//===- SPIRVBinaryUtils.cpp - SPIR-V Binary Module Utils --------*- C++ -*-===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// This file declares common utilities for SPIR-V binary module.
//
//===----------------------------------------------------------------------===//

#ifndef MLIR_TARGET_SPIRV_SPIRVBINARYUTILS_H
#define MLIR_TARGET_SPIRV_SPIRVBINARYUTILS_H

#include "mlir/Dialect/SPIRV/IR/SPIRVEnums.h"
#include "mlir/Support/LLVM.h"

#include <cstdint>
#include <optional>

namespace mlir {
namespace spirv {

/// SPIR-V binary header word count
constexpr unsigned kHeaderWordCount = 5;

/// SPIR-V magic number
constexpr uint32_t kMagicNumber = 0x07230203;

/// The serializer tool ID registered to the Khronos Group
constexpr uint32_t kGeneratorNumber = 22;

/// Max number of words
/// https://registry.khronos.org/SPIR-V/specs/unified1/SPIRV.html#_universal_limits
constexpr uint32_t kMaxWordCount = 65535;

/// Max number of words for literal
constexpr uint32_t kMaxLiteralWordCount = kMaxWordCount - 3;

/// Appends a SPRI-V module header to `header` with the given `version` and
/// `idBound`.
void appendModuleHeader(SmallVectorImpl<uint32_t> &header,
                        spirv::Version version, uint32_t idBound);

/// Returns the word-count-prefixed opcode for an SPIR-V instruction.
uint32_t getPrefixedOpcode(uint32_t wordCount, spirv::Opcode opcode);

/// Encodes an SPIR-V `literal` string into the given `binary` vector.
void encodeStringLiteralInto(SmallVectorImpl<uint32_t> &binary,
                             StringRef literal);

/// Decodes a string literal in `words` starting at `wordIndex`. Update the
/// latter to point to the position in words after the string literal.
inline StringRef decodeStringLiteral(ArrayRef<uint32_t> words,
                                     unsigned &wordIndex) {
  StringRef str(reinterpret_cast<const char *>(words.data() + wordIndex));
  wordIndex += str.size() / 4 + 1;
  return str;
}

/// Returns the SPV_INTEL_long_composites continuation opcode that may follow
/// `parent`, or std::nullopt if `parent` is not a splittable composite/struct
/// op.
inline std::optional<spirv::Opcode>
getContinuationOpcode(spirv::Opcode parent) {
  switch (parent) {
  case spirv::Opcode::OpTypeStruct:
    return spirv::Opcode::OpTypeStructContinuedINTEL;
  case spirv::Opcode::OpConstantComposite:
    return spirv::Opcode::OpConstantCompositeContinuedINTEL;
  case spirv::Opcode::OpSpecConstantComposite:
    return spirv::Opcode::OpSpecConstantCompositeContinuedINTEL;
  case spirv::Opcode::OpCompositeConstruct:
    return spirv::Opcode::OpCompositeConstructContinuedINTEL;
  default:
    return std::nullopt;
  }
}

} // namespace spirv
} // namespace mlir

#endif // MLIR_TARGET_SPIRV_SPIRVBINARYUTILS_H