);
  astDecls[param].instr = fnParamInstr;

  return fnParamInstr;
}

void DeclResultIdMapper::createCounterVarForDecl(const DeclaratorDecl *decl) {
  const QualType declType = getTypeOrFnRetType(decl);

  if (!counterVars.count(decl) && isRWAppendConsumeSBuffer(declType)) {
    createCounterVar(decl, /*declId=*/0, /*isAlias=*/true);
  } else if (!fieldCounterVars.count(decl) && declType->isStructureType() &&
             // Exclude other resource types which are represented as structs
             !hlsl::IsHLSLResourceType(declType)) {
    createFieldCounterVars(decl);
  }
}

SpirvVariable *
DeclResultIdMapper::createFnVar(const VarDecl *var,
                                llvm::Optional<SpirvInstruction *> init) {
  const auto type = getTypeOrFnRetType(var);
  const auto loc = var->getLocation();
  const auto name = var->getName();
  const bool isPrecise = var->hasAttr<HLSLPreciseAttr>();
  SpirvVariable *varInstr = spvBuilder.addFnVar(
      type, loc, name, isPrecise, init.hasValue() ? init.getValue() : nullptr);

  bool isAlias = false;
  (void)getTypeAndCreateCounterForPotentialAliasVar(var, &isAlias);
  varInstr->setContainsAliasComponent(isAlias);

  assert(astDecls[var].instr == nullptr);
  astDecls[var].instr = varInstr;

  return varInstr;
}

SpirvVariable *
DeclResultIdMapper::createFileVar(const VarDecl *var,
                                  llvm::Optional<SpirvInstruction *> init) {
  const auto type = getTypeOrFnRetType(var);
  const auto loc = var->getLocation();
  SpirvVariable *varInstr = spvBuilder.addModuleVar(
      type, spv::StorageClass::Private, var->hasAttr<HLSLPreciseAttr>(),
      var->getName(), init, loc);

  bool isAlias = false;
  (void)getTypeAndCreateCounterForPotentialAliasVar(var, &isAlias);
  varInstr->setContainsAliasComponent(isAlias);

  assert(astDecls[var].instr == nullptr);
  astDecls[var].instr = varInstr;

  return varInstr;
}

SpirvVariable *DeclResultIdMapper::createExternVar(const VarDecl *var) {
  auto storageClass = spv::StorageClass::UniformConstant;
  auto rule = SpirvLayoutRule::Void;
  bool isACRWSBuffer = false; // Whether is {Append|Consume|RW}StructuredBuffer

  if (var->getAttr<HLSLGroupSharedAttr>()) {
    // For CS groupshared variables
    storageClass = spv::StorageClass::Workgroup;
  } else if (isResourceType(var)) {
    // See through the possible outer arrays
    QualType resourceType = var->getType();
    while (resourceType->isArrayType()) {
      resourceType = resourceType->getAsArrayTypeUnsafe()->getElementType();
    }

    const llvm::StringRef typeName =
        resourceType->getAs<RecordType>()->getDecl()->getName();

    // These types are all translated into OpTypeStruct with BufferBlock
    // decoration. They should follow standard storage buffer layout,
    // which GLSL std430 rules statisfies.
    if (typeName == "StructuredBuffer" || typeName == "ByteAddressBuffer" ||
        typeName == "RWByteAddressBuffer") {
      storageClass = spv::StorageClass::Uniform;
      rule = spirvOptions.sBufferLayoutRule;
    } else if (typeName == "RWStructuredBuffer" ||
               typeName == "AppendStructuredBuffer" ||
               typeName == "ConsumeStructuredBuffer") {
      storageClass = spv::StorageClass::Uniform;
      rule = spirvOptions.sBufferLayoutRule;
      isACRWSBuffer = true;
    }
  } else {
    // This is a stand-alone externally-visiable non-resource-type variable.
    // They should be grouped into the $Globals cbuffer. We create that cbuffer
    // and record all variables inside it upon seeing the first such variable.
    if (astDecls.count(var) == 0)
      createGlobalsCBuffer(var);

    auto *varInstr = astDecls[var].instr;
    return varInstr ? cast<SpirvVariable>(varInstr) : nullptr;
  }

  const auto type = var->getType();
  const auto loc = var->getLocation();
  SpirvVariable *varInstr = spvBuilder.addModuleVar(
      type, storageClass, var->hasAttr<HLSLPreciseAttr>(), var->getName(),
      llvm::None, loc);
  varInstr->setLayoutRule(rule);
  DeclSpirvInfo info(varInstr);
  astDecls[var] = info;

  // Variables in Workgroup do not need descriptor decorations.
  if (storageClass == spv::StorageClass::Workgroup)
    return varInstr;

  const auto *regAttr = getResourceBinding(var);
  const auto *bindingAttr = var->getAttr<VKBindingAttr>();
  const auto *counterBindingAttr = var->getAttr<VKCounterBindingAttr>();

  resourceVars.emplace_back(varInstr, var, loc, regAttr, bindingAttr,
                            counterBindingAttr);

  if (const auto *inputAttachment = var->getAttr<VKInputAttachmentIndexAttr>())
    spvBuilder.decorateInputAttachmentIndex(varInstr,
                                            inputAttachment->getIndex(), loc);

  if (isACRWSBuffer) {
    // For {Append|Consume|RW}StructuredBuffer, we need to always create another
    // variable for its associated counter.
    createCounterVar(var, varInstr, /*isAlias=*/false);
  }

  return varInstr;
}

SpirvInstruction *
DeclResultIdMapper::createOrUpdateStringVar(const VarDecl *var) {
  assert(hlsl::IsStringType(var->getType()) ||
         hlsl::IsStringLiteralType(var->getType()));

  // If the string variable is not initialized to a string literal, we cannot
  // generate an OpString for it.
  if (!var->hasInit()) {
    emitError("Found uninitialized string variable.", var->getLocation());
    return nullptr;
  }

  const StringLiteral *stringLiteral =
      dyn_cast<StringLiteral>(var->getInit()->IgnoreParenCasts());
  SpirvString *init = spvBuilder.getString(stringLiteral->getString());
  DeclSpirvInfo info(init);
  astDecls[var] = info;
  return init;
}

SpirvVariable *DeclResultIdMapper::createStructOrStructArrayVarOfExplicitLayout(
    const DeclContext *decl, int arraySize, const ContextUsageKind usageKind,
    llvm::StringRef typeName, llvm::StringRef varName) {
  // cbuffers are translated into OpTypeStruct with Block decoration.
  // tbuffers are translated into OpTypeStruct with BufferBlock decoration.
  // Push constants are translated into OpTypeStruct with Block decoration.
  //
  // Both cbuffers and tbuffers have the SPIR-V Uniform storage class.
  // Push constants have the SPIR-V PushConstant storage class.

  const bool forCBuffer = usageKind == ContextUsageKind::CBuffer;
  const bool forTBuffer = usageKind == ContextUsageKind::TBuffer;
  const bool forGlobals = usageKind == ContextUsageKind::Globals;
  const bool forPC = usageKind == ContextUsageKind::PushConstant;
  const bool forShaderRecordNV =
      usageKind == ContextUsageKind::ShaderRecordBufferNV;

  const llvm::SmallVector<const Decl *, 4> &declGroup =
      collectDeclsInDeclContext(decl);

  // Collect the type and name for each field
  llvm::SmallVector<HybridStructType::FieldInfo, 4> fields;
  for (const auto *subDecl : declGroup) {
    // 'groupshared' variables should not be placed in $Globals cbuffer.
    if (forGlobals && subDecl->hasAttr<HLSLGroupSharedAttr>())
      continue;

    // The field can only be FieldDecl (for normal structs) or VarDecl (for
    // HLSLBufferDecls).
    assert(isa<VarDecl>(subDecl) || isa<FieldDecl>(subDecl));
    const auto *declDecl = cast<DeclaratorDecl>(subDecl);

    // In case 'register(c#)' annotation is placed on a global variable.
    const hlsl::RegisterAssignment *registerC =
        forGlobals ? getRegisterCAssignment(declDecl) : nullptr;

    // All fields are qualified with const. It will affect the debug name.
    // We don't need it here.
    auto varType = declDecl->getType();
    varType.removeLocalConst();
    HybridStructType::FieldInfo info(varType, declDecl->getName(),
                                     declDecl->getAttr<VKOffsetAttr>(),
                                     getPackOffset(declDecl), registerC,
                                     declDecl->hasAttr<HLSLPreciseAttr>());
    fields.push_back(info);
  }

  // Get the type for the whole struct
  // tbuffer/TextureBuffers are non-writable SSBOs.
  const SpirvType *resultType = spvContext.getHybridStructType(
      fields, typeName, /*isReadOnly*/ forTBuffer,
      forTBuffer ? StructInterfaceType::StorageBuffer
                 : StructInterfaceType::UniformBuffer);

  // Make an array if requested.
  if (arraySize > 0) {
    resultType = spvContext.getArrayType(resultType, arraySize,
                                         /*ArrayStride*/ llvm::None);
  } else if (arraySize == -1) {
    resultType =
        spvContext.getRuntimeArrayType(resultType, /*ArrayStride*/ llvm::None);
  }

  // Register the <type-id> for this decl
  ctBufferPCTypes[decl] = resultType;

  const auto sc = forPC ? spv::StorageClass::PushConstant
                        : forShaderRecordNV
                              ? spv::StorageClass::ShaderRecordBufferNV
                              : spv::StorageClass::Uniform;

  // Create the variable for the whole struct / struct array.
  // The fields may be 'precise', but the structure itself is not.
  SpirvVariable *var =
      spvBuilder.addModuleVar(resultType, sc, /*isPrecise*/ false, varName);

  const SpirvLayoutRule layoutRule =
      (forCBuffer || forGlobals)
          ? spirvOptions.cBufferLayoutRule
          : (forTBuffer ? spirvOptions.tBufferLayoutRule
                        : spirvOptions.sBufferLayoutRule);

  var->setHlslUserType(forCBuffer ? "cbuffer" : forTBuffer ? "tbuffer" : "");
  var->setLayoutRule(layoutRule);
  return var;
}

void DeclResultIdMapper::createEnumConstant(const EnumConstantDecl *decl) {
  const auto *valueDecl = dyn_cast<ValueDecl>(decl);
  const auto enumConstant =
      spvBuilder.getConstantInt(astContext.IntTy, decl->getInitVal());
  SpirvVariable *varInstr = spvBuilder.addModuleVar(
      astContext.IntTy, spv::StorageClass::Private, /*isPrecise*/ false,
      decl->getName(), enumConstant, decl->getLocation());
  astDecls[valueDecl] = DeclSpirvInfo(varInstr);
}

SpirvVariable *DeclResultIdMapper::createCTBuffer(const HLSLBufferDecl *decl) {
  const auto usageKind =
      decl->isCBuffer() ? ContextUsageKind::CBuffer : ContextUsageKind::TBuffer;
  const std::string structName = "type." + decl->getName().str();
  // The front-end does not allow arrays of cbuffer/tbuffer.
  SpirvVariable *bufferVar = createStructOrStructArrayVarOfExplicitLayout(
      decl, /*arraySize*/ 0, usageKind, structName, decl->getName());

  // We still register all VarDecls seperately here. All the VarDecls are
  // mapped to the <result-id> of the buffer object, which means when querying
  // querying the <result-id> for a certain VarDecl, we need to do an extra
  // OpAccessChain.
  int index = 0;
  for (const auto *subDecl : decl->decls()) {
    if (shouldSkipInStructLayout(subDecl))
      continue;

    const auto *varDecl = cast<VarDecl>(subDecl);
    astDecls[varDecl] = DeclSpirvInfo(bufferVar, index++);
  }
  resourceVars.emplace_back(
      bufferVar, decl, decl->getLocation(), getResourceBinding(decl),
      decl->getAttr<VKBindingAttr>(), decl->getAttr<VKCounterBindingAttr>());

  return bufferVar;
}

SpirvVariable *DeclResultIdMapper::createCTBuffer(const VarDecl *decl) {
  const RecordType *recordType = nullptr;
  int arraySize = 0;

  // In case we have an array of ConstantBuffer/TextureBuffer:
  if (const auto *arrayType = decl->getType()->getAsArrayTypeUnsafe()) {
    recordType = arrayType->getElementType()->getAs<RecordType>();
    if (const auto *caType =
            astContext.getAsConstantArrayType(decl->getType())) {
      arraySize = static_cast<uint32_t>(caType->getSize().getZExtValue());
    } else {
      arraySize = -1;
    }
  } else {
    recordType = decl->getType()->getAs<RecordType>();
  }
  if (!recordType) {
    emitError("constant/texture buffer type %0 unimplemented",
              decl->getLocStart())
        << decl->getType();
    return 0;
  }

  const auto *context = cast<HLSLBufferDecl>(decl->getDeclContext());
  const auto usageKind = context->isCBuffer() ? ContextUsageKind::CBuffer
                                              : ContextUsageKind::TBuffer;

  const char *ctBufferName =
      context->isCBuffer() ? "ConstantBuffer." : "TextureBuffer.";
  const std::string structName = "type." + std::string(ctBufferName) +
                                 recordType->getDecl()->getName().str();

  SpirvVariable *bufferVar = createStructOrStructArrayVarOfExplicitLayout(
      recordType->getDecl(), arraySize, usageKind, structName, decl->getName());

  // We register the VarDecl here.
  astDecls[decl] = DeclSpirvInfo(bufferVar);
  resourceVars.emplace_back(
      bufferVar, decl, decl->getLocation(), getResourceBinding(context),
      decl->getAttr<VKBindingAttr>(), decl->getAttr<VKCounterBindingAttr>());

  return bufferVar;
}

SpirvVariable *DeclResultIdMapper::createPushConstant(const VarDecl *decl) {
  // The front-end errors out if non-struct type push constant is used.
  const auto *recordType = decl->getType()->getAs<RecordType>();
  assert(recordType);

  const std::string structName =
      "type.PushConstant." + recordType->getDecl()->getName().str();
  SpirvVariable *var = createStructOrStructArrayVarOfExplicitLayout(
      recordType->getDecl(), /*arraySize*/ 0, ContextUsageKind::PushConstant,
      structName, decl->getName());

  // Register the VarDecl
  astDecls[decl] = DeclSpirvInfo(var);

  // Do not push this variable into resourceVars since it does not need
  // descriptor set.

  return var;
}

SpirvVariable *
DeclResultIdMapper::createShaderRecordBufferNV(const VarDecl *decl) {
  const auto *recordType = decl->getType()->getAs<RecordType>();
  assert(recordType);

  const std::string structName =
      "type.ShaderRecordBufferNV." + recordType->getDecl()->getName().str();
  SpirvVariable *var = createStructOrStructArrayVarOfExplicitLayout(
      recordType->getDecl(), /*arraySize*/ 0,
      ContextUsageKind::ShaderRecordBufferNV, structName, decl->getName());

  // Register the VarDecl
  astDecls[decl] = DeclSpirvInfo(var);

  // Do not push this variable into resourceVars since it does not need
  // descriptor set.

  return var;
}

SpirvVariable *
DeclResultIdMapper::createShaderRecordBufferNV(const HLSLBufferDecl *decl) {

  const std::string structName =
      "type.ShaderRecordBufferNV." + decl->getName().str();
  // The front-end does not allow arrays of cbuffer/tbuffer.
  SpirvVariable *bufferVar = createStructOrStructArrayVarOfExplicitLayout(
      decl, /*arraySize*/ 0, ContextUsageKind::ShaderRecordBufferNV, structName,
      decl->getName());

  // We still register all VarDecls seperately here. All the VarDecls are
  // mapped to the <result-id> of the buffer object, which means when
  // querying the <result-id> for a certain VarDecl, we need to do an extra
  // OpAccessChain.
  int index = 0;
  for (const auto *subDecl : decl->decls()) {
    if (shouldSkipInStructLayout(subDecl))
      continue;

    const auto *varDecl = cast<VarDecl>(subDecl);
    astDecls[varDecl] = DeclSpirvInfo(bufferVar, index++);
  }
  return bufferVar;
}

void DeclResultIdMapper::createGlobalsCBuffer(const VarDecl *var) {
  if (astDecls.count(var) != 0)
    return;

  const auto *context = var->getTranslationUnitDecl();
  SpirvVariable *globals = createStructOrStructArrayVarOfExplicitLayout(
      context, /*arraySize*/ 0, ContextUsageKind::Globals, "type.$Globals",
      "$Globals");

  resourceVars.emplace_back(globals, /*decl*/ nullptr, SourceLocation(),
                            nullptr, nullptr, nullptr, /*isCounterVar*/ false,
                            /*isGlobalsCBuffer*/ true);

  uint32_t index = 0;
  for (const auto *decl : collectDeclsInDeclContext(context)) {
    // 'groupshared' variables should not be placed in $Globals cbuffer.
    if (decl->hasAttr<HLSLGroupSharedAttr>())
      continue;
    if (const auto *varDecl = dyn_cast<VarDecl>(decl)) {
      if (!spirvOptions.noWarnIgnoredFeatures) {
        if (const auto *init = varDecl->getInit())
          emitWarning(
              "variable '%0' will be placed in $Globals so initializer ignored",
              init->getExprLoc())
              << var->getName() << init->getSourceRange();
      }
      if (const auto *attr = varDecl->getAttr<VKBindingAttr>()) {
        emitError("variable '%0' will be placed in $Globals so cannot have "
                  "vk::binding attribute",
                  attr->getLocation())
            << var->getName();
        return;
      }

      astDecls[varDecl] = DeclSpirvInfo(globals, index++);
    }
  }
}

SpirvFunction *DeclResultIdMapper::getOrRegisterFn(const FunctionDecl *fn) {
  // Return it if it's already been created.
  auto it = astFunctionDecls.find(fn);
  if (it != astFunctionDecls.end()) {
    return it->second;
  }

  bool isAlias = false;
  (void)getTypeAndCreateCounterForPotentialAliasVar(fn, &isAlias);

  const bool isPrecise = fn->hasAttr<HLSLPreciseAttr>();
  // Note: we do not need to worry about function parameter types at this point
  // as this is used when function declarations are seen. When function
  // definition is seen, the parameter types will be set properly and take into
  // account whether the function is a member function of a class/struct (in
  // which case a 'this' parameter is added at the beginnig).
  SpirvFunction *spirvFunction = new (spvContext)
      SpirvFunction(fn->getReturnType(), /* param QualTypes */ {},
                    fn->getLocation(), fn->getName(), isPrecise);

  // No need to dereference to get the pointer. Function returns that are
  // stand-alone aliases are already pointers to values. All other cases should
  // be normal rvalues.
  if (!isAlias || !isAKindOfStructuredOrByteBuffer(fn->getReturnType()))
    spirvFunction->setRValue();

  spirvFunction->setConstainsAliasComponent(isAlias);

  astFunctionDecls[fn] = spirvFunction;
  return spirvFunction;
}

const CounterIdAliasPair *DeclResultIdMapper::getCounterIdAliasPair(
    const DeclaratorDecl *decl, const llvm::SmallVector<uint32_t, 4> *indices) {
  if (!decl)
    return nullptr;

  if (indices) {
    // Indices are provided. Walk through the fields of the decl.
    const auto counter = fieldCounterVars.find(decl);
    if (counter != fieldCounterVars.end())
      return counter->second.get(*indices);
  } else {
    // No indices. Check the stand-alone entities.
    const auto counter = counterVars.find(decl);
    if (counter != counterVars.end())
      return &counter->second;
  }

  return nullptr;
}

const CounterVarFields *
DeclResultIdMapper::getCounterVarFields(const DeclaratorDecl *decl) {
  if (!decl)
    return nullptr;

  const auto found = fieldCounterVars.find(decl);
  if (found != fieldCounterVars.end())
    return &found->second;

  return nullptr;
}

void DeclResultIdMapper::registerSpecConstant(const VarDecl *decl,
                                              SpirvInstruction *specConstant) {
  specConstant->setRValue();
  astDecls[decl] = DeclSpirvInfo(specConstant);
}

void DeclResultIdMapper::createCounterVar(
    const DeclaratorDecl *decl, SpirvInstruction *declInstr, bool isAlias,
    const llvm::SmallVector<uint32_t, 4> *indices) {
  std::string counterName = "counter.var." + decl->getName().str();
  if (indices) {
    // Append field indices to the name
    for (const auto index : *indices)
      counterName += "." + std::to_string(index);
  }

  const SpirvType *counterType = spvContext.getACSBufferCounterType();
  // {RW|Append|Consume}StructuredBuffer are all in Uniform storage class.
  // Alias counter variables should be created into the Private storage class.
  const spv::StorageClass sc =
      isAlias ? spv::StorageClass::Private : spv::StorageClass::Uniform;

  if (isAlias) {
    // Apply an extra level of pointer for alias counter variable
    counterType =
        spvContext.getPointerType(counterType, spv::StorageClass::Uniform);
  }

  SpirvVariable *counterInstr = spvBuilder.addModuleVar(
      counterType, sc, /*isPrecise*/ false, counterName);

  if (!isAlias) {
    // Non-alias counter variables should be put in to resourceVars so that
    // descriptors can be allocated for them.
    resourceVars.emplace_back(counterInstr, decl, decl->getLocation(),
                              getResourceBinding(decl),
                              decl->getAttr<VKBindingAttr>(),
                              decl->getAttr<VKCounterBindingAttr>(), true);
    assert(declInstr);
    spvBuilder.decorateCounterBuffer(declInstr, counterInstr,
                                     decl->getLocation());
  }

  if (indices)
    fieldCounterVars[decl].append(*indices, counterInstr);
  else
    counterVars[decl] = {counterInstr, isAlias};
}

void DeclResultIdMapper::createFieldCounterVars(
    const DeclaratorDecl *rootDecl, const DeclaratorDecl *decl,
    llvm::SmallVector<uint32_t, 4> *indices) {
  const QualType type = getTypeOrFnRetType(decl);
  const auto *recordType = type->getAs<RecordType>();
  assert(recordType);
  const auto *recordDecl = recordType->getDecl();

  for (const auto *field : recordDecl->fields()) {
    // Build up the index chain
    indices->push_back(getNumBaseClasses(type) + field->getFieldIndex());

    const QualType fieldType = field->getType();
    if (isRWAppendConsumeSBuffer(fieldType))
      createCounterVar(rootDecl, /*declId=*/0, /*isAlias=*/true, indices);
    else if (fieldType->isStructureType() &&
             !hlsl::IsHLSLResourceType(fieldType))
      // Go recursively into all nested structs
      createFieldCounterVars(rootDecl, field, indices);

    indices->pop_back();
  }
}

const SpirvType *
DeclResultIdMapper::getCTBufferPushConstantType(const DeclContext *decl) {
  const auto found = ctBufferPCTypes.find(decl);
  assert(found != ctBufferPCTypes.end());
  return found->second;
}

std::vector<SpirvVariable *> DeclResultIdMapper::collectStageVars() const {
  std::vector<SpirvVariable *> vars;

  for (auto var : glPerVertex.getStageInVars())
    vars.push_back(var);
  for (auto var : glPerVertex.getStageOutVars())
    vars.push_back(var);

  llvm::DenseSet<SpirvInstruction *> seenVars;
  for (const auto &var : stageVars) {
    auto *instr = var.getSpirvInstr();
    if (seenVars.count(instr) == 0) {
      vars.push_back(instr);
      seenVars.insert(instr);
    }
  }

  return vars;
}

namespace {
/// A class for managing stage input/output locations to avoid duplicate uses of
/// the same location.
class LocationSet {
public:
  /// Maximum number of indices supported
  const static uint32_t kMaxIndex = 2;
  /// Maximum number of locations supported
  // Typically we won't have that many stage input or output variables.
  // Using 64 should be fine here.
  const static uint32_t kMaxLoc = 64;

  LocationSet() {
    for (uint32_t i = 0; i < kMaxIndex; ++i) {
      usedLocs[i].resize(kMaxLoc);
      nextLoc[i] = 0;
    }
  }

  /// Uses the given location.
  void useLoc(uint32_t loc, uint32_t index = 0) {
    assert(index < kMaxIndex);
    usedLocs[index].set(loc);
  }

  /// Uses the next |count| available location.
  int useNextLocs(uint32_t count, uint32_t index = 0) {
    assert(index < kMaxIndex);
    auto &locs = usedLocs[index];
    auto &next = nextLoc[index];
    while (locs[next])
      next++;

    int toUse = next;

    for (uint32_t i = 0; i < count; ++i) {
      assert(!locs[next]);
      locs.set(next++);
    }

    return toUse;
  }

  /// Returns true if the given location number is already used.
  bool isLocUsed(uint32_t loc, uint32_t index = 0) {
    assert(index < kMaxIndex);
    return usedLocs[index][loc];
  }

private:
  llvm::SmallBitVector usedLocs[kMaxIndex]; ///< All previously used locations
  uint32_t nextLoc[kMaxIndex];              ///< Next available location
};

/// A class for managing resource bindings to avoid duplicate uses of the same
/// set and binding number.
class BindingSet {
public:
  /// Uses the given set and binding number. Returns false if the binding number
  /// was already occupied in the set, and returns true otherwise.
  bool useBinding(uint32_t binding, uint32_t set) {
    bool inserted = false;
    std::tie(std::ignore, inserted) = usedBindings[set].insert(binding);
    return inserted;
  }

  /// Uses the next avaiable binding number in |set|. If more than one binding
  /// number is to be occupied, it finds the next available chunk that can fit
  /// |numBindingsToUse| in the |set|.
  uint32_t useNextBinding(uint32_t set, uint32_t numBindingsToUse = 1) {
    uint32_t bindingNoStart = getNextBindingChunk(set, numBindingsToUse);
    auto &binding = usedBindings[set];
    for (uint32_t i = 0; i < numBindingsToUse; ++i)
      binding.insert(bindingNoStart + i);
    return bindingNoStart;
  }

  /// Returns the first available binding number in the |set| for which |n|
  /// consecutive binding numbers are unused.
  uint32_t getNextBindingChunk(uint32_t set, uint32_t n) {
    auto &existingBindings = usedBindings[set];

    // There were no bindings in this set. Can start at binding zero.
    if (existingBindings.empty())
      return 0;

    // Check whether the chunk of |n| binding numbers can be fitted at the
    // very beginning of the list (start at binding 0 in the current set).
    uint32_t curBinding = *existingBindings.begin();
    if (curBinding >= n)
      return 0;

    auto iter = std::next(existingBindings.begin());
    while (iter != existingBindings.end()) {
      // There exists a next binding number that is used. Check to see if the
      // gap between current binding number and next binding number is large
      // enough to accommodate |n|.
      uint32_t nextBinding = *iter;
      if (n <= nextBinding - curBinding - 1)
        return curBinding + 1;

      curBinding = nextBinding;

      // Peek at the next binding that has already been used (if any).
      ++iter;
    }

    // |curBinding| was the last binding that was used in this set. The next
    // chunk of |n| bindings can start at |curBinding|+1.
    return curBinding + 1;
  }

private:
  ///< set number -> set of used binding number
  llvm::DenseMap<uint32_t, std::set<uint32_t>> usedBindings;
};
} // namespace

bool DeclResultIdMapper::checkSemanticDuplication(bool forInput) {
  llvm::StringSet<> seenSemantics;
  bool success = true;
  for (const auto &var : stageVars) {
    auto s = var.getSemanticStr();

    if (s.empty()) {
      // We translate WaveGetLaneCount(), WaveGetLaneIndex() and 'payload' param
      // block declaration into builtin variables. Those variables are inserted
      // into the normal stage IO processing pipeline, but with the semantics as
      // empty strings.
      assert(var.isSpirvBuitin());
      continue;
    }

    // Allow builtin variables to alias each other. We already have uniqify
    // mechanism in SpirvBuilder.
    if (var.isSpirvBuitin())
      continue;

    if (forInput && var.getSigPoint()->IsInput()) {
      if (seenSemantics.count(s)) {
        emitError("input semantic '%0' used more than once", {}) << s;
        success = false;
      }
      seenSemantics.insert(s);
    } else if (!forInput && var.getSigPoint()->IsOutput()) {
      if (seenSemantics.count(s)) {
        emitError("output semantic '%0' used more than once", {}) << s;
        success = false;
      }
      seenSemantics.insert(s);
    }
  }

  return success;
}

bool DeclResultIdMapper::finalizeStageIOLocations(bool forInput) {
  if (!checkSemanticDuplication(forInput))
    return false;

  // Returns false if the given StageVar is an input/output variable without
  // explicit location assignment. Otherwise, returns true.
  const auto locAssigned = [forInput, this](const StageVar &v) {
    if (forInput == isInputStorageClass(v))
      // No need to assign location for builtins. Treat as assigned.
      return v.isSpirvBuitin() || v.getLocationAttr() != nullptr;
    // For the ones we don't care, treat as assigned.
    return true;
  };

  // If we have explicit location specified for all input/output variables,
  // use them instead assign by ourselves.
  if (std::all_of(stageVars.begin(), stageVars.end(), locAssigned)) {
    LocationSet locSet;
    bool noError = true;

    for (const auto &var : stageVars) {
      // Skip builtins & those stage variables we are not handling for this call
      if (var.isSpirvBuitin() || forInput != isInputStorageClass(var))
        continue;

      const auto *attr = var.getLocationAttr();
      const auto loc = attr->getNumber();
      const auto attrLoc = attr->getLocation(); // Attr source code location
      const auto idx = var.getIndexAttr() ? var.getIndexAttr()->getNumber() : 0;

      if ((const unsigned)loc >= LocationSet::kMaxLoc) {
        emitError("stage %select{output|input}0 location #%1 too large",
                  attrLoc)
            << forInput << loc;
        return false;
      }

      // Make sure the same location is not assigned more than once
      if (locSet.isLocUsed(loc, idx)) {
        emitError("stage %select{output|input}0 location #%1 already assigned",
                  attrLoc)
            << forInput << loc;
        noError = false;
      }
      locSet.useLoc(loc, idx);

      spvBuilder.decorateLocation(var.getSpirvInstr(), loc);
      if (var.getIndexAttr())
        spvBuilder.decorateIndex(var.getSpirvInstr(), idx,
                                 var.getSemanticInfo().loc);
    }

    return noError;
  }

  std::vector<const StageVar *> vars;
  LocationSet locSet;

  for (const auto &var : stageVars) {
    if (var.isSpirvBuitin() || forInput != isInputStorageClass(var))
      continue;

    if (var.getLocationAttr()) {
      // We have checked that not all of the stage variables have explicit
      // location assignment.
      emitError("partial explicit stage %select{output|input}0 location "
                "assignment via vk::location(X) unsupported",
                {})
          << forInput;
      return false;
    }

    const auto &semaInfo = var.getSemanticInfo();

    // We should special rules for SV_Target: the location number comes from the
    // semantic string index.
    if (semaInfo.isTarget()) {
      spvBuilder.decorateLocation(var.getSpirvInstr(), semaInfo.index);
      locSet.useLoc(semaInfo.index);
    } else {
      vars.push_back(&var);
    }
  }

  // If alphabetical ordering was requested, sort by semantic string.
  // Since HS includes 2 sets of outputs (patch-constant output and
  // OutputPatch), running into location mismatches between HS and DS is very
  // likely. In order to avoid location mismatches between HS and DS, use
  // alphabetical ordering.
  if (spirvOptions.stageIoOrder == "alpha" ||
      (!forInput && spvContext.isHS()) || (forInput && spvContext.isDS())) {
    // Sort stage input/output variables alphabetically
    std::sort(vars.begin(), vars.end(),
              [](const StageVar *a, const StageVar *b) {
                return a->getSemanticStr() < b->getSemanticStr();
              });
  }

  for (const auto *var : vars)
    spvBuilder.decorateLocation(var->getSpirvInstr(),
                                locSet.useNextLocs(var->getLocationCount()));

  return true;
}

namespace {
/// A class for maintaining the binding number shift requested for descriptor
/// sets.
class BindingShiftMapper {
public:
  explicit BindingShiftMapper(const llvm::SmallVectorImpl<int32_t> &shifts)
      : masterShift(0) {
    assert(shifts.size() % 2 == 0);
    if (shifts.size() == 2 && shifts[1] == -1) {
      masterShift = shifts[0];
    } else {
      for (uint32_t i = 0; i < shifts.size(); i += 2)
        perSetShift[shifts[i + 1]] = shifts[i];
    }
  }

  /// Returns the shift amount for the given set.
  int32_t getShiftForSet(int32_t set) const {
    const auto found = perSetShift.find(set);
    if (found != perSetShift.end())
      return found->second;
    return masterShift;
  }

private:
  uint32_t masterShift; /// Shift amount applies to all sets.
  llvm::DenseMap<int32_t, int32_t> perSetShift;
};

/// A class for maintaining the mapping from source code register attributes to
/// descriptor set and number settings.
class RegisterBindingMapper {
public:
  /// Takes in the relation between register attributes and descriptor settings.
  /// Each relation is represented by four strings:
  ///   <register-type-number> <space> <descriptor-binding> <set>
  bool takeInRelation(const std::vector<std::string> &relation,
                      std::string *error) {
    assert(relation.size() % 4 == 0);
    mapping.clear();

    for (uint32_t i = 0; i < relation.size(); i += 4) {
      int32_t spaceNo = -1, setNo = -1, bindNo = -1;
      if (StringRef(relation[i + 1]).getAsInteger(10, spaceNo) || spaceNo < 0) {
        *error = "space number: " + relation[i + 1];
        return false;
      }
      if (StringRef(relation[i + 2]).getAsInteger(10, bindNo) || bindNo < 0) {
        *error = "binding number: " + relation[i + 2];
        return false;
      }
      if (StringRef(relation[i + 3]).getAsInteger(10, setNo) || setNo < 0) {
        *error = "set number: " + relation[i + 3];
        return false;
      }
      mapping[relation[i + 1] + relation[i]] = std::make_pair(setNo, bindNo);
    }
    return true;
  }

  /// Returns true and set the correct set and binding number if we can find a
  /// descriptor setting for the given register. False otherwise.
  bool getSetBinding(const hlsl::RegisterAssignment *regAttr,
                     uint32_t defaultSpace, int *setNo, int *bindNo) const {
    std::ostringstream iss;
    iss << regAttr->RegisterSpace.getValueOr(defaultSpace)
        << regAttr->RegisterType << regAttr->RegisterNumber;

    auto found = mapping.find(iss.str());
    if (found != mapping.end()) {
      *setNo = found->second.first;
      *bindNo = found->second.second;
      return true;
    }

    return false;
  }

private:
  llvm::StringMap<std::pair<int, int>> mapping;
};
} // namespace

bool DeclResultIdMapper::decorateResourceBindings() {
  // For normal resource, we support 4 approaches of setting binding numbers:
  // - m1: [[vk::binding(...)]]
  // - m2: :register(xX, spaceY)
  // - m3: None
  // - m4: :register(spaceY)
  //
  // For associated counters, we support 2 approaches:
  // - c1: [[vk::counter_binding(...)]
  // - c2: None
  //
  // In combination, we need to handle 12 cases:
  // - 4 cases for nomral resoures (m1, m2, m3, m4)
  // - 8 cases for associated counters (mX * cY)
  //
  // In the following order:
  // - m1, mX * c1
  // - m2
  // - m3, m4, mX * c2

  // The "-auto-binding-space" command line option can be used to specify a
  // certain space as default. UINT_MAX means the user has not provided this
  // option. If not provided, the SPIR-V backend uses space "0" as default.
  auto defaultSpaceOpt =
      theEmitter.getCompilerInstance().getCodeGenOpts().HLSLDefaultSpace;
  uint32_t defaultSpace = (defaultSpaceOpt == UINT_MAX) ? 0 : defaultSpaceOpt;

  const bool bindGlobals = !spirvOptions.bindGlobals.empty();
  int32_t globalsBindNo = -1, globalsSetNo = -1;
  if (bindGlobals) {
    assert(spirvOptions.bindGlobals.size() == 2);
    if (StringRef(spirvOptions.bindGlobals[0])
            .getAsInteger(10, globalsBindNo) ||
        globalsBindNo < 0) {
      emitError("invalid -fvk-bind-globals binding number: %0", {})
          << spirvOptions.bindGlobals[0];
      return false;
    }
    if (StringRef(spirvOptions.bindGlobals[1]).getAsInteger(10, globalsSetNo) ||
        globalsSetNo < 0) {
      emitError("invalid -fvk-bind-globals set number: %0", {})
          << spirvOptions.bindGlobals[1];
      return false;
    }
  }

  // Special handling of -fvk-bind-register, which requires
  // * All resources are annoated with :register() in the source code
  // * -fvk-bind-register is specified for every resource
  if (!spirvOptions.bindRegister.empty()) {
    RegisterBindingMapper bindingMapper;
    std::string error;

    if (!bindingMapper.takeInRelation(spirvOptions.bindRegister, &error)) {
      emitError("invalid -fvk-bind-register %0", {}) << error;
      return false;
    }

    for (const auto &var : resourceVars)
      if (const auto *regAttr = var.getRegister()) {
        if (var.isCounter()) {
          emitError("-fvk-bind-register for RW/Append/Consume StructuredBuffer "
                    "unimplemented",
                    var.getSourceLocation());
        } else {
          int setNo = 0, bindNo = 0;
          if (!bindingMapper.getSetBinding(regAttr, defaultSpace, &setNo,
                                           &bindNo)) {
            emitError("missing -fvk-bind-register for resource",
                      var.getSourceLocation());
            return false;
          }
          spvBuilder.decorateDSetBinding(var.getSpirvInstr(), setNo, bindNo);
        }
      } else if (bindGlobals && var.isGlobalsBuffer()) {
        spvBuilder.decorateDSetBinding(var.getSpirvInstr(), globalsSetNo,
                                       globalsBindNo);
      } else {
        emitError(
            "-fvk-bind-register requires register annotations on all resources",
            var.getSourceLocation());
        return false;
      }

    return true;
  }

  BindingSet bindingSet;

  // Decorates the given varId of the given category with set number
  // setNo, binding number bindingNo. Ignores overlaps.
  const auto tryToDecorate = [this, &bindingSet](const ResourceVar &var,
                                                 const uint32_t setNo,
                                                 const uint32_t bindingNo) {
    // By default we use one binding number per resource, and an array of
    // resources also gets only one binding number. However, for array of
    // resources (e.g. array of textures), DX uses one binding number per array
    // element. We can match this behavior via a command line option.
    uint32_t numBindingsToUse = 1;
    if (spirvOptions.flattenResourceArrays)
      numBindingsToUse = var.getArraySize();

    for (uint32_t i = 0; i < numBindingsToUse; ++i) {
      bool success = bindingSet.useBinding(bindingNo + i, setNo);
      // We will not emit an error if we find a set/binding overlap because it
      // is possible that the optimizer optimizes away a resource which resolves
      // the overlap.
      (void)success;
    }

    // No need to decorate multiple binding numbers for arrays. It will be done
    // by legalization/optimization.
    spvBuilder.decorateDSetBinding(var.getSpirvInstr(), setNo, bindingNo);
  };

  for (const auto &var : resourceVars) {
    if (var.isCounter()) {
      if (const auto *vkCBinding = var.getCounterBinding()) {
        // Process mX * c1
        uint32_t set = defaultSpace;
        if (const auto *vkBinding = var.getBinding())
          set = getVkBindingAttrSet(vkBinding, defaultSpace);
        else if (const auto *reg = var.getRegister())
          set = reg->RegisterSpace.getValueOr(defaultSpace);

        tryToDecorate(var, set, vkCBinding->getBinding());
      }
    } else {
      if (const auto *vkBinding = var.getBinding()) {
        // Process m1
        tryToDecorate(var, getVkBindingAttrSet(vkBinding, defaultSpace),
                      vkBinding->getBinding());
      }
    }
  }

  BindingShiftMapper bShiftMapper(spirvOptions.bShift);
  BindingShiftMapper tShiftMapper(spirvOptions.tShift);
  BindingShiftMapper sShiftMapper(spirvOptions.sShift);
  BindingShiftMapper uShiftMapper(spirvOptions.uShift);

  // Process m2
  for (const auto &var : resourceVars)
    if (!var.isCounter() && !var.getBinding())
      if (const auto *reg = var.getRegister()) {
        // Skip space-only register() annotations
        if (reg->isSpaceOnly())
          continue;

        const uint32_t set = reg->RegisterSpace.getValueOr(defaultSpace);
        uint32_t binding = reg->RegisterNumber;
        switch (reg->RegisterType) {
        case 'b':
          binding += bShiftMapper.getShiftForSet(set);
          break;
        case 't':
          binding += tShiftMapper.getShiftForSet(set);
          break;
        case 's':
          binding += sShiftMapper.getShiftForSet(set);
          break;
        case 'u':
          binding += uShiftMapper.getShiftForSet(set);
          break;
        case 'c':
          // For setting packing offset. Does not affect binding.
          break;
        default:
          llvm_unreachable("unknown register type found");
        }

        tryToDecorate(var, set, binding);
      }

  for (const auto &var : resourceVars) {
    // By default we use one binding number per resource, and an array of
    // resources also gets only one binding number. However, for array of
    // resources (e.g. array of textures), DX uses one binding number per array
    // element. We can match this behavior via a command line option.
    uint32_t numBindingsToUse = 1;
    if (spirvOptions.flattenResourceArrays)
      numBindingsToUse = var.getArraySize();

    if (var.isCounter()) {
      if (!var.getCounterBinding()) {
        // Process mX * c2
        uint32_t set = defaultSpace;
        if (const auto *vkBinding = var.getBinding())
          set = getVkBindingAttrSet(vkBinding, defaultSpace);
        else if (const auto *reg = var.getRegister())
          set = reg->RegisterSpace.getValueOr(defaultSpace);

        spvBuilder.decorateDSetBinding(
            var.getSpirvInstr(), set,
            bindingSet.useNextBinding(set, numBindingsToUse));
      }
    } else if (!var.getBinding()) {
      const auto *reg = var.getRegister();
      if (reg && reg->isSpaceOnly()) {
        const uint32_t set = reg->RegisterSpace.getValueOr(defaultSpace);
        spvBuilder.decorateDSetBinding(
            var.getSpirvInstr(), set,
            bindingSet.useNextBinding(set, numBindingsToUse));
      } else if (!reg) {
        // Process m3 (no 'vk::binding' and no ':register' assignment)

        // There is a special case for the $Globals cbuffer. The $Globals buffer
        // doesn't have either 'vk::binding' or ':register', but the user may
        // ask for a specific binding for it via command line options.
        if (bindGlobals && var.isGlobalsBuffer()) {
          spvBuilder.decorateDSetBinding(var.getSpirvInstr(), globalsSetNo,
                                         globalsBindNo);
        }
        // The normal case
        else {
          spvBuilder.decorateDSetBinding(
              var.getSpirvInstr(), defaultSpace,
              bindingSet.useNextBinding(defaultSpace, numBindingsToUse));
        }
      }
    }
  }

  return true;
}

bool DeclResultIdMapper::createStageVars(
    const hlsl::SigPoint *sigPoint, const NamedDecl *decl, bool asInput,
    QualType type, uint32_t arraySize, const llvm::StringRef namePrefix,
    llvm::Optional<SpirvInstruction *> invocationId, SpirvInstruction **value,
    bool noWriteBack, SemanticInfo *inheritSemantic) {
  assert(value);
  // invocationId should only be used for handling HS per-vertex output.
  if (invocationId.hasValue()) {
    assert(spvContext.isHS() && arraySize != 0 && !asInput);
  }

  assert(inheritSemantic);

  if (type->isVoidType()) {
    // No stage variables will be created for void type.
    return true;
  }

  // The type the variable is evaluated as for SPIR-V.
  QualType evalType = type;

  // We have several cases regarding HLSL semantics to handle here:
  // * If the currrent decl inherits a semantic from some enclosing entity,
  //   use the inherited semantic no matter whether there is a semantic
  //   attached to the current decl.
  // * If there is no semantic to inherit,
  //   * If the current decl is a struct,
  //     * If the current decl has a semantic, all its members inhert this
  //       decl's semantic, with the index sequentially increasing;
  //     * If the current decl does not have a semantic, all its members
  //       should have semantics attached;
  //   * If the current decl is not a struct, it should have semantic attached.

  auto thisSemantic = getStageVarSemantic(decl);

  // Which semantic we should use for this decl
  auto *semanticToUse = &thisSemantic;

  // Enclosing semantics override internal ones
  if (inheritSemantic->isValid()) {
    if (thisSemantic.isValid()) {
      emitWarning(
          "internal semantic '%0' overridden by enclosing semantic '%1'",
          thisSemantic.loc)
          << thisSemantic.str << inheritSemantic->str;
    }
    semanticToUse = inheritSemantic;
  }

  const auto loc = decl->getLocation();
  if (semanticToUse->isValid() &&
      // Structs with attached semantics will be handled later.
      !type->isStructureType()) {
    // Found semantic attached directly to this Decl. This means we need to
    // map this decl to a single stage variable.

    if (!validateVKAttributes(decl))
      return false;

    const auto semanticKind = semanticToUse->getKind();
    const auto sigPointKind = sigPoint->GetKind();

    // Error out when the given semantic is invalid in this shader model
    if (hlsl::SigPoint::GetInterpretation(semanticKind, sigPointKind,
                                          spvContext.getMajorVersion(),
                                          spvContext.getMinorVersion()) ==
        hlsl::DXIL::SemanticInterpretationKind::NA) {
      // Special handle MSIn/ASIn allowing VK-only builtin "DrawIndex".
      switch (sigPointKind) {
      case hlsl::SigPoint::Kind::MSIn:
      case hlsl::SigPoint::Kind::ASIn:
        if (const auto *builtinAttr = decl->getAttr<VKBuiltInAttr>()) {
          const llvm::StringRef builtin = builtinAttr->getBuiltIn();
          if (builtin == "DrawIndex") {
            break;
          }
        }
        // fall through
      default:
        emitError("invalid usage of semantic '%0' in shader profile %1", loc)
            << semanticToUse->str
            << hlsl::ShaderModel::GetKindName(
                   spvContext.getCurrentShaderModelKind());
        return false;
      }
    }

    if (!validateVKBuiltins(decl, sigPoint))
      return false;

    const auto *builtinAttr = decl->getAttr<VKBuiltInAttr>();

    // Special handling of certain mappings between HLSL semantics and
    // SPIR-V builtins:
    // * SV_CullDistance/SV_ClipDistance are outsourced to GlPerVertex.
    // * SV_DomainLocation can refer to a float2, whereas TessCoord is a float3.
    //   To ensure SPIR-V validity, we must create a float3 and  extract a
    //   float2 from it before passing it to the main function.
    // * SV_TessFactor is an array of size 2 for isoline patch, array of size 3
    //   for tri patch, and array of size 4 for quad patch, but it must always
    //   be an array of size 4 in SPIR-V for Vulkan.
    // * SV_InsideTessFactor is a single float for tri patch, and an array of
    //   size 2 for a quad patch, but it must always be an array of size 2 in
    //   SPIR-V for Vulkan.
    // * SV_Coverage is an uint value, but the builtin it corresponds to,
    //   SampleMask, must be an array of integers.
    // * SV_InnerCoverage is an uint value, but the corresponding builtin,
    //   FullyCoveredEXT, must be an boolean value.
    // * SV_DispatchThreadID, SV_GroupThreadID, and SV_GroupID are allowed to be
    //   uint, uint2, or uint3, but the corresponding builtins
    //   (GlobalInvocationId, LocalInvocationId, WorkgroupId) must be a uint3.
    // * SV_ShadingRate is a uint value, but the builtin it corresponds to is a
    //   int2.

    if (glPerVertex.tryToAccess(sigPointKind, semanticKind,
                                semanticToUse->index, invocationId, value,
                                noWriteBack, /*vecComponent=*/nullptr, loc))
      return true;

    switch (semanticKind) {
    case hlsl::Semantic::Kind::DomainLocation:
      evalType = astContext.getExtVectorType(astContext.FloatTy, 3);
      break;
    case hlsl::Semantic::Kind::TessFactor:
      evalType = astContext.getConstantArrayType(
          astContext.FloatTy, llvm::APInt(32, 4), clang::ArrayType::Normal, 0);
      break;
    case hlsl::Semantic::Kind::InsideTessFactor:
      evalType = astContext.getConstantArrayType(
          astContext.FloatTy, llvm::APInt(32, 2), clang::ArrayType::Normal, 0);
      break;
    case hlsl::Semantic::Kind::Coverage:
      evalType = astContext.getConstantArrayType(astContext.UnsignedIntTy,
                                                 llvm::APInt(32, 1),
                                                 clang::ArrayType::Normal, 0);
      break;
    case hlsl::Semantic::Kind::InnerCoverage:
      evalType = astContext.BoolTy;
      break;
    case hlsl::Semantic::Kind::Barycentrics:
      evalType = astContext.getExtVectorType(astContext.FloatTy, 2);
      break;
    case hlsl::Semantic::Kind::DispatchThreadID:
    case hlsl::Semantic::Kind::GroupThreadID:
    case hlsl::Semantic::Kind::GroupID:
      // Keep the original integer signedness
      evalType = astContext.getExtVectorType(
          hlsl::IsHLSLVecType(type) ? hlsl::GetHLSLVecElementType(type) : type,
          3);
      break;
    case hlsl::Semantic::Kind::ShadingRate:
      evalType = astContext.getExtVectorType(astContext.IntTy, 2);
      break;
    default:
      // Only the semantic kinds mentioned above are handled.
      break;
    }

    // Boolean stage I/O variables must be represented as unsigned integers.
    // Boolean built-in variables are represented as bool.
    if (isBooleanStageIOVar(decl, type, semanticKind, sigPointKind)) {
      evalType = getUintTypeWithSourceComponents(astContext, type);
    }

    // Handle the extra arrayness
    if (arraySize != 0) {
      evalType = astContext.getConstantArrayType(
          evalType, llvm::APInt(32, arraySize), clang::ArrayType::Normal, 0);
    }

    StageVar stageVar(
        sigPoint, *semanticToUse, builtinAttr, evalType,
        // For HS/DS/GS, we have already stripped the outmost arrayness on type.
        getLocationCount(astContext, type));
    const auto name = namePrefix.str() + "." + stageVar.getSemanticStr();
    SpirvVariable *varInstr =
        createSpirvStageVar(&stageVar, decl, name, semanticToUse->loc);

    if (!varInstr)
      return false;

    stageVar.setSpirvInstr(varInstr);
    stageVar.setLocationAttr(decl->getAttr<VKLocationAttr>());
    stageVar.setIndexAttr(decl->getAttr<VKIndexAttr>());
    stageVars.push_back(stageVar);

    // Emit OpDecorate* instructions to link this stage variable with the HLSL
    // semantic it is created for
    spvBuilder.decorateHlslSemantic(varInstr, stageVar.getSemanticStr());

    // We have semantics attached to this decl, which means it must be a
    // function/parameter/variable. All are DeclaratorDecls.
    stageVarInstructions[cast<DeclaratorDecl>(decl)] = varInstr;

    // Mark that we have used one index for this semantic
    ++semanticToUse->index;

    // TODO: the following may not be correct?
    if (sigPoint->GetSignatureKind() ==
        hlsl::DXIL::SignatureKind::PatchConstOrPrim) {
      if (sigPointKind == hlsl::SigPoint::Kind::MSPOut) {
        // Decorate with PerPrimitiveNV for per-primitive out variables.
        spvBuilder.decoratePerPrimitiveNV(varInstr,
                                          varInstr->getSourceLocation());
      } else {
        spvBuilder.decoratePatch(varInstr, varInstr->getSourceLocation());
      }
    }

    // Decorate with interpolation modes for pixel shader input variables
    // or vertex shader output variables.
    if (((spvContext.isPS() && sigPoint->IsInput()) ||
         (spvContext.isVS() && sigPoint->IsOutput())) &&
        // BaryCoord*AMD buitins already encode the interpolation mode.
        semanticKind != hlsl::Semantic::Kind::Barycentrics)
      decorateInterpolationMode(decl, type, varInstr);

    if (asInput) {
      *value = spvBuilder.createLoad(evalType, varInstr, loc);

      // Fix ups for corner cases

      // Special handling of SV_TessFactor DS patch constant input.
      // TessLevelOuter is always an array of size 4 in SPIR-V, but
      // SV_TessFactor could be an array of size 2, 3, or 4 in HLSL. Only the
      // relevant indexes must be loaded.
      if (semanticKind == hlsl::Semantic::Kind::TessFactor &&
          hlsl::GetArraySize(type) != 4) {
        llvm::SmallVector<SpirvInstruction *, 4> components;
        const auto tessFactorSize = hlsl::GetArraySize(type);
        const auto arrType = astContext.getConstantArrayType(
            astContext.FloatTy, llvm::APInt(32, tessFactorSize),
            clang::ArrayType::Normal, 0);
        for (uint32_t i = 0; i < tessFactorSize; ++i)
          components.push_back(spvBuilder.createCompositeExtract(
              astContext.FloatTy, *value, {i}, thisSemantic.loc));
        *value = spvBuilder.createCompositeConstruct(arrType, components,
                                                     thisSemantic.loc);
      }
      // Special handling of SV_InsideTessFactor DS patch constant input.
      // TessLevelInner is always an array of size 2 in SPIR-V, but
      // SV_InsideTessFactor could be an array of size 1 (scalar) or size 2 in
      // HLSL. If SV_InsideTessFactor is a scalar, only extract index 0 of
      // TessLevelInner.
      else if (semanticKind == hlsl::Semantic::Kind::InsideTessFactor &&
               // Some developers use float[1] instead of a scalar float.
               (!type->isArrayType() || hlsl::GetArraySize(type) == 1)) {
        *value = spvBuilder.createCompositeExtract(astContext.FloatTy, *value,
                                                   {0}, thisSemantic.loc);
        if (type->isArrayType()) { // float[1]
          const auto arrType = astContext.getConstantArrayType(
              astContext.FloatTy, llvm::APInt(32, 1), clang::ArrayType::Normal,
              0);
          *value = spvBuilder.createCompositeConstruct(arrType, {*value},
                                                       thisSemantic.loc);
        }
      }
      // SV_DomainLocation can refer to a float2 or a float3, whereas TessCoord
      // is always a float3. To ensure SPIR-V validity, a float3 stage variable
      // is created, and we must extract a float2 from it before passing it to
      // the main function.
      else if (semanticKind == hlsl::Semantic::Kind::DomainLocation &&
               hlsl::GetHLSLVecSize(type) != 3) {
        const auto domainLocSize = hlsl::GetHLSLVecSize(type);
        *value = spvBuilder.createVectorShuffle(
            astContext.getExtVectorType(astContext.FloatTy, domainLocSize),
            *value, *value, {0, 1}, thisSemantic.loc);
      }
      // Special handling of SV_Coverage, which is an uint value. We need to
      // read SampleMask and extract its first element.
      else if (semanticKind == hlsl::Semantic::Kind::Coverage) {
        *value = spvBuilder.createCompositeExtract(type, *value, {0},
                                                   thisSemantic.loc);
      }
      // Special handling of SV_InnerCoverage, which is an uint value. We need
      // to read FullyCoveredEXT, which is a boolean value, and convert it to an
      // uint value. According to D3D12 "Conservative Rasterization" doc: "The
      // Pixel Shader has a 32-bit scalar integer System Generate Value
      // available: InnerCoverage. This is a bit-field that has bit 0 from the
      // LSB set to 1 for a given conservatively rasterized pixel, only when
      // that pixel is guaranteed to be entirely inside the current primitive.
      // All other input register bits must be set to 0 when bit 0 is not set,
      // but are undefined when bit 0 is set to 1 (essentially, this bit-field
      // represents a Boolean value where false must be exactly 0, but true can
      // be any odd (i.e. bit 0 set) non-zero value)."
      else if (semanticKind == hlsl::Semantic::Kind::InnerCoverage) {
        const auto constOne = spvBuilder.getConstantInt(
            astContext.UnsignedIntTy, llvm::APInt(32, 1));
        const auto constZero = spvBuilder.getConstantInt(
            astContext.UnsignedIntTy, llvm::APInt(32, 0));
        *value = spvBuilder.createSelect(astContext.UnsignedIntTy, *value,
                                         constOne, constZero, thisSemantic.loc);
      }
      // Special handling of SV_Barycentrics, which is a float3, but the
      // underlying stage input variable is a float2 (only provides the first
      // two components). Calculate the third element.
      else if (semanticKind == hlsl::Semantic::Kind::Barycentrics) {
        const auto x = spvBuilder.createCompositeExtract(
            astContext.FloatTy, *value, {0}, thisSemantic.loc);
        const auto y = spvBuilder.createCompositeExtract(
            astContext.FloatTy, *value, {1}, thisSemantic.loc);
        const auto xy = spvBuilder.createBinaryOp(
            spv::Op::OpFAdd, astContext.FloatTy, x, y, thisSemantic.loc);
        const auto z = spvBuilder.createBinaryOp(
            spv::Op::OpFSub, astContext.FloatTy,
            spvBuilder.getConstantFloat(astContext.FloatTy,
                                        llvm::APFloat(1.0f)),
            xy, thisSemantic.loc);
        *value = spvBuilder.createCompositeConstruct(
            astContext.getExtVectorType(astContext.FloatTy, 3), {x, y, z},
            thisSemantic.loc);
      }
      // Special handling of SV_DispatchThreadID and SV_GroupThreadID, which may
      // be a uint or uint2, but the underlying stage input variable is a uint3.
      // The last component(s) should be discarded in needed.
      else if ((semanticKind == hlsl::Semantic::Kind::DispatchThreadID ||
                semanticKind == hlsl::Semantic::Kind::GroupThreadID ||
                semanticKind == hlsl::Semantic::Kind::GroupID) &&
               (!hlsl::IsHLSLVecType(type) ||
                hlsl::GetHLSLVecSize(type) != 3)) {
        const auto srcVecElemType = hlsl::IsHLSLVecType(type)
                                        ? hlsl::GetHLSLVecElementType(type)
                                        : type;
        const auto vecSize =
            hlsl::IsHLSLVecType(type) ? hlsl::GetHLSLVecSize(type) : 1;
        if (vecSize == 1)
          *value = spvBuilder.createCompositeExtract(srcVecElemType, *value,
                                                     {0}, thisSemantic.loc);
        else if (vecSize == 2)
          *value = spvBuilder.createVectorShuffle(
              astContext.getExtVectorType(srcVecElemType, 2), *value, *value,
              {0, 1}, thisSemantic.loc);
      }
      // Special handling of SV_ShadingRate, which is a bitpacked enum value,
      // but SPIR-V's FragSizeEXT uses an int2. We build the enum value from
      // the separate axis values.
      else if (semanticKind == hlsl::Semantic::Kind::ShadingRate) {
        // From the D3D12 functional spec for Variable-Rate Shading.
        // #define D3D12_MAKE_COARSE_SHADING_RATE(x,y) ((x) << 2 | (y))
        const auto x = spvBuilder.createCompositeExtract(
            astContext.IntTy, *value, {0}, thisSemantic.loc);
        const auto y = spvBuilder.createCompositeExtract(
            astContext.IntTy, *value, {1}, thisSemantic.loc);
        const auto constTwo =
            spvBuilder.getConstantInt(astContext.IntTy, llvm::APInt(32, 2));
        *value = spvBuilder.createBinaryOp(
            spv::Op::OpBitwiseOr, astContext.UnsignedIntTy,
            spvBuilder.createBinaryOp(spv::Op::OpShiftLeftLogical,
                                      astContext.IntTy, x, constTwo,
                                      thisSemantic.loc),
            y, thisSemantic.loc);
      }

      // Reciprocate SV_Position.w if requested
      if (semanticKind == hlsl::Semantic::Kind::Position)
        *value = invertWIfRequested(*value, thisSemantic.loc);

      // Since boolean stage input variables are represented as unsigned
      // integers, after loading them, we should cast them to boolean.
      if (isBooleanStageIOVar(decl, type, semanticKind, sigPointKind)) {
        *value =
            theEmitter.castToType(*value, evalType, type, thisSemantic.loc);
      }
    } else {
      if (noWriteBack)
        return true;

      // Negate SV_Position.y if requested
      if (semanticKind == hlsl::Semantic::Kind::Position)
        *value = invertYIfRequested(*value, thisSemantic.loc);

      SpirvInstruction *ptr = varInstr;

      // Special handling of SV_TessFactor HS patch constant output.
      // TessLevelOuter is always an array of size 4 in SPIR-V, but
      // SV_TessFactor could be an array of size 2, 3, or 4 in HLSL. Only the
      // relevant indexes must be written to.
      if (semanticKind == hlsl::Semantic::Kind::TessFactor &&
          hlsl::GetArraySize(type) != 4) {
        const auto tessFactorSize = hlsl::GetArraySize(type);
        for (uint32_t i = 0; i < tessFactorSize; ++i) {
          ptr = spvBuilder.createAccessChain(
              astContext.FloatTy, varInstr,
              {spvBuilder.getConstantInt(astContext.UnsignedIntTy,
                                         llvm::APInt(32, i))},
              thisSemantic.loc);
          spvBuilder.createStore(
              ptr,
              spvBuilder.createCompositeExtract(astContext.FloatTy, *value, {i},
                                                thisSemantic.loc),
              thisSemantic.loc);
        }
      }
      // Special handling of SV_InsideTessFactor HS patch constant output.
      // TessLevelInner is always an array of size 2 in SPIR-V, but
      // SV_InsideTessFactor could be an array of size 1 (scalar) or size 2 in
      // HLSL. If SV_InsideTessFactor is a scalar, only write to index 0 of
      // TessLevelInner.
      else if (semanticKind == hlsl::Semantic::Kind::InsideTessFactor &&
               // Some developers use float[1] instead of a scalar float.
               (!type->isArrayType() || hlsl::GetArraySize(type) == 1)) {
        ptr = spvBuilder.createAccessChain(
            astContext.FloatTy, varInstr,
            spvBuilder.getConstantInt(astContext.UnsignedIntTy,
                                      llvm::APInt(32, 0)),
            thisSemantic.loc);
        if (type->isArrayType()) // float[1]
          *value = spvBuilder.createCompositeExtract(astContext.FloatTy, *value,
                                                     {0}, thisSemantic.loc);
        spvBuilder.createStore(ptr, *value, thisSemantic.loc);
      }
      // Special handling of SV_Coverage, which is an unit value. We need to
      // write it to the first element in the SampleMask builtin.
      else if (semanticKind == hlsl::Semantic::Kind::Coverage) {
        ptr = spvBuilder.createAccessChain(
            type, varInstr,
            spvBuilder.getConstantInt(astContext.UnsignedIntTy,
                                      llvm::APInt(32, 0)),
            thisSemantic.loc);
        ptr->setStorageClass(spv::StorageClass::Output);
        spvBuilder.createStore(ptr, *value, thisSemantic.loc);
      }
      // Special handling of HS ouput, for which we write to only one
      // element in the per-vertex data array: the one indexed by
      // SV_ControlPointID.
      else if (invocationId.hasValue() && invocationId.getValue() != nullptr) {
        // Remove the arrayness to get the element type.
        assert(isa<ConstantArrayType>(evalType));
        const auto elementType =
            astContext.getAsArrayType(evalType)->getElementType();
        auto index = invocationId.getValue();
        ptr = spvBuilder.createAccessChain(elementType, varInstr, index,
                                           thisSemantic.loc);
        ptr->setStorageClass(spv::StorageClass::Output);
        spvBuilder.createStore(ptr, *value, thisSemantic.loc);
      }
      // Since boolean output stage variables are represented as unsigned
      // integers, we must cast the value to uint before storing.
      else if (isBooleanStageIOVar(decl, type, semanticKind, sigPointKind)) {
        *value =
            theEmitter.castToType(*value, type, evalType, thisSemantic.loc);
        spvBuilder.createStore(ptr, *value, thisSemantic.loc);
      }
      // For all normal cases
      else {
        spvBuilder.createStore(ptr, *value, thisSemantic.loc);
      }
    }

    return true;
  }

  // If the decl itself doesn't have semantic string attached and there is no
  // one to inherit, it should be a struct having all its fields with semantic
  // strings.
  if (!semanticToUse->isValid() && !type->isStructureType()) {
    emitError("semantic string missing for shader %select{output|input}0 "
              "variable '%1'",
              loc)
        << asInput << decl->getName();
    return false;
  }

  const auto *structDecl = type->getAs<RecordType>()->getDecl();

  if (asInput) {
    // If this decl translates into multiple stage input variables, we need to
    // load their values into a composite.
    llvm::SmallVector<SpirvInstruction *, 4> subValues;

    // If we have base classes, we need to handle them first.
    if (const auto *cxxDecl = type->getAsCXXRecordDecl()) {
      for (auto base : cxxDecl->bases()) {
        SpirvInstruction *subValue = nullptr;
        if (!createStageVars(sigPoint, base.getType()->getAsCXXRecordDecl(),
                             asInput, base.getType(), arraySize, namePrefix,
                             invocationId, &subValue, noWriteBack,
                             semanticToUse))
          return false;
        subValues.push_back(subValue);
      }
    }

    for (const auto *field : structDecl->fields()) {
      SpirvInstruction *subValue = nullptr;
      if (!createStageVars(sigPoint, field, asInput, field->getType(),
                           arraySize, namePrefix, invocationId, &subValue,
                           noWriteBack, semanticToUse))
        return false;
      subValues.push_back(subValue);
    }

    if (arraySize == 0) {
      *value = spvBuilder.createCompositeConstruct(evalType, subValues, loc);
      return true;
    }

    // Handle the extra level of arrayness.

    // We need to return an array of structs. But we get arrays of fields
    // from visiting all fields. So now we need to extract all the elements
    // at the same index of each field arrays and compose a new struct out
    // of them.
    const auto structType = type;
    const auto arrayType = astContext.getConstantArrayType(
        structType, llvm::APInt(32, arraySize), clang::ArrayType::Normal, 0);

    llvm::SmallVector<SpirvInstruction *, 16> arrayElements;

    for (uint32_t arrayIndex = 0; arrayIndex < arraySize; ++arrayIndex) {
      llvm::SmallVector<SpirvInstruction *, 8> fields;

      // If we have base classes, we need to handle them first.
      if (const auto *cxxDecl = type->getAsCXXRecordDecl()) {
        uint32_t baseIndex = 0;
        for (auto base : cxxDecl->bases()) {
          const auto baseType = base.getType();
          fields.push_back(spvBuilder.createCompositeExtract(
              baseType, subValues[baseIndex++], {arrayIndex}, loc));
        }
      }

      // Extract the element at index arrayIndex from each field
      for (const auto *field : structDecl->fields()) {
        const auto fieldType = field->getType();
        fields.push_back(spvBuilder.createCompositeExtract(
            fieldType,
            subValues[getNumBaseClasses(type) + field->getFieldIndex()],
            {arrayIndex}, loc));
      }
      // Compose a new struct out of them
      arrayElements.push_back(
          spvBuilder.createCompositeConstruct(structType, fields, loc));
    }

    *value = spvBuilder.createCompositeConstruct(arrayType, arrayElements, loc);
  } else {
    // If we have base classes, we need to handle them first.
    if (const auto *cxxDecl = type->getAsCXXRecordDecl()) {
      uint32_t baseIndex = 0;
      for (auto base : cxxDecl->bases()) {
        SpirvInstruction *subValue = nullptr;
        if (!noWriteBack)
          subValue = spvBuilder.createCompositeExtract(base.getType(), *value,
                                                       {baseIndex++}, loc);

        if (!createStageVars(sigPoint, base.getType()->getAsCXXRecordDecl(),
                             asInput, base.getType(), arraySize, namePrefix,
                             invocationId, &subValue, noWriteBack,
                             semanticToUse))
          return false;
      }
    }

    // Unlike reading, which may require us to read stand-alone builtins and
    // stage input variables and compose an array of structs out of them,
    // it happens that we don't need to write an array of structs in a bunch
    // for all shader stages:
    //
    // * VS: output is a single struct, without extra arrayness
    // * HS: output is an array of structs, with extra arrayness,
    //       but we only write to the struct at the InvocationID index
    // * DS: output is a single struct, without extra arrayness
    // * GS: output is controlled by OpEmitVertex, one vertex per time
    // * MS: output is an array of structs, with extra arrayness
    //
    // The interesting shader stage is HS. We need the InvocationID to write
    // out the value to the correct array element.
    for (const auto *field : structDecl->fields()) {
      const auto fieldType = field->getType();
      SpirvInstruction *subValue = nullptr;
      if (!noWriteBack)
        subValue = spvBuilder.createCompositeExtract(
            fieldType, *value,
            {getNumBaseClasses(type) + field->getFieldIndex()}, loc);

      if (!createStageVars(sigPoint, field, asInput, field->getType(),
                           arraySize, namePrefix, invocationId, &subValue,
                           noWriteBack, semanticToUse))
        return false;
    }
  }

  return true;
}

bool DeclResultIdMapper::createPayloadStageVars(
    const hlsl::SigPoint *sigPoint, spv::StorageClass sc, const NamedDecl *decl,
    bool asInput, QualType type, const llvm::StringRef namePrefix,
    SpirvInstruction **value, uint32_t payloadMemOffset) {
  assert(spvContext.isMS() || spvContext.isAS());
  assert(value);

  if (type->isVoidType()) {
    // No stage variables will be created for void type.
    return true;
  }

  const auto loc = decl->getLocation();
  if (!type->isStructureType()) {
    StageVar stageVar(sigPoint, /*semaInfo=*/{}, /*builtinAttr=*/nullptr, type,
                      getLocationCount(astContext, type));
    const auto name = namePrefix.str() + "." + decl->getNameAsString();
    SpirvVariable *varInstr =
        spvBuilder.addStageIOVar(type, sc, name, /*isPrecise=*/false, loc);

    if (!varInstr)
      return false;

    // Even though these as user defined IO stage variables, set them as SPIR-V
    // builtins in order to bypass any semantic string checks and location
    // assignment.
    stageVar.setIsSpirvBuiltin();
    stageVar.setSpirvInstr(varInstr);
    stageVars.push_back(stageVar);

    // Decorate with PerTaskNV for mesh/amplification shader payload variables.
    spvBuilder.decoratePerTaskNV(varInstr, payloadMemOffset,
                                 varInstr->getSourceLocation());

    if (asInput) {
      *value = spvBuilder.createLoad(type, varInstr, loc);
    } else {
      spvBuilder.createStore(varInstr, *value, loc);
    }
    return true;
  }

  // This decl translates into multiple stage input/output payload variables
  // and we need to load/store these individual member variables.
  const auto *structDecl = type->getAs<RecordType>()->getDecl();
  llvm::SmallVector<SpirvInstruction *, 4> subValues;
  AlignmentSizeCalculator alignmentCalc(astContext, spirvOptions);
  uint32_t nextMemberOffset = 0;

  for (const auto *field : structDecl->fields()) {
    const auto fieldType = field->getType();
    SpirvInstruction *subValue = nullptr;
    uint32_t memberAlignment = 0, memberSize = 0, stride = 0;

    // The next avaiable offset after laying out the previous members.
    std::tie(memberAlignment, memberSize) = alignmentCalc.getAlignmentAndSize(
        field->getType(), spirvOptions.ampPayloadLayoutRule,
        /*isRowMajor*/ llvm::None, &stride);
    alignmentCalc.alignUsingHLSLRelaxedLayout(
        field->getType(), memberSize, memberAlignment, &nextMemberOffset);

    // The vk::offset attribute takes precedence over all.
    if (field->getAttr<VKOffsetAttr>()) {
      nextMemberOffset = field->getAttr<VKOffsetAttr>()->getOffset();
    }

    // Each payload member must have an Offset Decoration.
    payloadMemOffset = nextMemberOffset;
    nextMemberOffset += memberSize;

    if (!asInput) {
      subValue = spvBuilder.createCompositeExtract(
          fieldType, *value, {getNumBaseClasses(type) + field->getFieldIndex()},
          loc);
    }

    if (!createPayloadStageVars(sigPoint, sc, field, asInput, field->getType(),
                                namePrefix, &subValue, payloadMemOffset))
      return false;

    if (asInput) {
      subValues.push_back(subValue);
    }
  }
  if (asInput) {
    *value = spvBuilder.createCompositeConstruct(type, subValues, loc);
  }
  return true;
}

bool DeclResultIdMapper::writeBackOutputStream(const NamedDecl *decl,
                                               QualType type,
                                               SpirvInstruction *value) {
  assert(spvContext.isGS()); // Only for GS use

  if (hlsl::IsHLSLStreamOutputType(type))
    type = hlsl::GetHLSLResourceResultType(type);
  if (hasGSPrimitiveTypeQualifier(decl))
    type = astContext.getAsConstantArrayType(type)->getElementType();

  auto semanticInfo = getStageVarSemantic(decl);
  const auto loc = decl->getLocation();

  if (semanticInfo.isValid()) {
    // Found semantic attached directly to this Decl. Write the value for this
    // Decl to the corresponding stage output variable.

    // Handle SV_ClipDistance, and SV_CullDistance
    if (glPerVertex.tryToAccess(
            hlsl::DXIL::SigPointKind::GSOut, semanticInfo.semantic->GetKind(),
            semanticInfo.index, llvm::None, &value,
            /*noWriteBack=*/false, /*vecComponent=*/nullptr, loc))
      return true;

    // Query the <result-id> for the stage output variable generated out
    // of this decl.
    // We have semantic string attached to this decl; therefore, it must be a
    // DeclaratorDecl.
    const auto found = stageVarInstructions.find(cast<DeclaratorDecl>(decl));

    // We should have recorded its stage output variable previously.
    assert(found != stageVarInstructions.end());

    // Negate SV_Position.y if requested
    if (semanticInfo.semantic->GetKind() == hlsl::Semantic::Kind::Position)
      value = invertYIfRequested(value, loc);

    // Boolean stage output variables are represented as unsigned integers.
    if (isBooleanStageIOVar(decl, type, semanticInfo.semantic->GetKind(),
                            hlsl::SigPoint::Kind::GSOut)) {
      QualType uintType = getUintTypeWithSourceComponents(astContext, type);
      value = theEmitter.castToType(value, type, uintType, loc);
    }

    spvBuilder.createStore(found->second, value, loc);
    return true;
  }

  // If the decl itself doesn't have semantic string attached, it should be
  // a struct having all its fields with semantic strings.
  if (!type->isStructureType()) {
    emitError("semantic string missing for shader output variable '%0'", loc)
        << decl->getName();
    return false;
  }

  // If we have base classes, we need to handle them first.
  if (const auto *cxxDecl = type->getAsCXXRecordDecl()) {
    uint32_t baseIndex = 0;
    for (auto base : cxxDecl->bases()) {
      auto *subValue = spvBuilder.createCompositeExtract(base.getType(), value,
                                                         {baseIndex++}, loc);

      if (!writeBackOutputStream(base.getType()->getAsCXXRecordDecl(),
                                 base.getType(), subValue))
        return false;
    }
  }

  const auto *structDecl = type->getAs<RecordType>()->getDecl();

  // Write out each field
  for (const auto *field : structDecl->fields()) {
    const auto fieldType = field->getType();
    auto *subValue = spvBuilder.createCompositeExtract(
        fieldType, value, {getNumBaseClasses(type) + field->getFieldIndex()},
        loc);

    if (!writeBackOutputStream(field, field->getType(), subValue))
      return false;
  }

  return true;
}

SpirvInstruction *
DeclResultIdMapper::invertYIfRequested(SpirvInstruction *position,
                                       SourceLocation loc) {
  // Negate SV_Position.y if requested
  if (spirvOptions.invertY) {
    const auto oldY = spvBuilder.createCompositeExtract(astContext.FloatTy,
                                                        position, {1}, loc);
    const auto newY = spvBuilder.createUnaryOp(spv::Op::OpFNegate,
                                               astContext.FloatTy, oldY, loc);
    position = spvBuilder.createCompositeInsert(
        astContext.getExtVectorType(astContext.FloatTy, 4), position, {1}, newY,
        loc);
  }
  return position;
}

SpirvInstruction *
DeclResultIdMapper::invertWIfRequested(SpirvInstruction *position,
                                       SourceLocation loc) {
  // Reciprocate SV_Position.w if requested
  if (spirvOptions.invertW && spvContext.isPS()) {
    const auto oldW = spvBuilder.createCompositeExtract(astContext.FloatTy,
                                                        position, {3}, loc);
    const auto newW = spvBuilder.createBinaryOp(
        spv::Op::OpFDiv, astContext.FloatTy,
        spvBuilder.getConstantFloat(astContext.FloatTy, llvm::APFloat(1.0f)),
        oldW, loc);
    position = spvBuilder.createCompositeInsert(
        astContext.getExtVectorType(astContext.FloatTy, 4), position, {3}, newW,
        loc);
  }
  return position;
}

void DeclResultIdMapper::decorateInterpolationMode(const NamedDecl *decl,
                                                   QualType type,
                                                   SpirvVariable *varInstr) {
  const auto loc = decl->getLocation();

  if (isUintOrVecMatOfUintType(type) || isSintOrVecMatOfSintType(type) ||
      isBoolOrVecMatOfBoolType(type)) {
    // TODO: Probably we can call hlsl::ValidateSignatureElement() for the
    // following check.
    if (decl->getAttr<HLSLLinearAttr>() || decl->getAttr<HLSLCentroidAttr>() ||
        decl->getAttr<HLSLNoPerspectiveAttr>() ||
        decl->getAttr<HLSLSampleAttr>()) {
      emitError("only nointerpolation mode allowed for integer input "
                "parameters in pixel shader or integer output in vertex shader",
                decl->getLocation());
    } else {
      spvBuilder.decorateFlat(varInstr, loc);
    }
  } else {
    // Do nothing for HLSLLinearAttr since its the default
    // Attributes can be used together. So cannot use else if.
    if (decl->getAttr<HLSLCentroidAttr>())
      spvBuilder.decorateCentroid(varInstr, loc);
    if (decl->getAttr<HLSLNoInterpolationAttr>())
      spvBuilder.decorateFlat(varInstr, loc);
    if (decl->getAttr<HLSLNoPerspectiveAttr>())
      spvBuilder.decorateNoPerspective(varInstr, loc);
    if (decl->getAttr<HLSLSampleAttr>()) {
      spvBuilder.decorateSample(varInstr, loc);
    }
  }
}

SpirvVariable *DeclResultIdMapper::getBuiltinVar(spv::BuiltIn builtIn,
                                                 QualType type,
                                                 SourceLocation loc) {
  // Guarantee uniqueness
  uint32_t spvBuiltinId = static_cast<uint32_t>(builtIn);
  const auto builtInVar = builtinToVarMap.find(spvBuiltinId);
  if (builtInVar != builtinToVarMap.end()) {
    return builtInVar->second;
  }
  spv::StorageClass sc = spv::StorageClass::Max;
  // Valid builtins supported
  switch (builtIn) {
  case spv::BuiltIn::SubgroupSize:
  case spv::BuiltIn::SubgroupLocalInvocationId:
  case spv::BuiltIn::HitTNV:
  case spv::BuiltIn::RayTminNV:
  case spv::BuiltIn::HitKindNV:
  case spv::BuiltIn::IncomingRayFlagsNV:
  case spv::BuiltIn::InstanceCustomIndexNV:
  case spv::BuiltIn::RayGeometryIndexKHR:
  case spv::BuiltIn::PrimitiveId:
  case spv::BuiltIn::InstanceId:
  case spv::BuiltIn::WorldRayDirectionNV:
  case spv::BuiltIn::WorldRayOriginNV:
  case spv::BuiltIn::ObjectRayDirectionNV:
  case spv::BuiltIn::ObjectRayOriginNV:
  case spv::BuiltIn::ObjectToWorldNV:
  case spv::BuiltIn::WorldToObjectNV:
  case spv::BuiltIn::LaunchIdNV:
  case spv::BuiltIn::LaunchSizeNV:
    sc = spv::StorageClass::Input;
    break;
  case spv::BuiltIn::PrimitiveCountNV:
  case spv::BuiltIn::PrimitiveIndicesNV:
  case spv::BuiltIn::TaskCountNV:
    sc = spv::StorageClass::Output;
    break;
  default:
    assert(false && "unsupported SPIR-V builtin");
    return nullptr;
  }

  // Create a dummy StageVar for this builtin variable
  auto var = spvBuilder.addStageBuiltinVar(type, sc, builtIn,
                                           /*isPrecise*/ false, loc);

  const hlsl::SigPoint *sigPoint =
      hlsl::SigPoint::GetSigPoint(hlsl::SigPointFromInputQual(
          hlsl::DxilParamInputQual::In, spvContext.getCurrentShaderModelKind(),
          /*isPatchConstant=*/false));

  StageVar stageVar(sigPoint, /*semaInfo=*/{}, /*builtinAttr=*/nullptr, type,
                    /*locCount=*/0);

  stageVar.setIsSpirvBuiltin();
  stageVar.setSpirvInstr(var);
  stageVars.push_back(stageVar);

  // Store in map for re-use
  builtinToVarMap[spvBuiltinId] = var;
  return var;
}

SpirvVariable *DeclResultIdMapper::createSpirvStageVar(
    StageVar *stageVar, const NamedDecl *decl, const llvm::StringRef name,
    SourceLocation srcLoc) {
  using spv::BuiltIn;

  const auto sigPoint = stageVar->getSigPoint();
  const auto semanticKind = stageVar->getSemanticInfo().getKind();
  const auto sigPointKind = sigPoint->GetKind();
  const auto type = stageVar->getAstType();
  const auto isPrecise = decl->hasAttr<HLSLPreciseAttr>();

  spv::StorageClass sc = getStorageClassForSigPoint(sigPoint);
  if (sc == spv::StorageClass::Max)
    return 0;
  stageVar->setStorageClass(sc);

  // [[vk::builtin(...)]] takes precedence.
  if (const auto *builtinAttr = stageVar->getBuiltInAttr()) {
    const auto spvBuiltIn =
        llvm::StringSwitch<BuiltIn>(builtinAttr->getBuiltIn())
            .Case("PointSize", BuiltIn::PointSize)
            .Case("HelperInvocation", BuiltIn::HelperInvocation)
            .Case("BaseVertex", BuiltIn::BaseVertex)
            .Case("BaseInstance", BuiltIn::BaseInstance)
            .Case("DrawIndex", BuiltIn::DrawIndex)
            .Case("DeviceIndex", BuiltIn::DeviceIndex)
            .Case("ViewportMaskNV", BuiltIn::ViewportMaskNV)
            .Default(BuiltIn::Max);

    assert(spvBuiltIn != BuiltIn::Max); // The frontend should guarantee this.
    return spvBuilder.addStageBuiltinVar(type, sc, spvBuiltIn, isPrecise,
                                         srcLoc);
  }

  // The following translation assumes that semantic validity in the current
  // shader model is already checked, so it only covers valid SigPoints for
  // each semantic.
  switch (semanticKind) {
  // According to DXIL spec, the Position SV can be used by all SigPoints
  // other than PCIn, HSIn, GSIn, PSOut, CSIn, MSIn, MSPOut, ASIn.
  // According to Vulkan spec, the Position BuiltIn can only be used
  // by VSOut, HS/DS/GS In/Out, MSOut.
  case hlsl::Semantic::Kind::Position: {
    switch (sigPointKind) {
    case hlsl::SigPoint::Kind::VSIn:
    case hlsl::SigPoint::Kind::PCOut:
    case hlsl::SigPoint::Kind::DSIn:
      return spvBuilder.addStageIOVar(type, sc, name.str(), isPrecise, srcLoc);
    case hlsl::SigPoint::Kind::VSOut:
    case hlsl::SigPoint::Kind::HSCPIn:
    case hlsl::SigPoint::Kind::HSCPOut:
    case hlsl::SigPoint::Kind::DSCPIn:
    case hlsl::SigPoint::Kind::DSOut:
    case hlsl::SigPoint::Kind::GSVIn:
    case hlsl::SigPoint::Kind::GSOut:
    case hlsl::SigPoint::Kind::MSOut:
      stageVar->setIsSpirvBuiltin();
      return spvBuilder.addStageBuiltinVar(type, sc, BuiltIn::Position,
                                           isPrecise, srcLoc);
    case hlsl::SigPoint::Kind::PSIn:
      stageVar->setIsSpirvBuiltin();
      return spvBuilder.addStageBuiltinVar(type, sc, BuiltIn::FragCoord,
                                           isPrecise, srcLoc);
    default:
      llvm_unreachable("invalid usage of SV_Position sneaked in");
    }
  }
  // According to DXIL spec, the VertexID SV can only be used by VSIn.
  // According to Vulkan spec, the VertexIndex BuiltIn can only be used by
  // VSIn.
  case hlsl::Semantic::Kind::VertexID: {
    stageVar->setIsSpirvBuiltin();
    return spvBuilder.addStageBuiltinVar(type, sc, BuiltIn::VertexIndex,
                                         isPrecise, srcLoc);
  }
  // According to DXIL spec, the InstanceID SV can be used by VSIn, VSOut,
  // HSCPIn, HSCPOut, DSCPIn, DSOut, GSVIn, GSOut, PSIn.
  // According to Vulkan spec, the InstanceIndex BuitIn can only be used by
  // VSIn.
  case hlsl::Semantic::Kind::InstanceID: {
    switch (sigPointKind) {
    case hlsl::SigPoint::Kind::VSIn:
      stageVar->setIsSpirvBuiltin();
      return spvBuilder.addStageBuiltinVar(type, sc, BuiltIn::InstanceIndex,
                                           isPrecise, srcLoc);
    case hlsl::SigPoint::Kind::VSOut:
    case hlsl::SigPoint::Kind::HSCPIn:
    case hlsl::SigPoint::Kind::HSCPOut:
    case hlsl::SigPoint::Kind::DSCPIn:
    case hlsl::SigPoint::Kind::DSOut:
    case hlsl::SigPoint::Kind::GSVIn:
    case hlsl::SigPoint::Kind::GSOut:
    case hlsl::SigPoint::Kind::PSIn:
      return spvBuilder.addStageIOVar(type, sc, name.str(), isPrecise, srcLoc);
    default:
      llvm_unreachable("invalid usage of SV_InstanceID sneaked in");
    }
  }
  // According to DXIL spec, the Depth{|GreaterEqual|LessEqual} SV can only be
  // used by PSOut.
  // According to Vulkan spec, the FragDepth BuiltIn can only be used by PSOut.
  case hlsl::Semantic::Kind::Depth:
  case hlsl::Semantic::Kind::DepthGreaterEqual:
  case hlsl::Semantic::Kind::DepthLessEqual: {
    stageVar->setIsSpirvBuiltin();
    // Vulkan requires the DepthReplacing execution mode to write to FragDepth.
    spvBuilder.addExecutionMode(entryFunction,
                                spv::ExecutionMode::DepthReplacing, {}, srcLoc);
    if (semanticKind == hlsl::Semantic::Kind::DepthGreaterEqual)
      spvBuilder.addExecutionMode(entryFunction,
                                  spv::ExecutionMode::DepthGreater, {}, srcLoc);
    else if (semanticKind == hlsl::Semantic::Kind::DepthLessEqual)
      spvBuilder.addExecutionMode(entryFunction, spv::ExecutionMode::DepthLess,
                                  {}, srcLoc);
    return spvBuilder.addStageBuiltinVar(type, sc, BuiltIn::FragDepth,
                                         isPrecise, srcLoc);
  }
  // According to DXIL spec, the ClipDistance/CullDistance SV can be used by all
  // SigPoints other than PCIn, HSIn, GSIn, PSOut, CSIn, MSIn, MSPOut, ASIn.
  // According to Vulkan spec, the ClipDistance/CullDistance
  // BuiltIn can only be used by VSOut, HS/DS/GS In/Out, MSOut.
  case hlsl::Semantic::Kind::ClipDistance:
  case hlsl::Semantic::Kind::CullDistance: {
    switch (sigPointKind) {
    case hlsl::SigPoint::Kind::VSIn:
    case hlsl::SigPoint::Kind::PCOut:
    case hlsl::SigPoint::Kind::DSIn:
      return spvBuilder.addStageIOVar(type, sc, name.str(), isPrecise, srcLoc);
    case hlsl::SigPoint::Kind::VSOut:
    case hlsl::SigPoint::Kind::HSCPIn:
    case hlsl::SigPoint::Kind::HSCPOut:
    case hlsl::SigPoint::Kind::DSCPIn:
    case hlsl::SigPoint::Kind::DSOut:
    case hlsl::SigPoint::Kind::GSVIn:
    case hlsl::SigPoint::Kind::GSOut:
    case hlsl::SigPoint::Kind::PSIn:
    case hlsl::SigPoint::Kind::MSOut:
      llvm_unreachable("should be handled in gl_PerVertex struct");
    default:
      llvm_unreachable(
          "invalid usage of SV_ClipDistance/SV_CullDistance sneaked in");
    }
  }
  // According to DXIL spec, the IsFrontFace SV can only be used by GSOut and
  // PSIn.
  // According to Vulkan spec, the FrontFacing BuitIn can only be used in PSIn.
  case hlsl::Semantic::Kind::IsFrontFace: {
    switch (sigPointKind) {
    case hlsl::SigPoint::Kind::GSOut:
      return spvBuilder.addStageIOVar(type, sc, name.str(), isPrecise, srcLoc);
    case hlsl::SigPoint::Kind::PSIn:
      stageVar->setIsSpirvBuiltin();
      return spvBuilder.addStageBuiltinVar(type, sc, BuiltIn::FrontFacing,
                                           isPrecise, srcLoc);
    default:
      llvm_unreachable("invalid usage of SV_IsFrontFace sneaked in");
    }
  }
  // According to DXIL spec, the Target SV can only be used by PSOut.
  // There is no corresponding builtin decoration in SPIR-V. So generate normal
  // Vulkan stage input/output variables.
  case hlsl::Semantic::Kind::Target:
  // An arbitrary semantic is defined by users. Generate normal Vulkan stage
  // input/output variables.
  case hlsl::Semantic::Kind::Arbitrary: {
    return spvBuilder.addStageIOVar(type, sc, name.str(), isPrecise, srcLoc);
    // TODO: patch constant function in hull shader
  }
  // According to DXIL spec, the DispatchThreadID SV can only be used by CSIn.
  // According to Vulkan spec, the GlobalInvocationId can only be used in CSIn.
  case hlsl::Semantic::Kind::DispatchThreadID: {
    stageVar->setIsSpirvBuiltin();
    return spvBuilder.addStageBuiltinVar(type, sc, BuiltIn::GlobalInvocationId,
                                         isPrecise, srcLoc);
  }
  // According to DXIL spec, the GroupID SV can only be used by CSIn.
  // According to Vulkan spec, the WorkgroupId can only be used in CSIn.
  case hlsl::Semantic::Kind::GroupID: {
    stageVar->setIsSpirvBuiltin();
    return spvBuilder.addStageBuiltinVar(type, sc, BuiltIn::WorkgroupId,
                                         isPrecise, srcLoc);
  }
  // According to DXIL spec, the GroupThreadID SV can only be used by CSIn.
  // According to Vulkan spec, the LocalInvocationId can only be used in CSIn.
  case hlsl::Semantic::Kind::GroupThreadID: {
    stageVar->setIsSpirvBuiltin();
    return spvBuilder.addStageBuiltinVar(type, sc, BuiltIn::LocalInvocationId,
                                         isPrecise, srcLoc);
  }
  // According to DXIL spec, the GroupIndex SV can only be used by CSIn.
  // According to Vulkan spec, the LocalInvocationIndex can only be used in
  // CSIn.
  case hlsl::Semantic::Kind::GroupIndex: {
    stageVar->setIsSpirvBuiltin();
    return spvBuilder.addStageBuiltinVar(
        type, sc, BuiltIn::LocalInvocationIndex, isPrecise, srcLoc);
  }
  // According to DXIL spec, the OutputControlID SV can only be used by HSIn.
  // According to Vulkan spec, the InvocationId BuiltIn can only be used in
  // HS/GS In.
  case hlsl::Semantic::Kind::OutputControlPointID: {
    stageVar->setIsSpirvBuiltin();
    return spvBuilder.addStageBuiltinVar(type, sc, BuiltIn::InvocationId,
                                         isPrecise, srcLoc);
  }
  // According to DXIL spec, the PrimitiveID SV can only be used by PCIn, HSIn,
  // DSIn, GSIn, GSOut, PSIn, and MSPOut.
  // According to Vulkan spec, the PrimitiveId BuiltIn can only be used in
  // HS/DS/PS In, GS In/Out, MSPOut.
  case hlsl::Semantic::Kind::PrimitiveID: {
    // Translate to PrimitiveId BuiltIn for all valid SigPoints.
    stageVar->setIsSpirvBuiltin();
    return spvBuilder.addStageBuiltinVar(type, sc, BuiltIn::PrimitiveId,
                                         isPrecise, srcLoc);
  }
  // According to DXIL spec, the TessFactor SV can only be used by PCOut and
  // DSIn.
  // According to Vulkan spec, the TessLevelOuter BuiltIn can only be used in
  // PCOut and DSIn.
  case hlsl::Semantic::Kind::TessFactor: {
    stageVar->setIsSpirvBuiltin();
    return spvBuilder.addStageBuiltinVar(type, sc, BuiltIn::TessLevelOuter,
                                         isPrecise, srcLoc);
  }
  // According to DXIL spec, the InsideTessFactor SV can only be used by PCOut
  // and DSIn.
  // According to Vulkan spec, the TessLevelInner BuiltIn can only be used in
  // PCOut and DSIn.
  case hlsl::Semantic::Kind::InsideTessFactor: {
    stageVar->setIsSpirvBuiltin();
    return spvBuilder.addStageBuiltinVar(type, sc, BuiltIn::TessLevelInner,
                                         isPrecise, srcLoc);
  }
  // According to DXIL spec, the DomainLocation SV can only be used by DSIn.
  // According to Vulkan spec, the TessCoord BuiltIn can only be used in DSIn.
  case hlsl::Semantic::Kind::DomainLocation: {
    stageVar->setIsSpirvBuiltin();
    return spvBuilder.addStageBuiltinVar(type, sc, BuiltIn::TessCoord,
                                         isPrecise, srcLoc);
  }
  // According to DXIL spec, the GSInstanceID SV can only be used by GSIn.
  // According to Vulkan spec, the InvocationId BuiltIn can only be used in
  // HS/GS In.
  case hlsl::Semantic::Kind::GSInstanceID: {
    stageVar->setIsSpirvBuiltin();
    return spvBuilder.addStageBuiltinVar(type, sc, BuiltIn::InvocationId,
                                         isPrecise, srcLoc);
  }
  // According to DXIL spec, the SampleIndex SV can only be used by PSIn.
  // According to Vulkan spec, the SampleId BuiltIn can only be used in PSIn.
  case hlsl::Semantic::Kind::SampleIndex: {
    stageVar->setIsSpirvBuiltin();
    return spvBuilder.addStageBuiltinVar(type, sc, BuiltIn::SampleId, isPrecise,
                                         srcLoc);
  }
  // According to DXIL spec, the StencilRef SV can only be used by PSOut.
  case hlsl::Semantic::Kind::StencilRef: {
    stageVar->setIsSpirvBuiltin();
    return spvBuilder.addStageBuiltinVar(type, sc, BuiltIn::FragStencilRefEXT,
                                         isPrecise, srcLoc);
  }
  // According to DXIL spec, the Barycentrics SV can only be used by PSIn.
  case hlsl::Semantic::Kind::Barycentrics: {
    stageVar->setIsSpirvBuiltin();

    // Selecting the correct builtin according to interpolation mode
    auto bi = BuiltIn::Max;
    if (decl->hasAttr<HLSLNoPerspectiveAttr>()) {
      if (decl->hasAttr<HLSLCentroidAttr>()) {
        bi = BuiltIn::BaryCoordNoPerspCentroidAMD;
      } else if (decl->hasAttr<HLSLSampleAttr>()) {
        bi = BuiltIn::BaryCoordNoPerspSampleAMD;
      } else {
        bi = BuiltIn::BaryCoordNoPerspAMD;
      }
    } else {
      if (decl->hasAttr<HLSLCentroidAttr>()) {
        bi = BuiltIn::BaryCoordSmoothCentroidAMD;
      } else if (decl->hasAttr<HLSLSampleAttr>()) {
        bi = BuiltIn::BaryCoordSmoothSampleAMD;
      } else {
        bi = BuiltIn::BaryCoordSmoothAMD;
      }
    }

    return spvBuilder.addStageBuiltinVar(type, sc, bi, isPrecise, srcLoc);
  }
  // According to DXIL spec, the RenderTargetArrayIndex SV can only be used by
  // VSIn, VSOut, HSCPIn, HSCPOut, DSIn, DSOut, GSVIn, GSOut, PSIn, MSPOut.
  // According to Vulkan spec, the Layer BuiltIn can only be used in GSOut
  // PSIn, and MSPOut.
  case hlsl::Semantic::Kind::RenderTargetArrayIndex: {
    switch (sigPointKind) {
    case hlsl::SigPoint::Kind::VSIn:
    case hlsl::SigPoint::Kind::HSCPIn:
    case hlsl::SigPoint::Kind::HSCPOut:
    case hlsl::SigPoint::Kind::PCOut:
    case hlsl::SigPoint::Kind::DSIn:
    case hlsl::SigPoint::Kind::DSCPIn:
    case hlsl::SigPoint::Kind::GSVIn:
      return spvBuilder.addStageIOVar(type, sc, name.str(), isPrecise, srcLoc);
    case hlsl::SigPoint::Kind::VSOut:
    case hlsl::SigPoint::Kind::DSOut:
      stageVar->setIsSpirvBuiltin();
      return spvBuilder.addStageBuiltinVar(type, sc, BuiltIn::Layer, isPrecise,
                                           srcLoc);
    case hlsl::SigPoint::Kind::GSOut:
    case hlsl::SigPoint::Kind::PSIn:
    case hlsl::SigPoint::Kind::MSPOut:
      stageVar->setIsSpirvBuiltin();
      return spvBuilder.addStageBuiltinVar(type, sc, BuiltIn::Layer, isPrecise,
                                           srcLoc);
    default:
      llvm_unreachable("invalid usage of SV_RenderTargetArrayIndex sneaked in");
    }
  }
  // According to DXIL spec, the ViewportArrayIndex SV can only be used by
  // VSIn, VSOut, HSCPIn, HSCPOut, DSIn, DSOut, GSVIn, GSOut, PSIn, MSPOut.
  // According to Vulkan spec, the ViewportIndex BuiltIn can only be used in
  // GSOut, PSIn, and MSPOut.
  case hlsl::Semantic::Kind::ViewPortArrayIndex: {
    switch (sigPointKind) {
    case hlsl::SigPoint::Kind::VSIn:
    case hlsl::SigPoint::Kind::HSCPIn:
    case hlsl::SigPoint::Kind::HSCPOut:
    case hlsl::SigPoint::Kind::PCOut:
    case hlsl::SigPoint::Kind::DSIn:
    case hlsl::SigPoint::Kind::DSCPIn:
    case hlsl::SigPoint::Kind::GSVIn:
      return spvBuilder.addStageIOVar(type, sc, name.str(), isPrecise, srcLoc);
    case hlsl::SigPoint::Kind::VSOut:
    case hlsl::SigPoint::Kind::DSOut:
      stageVar->setIsSpirvBuiltin();
      return spvBuilder.addStageBuiltinVar(type, sc, BuiltIn::ViewportIndex,
                                           isPrecise, srcLoc);
    case hlsl::SigPoint::Kind::GSOut:
    case hlsl::SigPoint::Kind::PSIn:
    case hlsl::SigPoint::Kind::MSPOut:
      stageVar->setIsSpirvBuiltin();
      return spvBuilder.addStageBuiltinVar(type, sc, BuiltIn::ViewportIndex,
                                           isPrecise, srcLoc);
    default:
      llvm_unreachable("invalid usage of SV_ViewportArrayIndex sneaked in");
    }
  }
  // According to DXIL spec, the Coverage SV can only be used by PSIn and PSOut.
  // According to Vulkan spec, the SampleMask BuiltIn can only be used in
  // PSIn and PSOut.
  case hlsl::Semantic::Kind::Coverage: {
    stageVar->setIsSpirvBuiltin();
    return spvBuilder.addStageBuiltinVar(type, sc, BuiltIn::SampleMask,
                                         isPrecise, srcLoc);
  }
  // According to DXIL spec, the ViewID SV can only be used by VSIn, PCIn,
  // HSIn, DSIn, GSIn, PSIn.
  // According to Vulkan spec, the ViewIndex BuiltIn can only be used in
  // VS/HS/DS/GS/PS input.
  case hlsl::Semantic::Kind::ViewID: {
    stageVar->setIsSpirvBuiltin();
    return spvBuilder.addStageBuiltinVar(type, sc, BuiltIn::ViewIndex,
                                         isPrecise, srcLoc);
  }
    // According to DXIL spec, the InnerCoverage SV can only be used as PSIn.
    // According to Vulkan spec, the FullyCoveredEXT BuiltIn can only be used as
    // PSIn.
  case hlsl::Semantic::Kind::InnerCoverage: {
    stageVar->setIsSpirvBuiltin();
    return spvBuilder.addStageBuiltinVar(type, sc, BuiltIn::FullyCoveredEXT,
                                         isPrecise, srcLoc);
  }
  // According to DXIL spec, the ShadingRate SV can only be used by GSOut,
  // VSOut, or PSIn. According to Vulkan spec, the FragSizeEXT BuiltIn can only
  // be used as PSIn.
  case hlsl::Semantic::Kind::ShadingRate: {
    switch (sigPointKind) {
    case hlsl::SigPoint::Kind::PSIn:
      stageVar->setIsSpirvBuiltin();
      return spvBuilder.addStageBuiltinVar(type, sc, BuiltIn::FragSizeEXT,
                                           isPrecise, srcLoc);
    default:
      emitError("semantic ShadingRate currently unsupported in non-PS shader"
                " stages",
                srcLoc);
      break;
    }
    break;
  }
  default:
    emitError("semantic %0 unimplemented", srcLoc)
        << stageVar->getSemanticStr();
    break;
  }

  return 0;
}

bool DeclResultIdMapper::validateVKAttributes(const NamedDecl *decl) {
  bool success = true;
  if (const auto *idxAttr = decl->getAttr<VKIndexAttr>()) {
    if (!spvContext.isPS()) {
      emitError("vk::index only allowed in pixel shader",
                idxAttr->getLocation());
      success = false;
    }

    const auto *locAttr = decl->getAttr<VKLocationAttr>();

    if (!locAttr) {
      emitError("vk::index should be used together with vk::location for "
                "dual-source blending",
                idxAttr->getLocation());
      success = false;
    } else {
      const auto locNumber = locAttr->getNumber();
      if (locNumber != 0) {
        emitError("dual-source blending should use vk::location 0",
                  locAttr->getLocation());
        success = false;
      }
    }

    const auto idxNumber = idxAttr->getNumber();
    if (idxNumber != 0 && idxNumber != 1) {
      emitError("dual-source blending only accepts 0 or 1 as vk::index",
                idxAttr->getLocation());
      success = false;
    }
  }

  return success;
}

bool DeclResultIdMapper::validateVKBuiltins(const NamedDecl *decl,
                                            const hlsl::SigPoint *sigPoint) {
  bool success = true;

  if (const auto *builtinAttr = decl->getAttr<VKBuiltInAttr>()) {
    // The front end parsing only allows vk::builtin to be attached to a
    // function/parameter/variable; all of them are DeclaratorDecls.
    const auto declType = getTypeOrFnRetType(cast<DeclaratorDecl>(decl));
    const auto loc = builtinAttr->getLocation();

    if (decl->hasAttr<VKLocationAttr>()) {
      emitError("cannot use vk::builtin and vk::location together", loc);
      success = false;
    }

    const llvm::StringRef builtin = builtinAttr->getBuiltIn();

    if (builtin == "HelperInvocation") {
      if (!declType->isBooleanType()) {
        emitError("HelperInvocation builtin must be of boolean type", loc);
        success = false;
      }

      if (sigPoint->GetKind() != hlsl::SigPoint::Kind::PSIn) {
        emitError(
            "HelperInvocation builtin can only be used as pixel shader input",
            loc);
        success = false;
      }
    } else if (builtin == "PointSize") {
      if (!declType->isFloatingType()) {
        emitError("PointSize builtin must be of float type", loc);
        success = false;
      }

      switch (sigPoint->GetKind()) {
      case hlsl::SigPoint::Kind::VSOut:
      case hlsl::SigPoint::Kind::HSCPIn:
      case hlsl::SigPoint::Kind::HSCPOut:
      case hlsl::SigPoint::Kind::DSCPIn:
      case hlsl::SigPoint::Kind::DSOut:
      case hlsl::SigPoint::Kind::GSVIn:
      case hlsl::SigPoint::Kind::GSOut:
      case hlsl::SigPoint::Kind::PSIn:
      case hlsl::SigPoint::Kind::MSOut:
        break;
      default:
        emitError("PointSize builtin cannot be used as %0", loc)
            << sigPoint->GetName();
        success = false;
      }
    } else if (builtin == "BaseVertex" || builtin == "BaseInstance" ||
               builtin == "DrawIndex") {
      if (!declType->isSpecificBuiltinType(BuiltinType::Kind::Int) &&
          !declType->isSpecificBuiltinType(BuiltinType::Kind::UInt)) {
        emitError("%0 builtin must be of 32-bit scalar integer type", loc)
            << builtin;
        success = false;
      }

      switch (sigPoint->GetKind()) {
      case hlsl::SigPoint::Kind::VSIn:
        break;
      case hlsl::SigPoint::Kind::MSIn:
      case hlsl::SigPoint::Kind::ASIn:
        if (builtin != "DrawIndex") {
          emitError("%0 builtin cannot be used as %1", loc)
              << builtin << sigPoint->GetName();
          success = false;
        }
        break;
      default:
        emitError("%0 builtin cannot be used as %1", loc)
            << builtin << sigPoint->GetName();
        success = false;
      }
    } else if (builtin == "DeviceIndex") {
      if (getStorageClassForSigPoint(sigPoint) != spv::StorageClass::Input) {
        emitError("%0 builtin can only be used as shader input", loc)
            << builtin;
        success = false;
      }
      if (!declType->isSpecificBuiltinType(BuiltinType::Kind::Int) &&
          !declType->isSpecificBuiltinType(BuiltinType::Kind::UInt)) {
        emitError("%0 builtin must be of 32-bit scalar integer type", loc)
            << builtin;
        success = false;
      }
    } else if (builtin == "ViewportMaskNV") {
      if (sigPoint->GetKind() != hlsl::SigPoint::Kind::MSPOut) {
        emitError("%0 builtin can only be used as 'primitives' output in MS",
                  loc)
            << builtin;
        success = false;
      }
      if (!declType->isArrayType() ||
          !declType->getArrayElementTypeNoTypeQual()->isSpecificBuiltinType(
              BuiltinType::Kind::Int)) {
        emitError("%0 builtin must be of type array of integers", loc)
            << builtin;
        success = false;
      }
    }
  }

  return success;
}

spv::StorageClass
DeclResultIdMapper::getStorageClassForSigPoint(const hlsl::SigPoint *sigPoint) {
  // This translation is done based on the HLSL reference (see docs/dxil.rst).
  const auto sigPointKind = sigPoint->GetKind();
  const auto signatureKind = sigPoint->GetSignatureKind();
  spv::StorageClass sc = spv::StorageClass::Max;
  switch (signatureKind) {
  case hlsl::DXIL::SignatureKind::Input:
    sc = spv::StorageClass::Input;
    break;
  case hlsl::DXIL::SignatureKind::Output:
    sc = spv::StorageClass::Output;
    break;
  case hlsl::DXIL::SignatureKind::Invalid: {
    // There are some special cases in HLSL (See docs/dxil.rst):
    // SignatureKind is "invalid" for PCIn, HSIn, GSIn, and CSIn.
    switch (sigPointKind) {
    case hlsl::DXIL::SigPointKind::PCIn:
    case hlsl::DXIL::SigPointKind::HSIn:
    case hlsl::DXIL::SigPointKind::GSIn:
    case hlsl::DXIL::SigPointKind::CSIn:
    case hlsl::DXIL::SigPointKind::MSIn:
    case hlsl::DXIL::SigPointKind::ASIn:
      sc = spv::StorageClass::Input;
      break;
    default:
      llvm_unreachable("Found invalid SigPoint kind for semantic");
    }
    break;
  }
  case hlsl::DXIL::SignatureKind::PatchConstOrPrim: {
    // There are some special cases in HLSL (See docs/dxil.rst):
    // SignatureKind is "PatchConstOrPrim" for PCOut, MSPOut and DSIn.
    switch (sigPointKind) {
    case hlsl::DXIL::SigPointKind::PCOut:
    case hlsl::DXIL::SigPointKind::MSPOut:
      // Patch Constant Output (Output of Hull which is passed to Domain).
      // Mesh Shader per-primitive output attributes.
      sc = spv::StorageClass::Output;
      break;
    case hlsl::DXIL::SigPointKind::DSIn:
      // Domain Shader regular input - Patch Constant data plus system values.
      sc = spv::StorageClass::Input;
      break;
    default:
      llvm_unreachable("Found invalid SigPoint kind for semantic");
    }
    break;
  }
  default:
    llvm_unreachable("Found invalid SigPoint kind for semantic");
  }
  return sc;
}

QualType DeclResultIdMapper::getTypeAndCreateCounterForPotentialAliasVar(
    const DeclaratorDecl *decl, bool *shouldBeAlias) {
  if (const auto *varDecl = dyn_cast<VarDecl>(decl)) {
    // This method is only intended to be used to create SPIR-V variables in the
    // Function or Private storage class.
    assert(!varDecl->isExternallyVisible() || varDecl->isStaticDataMember());
  }

  const QualType type = getTypeOrFnRetType(decl);
  // Whether we should generate this decl as an alias variable.
  bool genAlias = false;

  if (const auto *buffer = dyn_cast<HLSLBufferDecl>(decl->getDeclContext())) {
    // For ConstantBuffer and TextureBuffer
    if (buffer->isConstantBufferView())
      genAlias = true;
  } else if (isOrContainsAKindOfStructuredOrByteBuffer(type)) {
    genAlias = true;
  }

  // Return via parameter whether alias was generated.
  if (shouldBeAlias)
    *shouldBeAlias = genAlias;

  if (genAlias) {
    needsLegalization = true;
    createCounterVarForDecl(decl);
  }

  return type;
}

SpirvVariable *
DeclResultIdMapper::createRayTracingNVStageVar(spv::StorageClass sc,
                                               const VarDecl *decl) {
  QualType type = decl->getType();
  SpirvVariable *retVal = nullptr;

  // Raytracing interface variables are special since they do not participate
  // in any interface matching and hence do not create StageVar and
  // track them under StageVars vector

  const auto name = decl->getName();

  switch (sc) {
  case spv::StorageClass::IncomingRayPayloadNV:
  case spv::StorageClass::IncomingCallableDataNV:
  case spv::StorageClass::HitAttributeNV:
  case spv::StorageClass::RayPayloadNV:
  case spv::StorageClass::CallableDataNV:
    retVal = spvBuilder.addModuleVar(type, sc, decl->hasAttr<HLSLPreciseAttr>(),
                                     name.str());
    break;

  default:
    assert(false && "Unsupported SPIR-V storage class for raytracing");
  }

  return retVal;
}

void DeclResultIdMapper::createRayTracingNVImplicitVar(const VarDecl *varDecl) {
  APValue *val = varDecl->evaluateValue();
  assert(val);
  SpirvInstruction *constVal =
      spvBuilder.getConstantInt(astContext.UnsignedIntTy, val->getInt());
  constVal->setRValue(true);
  astDecls[varDecl].instr = constVal;
}

} // end namespace spirv
} // end namespace clang