Refactor some more PDB reading code into DebugInfoPDB

[zturner]

Summary

The code that reads the name map and the pdb header information was still lingering in llvm-pdbdump.

The NameMap, it turns out, is a common data structure used in other places in the PDB file as well. So the ability to parse a name map out of a PDB file will be useful for us down the line. So I abstracted that into a PDBNameMap class. It's very simple right now, but at least it can be re-used on an arbitrary stream.

I'm also moving towards an approach where we have concrete implementations of each stream type that provides friendly class-like access to the fields of different streams. The basic layout and format of which streams are what is described here [https://github.com/Microsoft/microsoft-pdb/]. Currently llvm-pdbdump has only attempted to parse data out of Stream 1 -- called the PDB Stream -- so I made a class called PDBInfoStream which provides convenient access to fields of the PDB stream. In the future we would probably add PDBDbiStream, and PDBModuleStream, etc.

This patch loses some of the output of llvm-pdbdump -dump-headers, because previously it was dumping every entry in the name map. And now that the name map parsing is handled separately, I felt it wasn't important to print so much detail anymore. Let me know if you disagree.

[majnemer]

include/llvm/DebugInfo/PDB/Raw/PDBInfoStream.h

40–51

It's a little unusual to have these be members be support::ulittle32_t. Instead, can you have them be uint32_t and initialize them via readInteger?

include/llvm/DebugInfo/PDB/Raw/PDBNameMap.h

27

tryGetValue

lib/DebugInfo/PDB/Raw/PDBInfoStream.cpp

42

This cast can be removed if you make Version a uint32_t.

include/llvm/DebugInfo/PDB/Raw/PDBFile.h

 class MemoryBuffer;
 
 struct PDBFileContext;
+class PDBStream;
 
 class PDBFile {
 public:

     return BlockNumber * BlockSize;
   }
 
+  PDBStream *getPDBStream() const;
+
 private:
   std::unique_ptr<PDBFileContext> Context;
 };

include/llvm/DebugInfo/PDB/Raw/PDBInfoStream.h

+//===- PDBInfoStream.h - PDB Info Stream (Stream 1) Access ------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_DEBUGINFO_PDB_RAW_PDBINFOSTREAM_H
+#define LLVM_DEBUGINFO_PDB_RAW_PDBINFOSTREAM_H
+
+#include "llvm/ADT/StringMap.h"
+#include "llvm/DebugInfo/PDB/PDBTypes.h"
+#include "llvm/DebugInfo/PDB/Raw/PDBNameMap.h"
+#include "llvm/DebugInfo/PDB/Raw/PDBRawConstants.h"
+#include "llvm/DebugInfo/PDB/Raw/PDBStream.h"
+
+#include "llvm/Support/Endian.h"
+
+namespace llvm {
+
+class PDBInfoStream {
+public:
+  PDBInfoStream(const PDBFile &File);
+
+  std::error_code reload();
+
+  PdbRaw_ImplVer getVersion() const;
+  uint32_t getSignature() const;
+  uint32_t getAge() const;
+  PDB_UniqueId getGuid() const;
+
+  uint32_t getNamedStreamIndex(llvm::StringRef Name) const;
+
+private:
+  PDBStream Stream1;
+  const PDBFile &Pdb;
+
+  // PDB file format version.  We only support VC70.  See the enumeration
+  // `PdbRaw_ImplVer` for the other possible values.
+  support::ulittle32_t Version;
+
+  // A 32-bit signature unique across all PDBs.  This is generated with
+  // a call to time() when the PDB is written, but obviously this is not
+  // universally unique.
+  support::ulittle32_t Signature;
+
+  // The number of times the PDB has been written.  Might also be used to
+  // ensure that the PDB matches the executable.
+  support::ulittle32_t Age;
+
+  // Due to the aforementioned limitations with `Signature`, this is a new
+  // signature present on VC70 and higher PDBs which is guaranteed to be
+  // universally unique.
+  PDB_UniqueId Guid;
+
+  PDBNameMap NamedStreams;
+};
+}
+
+#endif

include/llvm/DebugInfo/PDB/Raw/PDBNameMap.h

+//===- PDBNameMap.h - PDB Name Map ------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_DEBUGINFO_PDB_RAW_PDBNAMEMAP_H
+#define LLVM_DEBUGINFO_PDB_RAW_PDBNAMEMAP_H
+
+#include "llvm/ADT/StringMap.h"
+#include "llvm/ADT/StringRef.h"
+
+#include <stdint.h>
+#include <utility>
+
+namespace llvm {
+class PDBStream;
+class PDBNameMap {
+public:
+  PDBNameMap();
+
+  std::error_code load(PDBStream &Stream);
+
+  bool TryGetValue(StringRef Name, uint32_t &Value) const;
+
+private:
+  StringMap<uint32_t> Mapping;
+};
+}
+
+#endif
 No newline at end of file

include/llvm/DebugInfo/PDB/Raw/PDBRawConstants.h

+//===- PDBRawConstants.h ----------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_DEBUGINFO_PDB_RAW_PDBRAWCONSTANTS_H
+#define LLVM_DEBUGINFO_PDB_RAW_PDBRAWCONSTANTS_H
+
+#include <stdint.h>
+
+namespace llvm {
+
+enum PdbRaw_ImplVer : uint32_t {
+  VC2 = 19941610,
+  VC4 = 19950623,
+  VC41 = 19950814,
+  VC50 = 19960307,
+  VC98 = 19970604,
+  VC70Dep = 19990604, // deprecated
+  VC70 = 20000404,
+  VC80 = 20030901,
+  VC110 = 20091201,
+  VC140 = 20140508,
+};
+}
+
+#endif

lib/DebugInfo/PDB/CMakeLists.txt

 
 add_pdb_impl_folder(Raw
   Raw/PDBFile.cpp
+  Raw/PDBInfoStream.cpp
+  Raw/PDBNameMap.cpp
   Raw/PDBStream.cpp
   Raw/RawSession.cpp)
 

lib/DebugInfo/PDB/Raw/PDBInfoStream.cpp

+//===- PDBInfoStream.cpp - PDB Info Stream (Stream 1) Access ----*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/DebugInfo/PDB/Raw/PDBInfoStream.h"
+#include "llvm/ADT/BitVector.h"
+#include "llvm/ADT/SmallVector.h"
+
+using namespace llvm;
+
+PDBInfoStream::PDBInfoStream(const PDBFile &File)
+    : Pdb(File), Stream1(1, File) {}
+
+std::error_code PDBInfoStream::reload() {
+  Stream1.setOffset(0);
+
+  Stream1.readObject(&Version);
+  if (Version < PdbRaw_ImplVer::VC70)
+    return std::make_error_code(std::errc::not_supported);
+
+  Stream1.readObject(&Signature);
+  Stream1.readObject(&Age);
+  Stream1.readObject(&Guid);
+  NamedStreams.load(Stream1);
+
+  return std::error_code();
+}
+
+uint32_t PDBInfoStream::getNamedStreamIndex(llvm::StringRef Name) const {
+  uint32_t Result;
+  if (!NamedStreams.TryGetValue(Name, Result))
+    return 0;
+  return Result;
+}
+
+PdbRaw_ImplVer PDBInfoStream::getVersion() const {
+  uint32_t Value = static_cast<uint32_t>(Version);
+  return static_cast<PdbRaw_ImplVer>(Value);
+}
+
+uint32_t PDBInfoStream::getSignature() const { return Signature; }
+
+uint32_t PDBInfoStream::getAge() const { return Age; }
+
+PDB_UniqueId PDBInfoStream::getGuid() const { return Guid; }

lib/DebugInfo/PDB/Raw/PDBNameMap.cpp

+//===- PDBNameMap.cpp - PDB Name Map ----------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/DebugInfo/PDB/Raw/PDBNameMap.h"
+#include "llvm/ADT/BitVector.h"
+#include "llvm/DebugInfo/PDB/Raw/PDBStream.h"
+
+using namespace llvm;
+
+PDBNameMap::PDBNameMap() {}
+
+std::error_code PDBNameMap::load(PDBStream &Stream) {
+  // This is some sort of weird string-set/hash table encoded in the stream.
+  // It starts with the number of bytes in the table.
+  uint32_t NumberOfBytes;
+  Stream.readInteger(NumberOfBytes);
+
+  // Following that field is the starting offset of strings in the name table.
+  uint32_t StringsOffset = Stream.getOffset();
+  Stream.setOffset(StringsOffset + NumberOfBytes);
+
+  // This appears to be equivalent to the total number of strings *actually*
+  // in the name table.
+  uint32_t HashSize;
+  Stream.readInteger(HashSize);
+
+  // This appears to be an upper bound on the number of strings in the name
+  // table.
+  uint32_t MaxNumberOfStrings;
+  Stream.readInteger(MaxNumberOfStrings);
+
+  // This appears to be a hash table which uses bitfields to determine whether
+  // or not a bucket is 'present'.
+  uint32_t NumPresentWords;
+  Stream.readInteger(NumPresentWords);
+
+  // Store all the 'present' bits in a vector for later processing.
+  SmallVector<uint32_t, 1> PresentWords;
+  for (uint32_t I = 0; I != NumPresentWords; ++I) {
+    uint32_t Word;
+    Stream.readInteger(Word);
+    PresentWords.push_back(Word);
+  }
+
+  // This appears to be a hash table which uses bitfields to determine whether
+  // or not a bucket is 'deleted'.
+  uint32_t NumDeletedWords;
+  Stream.readInteger(NumDeletedWords);
+
+  // Store all the 'deleted' bits in a vector for later processing.
+  SmallVector<uint32_t, 1> DeletedWords;
+  for (uint32_t I = 0; I != NumDeletedWords; ++I) {
+    uint32_t Word;
+    Stream.readInteger(Word);
+    DeletedWords.push_back(Word);
+  }
+
+  BitVector Present(MaxNumberOfStrings, false);
+  if (!PresentWords.empty())
+    Present.setBitsInMask(PresentWords.data(), PresentWords.size());
+  BitVector Deleted(MaxNumberOfStrings, false);
+  if (!DeletedWords.empty())
+    Deleted.setBitsInMask(DeletedWords.data(), DeletedWords.size());
+
+  for (uint32_t I = 0; I < MaxNumberOfStrings; ++I) {
+    if (!Present.test(I))
+      continue;
+
+    // For all present entries, dump out their mapping.
+
+    // This appears to be an offset relative to the start of the strings.
+    // It tells us where the null-terminated string begins.
+    uint32_t NameOffset;
+    Stream.readInteger(NameOffset);
+
+    // This appears to be a stream number into the stream directory.
+    uint32_t NameIndex;
+    Stream.readInteger(NameIndex);
+
+    // Compute the offset of the start of the string relative to the stream.
+    uint32_t StringOffset = StringsOffset + NameOffset;
+    uint32_t OldOffset = Stream.getOffset();
+    // Pump out our c-string from the stream.
+    std::string Str;
+    Stream.setOffset(StringOffset);
+    Stream.readZeroString(Str);
+
+    Stream.setOffset(OldOffset);
+    // Add this to a string-map from name to stream number.
+    Mapping.insert({Str, NameIndex});
+  }
+
+  return std::error_code();
+}
+
+bool PDBNameMap::TryGetValue(StringRef Name, uint32_t &Value) const {
+  auto Iter = Mapping.find(Name);
+  if (Iter == Mapping.end())
+    return false;
+  Value = Iter->second;
+  return true;
+}

test/DebugInfo/PDB/pdbdump-headers.test

 ; CHECK-NEXT: Signature: 54e507e2
 ; CHECK-NEXT: Age: 1
 ; CHECK-NEXT: Guid: {0B355641-86A0-A249-896F-9988FAE52FF0}
-; CHECK-NEXT: NumberOfBytes: 34
-; CHECK-NEXT: HashSize: 3
-; CHECK-NEXT: MaxNumberOfStrings: 6
-; CHECK-NEXT: NumPresentWords: 1
-; CHECK-NEXT: Word: 26
-; CHECK-NEXT: NumDeletedWords: 0
-; CHECK-NEXT: NameOffset: 17
-; CHECK-NEXT: NameIndex: 9
-; CHECK-NEXT: String: /src/headerblock
-
-; CHECK:      NameOffset: 10
-; CHECK-NEXT: NameIndex: 13
-; CHECK-NEXT: String: /names
-
-; CHECK:      NameOffset: 0
-; CHECK-NEXT: NameIndex: 5
-; CHECK-NEXT: String: /LinkInfo
 
 ; CHECK:      NameStream: 13
 ; CHECK-NEXT: NameStreamSignature: effeeffe

tools/llvm-pdbdump/llvm-pdbdump.cpp

 #include "llvm/DebugInfo/PDB/PDBSymbolFunc.h"
 #include "llvm/DebugInfo/PDB/PDBSymbolThunk.h"
 #include "llvm/DebugInfo/PDB/Raw/PDBFile.h"
+#include "llvm/DebugInfo/PDB/Raw/PDBInfoStream.h"
 #include "llvm/DebugInfo/PDB/Raw/PDBStream.h"
 #include "llvm/DebugInfo/PDB/Raw/RawSession.h"
 #include "llvm/Support/CommandLine.h"

     }
   }
 
-  // Stream 1 starts with the following header:
-  //   uint32_t Version;
-  //   uint32_t Signature;
-  //   uint32_t Age;
-  //   GUID Guid;
-  PDBStream Stream1(1, File);
-  uint32_t Version;
-  uint32_t Signature;
-  uint32_t Age;
-  PDB_UniqueId Guid;
-
-  Stream1.readInteger(Version);
-  outs() << "Version: " << Version << '\n';
-  // PDB's with versions before PDBImpvVC70 might not have the Guid field, we
-  // don't support them.
-  if (Version < 20000404)
-    reportError("", std::make_error_code(std::errc::not_supported));
-
-  // This appears to be the time the PDB was last opened by an MSVC tool?
-  // It is definitely a timestamp of some sort.
-  Stream1.readInteger(Signature);
-  outs() << "Signature: ";
-  outs().write_hex(Signature) << '\n';
-
-  // This appears to be a number which is used to determine that the PDB is kept
-  // in sync with the EXE.
-  Stream1.readInteger(Age);
-  outs() << "Age: " << Age << '\n';
-
-  // I'm not sure what the purpose of the GUID is.
-  Stream1.readObject(&Guid);
-  outs() << "Guid: " << Guid << '\n';
-
-  // This is some sort of weird string-set/hash table encoded in the stream.
-  // It starts with the number of bytes in the table.
-  uint32_t NumberOfBytes;
-  Stream1.readInteger(NumberOfBytes);
-  outs() << "NumberOfBytes: " << NumberOfBytes << '\n';
-
-  // Following that field is the starting offset of strings in the name table.
-  uint32_t StringsOffset = Stream1.getOffset();
-  Stream1.setOffset(StringsOffset + NumberOfBytes);
-
-  // This appears to be equivalent to the total number of strings *actually*
-  // in the name table.
-  uint32_t HashSize;
-  Stream1.readInteger(HashSize);
-  outs() << "HashSize: " << HashSize << '\n';
-
-  // This appears to be an upper bound on the number of strings in the name
-  // table.
-  uint32_t MaxNumberOfStrings;
-  Stream1.readInteger(MaxNumberOfStrings);
-  outs() << "MaxNumberOfStrings: " << MaxNumberOfStrings << '\n';
-
-  // This appears to be a hash table which uses bitfields to determine whether
-  // or not a bucket is 'present'.
-  uint32_t NumPresentWords;
-  Stream1.readInteger(NumPresentWords);
-  outs() << "NumPresentWords: " << NumPresentWords << '\n';
-
-  // Store all the 'present' bits in a vector for later processing.
-  SmallVector<uint32_t, 1> PresentWords;
-  for (uint32_t I = 0; I != NumPresentWords; ++I) {
-    uint32_t Word;
-    Stream1.readInteger(Word);
-    PresentWords.push_back(Word);
-    outs() << "Word: " << Word << '\n';
-  }
-
-  // This appears to be a hash table which uses bitfields to determine whether
-  // or not a bucket is 'deleted'.
-  uint32_t NumDeletedWords;
-  Stream1.readInteger(NumDeletedWords);
-  outs() << "NumDeletedWords: " << NumDeletedWords << '\n';
-
-  // Store all the 'deleted' bits in a vector for later processing.
-  SmallVector<uint32_t, 1> DeletedWords;
-  for (uint32_t I = 0; I != NumDeletedWords; ++I) {
-    uint32_t Word;
-    Stream1.readInteger(Word);
-    DeletedWords.push_back(Word);
-    outs() << "Word: " << Word << '\n';
-  }
+  PDBInfoStream InfoStream(File);
+  if (auto EC = InfoStream.reload())
+    reportError("", EC);
 
-  BitVector Present(MaxNumberOfStrings, false);
-  if (!PresentWords.empty())
-    Present.setBitsInMask(PresentWords.data(), PresentWords.size());
-  BitVector Deleted(MaxNumberOfStrings, false);
-  if (!DeletedWords.empty())
-    Deleted.setBitsInMask(DeletedWords.data(), DeletedWords.size());
-
-  StringMap<uint32_t> NamedStreams;
-  for (uint32_t I = 0; I < MaxNumberOfStrings; ++I) {
-    if (!Present.test(I))
-      continue;
-
-    // For all present entries, dump out their mapping.
-
-    // This appears to be an offset relative to the start of the strings.
-    // It tells us where the null-terminated string begins.
-    uint32_t NameOffset;
-    Stream1.readInteger(NameOffset);
-    outs() << "NameOffset: " << NameOffset << '\n';
-
-    // This appears to be a stream number into the stream directory.
-    uint32_t NameIndex;
-    Stream1.readInteger(NameIndex);
-    outs() << "NameIndex: " << NameIndex << '\n';
-
-    // Compute the offset of the start of the string relative to the stream.
-    uint32_t StringOffset = StringsOffset + NameOffset;
-    uint32_t OldOffset = Stream1.getOffset();
-    // Pump out our c-string from the stream.
-    std::string Str;
-    Stream1.setOffset(StringOffset);
-    Stream1.readZeroString(Str);
-    outs() << "String: " << Str << "\n\n";
-
-    Stream1.setOffset(OldOffset);
-    // Add this to a string-map from name to stream number.
-    NamedStreams.insert({Str, NameIndex});
-  }
+  outs() << "Version: " << InfoStream.getVersion() << '\n';
+  outs() << "Signature: ";
+  outs().write_hex(InfoStream.getSignature()) << '\n';
+  outs() << "Age: " << InfoStream.getAge() << '\n';
+  outs() << "Guid: " << InfoStream.getGuid() << '\n';
 
   // Let's try to dump out the named stream "/names".
-  auto NameI = NamedStreams.find("/names");
-  if (NameI != NamedStreams.end()) {
-    PDBStream NameStream(NameI->second, File);
-    outs() << "NameStream: " << NameI->second << '\n';
+  uint32_t NameStreamIndex = InfoStream.getNamedStreamIndex("/names");
+  if (NameStreamIndex != 0) {
+    PDBStream NameStream(NameStreamIndex, File);
+    outs() << "NameStream: " << NameStreamIndex << '\n';
 
     // The name stream appears to start with a signature and version.
     uint32_t NameStreamSignature;