//===--- unittests/DebugInfo/DWARF/DwarfGenerator.h -------------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// A file that can generate DWARF debug info for unit tests.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_UNITTESTS_DEBUG_INFO_DWARF_DWARFGENERATOR_H
#define LLVM_UNITTESTS_DEBUG_INFO_DWARF_DWARFGENERATOR_H

#include "llvm/ADT/StringRef.h"
#include "llvm/CodeGen/DIE.h"
#include "llvm/DebugInfo/DWARF/DWARFDebugLine.h"
#include "llvm/Support/Error.h"

#include <memory>
#include <string>
#include <tuple>
#include <vector>

namespace llvm {

class AsmPrinter;
class DIE;
class DIEAbbrev;
class DwarfStringPool;
class MCAsmBackend;
class MCAsmInfo;
class MCCodeEmitter;
class MCContext;
struct MCDwarfLineTableParams;
class MCInstrInfo;
class MCObjectFileInfo;
class MCRegisterInfo;
class MCStreamer;
class MCSubtargetInfo;
class raw_fd_ostream;
class TargetMachine;
class Triple;

namespace dwarfgen {

class Generator;
class CompileUnit;

/// A DWARF debug information entry class used to generate DWARF DIEs.
///
/// This class is used to quickly generate DWARF debug information by creating
/// child DIEs or adding attributes to the current DIE. Instances of this class
/// are created from the compile unit (dwarfgen::CompileUnit::getUnitDIE()) or
/// by calling dwarfgen::DIE::addChild(...) and using the returned DIE object.
class DIE {
  dwarfgen::CompileUnit *CU;
  llvm::DIE *Die;

protected:
  friend class Generator;
  friend class CompileUnit;

  DIE(CompileUnit *U = nullptr, llvm::DIE *D = nullptr) : CU(U), Die(D) {}

  /// Called with a compile/type unit relative offset prior to generating the
  /// DWARF debug info.
  ///
  /// \param CUOffset the compile/type unit relative offset where the
  /// abbreviation code for this DIE will be encoded.
  unsigned computeSizeAndOffsets(unsigned CUOffset);

public:
  /// Add an attribute value that has no value.
  ///
  /// \param Attr a dwarf::Attribute enumeration value or any uint16_t that
  /// represents a user defined DWARF attribute.
  /// \param Form the dwarf::Form to use when encoding the attribute. This is
  /// only used with the DW_FORM_flag_present form encoding.
  void addAttribute(uint16_t Attr, dwarf::Form Form);

  /// Add an attribute value to be encoded as a DIEInteger
  ///
  /// \param Attr a dwarf::Attribute enumeration value or any uint16_t that
  /// represents a user defined DWARF attribute.
  /// \param Form the dwarf::Form to use when encoding the attribute.
  /// \param U the unsigned integer to encode.
  void addAttribute(uint16_t Attr, dwarf::Form Form, uint64_t U);

  /// Add an attribute value to be encoded as a DIEString or DIEInlinedString.
  ///
  /// \param Attr a dwarf::Attribute enumeration value or any uint16_t that
  /// represents a user defined DWARF attribute.
  /// \param Form the dwarf::Form to use when encoding the attribute. The form
  /// must be one of DW_FORM_strp or DW_FORM_string.
  /// \param String the string to encode.
  void addAttribute(uint16_t Attr, dwarf::Form Form, StringRef String);

  /// Add an attribute value to be encoded as a DIEEntry.
  ///
  /// DIEEntry attributes refer to other llvm::DIE objects that have been
  /// created.
  ///
  /// \param Attr a dwarf::Attribute enumeration value or any uint16_t that
  /// represents a user defined DWARF attribute.
  /// \param Form the dwarf::Form to use when encoding the attribute. The form
  /// must be one of DW_FORM_strp or DW_FORM_string.
  /// \param RefDie the DIE that this attriute refers to.
  void addAttribute(uint16_t Attr, dwarf::Form Form, dwarfgen::DIE &RefDie);

  /// Add an attribute value to be encoded as a DIEBlock.
  ///
  /// DIEBlock attributes refers to binary data that is stored as the
  /// attribute's value.
  ///
  /// \param Attr a dwarf::Attribute enumeration value or any uint16_t that
  /// represents a user defined DWARF attribute.
  /// \param Form the dwarf::Form to use when encoding the attribute. The form
  /// must be one of DW_FORM_strp or DW_FORM_string.
  /// \param P a pointer to the data to store as the attribute value.
  /// \param S the size in bytes of the data pointed to by P .
  void addAttribute(uint16_t Attr, dwarf::Form Form, const void *P, size_t S);

  /// Add a new child to this DIE object.
  ///
  /// \param Tag the dwarf::Tag to assing to the llvm::DIE object.
  /// \returns the newly created DIE object that is now a child owned by this
  /// object.
  dwarfgen::DIE addChild(dwarf::Tag Tag);
};

/// A DWARF compile unit used to generate DWARF compile/type units.
///
/// Instances of these classes are created by instances of the Generator
/// class. All information required to generate a DWARF compile unit is
/// contained inside this class.
class CompileUnit {
  Generator &DG;
  BasicDIEUnit DU;

public:
  CompileUnit(Generator &D, uint16_t V, uint8_t A)
      : DG(D), DU(V, A, dwarf::DW_TAG_compile_unit) {}
  DIE getUnitDIE();
  Generator &getGenerator() { return DG; }
  uint64_t getOffset() const { return DU.getDebugSectionOffset(); }
  uint64_t getLength() const { return DU.getLength(); }
  uint16_t getVersion() const { return DU.getDwarfVersion(); }
  uint16_t getAddressSize() const { return DU.getAddressSize(); }
  void setOffset(uint64_t Offset) { DU.setDebugSectionOffset(Offset); }
  void setLength(uint64_t Length) { DU.setLength(Length); }
};

/// A DWARF generator.
///
/// Generate DWARF for unit tests by creating any instance of this class and
/// calling Generator::addCompileUnit(), and then getting the dwarfgen::DIE from
/// the returned compile unit and adding attributes and children to each DIE.
class Generator {
  std::unique_ptr<MCRegisterInfo> MRI;
  std::unique_ptr<MCAsmInfo> MAI;
  std::unique_ptr<MCObjectFileInfo> MOFI;
  std::unique_ptr<MCContext> MC;
  MCAsmBackend *MAB; // Owned by MCStreamer
  std::unique_ptr<MCInstrInfo> MII;
  std::unique_ptr<MCSubtargetInfo> MSTI;
  MCCodeEmitter *MCE; // Owned by MCStreamer
  MCStreamer *MS;     // Owned by AsmPrinter
  std::unique_ptr<TargetMachine> TM;
  std::unique_ptr<AsmPrinter> Asm;
  BumpPtrAllocator Allocator;
  std::unique_ptr<DwarfStringPool> StringPool; // Entries owned by Allocator.
  std::vector<std::unique_ptr<CompileUnit>> CompileUnits;
  DIEAbbrevSet Abbreviations;

  SmallString<4096> FileBytes;
  /// The stream we use to generate the DWARF into as an ELF file.
  std::unique_ptr<raw_svector_ostream> Stream;
  /// The DWARF version to generate.
  uint16_t Version;

  /// Private constructor, call Generator::Create(...) to get a DWARF generator
  /// expected.
  Generator();

  /// Create the streamer and setup the output buffer.
  llvm::Error init(Triple TheTriple, uint16_t DwarfVersion);

public:
  /// Create a DWARF generator or get an appropriate error.
  ///
  /// \param TheTriple the triple to use when creating any required support
  /// classes needed to emit the DWARF.
  /// \param DwarfVersion the version of DWARF to emit.
  ///
  /// \returns a llvm::Expected that either contains a unique_ptr to a Generator
  /// or a llvm::Error.
  static llvm::Expected<std::unique_ptr<Generator>>
  create(Triple TheTriple, uint16_t DwarfVersion);

  ~Generator();

  /// Generate all DWARF sections and return a memory buffer that
  /// contains an ELF file that contains the DWARF.
  StringRef generate();

  /// Add a compile unit to be generated.
  ///
  /// \returns a dwarfgen::CompileUnit that can be used to retrieve the compile
  /// unit dwarfgen::DIE that can be used to add attributes and add child DIE
  /// objedts to.
  dwarfgen::CompileUnit &addCompileUnit();

  BumpPtrAllocator &getAllocator() { return Allocator; }
  AsmPrinter *getAsmPrinter() const { return Asm.get(); }
  MCContext *getMCContext() const { return MC.get(); }
  DIEAbbrevSet &getAbbrevSet() { return Abbreviations; }
  DwarfStringPool &getStringPool() { return *StringPool; }

  /// Save the generated DWARF file to disk.
  ///
  /// \param Path the path to save the ELF file to.
  bool saveFile(StringRef Path);
};

} // end namespace dwarfgen

} // end namespace llvm

#endif // LLVM_UNITTESTS_DEBUG_INFO_DWARF_DWARFGENERATOR_H