//===- HLSLRootSignatureValidations.cpp - 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 contains helpers for working with HLSL Root Signatures.
///
//===----------------------------------------------------------------------===//

#include "llvm/Frontend/HLSL/RootSignatureValidations.h"

#include <cmath>

namespace llvm {
namespace hlsl {
namespace rootsig {

bool verifyRootFlag(uint32_t Flags) { return (Flags & ~0xfff) == 0; }

bool verifyVersion(uint32_t Version) {
  return (Version == 1 || Version == 2 || Version == 3);
}

bool verifyRegisterValue(uint32_t RegisterValue) {
  return RegisterValue != ~0U;
}

// This Range is reserverved, therefore invalid, according to the spec
// https://github.com/llvm/wg-hlsl/blob/main/proposals/0002-root-signature-in-clang.md#all-the-values-should-be-legal
bool verifyRegisterSpace(uint32_t RegisterSpace) {
  return !(RegisterSpace >= 0xFFFFFFF0);
}

bool verifyRootDescriptorFlag(uint32_t Version,
                              dxbc::RootDescriptorFlags FlagsVal) {
  using FlagT = dxbc::RootDescriptorFlags;
  FlagT Flags = FlagT(FlagsVal);
  if (Version == 1)
    return Flags == FlagT::DataVolatile;

  // The data-specific flags are mutually exclusive.
  FlagT DataFlags = FlagT::DataVolatile | FlagT::DataStatic |
                    FlagT::DataStaticWhileSetAtExecute;

  if (popcount(llvm::to_underlying(Flags & DataFlags)) > 1)
    return false;

  // Only a data flag or no flags is valid
  return (Flags | DataFlags) == DataFlags;
}

bool verifyDescriptorRangeFlag(uint32_t Version, dxil::ResourceClass Type,
                               dxbc::DescriptorRangeFlags Flags) {
  using FlagT = dxbc::DescriptorRangeFlags;
  const bool IsSampler = (Type == dxil::ResourceClass::Sampler);

  if (Version == 1) {
    // Since the metadata is unversioned, we expect to explicitly see the values
    // that map to the version 1 behaviour here.
    if (IsSampler)
      return Flags == FlagT::DescriptorsVolatile;
    return Flags == (FlagT::DataVolatile | FlagT::DescriptorsVolatile);
  }

  // The data-specific flags are mutually exclusive.
  FlagT DataFlags = FlagT::DataVolatile | FlagT::DataStatic |
                    FlagT::DataStaticWhileSetAtExecute;

  if (popcount(llvm::to_underlying(Flags & DataFlags)) > 1)
    return false;

  // The descriptor-specific flags are mutually exclusive.
  FlagT DescriptorFlags = FlagT::DescriptorsStaticKeepingBufferBoundsChecks |
                          FlagT::DescriptorsVolatile;
  if (popcount(llvm::to_underlying(Flags & DescriptorFlags)) > 1)
    return false;

  // For volatile descriptors, DATA_is never valid.
  if ((Flags & FlagT::DescriptorsVolatile) == FlagT::DescriptorsVolatile) {
    FlagT Mask = FlagT::DescriptorsVolatile;
    if (!IsSampler) {
      Mask |= FlagT::DataVolatile;
      Mask |= FlagT::DataStaticWhileSetAtExecute;
    }
    return (Flags & ~Mask) == FlagT::None;
  }

  // For "KEEPING_BUFFER_BOUNDS_CHECKS" descriptors,
  // the other data-specific flags may all be set.
  if ((Flags & FlagT::DescriptorsStaticKeepingBufferBoundsChecks) ==
      FlagT::DescriptorsStaticKeepingBufferBoundsChecks) {
    FlagT Mask = FlagT::DescriptorsStaticKeepingBufferBoundsChecks;
    if (!IsSampler) {
      Mask |= FlagT::DataVolatile;
      Mask |= FlagT::DataStatic;
      Mask |= FlagT::DataStaticWhileSetAtExecute;
    }
    return (Flags & ~Mask) == FlagT::None;
  }

  // When no descriptor flag is set, any data flag is allowed.
  FlagT Mask = FlagT::None;
  if (!IsSampler) {
    Mask |= FlagT::DataVolatile;
    Mask |= FlagT::DataStaticWhileSetAtExecute;
    Mask |= FlagT::DataStatic;
  }
  return (Flags & ~Mask) == FlagT::None;
}

bool verifyStaticSamplerFlags(uint32_t Version,
                              dxbc::StaticSamplerFlags Flags) {
  if (Version <= 2)
    return Flags == dxbc::StaticSamplerFlags::None;

  dxbc::StaticSamplerFlags Mask =
      dxbc::StaticSamplerFlags::NonNormalizedCoordinates |
      dxbc::StaticSamplerFlags::UintBorderColor |
      dxbc::StaticSamplerFlags::None;
  return (Flags | Mask) == Mask;
}

bool verifyNumDescriptors(uint32_t NumDescriptors) {
  return NumDescriptors > 0;
}

bool verifyMipLODBias(float MipLODBias) {
  return MipLODBias >= -16.f && MipLODBias <= 15.99f;
}

bool verifyMaxAnisotropy(uint32_t MaxAnisotropy) {
  return MaxAnisotropy <= 16u;
}

bool verifyLOD(float LOD) { return !std::isnan(LOD); }

bool verifyNoOverflowedOffset(uint64_t Offset) {
  return Offset <= std::numeric_limits<uint32_t>::max();
}

uint64_t computeRangeBound(uint64_t Offset, uint32_t Size) {
  assert(0 < Size && "Must be a non-empty range");
  if (Size == NumDescriptorsUnbounded)
    return NumDescriptorsUnbounded;

  return Offset + uint64_t(Size) - 1;
}
} // namespace rootsig
} // namespace hlsl
} // namespace llvm