DebugSubsectionRecord.h

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//===- DebugSubsectionRecord.h ----------------------------------*- 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
//
//===----------------------------------------------------------------------===//
 
#ifndef LLVM_DEBUGINFO_CODEVIEW_DEBUGSUBSECTIONRECORD_H
#define LLVM_DEBUGINFO_CODEVIEW_DEBUGSUBSECTIONRECORD_H
 
#include "llvm/DebugInfo/CodeView/CodeView.h"
#include "llvm/Support/BinaryStreamArray.h"
#include "llvm/Support/BinaryStreamRef.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Endian.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/MathExtras.h"
#include <cstdint>
#include <memory>
 
namespace llvm {
 
class BinaryStreamWriter;
 
namespace codeview {
 
class DebugSubsection;
 
// Corresponds to the `CV_DebugSSubsectionHeader_t` structure.
struct DebugSubsectionHeader {
  support::ulittle32_t Kind;   // codeview::DebugSubsectionKind enum
  support::ulittle32_t Length; // number of bytes occupied by this record.
};
 
class DebugSubsectionRecord {
public:
  LLVM_ABI DebugSubsectionRecord();
  LLVM_ABI DebugSubsectionRecord(DebugSubsectionKind Kind,
                                 BinaryStreamRef Data);
 
  LLVM_ABI static Error initialize(BinaryStreamRef Stream,
                                   DebugSubsectionRecord &Info);
 
  LLVM_ABI uint32_t getRecordLength() const;
  LLVM_ABI DebugSubsectionKind kind() const;
  LLVM_ABI BinaryStreamRef getRecordData() const;
 
private:
  DebugSubsectionKind Kind = DebugSubsectionKind::None;
  BinaryStreamRef Data;
};
 
class DebugSubsectionRecordBuilder {
public:
  LLVM_ABI
  DebugSubsectionRecordBuilder(std::shared_ptr<DebugSubsection> Subsection);
 
  /// Use this to copy existing subsections directly from source to destination.
  /// For example, line table subsections in an object file only need to be
  /// relocated before being copied into the PDB.
  LLVM_ABI DebugSubsectionRecordBuilder(const DebugSubsectionRecord &Contents);
 
  LLVM_ABI uint32_t calculateSerializedLength() const;
  LLVM_ABI Error commit(BinaryStreamWriter &Writer,
                        CodeViewContainer Container) const;
 
private:
  /// The subsection to build. Will be null if Contents is non-empty.
  std::shared_ptr<DebugSubsection> Subsection;
 
  /// The bytes of the subsection. Only non-empty if Subsection is null.
  /// FIXME: Reduce the size of this.
  DebugSubsectionRecord Contents;
};
 
} // end namespace codeview
 
template <> struct VarStreamArrayExtractor<codeview::DebugSubsectionRecord> {
  Error operator()(BinaryStreamRef Stream, uint32_t &Length,
                   codeview::DebugSubsectionRecord &Info) {
    // FIXME: We need to pass the container type through to this function.  In
    // practice this isn't super important since the subsection header describes
    // its length and we can just skip it.  It's more important when writing.
    if (auto EC = codeview::DebugSubsectionRecord::initialize(Stream, Info))
      return EC;
    Length = alignTo(Info.getRecordLength(), 4);
    return Error::success();
  }
};
 
namespace codeview {
 
using DebugSubsectionArray = VarStreamArray<DebugSubsectionRecord>;
 
} // end namespace codeview
 
} // end namespace llvm
 
#endif // LLVM_DEBUGINFO_CODEVIEW_DEBUGSUBSECTIONRECORD_H