RootSignatureMetadata.cpp

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//===- RootSignatureMetadata.h - HLSL Root Signature helpers --------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
///
/// \file This file implements a library for working with HLSL Root Signatures
/// and their metadata representation.
///
//===----------------------------------------------------------------------===//
 
#include "llvm/Frontend/HLSL/RootSignatureMetadata.h"
#include "llvm/Frontend/HLSL/RootSignatureValidations.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/Metadata.h"
#include "llvm/Support/DXILABI.h"
#include "llvm/Support/ScopedPrinter.h"
 
using namespace llvm;
 
namespace llvm {
namespace hlsl {
namespace rootsig {
 
char GenericRSMetadataError::ID;
char InvalidRSMetadataFormat::ID;
char InvalidRSMetadataValue::ID;
char TableSamplerMixinError::ID;
char ShaderRegisterOverflowError::ID;
char OffsetOverflowError::ID;
char OffsetAppendAfterOverflow::ID;
 
template <typename T> char RootSignatureValidationError<T>::ID;
 
static std::optional<uint32_t> extractMdIntValue(MDNode *Node,
                                                 unsigned int OpId) {
  if (auto *CI =
          mdconst::dyn_extract<ConstantInt>(Node->getOperand(OpId).get()))
    return CI->getZExtValue();
  return std::nullopt;
}
 
static std::optional<float> extractMdFloatValue(MDNode *Node,
                                                unsigned int OpId) {
  if (auto *CI = mdconst::dyn_extract<ConstantFP>(Node->getOperand(OpId).get()))
    return CI->getValueAPF().convertToFloat();
  return std::nullopt;
}
 
static std::optional<StringRef> extractMdStringValue(MDNode *Node,
                                                     unsigned int OpId) {
  MDString *NodeText = dyn_cast<MDString>(Node->getOperand(OpId));
  if (NodeText == nullptr)
    return std::nullopt;
  return NodeText->getString();
}
 
template <typename T, typename = std::enable_if_t<
                          std::is_enum_v<T> &&
                          std::is_same_v<std::underlying_type_t<T>, uint32_t>>>
static Expected<T>
extractEnumValue(MDNode *Node, unsigned int OpId, StringRef ErrText,
                 llvm::function_ref<bool(uint32_t)> VerifyFn) {
  if (std::optional<uint32_t> Val = extractMdIntValue(Node, OpId)) {
    if (!VerifyFn(*Val))
      return make_error<RootSignatureValidationError<uint32_t>>(ErrText, *Val);
    return static_cast<T>(*Val);
  }
  return make_error<InvalidRSMetadataValue>("ShaderVisibility");
}
 
namespace {
 
// We use the OverloadVisit with std::visit to ensure the compiler catches if a
// new RootElement variant type is added but it's metadata generation isn't
// handled.
template <class... Ts> struct OverloadedVisit : Ts... {
  using Ts::operator()...;
};
template <class... Ts> OverloadedVisit(Ts...) -> OverloadedVisit<Ts...>;
 
} // namespace
 
MDNode *MetadataBuilder::BuildRootSignature() {
  const auto Visitor = OverloadedVisit{
      [this](const dxbc::RootFlags &Flags) -> MDNode * {
        return BuildRootFlags(Flags);
      },
      [this](const RootConstants &Constants) -> MDNode * {
        return BuildRootConstants(Constants);
      },
      [this](const RootDescriptor &Descriptor) -> MDNode * {
        return BuildRootDescriptor(Descriptor);
      },
      [this](const DescriptorTableClause &Clause) -> MDNode * {
        return BuildDescriptorTableClause(Clause);
      },
      [this](const DescriptorTable &Table) -> MDNode * {
        return BuildDescriptorTable(Table);
      },
      [this](const StaticSampler &Sampler) -> MDNode * {
        return BuildStaticSampler(Sampler);
      },
  };
 
  for (const RootElement &Element : Elements) {
    MDNode *ElementMD = std::visit(Visitor, Element);
    assert(ElementMD != nullptr &&
           "Root Element must be initialized and validated");
    GeneratedMetadata.push_back(ElementMD);
  }
 
  return MDNode::get(Ctx, GeneratedMetadata);
}
 
MDNode *MetadataBuilder::BuildRootFlags(const dxbc::RootFlags &Flags) {
  IRBuilder<> Builder(Ctx);
  Metadata *Operands[] = {
      MDString::get(Ctx, "RootFlags"),
      ConstantAsMetadata::get(Builder.getInt32(to_underlying(Flags))),
  };
  return MDNode::get(Ctx, Operands);
}
 
MDNode *MetadataBuilder::BuildRootConstants(const RootConstants &Constants) {
  IRBuilder<> Builder(Ctx);
  Metadata *Operands[] = {
      MDString::get(Ctx, "RootConstants"),
      ConstantAsMetadata::get(
          Builder.getInt32(to_underlying(Constants.Visibility))),
      ConstantAsMetadata::get(Builder.getInt32(Constants.Reg.Number)),
      ConstantAsMetadata::get(Builder.getInt32(Constants.Space)),
      ConstantAsMetadata::get(Builder.getInt32(Constants.Num32BitConstants)),
  };
  return MDNode::get(Ctx, Operands);
}
 
MDNode *MetadataBuilder::BuildRootDescriptor(const RootDescriptor &Descriptor) {
  IRBuilder<> Builder(Ctx);
  StringRef ResName = dxil::getResourceClassName(Descriptor.Type);
  assert(!ResName.empty() && "Provided an invalid Resource Class");
  SmallString<7> Name({"Root", ResName});
  Metadata *Operands[] = {
      MDString::get(Ctx, Name),
      ConstantAsMetadata::get(
          Builder.getInt32(to_underlying(Descriptor.Visibility))),
      ConstantAsMetadata::get(Builder.getInt32(Descriptor.Reg.Number)),
      ConstantAsMetadata::get(Builder.getInt32(Descriptor.Space)),
      ConstantAsMetadata::get(
          Builder.getInt32(to_underlying(Descriptor.Flags))),
  };
  return MDNode::get(Ctx, Operands);
}
 
MDNode *MetadataBuilder::BuildDescriptorTable(const DescriptorTable &Table) {
  IRBuilder<> Builder(Ctx);
  SmallVector<Metadata *> TableOperands;
  // Set the mandatory arguments
  TableOperands.push_back(MDString::get(Ctx, "DescriptorTable"));
  TableOperands.push_back(ConstantAsMetadata::get(
      Builder.getInt32(to_underlying(Table.Visibility))));
 
  // Remaining operands are references to the table's clauses. The in-memory
  // representation of the Root Elements created from parsing will ensure that
  // the previous N elements are the clauses for this table.
  assert(Table.NumClauses <= GeneratedMetadata.size() &&
         "Table expected all owned clauses to be generated already");
  // So, add a refence to each clause to our operands
  TableOperands.append(GeneratedMetadata.end() - Table.NumClauses,
                       GeneratedMetadata.end());
  // Then, remove those clauses from the general list of Root Elements
  GeneratedMetadata.pop_back_n(Table.NumClauses);
 
  return MDNode::get(Ctx, TableOperands);
}
 
MDNode *MetadataBuilder::BuildDescriptorTableClause(
    const DescriptorTableClause &Clause) {
  IRBuilder<> Builder(Ctx);
  StringRef ResName = dxil::getResourceClassName(Clause.Type);
  assert(!ResName.empty() && "Provided an invalid Resource Class");
  Metadata *Operands[] = {
      MDString::get(Ctx, ResName),
      ConstantAsMetadata::get(Builder.getInt32(Clause.NumDescriptors)),
      ConstantAsMetadata::get(Builder.getInt32(Clause.Reg.Number)),
      ConstantAsMetadata::get(Builder.getInt32(Clause.Space)),
      ConstantAsMetadata::get(Builder.getInt32(Clause.Offset)),
      ConstantAsMetadata::get(Builder.getInt32(to_underlying(Clause.Flags))),
  };
  return MDNode::get(Ctx, Operands);
}
 
MDNode *MetadataBuilder::BuildStaticSampler(const StaticSampler &Sampler) {
  IRBuilder<> Builder(Ctx);
  Metadata *Operands[] = {
      MDString::get(Ctx, "StaticSampler"),
      ConstantAsMetadata::get(Builder.getInt32(to_underlying(Sampler.Filter))),
      ConstantAsMetadata::get(
          Builder.getInt32(to_underlying(Sampler.AddressU))),
      ConstantAsMetadata::get(
          Builder.getInt32(to_underlying(Sampler.AddressV))),
      ConstantAsMetadata::get(
          Builder.getInt32(to_underlying(Sampler.AddressW))),
      ConstantAsMetadata::get(
          ConstantFP::get(Type::getFloatTy(Ctx), Sampler.MipLODBias)),
      ConstantAsMetadata::get(Builder.getInt32(Sampler.MaxAnisotropy)),
      ConstantAsMetadata::get(
          Builder.getInt32(to_underlying(Sampler.CompFunc))),
      ConstantAsMetadata::get(
          Builder.getInt32(to_underlying(Sampler.BorderColor))),
      ConstantAsMetadata::get(
          ConstantFP::get(Type::getFloatTy(Ctx), Sampler.MinLOD)),
      ConstantAsMetadata::get(
          ConstantFP::get(Type::getFloatTy(Ctx), Sampler.MaxLOD)),
      ConstantAsMetadata::get(Builder.getInt32(Sampler.Reg.Number)),
      ConstantAsMetadata::get(Builder.getInt32(Sampler.Space)),
      ConstantAsMetadata::get(
          Builder.getInt32(to_underlying(Sampler.Visibility))),
  };
  return MDNode::get(Ctx, Operands);
}
 
Error MetadataParser::parseRootFlags(mcdxbc::RootSignatureDesc &RSD,
                                     MDNode *RootFlagNode) {
  if (RootFlagNode->getNumOperands() != 2)
    return make_error<InvalidRSMetadataFormat>("RootFlag Element");
 
  if (std::optional<uint32_t> Val = extractMdIntValue(RootFlagNode, 1))
    RSD.Flags = *Val;
  else
    return make_error<InvalidRSMetadataValue>("RootFlag");
 
  return Error::success();
}
 
Error MetadataParser::parseRootConstants(mcdxbc::RootSignatureDesc &RSD,
                                         MDNode *RootConstantNode) {
  if (RootConstantNode->getNumOperands() != 5)
    return make_error<InvalidRSMetadataFormat>("RootConstants Element");
 
  Expected<dxbc::ShaderVisibility> Visibility =
      extractEnumValue<dxbc::ShaderVisibility>(RootConstantNode, 1,
                                               "ShaderVisibility",
                                               dxbc::isValidShaderVisibility);
  if (auto E = Visibility.takeError())
    return Error(std::move(E));
 
  mcdxbc::RootConstants Constants;
  if (std::optional<uint32_t> Val = extractMdIntValue(RootConstantNode, 2))
    Constants.ShaderRegister = *Val;
  else
    return make_error<InvalidRSMetadataValue>("ShaderRegister");
 
  if (std::optional<uint32_t> Val = extractMdIntValue(RootConstantNode, 3))
    Constants.RegisterSpace = *Val;
  else
    return make_error<InvalidRSMetadataValue>("RegisterSpace");
 
  if (std::optional<uint32_t> Val = extractMdIntValue(RootConstantNode, 4))
    Constants.Num32BitValues = *Val;
  else
    return make_error<InvalidRSMetadataValue>("Num32BitValues");
 
  RSD.ParametersContainer.addParameter(dxbc::RootParameterType::Constants32Bit,
                                       *Visibility, Constants);
 
  return Error::success();
}
 
Error MetadataParser::parseRootDescriptors(
    mcdxbc::RootSignatureDesc &RSD, MDNode *RootDescriptorNode,
    RootSignatureElementKind ElementKind) {
  assert((ElementKind == RootSignatureElementKind::SRV ||
          ElementKind == RootSignatureElementKind::UAV ||
          ElementKind == RootSignatureElementKind::CBV) &&
         "parseRootDescriptors should only be called with RootDescriptor "
         "element kind.");
  if (RootDescriptorNode->getNumOperands() != 5)
    return make_error<InvalidRSMetadataFormat>("Root Descriptor Element");
 
  dxbc::RootParameterType Type;
  switch (ElementKind) {
  case RootSignatureElementKind::SRV:
    Type = dxbc::RootParameterType::SRV;
    break;
  case RootSignatureElementKind::UAV:
    Type = dxbc::RootParameterType::UAV;
    break;
  case RootSignatureElementKind::CBV:
    Type = dxbc::RootParameterType::CBV;
    break;
  default:
    llvm_unreachable("invalid Root Descriptor kind");
    break;
  }
 
  Expected<dxbc::ShaderVisibility> Visibility =
      extractEnumValue<dxbc::ShaderVisibility>(RootDescriptorNode, 1,
                                               "ShaderVisibility",
                                               dxbc::isValidShaderVisibility);
  if (auto E = Visibility.takeError())
    return Error(std::move(E));
 
  mcdxbc::RootDescriptor Descriptor;
  if (std::optional<uint32_t> Val = extractMdIntValue(RootDescriptorNode, 2))
    Descriptor.ShaderRegister = *Val;
  else
    return make_error<InvalidRSMetadataValue>("ShaderRegister");
 
  if (std::optional<uint32_t> Val = extractMdIntValue(RootDescriptorNode, 3))
    Descriptor.RegisterSpace = *Val;
  else
    return make_error<InvalidRSMetadataValue>("RegisterSpace");
 
  if (RSD.Version == 1) {
    RSD.ParametersContainer.addParameter(Type, *Visibility, Descriptor);
    return Error::success();
  }
  assert(RSD.Version > 1);
 
  if (std::optional<uint32_t> Val = extractMdIntValue(RootDescriptorNode, 4))
    Descriptor.Flags = *Val;
  else
    return make_error<InvalidRSMetadataValue>("Root Descriptor Flags");
 
  RSD.ParametersContainer.addParameter(Type, *Visibility, Descriptor);
  return Error::success();
}
 
Error MetadataParser::parseDescriptorRange(mcdxbc::DescriptorTable &Table,
                                           MDNode *RangeDescriptorNode) {
  if (RangeDescriptorNode->getNumOperands() != 6)
    return make_error<InvalidRSMetadataFormat>("Descriptor Range");
 
  mcdxbc::DescriptorRange Range;
 
  std::optional<StringRef> ElementText =
      extractMdStringValue(RangeDescriptorNode, 0);
 
  if (!ElementText.has_value())
    return make_error<InvalidRSMetadataFormat>("Descriptor Range");
 
  if (*ElementText == "CBV")
    Range.RangeType = dxil::ResourceClass::CBuffer;
  else if (*ElementText == "SRV")
    Range.RangeType = dxil::ResourceClass::SRV;
  else if (*ElementText == "UAV")
    Range.RangeType = dxil::ResourceClass::UAV;
  else if (*ElementText == "Sampler")
    Range.RangeType = dxil::ResourceClass::Sampler;
  else
    return make_error<GenericRSMetadataError>("Invalid Descriptor Range type.",
                                              RangeDescriptorNode);
 
  if (std::optional<uint32_t> Val = extractMdIntValue(RangeDescriptorNode, 1))
    Range.NumDescriptors = *Val;
  else
    return make_error<GenericRSMetadataError>("Number of Descriptor in Range",
                                              RangeDescriptorNode);
 
  if (std::optional<uint32_t> Val = extractMdIntValue(RangeDescriptorNode, 2))
    Range.BaseShaderRegister = *Val;
  else
    return make_error<InvalidRSMetadataValue>("BaseShaderRegister");
 
  if (std::optional<uint32_t> Val = extractMdIntValue(RangeDescriptorNode, 3))
    Range.RegisterSpace = *Val;
  else
    return make_error<InvalidRSMetadataValue>("RegisterSpace");
 
  if (std::optional<uint32_t> Val = extractMdIntValue(RangeDescriptorNode, 4))
    Range.OffsetInDescriptorsFromTableStart = *Val;
  else
    return make_error<InvalidRSMetadataValue>(
        "OffsetInDescriptorsFromTableStart");
 
  if (std::optional<uint32_t> Val = extractMdIntValue(RangeDescriptorNode, 5))
    Range.Flags = *Val;
  else
    return make_error<InvalidRSMetadataValue>("Descriptor Range Flags");
 
  Table.Ranges.push_back(Range);
  return Error::success();
}
 
Error MetadataParser::parseDescriptorTable(mcdxbc::RootSignatureDesc &RSD,
                                           MDNode *DescriptorTableNode) {
  const unsigned int NumOperands = DescriptorTableNode->getNumOperands();
  if (NumOperands < 2)
    return make_error<InvalidRSMetadataFormat>("Descriptor Table");
 
  Expected<dxbc::ShaderVisibility> Visibility =
      extractEnumValue<dxbc::ShaderVisibility>(DescriptorTableNode, 1,
                                               "ShaderVisibility",
                                               dxbc::isValidShaderVisibility);
  if (auto E = Visibility.takeError())
    return Error(std::move(E));
 
  mcdxbc::DescriptorTable Table;
 
  for (unsigned int I = 2; I < NumOperands; I++) {
    MDNode *Element = dyn_cast<MDNode>(DescriptorTableNode->getOperand(I));
    if (Element == nullptr)
      return make_error<GenericRSMetadataError>(
          "Missing Root Element Metadata Node.", DescriptorTableNode);
 
    if (auto Err = parseDescriptorRange(Table, Element))
      return Err;
  }
 
  RSD.ParametersContainer.addParameter(dxbc::RootParameterType::DescriptorTable,
                                       *Visibility, Table);
  return Error::success();
}
 
Error MetadataParser::parseStaticSampler(mcdxbc::RootSignatureDesc &RSD,
                                         MDNode *StaticSamplerNode) {
  if (StaticSamplerNode->getNumOperands() != 14)
    return make_error<InvalidRSMetadataFormat>("Static Sampler");
 
  mcdxbc::StaticSampler Sampler;
 
  Expected<dxbc::SamplerFilter> Filter = extractEnumValue<dxbc::SamplerFilter>(
      StaticSamplerNode, 1, "Filter", dxbc::isValidSamplerFilter);
  if (auto E = Filter.takeError())
    return Error(std::move(E));
  Sampler.Filter = *Filter;
 
  Expected<dxbc::TextureAddressMode> AddressU =
      extractEnumValue<dxbc::TextureAddressMode>(
          StaticSamplerNode, 2, "AddressU", dxbc::isValidAddress);
  if (auto E = AddressU.takeError())
    return Error(std::move(E));
  Sampler.AddressU = *AddressU;
 
  Expected<dxbc::TextureAddressMode> AddressV =
      extractEnumValue<dxbc::TextureAddressMode>(
          StaticSamplerNode, 3, "AddressV", dxbc::isValidAddress);
  if (auto E = AddressV.takeError())
    return Error(std::move(E));
  Sampler.AddressV = *AddressV;
 
  Expected<dxbc::TextureAddressMode> AddressW =
      extractEnumValue<dxbc::TextureAddressMode>(
          StaticSamplerNode, 4, "AddressW", dxbc::isValidAddress);
  if (auto E = AddressW.takeError())
    return Error(std::move(E));
  Sampler.AddressW = *AddressW;
 
  if (std::optional<float> Val = extractMdFloatValue(StaticSamplerNode, 5))
    Sampler.MipLODBias = *Val;
  else
    return make_error<InvalidRSMetadataValue>("MipLODBias");
 
  if (std::optional<uint32_t> Val = extractMdIntValue(StaticSamplerNode, 6))
    Sampler.MaxAnisotropy = *Val;
  else
    return make_error<InvalidRSMetadataValue>("MaxAnisotropy");
 
  Expected<dxbc::ComparisonFunc> ComparisonFunc =
      extractEnumValue<dxbc::ComparisonFunc>(
          StaticSamplerNode, 7, "ComparisonFunc", dxbc::isValidComparisonFunc);
  if (auto E = ComparisonFunc.takeError())
    return Error(std::move(E));
  Sampler.ComparisonFunc = *ComparisonFunc;
 
  Expected<dxbc::StaticBorderColor> BorderColor =
      extractEnumValue<dxbc::StaticBorderColor>(
          StaticSamplerNode, 8, "BorderColor", dxbc::isValidBorderColor);
  if (auto E = BorderColor.takeError())
    return Error(std::move(E));
  Sampler.BorderColor = *BorderColor;
 
  if (std::optional<float> Val = extractMdFloatValue(StaticSamplerNode, 9))
    Sampler.MinLOD = *Val;
  else
    return make_error<InvalidRSMetadataValue>("MinLOD");
 
  if (std::optional<float> Val = extractMdFloatValue(StaticSamplerNode, 10))
    Sampler.MaxLOD = *Val;
  else
    return make_error<InvalidRSMetadataValue>("MaxLOD");
 
  if (std::optional<uint32_t> Val = extractMdIntValue(StaticSamplerNode, 11))
    Sampler.ShaderRegister = *Val;
  else
    return make_error<InvalidRSMetadataValue>("ShaderRegister");
 
  if (std::optional<uint32_t> Val = extractMdIntValue(StaticSamplerNode, 12))
    Sampler.RegisterSpace = *Val;
  else
    return make_error<InvalidRSMetadataValue>("RegisterSpace");
 
  Expected<dxbc::ShaderVisibility> Visibility =
      extractEnumValue<dxbc::ShaderVisibility>(StaticSamplerNode, 13,
                                               "ShaderVisibility",
                                               dxbc::isValidShaderVisibility);
  if (auto E = Visibility.takeError())
    return Error(std::move(E));
  Sampler.ShaderVisibility = *Visibility;
 
  RSD.StaticSamplers.push_back(Sampler);
  return Error::success();
}
 
Error MetadataParser::parseRootSignatureElement(mcdxbc::RootSignatureDesc &RSD,
                                                MDNode *Element) {
  std::optional<StringRef> ElementText = extractMdStringValue(Element, 0);
  if (!ElementText.has_value())
    return make_error<InvalidRSMetadataFormat>("Root Element");
 
  RootSignatureElementKind ElementKind =
      StringSwitch<RootSignatureElementKind>(*ElementText)
          .Case("RootFlags", RootSignatureElementKind::RootFlags)
          .Case("RootConstants", RootSignatureElementKind::RootConstants)
          .Case("RootCBV", RootSignatureElementKind::CBV)
          .Case("RootSRV", RootSignatureElementKind::SRV)
          .Case("RootUAV", RootSignatureElementKind::UAV)
          .Case("DescriptorTable", RootSignatureElementKind::DescriptorTable)
          .Case("StaticSampler", RootSignatureElementKind::StaticSamplers)
          .Default(RootSignatureElementKind::Error);
 
  switch (ElementKind) {
 
  case RootSignatureElementKind::RootFlags:
    return parseRootFlags(RSD, Element);
  case RootSignatureElementKind::RootConstants:
    return parseRootConstants(RSD, Element);
  case RootSignatureElementKind::CBV:
  case RootSignatureElementKind::SRV:
  case RootSignatureElementKind::UAV:
    return parseRootDescriptors(RSD, Element, ElementKind);
  case RootSignatureElementKind::DescriptorTable:
    return parseDescriptorTable(RSD, Element);
  case RootSignatureElementKind::StaticSamplers:
    return parseStaticSampler(RSD, Element);
  case RootSignatureElementKind::Error:
    return make_error<GenericRSMetadataError>("Invalid Root Signature Element",
                                              Element);
  }
 
  llvm_unreachable("Unhandled RootSignatureElementKind enum.");
}
 
static Error
validateDescriptorTableSamplerMixin(const mcdxbc::DescriptorTable &Table,
                                    uint32_t Location) {
  dxil::ResourceClass CurrRC = dxil::ResourceClass::Sampler;
  for (const mcdxbc::DescriptorRange &Range : Table.Ranges) {
    if (Range.RangeType == dxil::ResourceClass::Sampler &&
        CurrRC != dxil::ResourceClass::Sampler)
      return make_error<TableSamplerMixinError>(CurrRC, Location);
    CurrRC = Range.RangeType;
  }
  return Error::success();
}
 
static Error
validateDescriptorTableRegisterOverflow(const mcdxbc::DescriptorTable &Table,
                                        uint32_t Location) {
  uint64_t Offset = 0;
  bool IsPrevUnbound = false;
  for (const mcdxbc::DescriptorRange &Range : Table.Ranges) {
    // Validation of NumDescriptors should have happened by this point.
    if (Range.NumDescriptors == 0)
      continue;
 
    const uint64_t RangeBound = llvm::hlsl::rootsig::computeRangeBound(
        Range.BaseShaderRegister, Range.NumDescriptors);
 
    if (!verifyNoOverflowedOffset(RangeBound))
      return make_error<ShaderRegisterOverflowError>(
          Range.RangeType, Range.BaseShaderRegister, Range.RegisterSpace);
 
    bool IsAppending =
        Range.OffsetInDescriptorsFromTableStart == DescriptorTableOffsetAppend;
    if (!IsAppending)
      Offset = Range.OffsetInDescriptorsFromTableStart;
 
    if (IsPrevUnbound && IsAppending)
      return make_error<OffsetAppendAfterOverflow>(
          Range.RangeType, Range.BaseShaderRegister, Range.RegisterSpace);
 
    const uint64_t OffsetBound =
        llvm::hlsl::rootsig::computeRangeBound(Offset, Range.NumDescriptors);
 
    if (!verifyNoOverflowedOffset(OffsetBound))
      return make_error<OffsetOverflowError>(
          Range.RangeType, Range.BaseShaderRegister, Range.RegisterSpace);
 
    Offset = OffsetBound + 1;
    IsPrevUnbound =
        Range.NumDescriptors == llvm::hlsl::rootsig::NumDescriptorsUnbounded;
  }
 
  return Error::success();
}
 
Error MetadataParser::validateRootSignature(
    const mcdxbc::RootSignatureDesc &RSD) {
  Error DeferredErrs = Error::success();
  if (!hlsl::rootsig::verifyVersion(RSD.Version)) {
    DeferredErrs =
        joinErrors(std::move(DeferredErrs),
                   make_error<RootSignatureValidationError<uint32_t>>(
                       "Version", RSD.Version));
  }
 
  if (!hlsl::rootsig::verifyRootFlag(RSD.Flags)) {
    DeferredErrs =
        joinErrors(std::move(DeferredErrs),
                   make_error<RootSignatureValidationError<uint32_t>>(
                       "RootFlags", RSD.Flags));
  }
 
  for (const mcdxbc::RootParameterInfo &Info : RSD.ParametersContainer) {
 
    switch (Info.Type) {
    case dxbc::RootParameterType::Constants32Bit:
      break;
 
    case dxbc::RootParameterType::CBV:
    case dxbc::RootParameterType::UAV:
    case dxbc::RootParameterType::SRV: {
      const mcdxbc::RootDescriptor &Descriptor =
          RSD.ParametersContainer.getRootDescriptor(Info.Location);
      if (!hlsl::rootsig::verifyRegisterValue(Descriptor.ShaderRegister))
        DeferredErrs =
            joinErrors(std::move(DeferredErrs),
                       make_error<RootSignatureValidationError<uint32_t>>(
                           "ShaderRegister", Descriptor.ShaderRegister));
 
      if (!hlsl::rootsig::verifyRegisterSpace(Descriptor.RegisterSpace))
        DeferredErrs =
            joinErrors(std::move(DeferredErrs),
                       make_error<RootSignatureValidationError<uint32_t>>(
                           "RegisterSpace", Descriptor.RegisterSpace));
 
      if (RSD.Version > 1) {
        if (!hlsl::rootsig::verifyRootDescriptorFlag(RSD.Version,
                                                     Descriptor.Flags))
          DeferredErrs =
              joinErrors(std::move(DeferredErrs),
                         make_error<RootSignatureValidationError<uint32_t>>(
                             "RootDescriptorFlag", Descriptor.Flags));
      }
      break;
    }
    case dxbc::RootParameterType::DescriptorTable: {
      const mcdxbc::DescriptorTable &Table =
          RSD.ParametersContainer.getDescriptorTable(Info.Location);
      for (const mcdxbc::DescriptorRange &Range : Table) {
        if (!hlsl::rootsig::verifyRegisterSpace(Range.RegisterSpace))
          DeferredErrs =
              joinErrors(std::move(DeferredErrs),
                         make_error<RootSignatureValidationError<uint32_t>>(
                             "RegisterSpace", Range.RegisterSpace));
 
        if (!hlsl::rootsig::verifyNumDescriptors(Range.NumDescriptors))
          DeferredErrs =
              joinErrors(std::move(DeferredErrs),
                         make_error<RootSignatureValidationError<uint32_t>>(
                             "NumDescriptors", Range.NumDescriptors));
 
        if (!hlsl::rootsig::verifyDescriptorRangeFlag(
                RSD.Version, Range.RangeType,
                dxbc::DescriptorRangeFlags(Range.Flags)))
          DeferredErrs =
              joinErrors(std::move(DeferredErrs),
                         make_error<RootSignatureValidationError<uint32_t>>(
                             "DescriptorFlag", Range.Flags));
 
        if (Error Err =
                validateDescriptorTableSamplerMixin(Table, Info.Location))
          DeferredErrs = joinErrors(std::move(DeferredErrs), std::move(Err));
 
        if (Error Err =
                validateDescriptorTableRegisterOverflow(Table, Info.Location))
          DeferredErrs = joinErrors(std::move(DeferredErrs), std::move(Err));
      }
      break;
    }
    }
  }
 
  for (const mcdxbc::StaticSampler &Sampler : RSD.StaticSamplers) {
 
    if (!hlsl::rootsig::verifyMipLODBias(Sampler.MipLODBias))
      DeferredErrs = joinErrors(std::move(DeferredErrs),
                                make_error<RootSignatureValidationError<float>>(
                                    "MipLODBias", Sampler.MipLODBias));
 
    if (!hlsl::rootsig::verifyMaxAnisotropy(Sampler.MaxAnisotropy))
      DeferredErrs =
          joinErrors(std::move(DeferredErrs),
                     make_error<RootSignatureValidationError<uint32_t>>(
                         "MaxAnisotropy", Sampler.MaxAnisotropy));
 
    if (!hlsl::rootsig::verifyLOD(Sampler.MinLOD))
      DeferredErrs = joinErrors(std::move(DeferredErrs),
                                make_error<RootSignatureValidationError<float>>(
                                    "MinLOD", Sampler.MinLOD));
 
    if (!hlsl::rootsig::verifyLOD(Sampler.MaxLOD))
      DeferredErrs = joinErrors(std::move(DeferredErrs),
                                make_error<RootSignatureValidationError<float>>(
                                    "MaxLOD", Sampler.MaxLOD));
 
    if (!hlsl::rootsig::verifyRegisterValue(Sampler.ShaderRegister))
      DeferredErrs =
          joinErrors(std::move(DeferredErrs),
                     make_error<RootSignatureValidationError<uint32_t>>(
                         "ShaderRegister", Sampler.ShaderRegister));
 
    if (!hlsl::rootsig::verifyRegisterSpace(Sampler.RegisterSpace))
      DeferredErrs =
          joinErrors(std::move(DeferredErrs),
                     make_error<RootSignatureValidationError<uint32_t>>(
                         "RegisterSpace", Sampler.RegisterSpace));
 
    if (!hlsl::rootsig::verifyStaticSamplerFlags(RSD.Version, Sampler.Flags))
      DeferredErrs =
          joinErrors(std::move(DeferredErrs),
                     make_error<RootSignatureValidationError<uint32_t>>(
                         "Static Sampler Flag", Sampler.Flags));
  }
 
  return DeferredErrs;
}
 
Expected<mcdxbc::RootSignatureDesc>
MetadataParser::ParseRootSignature(uint32_t Version) {
  Error DeferredErrs = Error::success();
  mcdxbc::RootSignatureDesc RSD;
  RSD.Version = Version;
  for (const auto &Operand : Root->operands()) {
    MDNode *Element = dyn_cast<MDNode>(Operand);
    if (Element == nullptr)
      return joinErrors(std::move(DeferredErrs),
                        make_error<GenericRSMetadataError>(
                            "Missing Root Element Metadata Node.", nullptr));
 
    if (auto Err = parseRootSignatureElement(RSD, Element))
      DeferredErrs = joinErrors(std::move(DeferredErrs), std::move(Err));
  }
 
  if (auto Err = validateRootSignature(RSD))
    DeferredErrs = joinErrors(std::move(DeferredErrs), std::move(Err));
 
  if (DeferredErrs)
    return std::move(DeferredErrs);
 
  return std::move(RSD);
}
} // namespace rootsig
} // namespace hlsl
} // namespace llvm