llvm-project/lld/COFF/PDB.cpp

//===- PDB.cpp ------------------------------------------------------------===//
//
//                             The LLVM Linker
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//

#include "PDB.h"
#include "Chunks.h"
#include "Config.h"
#include "Error.h"
#include "SymbolTable.h"
#include "Symbols.h"
#include "llvm/DebugInfo/CodeView/SymbolDumper.h"
#include "llvm/DebugInfo/CodeView/TypeDumper.h"
#include "llvm/DebugInfo/MSF/ByteStream.h"
#include "llvm/DebugInfo/MSF/MSFBuilder.h"
#include "llvm/DebugInfo/MSF/MSFCommon.h"
#include "llvm/DebugInfo/PDB/Raw/DbiStream.h"
#include "llvm/DebugInfo/PDB/Raw/DbiStreamBuilder.h"
#include "llvm/DebugInfo/PDB/Raw/InfoStream.h"
#include "llvm/DebugInfo/PDB/Raw/InfoStreamBuilder.h"
#include "llvm/DebugInfo/PDB/Raw/PDBFile.h"
#include "llvm/DebugInfo/PDB/Raw/PDBFileBuilder.h"
#include "llvm/DebugInfo/PDB/Raw/TpiStream.h"
#include "llvm/DebugInfo/PDB/Raw/TpiStreamBuilder.h"
#include "llvm/Object/COFF.h"
#include "llvm/Support/Endian.h"
#include "llvm/Support/FileOutputBuffer.h"
#include "llvm/Support/ScopedPrinter.h"
#include <memory>

using namespace lld;
using namespace lld::coff;
using namespace llvm;
using namespace llvm::codeview;
using namespace llvm::support;
using namespace llvm::support::endian;

using llvm::object::coff_section;

static ExitOnError ExitOnErr;

// Returns a list of all SectionChunks.
static std::vector<coff_section> getInputSections(SymbolTable *Symtab) {
  std::vector<coff_section> V;
  for (Chunk *C : Symtab->getChunks())
    if (auto *SC = dyn_cast<SectionChunk>(C))
      V.push_back(*SC->Header);
  return V;
}

static SectionChunk *findByName(std::vector<SectionChunk *> &Sections,
                                StringRef Name) {
  for (SectionChunk *C : Sections)
    if (C->getSectionName() == Name)
      return C;
  return nullptr;
}

static ArrayRef<uint8_t> getDebugT(ObjectFile *File) {
  SectionChunk *Sec = findByName(File->getDebugChunks(), ".debug$T");
  if (!Sec)
    return {};

  // First 4 bytes are section magic.
  ArrayRef<uint8_t> Data = Sec->getContents();
  if (Data.size() < 4)
    fatal(".debug$T too short");
  if (read32le(Data.data()) != COFF::DEBUG_SECTION_MAGIC)
    fatal(".debug$T has an invalid magic");
  return Data.slice(4);
}

static void dumpDebugT(ScopedPrinter &W, ObjectFile *File) {
  ArrayRef<uint8_t> Data = getDebugT(File);
  if (Data.empty())
    return;

  msf::ByteStream Stream(Data);
  CVTypeDumper TypeDumper(&W, false);
  if (auto EC = TypeDumper.dump(Data))
    fatal(EC, "CVTypeDumper::dump failed");
}

static void dumpDebugS(ScopedPrinter &W, ObjectFile *File) {
  SectionChunk *Sec = findByName(File->getDebugChunks(), ".debug$S");
  if (!Sec)
    return;

  msf::ByteStream Stream(Sec->getContents());
  CVSymbolArray Symbols;
  msf::StreamReader Reader(Stream);
  if (auto EC = Reader.readArray(Symbols, Reader.getLength()))
    fatal(EC, "StreamReader.readArray<CVSymbolArray> failed");

  CVTypeDumper TypeDumper(&W, false);
  CVSymbolDumper SymbolDumper(W, TypeDumper, nullptr, false);
  if (auto EC = SymbolDumper.dump(Symbols))
    fatal(EC, "CVSymbolDumper::dump failed");
}

// Dump CodeView debug info. This is for debugging.
static void dumpCodeView(SymbolTable *Symtab) {
  ScopedPrinter W(outs());

  for (ObjectFile *File : Symtab->ObjectFiles) {
    dumpDebugT(W, File);
    dumpDebugS(W, File);
  }
}

static void addTypeInfo(SymbolTable *Symtab,
                        pdb::TpiStreamBuilder &TpiBuilder) {
  for (ObjectFile *File : Symtab->ObjectFiles) {
    ArrayRef<uint8_t> Data = getDebugT(File);
    if (Data.empty())
      continue;

    msf::ByteStream Stream(Data);
    codeview::CVTypeArray Records;
    msf::StreamReader Reader(Stream);
    if (auto EC = Reader.readArray(Records, Reader.getLength()))
      fatal(EC, "Reader.readArray failed");
    for (const codeview::CVType &Rec : Records)
      TpiBuilder.addTypeRecord(Rec);
  }
}

// Creates a PDB file.
void coff::createPDB(StringRef Path, SymbolTable *Symtab,
                     ArrayRef<uint8_t> SectionTable) {
  if (Config->DumpPdb)
    dumpCodeView(Symtab);

  BumpPtrAllocator Alloc;
  pdb::PDBFileBuilder Builder(Alloc);
  ExitOnErr(Builder.initialize(4096)); // 4096 is blocksize

  // Create streams in MSF for predefined streams, namely
  // PDB, TPI, DBI and IPI.
  for (int I = 0; I < (int)pdb::kSpecialStreamCount; ++I)
    ExitOnErr(Builder.getMsfBuilder().addStream(0));

  // Add an Info stream.
  auto &InfoBuilder = Builder.getInfoBuilder();
  InfoBuilder.setAge(1);

  // Should be a random number, 0 for now.
  InfoBuilder.setGuid({});

  // Should be the current time, but set 0 for reproducibilty.
  InfoBuilder.setSignature(0);
  InfoBuilder.setVersion(pdb::PdbRaw_ImplVer::PdbImplVC70);

  // Add an empty DPI stream.
  auto &DbiBuilder = Builder.getDbiBuilder();
  DbiBuilder.setVersionHeader(pdb::PdbDbiV110);

  // Add an empty TPI stream.
  auto &TpiBuilder = Builder.getTpiBuilder();
  TpiBuilder.setVersionHeader(pdb::PdbTpiV80);
  if (Config->DebugPdb)
    addTypeInfo(Symtab, TpiBuilder);

  // Add an empty IPI stream.
  auto &IpiBuilder = Builder.getIpiBuilder();
  IpiBuilder.setVersionHeader(pdb::PdbTpiV80);

  // Add Section Contributions.
  std::vector<pdb::SectionContrib> Contribs =
      pdb::DbiStreamBuilder::createSectionContribs(getInputSections(Symtab));
  DbiBuilder.setSectionContribs(Contribs);

  // Add Section Map stream.
  ArrayRef<object::coff_section> Sections = {
      (const object::coff_section *)SectionTable.data(),
      SectionTable.size() / sizeof(object::coff_section)};
  std::vector<pdb::SecMapEntry> SectionMap =
      pdb::DbiStreamBuilder::createSectionMap(Sections);
  DbiBuilder.setSectionMap(SectionMap);

  ExitOnErr(DbiBuilder.addModuleInfo("", "* Linker *"));

  // Add COFF section header stream.
  ExitOnErr(
      DbiBuilder.addDbgStream(pdb::DbgHeaderType::SectionHdr, SectionTable));

  // Write to a file.
  ExitOnErr(Builder.commit(Path));
}