SemanticSignatures.cpp

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//===- SemanticSignatures.cpp - HLSL Semantic 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 shader input and
/// output semantic signatures and their DirectX metadata representation.
///
//===----------------------------------------------------------------------===//
 
#include "llvm/Frontend/HLSL/SemanticSignatures.h"
#include "llvm/ADT/Enum.h"
#include "llvm/ADT/STLForwardCompat.h"
#include "llvm/ADT/bit.h"
#include "llvm/IR/Constants.h"
#include "llvm/IR/Metadata.h"
#include "llvm/IR/Type.h"
#include "llvm/Support/ErrorHandling.h"
#include <algorithm>
#include <cassert>
 
using namespace llvm;
using namespace llvm::hlsl;
using llvm::dxbc::PSV::InterpolationMode;
 
namespace {
 
// Inclusive upper bounds of the operand enums
constexpr uint32_t MaxCompType =
    static_cast<uint32_t>(dxil::ElementType::LastEntry);
constexpr uint32_t MaxSemanticKind =
    static_cast<uint32_t>(dxbc::PSV::SemanticKind::Invalid);
constexpr uint32_t MaxInterpMode =
    static_cast<uint32_t>(dxbc::PSV::InterpolationMode::Invalid);
 
Error makeError(const Twine &Msg) {
  return createStringError(inconvertibleErrorCode(), Msg);
}
 
Expected<uint64_t> extractInt(const MDNode *Node, unsigned OpId) {
  auto *CI = mdconst::dyn_extract_or_null<ConstantInt>(Node->getOperand(OpId));
  if (!CI)
    return makeError("expected integer operand " + Twine(OpId));
  return CI->getZExtValue();
}
} // namespace
 
InterpolationModifier
hlsl::getInterpolationSamplingLocation(InterpolationModifier Modifiers) {
  return std::max({Modifiers & InterpolationModifier::Center,
                   Modifiers & InterpolationModifier::Centroid,
                   Modifiers & InterpolationModifier::Sample});
}
 
dxbc::PSV::InterpolationMode
hlsl::getInterpolationMode(InterpolationModifier Modifiers) {
  if (Modifiers == InterpolationModifier::None)
    return InterpolationMode::Undefined;
  if (any(Modifiers & InterpolationModifier::NoInterpolation))
    return Modifiers == InterpolationModifier::NoInterpolation
               ? InterpolationMode::Constant
               : InterpolationMode::Invalid;
 
  bool NoPerspective = any(Modifiers & InterpolationModifier::NoPerspective);
  switch (getInterpolationSamplingLocation(Modifiers)) {
  case InterpolationModifier::Sample:
    return NoPerspective ? InterpolationMode::LinearNoperspectiveSample
                         : InterpolationMode::LinearSample;
  case InterpolationModifier::Centroid:
    return NoPerspective ? InterpolationMode::LinearNoperspectiveCentroid
                         : InterpolationMode::LinearCentroid;
  case InterpolationModifier::Center:
  case InterpolationModifier::None:
    return NoPerspective ? InterpolationMode::LinearNoperspective
                         : InterpolationMode::Linear;
  default:
    llvm_unreachable("invalid interpolation sampling location");
  }
}
 
dxbc::PSV::InterpolationMode hlsl::normalizeInterpolationMode(
    dxbc::PSV::InterpolationMode Mode, dxil::ElementType CompType,
    dxbc::PSV::SemanticKind Kind, Triple::EnvironmentType Stage, IOType IO) {
  if (!((Stage == Triple::Pixel && IO == IOType::In) ||
        (Stage == Triple::Vertex && IO == IOType::Out)))
    return InterpolationMode::Undefined;
 
  if (Mode == InterpolationMode::Undefined) {
    switch (CompType) {
    case dxil::ElementType::F16:
    case dxil::ElementType::F32:
    case dxil::ElementType::SNormF16:
    case dxil::ElementType::UNormF16:
    case dxil::ElementType::SNormF32:
    case dxil::ElementType::UNormF32:
      Mode = InterpolationMode::Linear;
      break;
    default:
      Mode = InterpolationMode::Constant;
      break;
    }
  }
 
  if (Kind == dxbc::PSV::SemanticKind::Position) {
    switch (Mode) {
    case InterpolationMode::Linear:
      return InterpolationMode::LinearNoperspective;
    case InterpolationMode::LinearCentroid:
      return InterpolationMode::LinearNoperspectiveCentroid;
    case InterpolationMode::LinearSample:
      return InterpolationMode::LinearNoperspectiveSample;
    default:
      break;
    }
  }
  return Mode;
}
 
dxbc::PSV::SemanticKind hlsl::getSemanticKind(StringRef SemanticName) {
  if (!SemanticName.consume_front_insensitive("SV_"))
    return dxbc::PSV::SemanticKind::Arbitrary;
 
  for (const auto &Kind : dxbc::PSV::getSemanticKinds())
    if (SemanticName.equals_insensitive(Kind.name()))
      return Kind.value();
 
  return dxbc::PSV::SemanticKind::Invalid;
}
 
ArrayRef<SemanticStageInfo>
hlsl::getAvailableStages(dxbc::PSV::SemanticKind SemanticKind) {
  switch (SemanticKind) {
  case dxbc::PSV::SemanticKind::Arbitrary: {
    static constexpr IOType OutOrPatchConstant =
        IOType::Out | IOType::PatchConstantOrPrimitive;
    static constexpr SemanticStageInfo Stages[] = {
        {Triple::Vertex, IOType::InOut, SemanticInterpretation::Arbitrary},
        {Triple::Geometry, IOType::InOut, SemanticInterpretation::Arbitrary},
        {Triple::Hull, IOType::All, SemanticInterpretation::Arbitrary},
        {Triple::Domain, IOType::All, SemanticInterpretation::Arbitrary},
        {Triple::Pixel, IOType::In, SemanticInterpretation::Arbitrary},
        {Triple::Mesh, OutOrPatchConstant, SemanticInterpretation::Arbitrary},
    };
    return Stages;
  }
  case dxbc::PSV::SemanticKind::DispatchThreadID:
  case dxbc::PSV::SemanticKind::GroupID:
  case dxbc::PSV::SemanticKind::GroupIndex:
  case dxbc::PSV::SemanticKind::GroupThreadID: {
    static constexpr SemanticStageInfo Stages[] = {
        {Triple::Compute, IOType::In, SemanticInterpretation::NotAllocated},
        {Triple::Mesh, IOType::In, SemanticInterpretation::NotAllocated},
        {Triple::Amplification, IOType::In,
         SemanticInterpretation::NotAllocated},
    };
    return Stages;
  }
  case dxbc::PSV::SemanticKind::ViewID: {
    static constexpr IOType InOrPatchConstant =
        IOType::In | IOType::PatchConstantOrPrimitive;
    static constexpr SemanticStageInfo Stages[] = {
        {Triple::Vertex, IOType::In, SemanticInterpretation::NotAllocated},
        {Triple::Hull, InOrPatchConstant, SemanticInterpretation::NotAllocated},
        {Triple::Domain, InOrPatchConstant,
         SemanticInterpretation::NotAllocated},
        {Triple::Geometry, IOType::In, SemanticInterpretation::NotAllocated},
        {Triple::Pixel, IOType::In, SemanticInterpretation::NotAllocated},
        {Triple::Mesh, InOrPatchConstant, SemanticInterpretation::NotAllocated},
        {Triple::Amplification, IOType::In,
         SemanticInterpretation::NotAllocated},
    };
    return Stages;
  }
  case dxbc::PSV::SemanticKind::Target: {
    static constexpr SemanticStageInfo Stages[] = {
        {Triple::Pixel, IOType::Out, SemanticInterpretation::Target}};
    return Stages;
  }
  case dxbc::PSV::SemanticKind::VertexID:
  case dxbc::PSV::SemanticKind::InstanceID: {
    static constexpr SemanticStageInfo Stages[] = {
        {Triple::Vertex, IOType::In, SemanticInterpretation::SV}};
    return Stages;
  }
  case dxbc::PSV::SemanticKind::IsFrontFace: {
    static constexpr SemanticStageInfo Stages[] = {
        {Triple::Geometry, IOType::Out, SemanticInterpretation::SGV},
        {Triple::Pixel, IOType::In, SemanticInterpretation::SGV}};
    return Stages;
  }
  case dxbc::PSV::SemanticKind::ShadingRate: {
    static constexpr SemanticStageInfo Stages[] = {
        {Triple::Vertex, IOType::Out, SemanticInterpretation::SV},
        {Triple::Hull, IOType::InOut, SemanticInterpretation::SV},
        {Triple::Domain, IOType::InOut, SemanticInterpretation::SV},
        {Triple::Geometry, IOType::InOut, SemanticInterpretation::SV},
        {Triple::Pixel, IOType::In, SemanticInterpretation::SV},
        {Triple::Mesh, IOType::PatchConstantOrPrimitive,
         SemanticInterpretation::SV}};
    return Stages;
  }
  case dxbc::PSV::SemanticKind::Position: {
    static constexpr SemanticStageInfo Stages[] = {
        {Triple::Vertex, IOType::In, SemanticInterpretation::Arbitrary},
        {Triple::Vertex, IOType::Out, SemanticInterpretation::SV},
        {Triple::Hull, IOType::InOut, SemanticInterpretation::SV},
        {Triple::Hull, IOType::PatchConstantOrPrimitive,
         SemanticInterpretation::Arbitrary},
        {Triple::Domain, IOType::InOut, SemanticInterpretation::SV},
        {Triple::Domain, IOType::PatchConstantOrPrimitive,
         SemanticInterpretation::Arbitrary},
        {Triple::Geometry, IOType::InOut, SemanticInterpretation::SV},
        {Triple::Pixel, IOType::In, SemanticInterpretation::SV},
        {Triple::Mesh, IOType::Out, SemanticInterpretation::SV},
    };
    return Stages;
  }
  case dxbc::PSV::SemanticKind::ClipDistance:
  case dxbc::PSV::SemanticKind::CullDistance: {
    static constexpr SemanticStageInfo Stages[] = {
        {Triple::Vertex, IOType::In, SemanticInterpretation::Arbitrary},
        {Triple::Vertex, IOType::Out, SemanticInterpretation::ClipCull},
        {Triple::Hull, IOType::InOut, SemanticInterpretation::ClipCull},
        {Triple::Hull, IOType::PatchConstantOrPrimitive,
         SemanticInterpretation::Arbitrary},
        {Triple::Domain, IOType::InOut, SemanticInterpretation::ClipCull},
        {Triple::Domain, IOType::PatchConstantOrPrimitive,
         SemanticInterpretation::Arbitrary},
        {Triple::Geometry, IOType::InOut, SemanticInterpretation::ClipCull},
        {Triple::Pixel, IOType::In, SemanticInterpretation::ClipCull},
        {Triple::Mesh, IOType::Out, SemanticInterpretation::ClipCull},
    };
    return Stages;
  }
  case dxbc::PSV::SemanticKind::TessFactor:
  case dxbc::PSV::SemanticKind::InsideTessFactor: {
    static constexpr SemanticStageInfo Stages[] = {
        {Triple::Hull, IOType::PatchConstantOrPrimitive,
         SemanticInterpretation::TessFactor},
        {Triple::Domain, IOType::PatchConstantOrPrimitive,
         SemanticInterpretation::TessFactor},
    };
    return Stages;
  }
  default:
    return {};
  }
}
 
SemanticInterpretation
hlsl::getInterpretationKind(dxbc::PSV::SemanticKind SemanticKind,
                            Triple::EnvironmentType ShaderStage, IOType IOTy) {
  assert(llvm::has_single_bit(static_cast<unsigned>(IOTy)) &&
         "a single IOType is expected, not a mask of IOTypes");
  for (const SemanticStageInfo &Info : getAvailableStages(SemanticKind))
    if (Info.Stage == ShaderStage && any(Info.AllowedIOTypesMask & IOTy))
      return Info.Interpretation;
  return SemanticInterpretation::Invalid;
}
 
Expected<SemanticSignatureElement>
SemanticSignatureElement::fromMetadata(const MDNode *Node) {
  // Operand positions within a signature element metadata node.
  enum class OpIdx : unsigned {
    SigId,
    SemanticName,
    CompType,
    SemanticKind,
    SemanticIndices,
    InterpMode,
    Rows,
    Cols,
    StartRow,
    StartCol,
    UsageMask,
    DynIndexMask,
    GSStream,
    LastEntry = GSStream,
  };
  const unsigned NumElementOperands = to_underlying(OpIdx::LastEntry) + 1;
 
  if (!Node)
    return makeError("signature element node is null");
  if (Node->getNumOperands() != NumElementOperands)
    return makeError("signature element node has wrong number of operands");
 
  SemanticSignatureElement Elem;
 
  Expected<uint64_t> SigId = extractInt(Node, to_underlying(OpIdx::SigId));
  if (!SigId)
    return SigId.takeError();
  Elem.SigId = *SigId;
 
  auto *Name =
      dyn_cast<MDString>(Node->getOperand(to_underlying(OpIdx::SemanticName)));
  if (!Name)
    return makeError("expected semantic name string");
  Elem.SemanticName = Name->getString();
 
  Expected<uint64_t> CompType =
      extractInt(Node, to_underlying(OpIdx::CompType));
  if (!CompType)
    return CompType.takeError();
  if (*CompType > MaxCompType)
    return makeError("invalid component type");
  Elem.CompType = static_cast<dxil::ElementType>(*CompType);
 
  Expected<uint64_t> SemanticKind =
      extractInt(Node, to_underlying(OpIdx::SemanticKind));
  if (!SemanticKind)
    return SemanticKind.takeError();
  if (*SemanticKind > MaxSemanticKind)
    return makeError("invalid semantic kind");
  Elem.SemanticKind = static_cast<dxbc::PSV::SemanticKind>(*SemanticKind);
 
  auto *Indices =
      dyn_cast<MDNode>(Node->getOperand(to_underlying(OpIdx::SemanticIndices)));
  if (!Indices)
    return makeError("expected semantic indices node");
  for (unsigned I = 0, E = Indices->getNumOperands(); I != E; ++I) {
    Expected<uint64_t> Index = extractInt(Indices, I);
    if (!Index)
      return Index.takeError();
    Elem.SemanticIndices.push_back(*Index);
  }
 
  Expected<uint64_t> InterpMode =
      extractInt(Node, to_underlying(OpIdx::InterpMode));
  if (!InterpMode)
    return InterpMode.takeError();
  if (*InterpMode > MaxInterpMode)
    return makeError("invalid interpolation mode");
  Elem.InterpMode = static_cast<dxbc::PSV::InterpolationMode>(*InterpMode);
 
  Expected<uint64_t> Rows = extractInt(Node, to_underlying(OpIdx::Rows));
  if (!Rows)
    return Rows.takeError();
  Elem.Rows = *Rows;
 
  Expected<uint64_t> Cols = extractInt(Node, to_underlying(OpIdx::Cols));
  if (!Cols)
    return Cols.takeError();
  if (*Cols < 1 || *Cols > 4)
    return makeError("number of components per row must be within 1-4");
  Elem.Cols = *Cols;
 
  Expected<uint64_t> StartRow =
      extractInt(Node, to_underlying(OpIdx::StartRow));
  if (!StartRow)
    return StartRow.takeError();
  Elem.StartRow = *StartRow;
 
  Expected<uint64_t> StartCol =
      extractInt(Node, to_underlying(OpIdx::StartCol));
  if (!StartCol)
    return StartCol.takeError();
  if (*StartCol > 3 && *StartCol != UnallocatedCol)
    return makeError("start column must be within 0-3 or unallocated");
  Elem.StartCol = *StartCol;
 
  // The row/col sentinels are always set together
  if ((Elem.StartRow == UnallocatedRow) != (Elem.StartCol == UnallocatedCol))
    return makeError("start row and column sentinels must be set together");
 
  Expected<uint64_t> UsageMask =
      extractInt(Node, to_underlying(OpIdx::UsageMask));
  if (!UsageMask)
    return UsageMask.takeError();
  if (*UsageMask > 0xF)
    return makeError("usage mask must be a 4-bit value");
  Elem.UsageMask = *UsageMask;
 
  Expected<uint64_t> DynIndexMask =
      extractInt(Node, to_underlying(OpIdx::DynIndexMask));
  if (!DynIndexMask)
    return DynIndexMask.takeError();
  if (*DynIndexMask > 0xF)
    return makeError("dynamic index mask must be a 4-bit value");
  Elem.DynIndexMask = *DynIndexMask;
 
  Expected<uint64_t> GSStream =
      extractInt(Node, to_underlying(OpIdx::GSStream));
  if (!GSStream)
    return GSStream.takeError();
  if (*GSStream > 3)
    return makeError("geometry shader stream index must be within 0-3");
  Elem.GSStream = *GSStream;
 
  if (Elem.SemanticIndices.size() != Elem.Rows)
    return makeError(
        "number of semantic indices must equal the number of rows");
 
  return Elem;
}
 
MDNode *SemanticSignatureElement::toMetadata(LLVMContext &Ctx) const {
  Type *I32Ty = Type::getInt32Ty(Ctx);
  Type *I8Ty = Type::getInt8Ty(Ctx);
  auto GetI32 = [&](uint32_t Val) -> Metadata * {
    return ConstantAsMetadata::get(ConstantInt::get(I32Ty, Val));
  };
  auto GetI8 = [&](uint8_t Val) -> Metadata * {
    return ConstantAsMetadata::get(ConstantInt::get(I8Ty, Val));
  };
 
  SmallVector<Metadata *> IndexOps;
  for (uint32_t Index : SemanticIndices)
    IndexOps.push_back(GetI32(Index));
 
  return MDNode::get(Ctx,
                     {GetI32(SigId), MDString::get(Ctx, SemanticName),
                      GetI32(static_cast<uint32_t>(CompType)),
                      GetI32(static_cast<uint32_t>(SemanticKind)),
                      MDNode::get(Ctx, IndexOps),
                      GetI32(static_cast<uint32_t>(InterpMode)), GetI32(Rows),
                      GetI8(Cols), GetI32(StartRow), GetI8(StartCol),
                      GetI8(UsageMask), GetI8(DynIndexMask), GetI32(GSStream)});
}