llvm/lib/DebugInfo/CodeView/TypeStreamMerger.cpp

   1 //===-- TypeStreamMerger.cpp ------------------------------------*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 #include "llvm/DebugInfo/CodeView/TypeStreamMerger.h"
  10 #include "llvm/ADT/SmallString.h"
  11 #include "llvm/ADT/StringExtras.h"
  12 #include "llvm/DebugInfo/CodeView/GlobalTypeTableBuilder.h"
  13 #include "llvm/DebugInfo/CodeView/MergingTypeTableBuilder.h"
  14 #include "llvm/DebugInfo/CodeView/TypeDeserializer.h"
  15 #include "llvm/DebugInfo/CodeView/TypeIndex.h"
  16 #include "llvm/DebugInfo/CodeView/TypeIndexDiscovery.h"
  17 #include "llvm/DebugInfo/CodeView/TypeRecord.h"
  18 #include "llvm/DebugInfo/CodeView/TypeRecordHelpers.h"
  19 #include "llvm/Support/Error.h"
  20
  21 using namespace llvm;
  22 using namespace llvm::codeview;
  23
  24 static inline size_t slotForIndex(TypeIndex Idx) {
  25   assert(!Idx.isSimple() && "simple type indices have no slots");
  26   return Idx.getIndex() - TypeIndex::FirstNonSimpleIndex;
  27 }
  28
  29 namespace {
  30
  31 /// Implementation of CodeView type stream merging.
  32 ///
  33 /// A CodeView type stream is a series of records that reference each other
  34 /// through type indices. A type index is either "simple", meaning it is less
  35 /// than 0x1000 and refers to a builtin type, or it is complex, meaning it
  36 /// refers to a prior type record in the current stream. The type index of a
  37 /// record is equal to the number of records before it in the stream plus
  38 /// 0x1000.
  39 ///
  40 /// Type records are only allowed to use type indices smaller than their own, so
  41 /// a type stream is effectively a topologically sorted DAG. Cycles occurring in
  42 /// the type graph of the source program are resolved with forward declarations
  43 /// of composite types. This class implements the following type stream merging
  44 /// algorithm, which relies on this DAG structure:
  45 ///
  46 /// - Begin with a new empty stream, and a new empty hash table that maps from
  47 ///   type record contents to new type index.
  48 /// - For each new type stream, maintain a map from source type index to
  49 ///   destination type index.
  50 /// - For each record, copy it and rewrite its type indices to be valid in the
  51 ///   destination type stream.
  52 /// - If the new type record is not already present in the destination stream
  53 ///   hash table, append it to the destination type stream, assign it the next
  54 ///   type index, and update the two hash tables.
  55 /// - If the type record already exists in the destination stream, discard it
  56 ///   and update the type index map to forward the source type index to the
  57 ///   existing destination type index.
  58 ///
  59 /// As an additional complication, type stream merging actually produces two
  60 /// streams: an item (or IPI) stream and a type stream, as this is what is
  61 /// actually stored in the final PDB. We choose which records go where by
  62 /// looking at the record kind.
  63 class TypeStreamMerger {
  64 public:
  65   explicit TypeStreamMerger(SmallVectorImpl<TypeIndex> &SourceToDest)
  66       : IndexMap(SourceToDest) {
  67     // When dealing with precompiled headers objects, all data in SourceToDest
  68     // belongs to the precompiled headers object, and is assumed to be already
  69     // remapped to the target PDB. Any forthcoming type that will be merged in
  70     // might potentially back-reference this data. We also don't want to resolve
  71     // twice the types in the precompiled object.
  72     CurIndex += SourceToDest.size();
  73   }
  74
  75   static const TypeIndex Untranslated;
  76
  77   // Local hashing entry points
  78   Error mergeTypesAndIds(MergingTypeTableBuilder &DestIds,
  79                          MergingTypeTableBuilder &DestTypes,
  80                          const CVTypeArray &IdsAndTypes, Optional<uint32_t> &S);
  81   Error mergeIdRecords(MergingTypeTableBuilder &Dest,
  82                        ArrayRef<TypeIndex> TypeSourceToDest,
  83                        const CVTypeArray &Ids);
  84   Error mergeTypeRecords(MergingTypeTableBuilder &Dest,
  85                          const CVTypeArray &Types);
  86
  87   // Global hashing entry points
  88   Error mergeTypesAndIds(GlobalTypeTableBuilder &DestIds,
  89                          GlobalTypeTableBuilder &DestTypes,
  90                          const CVTypeArray &IdsAndTypes,
  91                          ArrayRef<GloballyHashedType> Hashes,
  92                          Optional<uint32_t> &S);
  93   Error mergeIdRecords(GlobalTypeTableBuilder &Dest,
  94                        ArrayRef<TypeIndex> TypeSourceToDest,
  95                        const CVTypeArray &Ids,
  96                        ArrayRef<GloballyHashedType> Hashes);
  97   Error mergeTypeRecords(GlobalTypeTableBuilder &Dest, const CVTypeArray &Types,
  98                          ArrayRef<GloballyHashedType> Hashes,
  99                          Optional<uint32_t> &S);
 100
 101 private:
 102   Error doit(const CVTypeArray &Types);
 103
 104   Error remapAllTypes(const CVTypeArray &Types);
 105
 106   Error remapType(const CVType &Type);
 107
 108   void addMapping(TypeIndex Idx);
 109
 110   inline bool remapTypeIndex(TypeIndex &Idx) {
 111     // If we're mapping a pure index stream, then IndexMap only contains
 112     // mappings from OldIdStream -> NewIdStream, in which case we will need to
 113     // use the special mapping from OldTypeStream -> NewTypeStream which was
 114     // computed externally.  Regardless, we use this special map if and only if
 115     // we are doing an id-only mapping.
 116     if (!hasTypeStream())
 117       return remapIndex(Idx, TypeLookup);
 118
 119     assert(TypeLookup.empty());
 120     return remapIndex(Idx, IndexMap);
 121   }
 122   inline bool remapItemIndex(TypeIndex &Idx) {
 123     assert(hasIdStream());
 124     return remapIndex(Idx, IndexMap);
 125   }
 126
 127   bool hasTypeStream() const {
 128     return (UseGlobalHashes) ? (!!DestGlobalTypeStream) : (!!DestTypeStream);
 129   }
 130
 131   bool hasIdStream() const {
 132     return (UseGlobalHashes) ? (!!DestGlobalIdStream) : (!!DestIdStream);
 133   }
 134
 135   ArrayRef<uint8_t> remapIndices(const CVType &OriginalType,
 136                                  MutableArrayRef<uint8_t> Storage);
 137
 138   inline bool remapIndex(TypeIndex &Idx, ArrayRef<TypeIndex> Map) {
 139     if (LLVM_LIKELY(remapIndexSimple(Idx, Map)))
 140       return true;
 141
 142     return remapIndexFallback(Idx, Map);
 143   }
 144
 145   inline bool remapIndexSimple(TypeIndex &Idx, ArrayRef<TypeIndex> Map) const {
 146     // Simple types are unchanged.
 147     if (Idx.isSimple())
 148       return true;
 149
 150     // Check if this type index refers to a record we've already translated
 151     // successfully. If it refers to a type later in the stream or a record we
 152     // had to defer, defer it until later pass.
 153     unsigned MapPos = slotForIndex(Idx);
 154     if (LLVM_UNLIKELY(MapPos >= Map.size() || Map[MapPos] == Untranslated))
 155       return false;
 156
 157     Idx = Map[MapPos];
 158     return true;
 159   }
 160
 161   bool remapIndexFallback(TypeIndex &Idx, ArrayRef<TypeIndex> Map);
 162
 163   Error errorCorruptRecord() const {
 164     return llvm::make_error<CodeViewError>(cv_error_code::corrupt_record);
 165   }
 166
 167   Expected<bool> shouldRemapType(const CVType &Type);
 168
 169   Optional<Error> LastError;
 170
 171   bool UseGlobalHashes = false;
 172
 173   bool IsSecondPass = false;
 174
 175   unsigned NumBadIndices = 0;
 176
 177   TypeIndex CurIndex{TypeIndex::FirstNonSimpleIndex};
 178
 179   MergingTypeTableBuilder *DestIdStream = nullptr;
 180   MergingTypeTableBuilder *DestTypeStream = nullptr;
 181
 182   GlobalTypeTableBuilder *DestGlobalIdStream = nullptr;
 183   GlobalTypeTableBuilder *DestGlobalTypeStream = nullptr;
 184
 185   ArrayRef<GloballyHashedType> GlobalHashes;
 186
 187   // If we're only mapping id records, this array contains the mapping for
 188   // type records.
 189   ArrayRef<TypeIndex> TypeLookup;
 190
 191   /// Map from source type index to destination type index. Indexed by source
 192   /// type index minus 0x1000.
 193   SmallVectorImpl<TypeIndex> &IndexMap;
 194
 195   /// Temporary storage that we use to copy a record's data while re-writing
 196   /// its type indices.
 197   SmallVector<uint8_t, 256> RemapStorage;
 198
 199   Optional<uint32_t> PCHSignature;
 200 };
 201
 202 } // end anonymous namespace
 203
 204 const TypeIndex TypeStreamMerger::Untranslated(SimpleTypeKind::NotTranslated);
 205
 206 void TypeStreamMerger::addMapping(TypeIndex Idx) {
 207   if (!IsSecondPass) {
 208     assert(IndexMap.size() == slotForIndex(CurIndex) &&
 209            "visitKnownRecord should add one index map entry");
 210     IndexMap.push_back(Idx);
 211   } else {
 212     assert(slotForIndex(CurIndex) < IndexMap.size());
 213     IndexMap[slotForIndex(CurIndex)] = Idx;
 214   }
 215 }
 216
 217 bool TypeStreamMerger::remapIndexFallback(TypeIndex &Idx,
 218                                           ArrayRef<TypeIndex> Map) {
 219   size_t MapPos = slotForIndex(Idx);
 220
 221   // If this is the second pass and this index isn't in the map, then it points
 222   // outside the current type stream, and this is a corrupt record.
 223   if (IsSecondPass && MapPos >= Map.size()) {
 224     // FIXME: Print a more useful error. We can give the current record and the
 225     // index that we think its pointing to.
 226     if (LastError)
 227       LastError = joinErrors(std::move(*LastError), errorCorruptRecord());
 228     else
 229       LastError = errorCorruptRecord();
 230   }
 231
 232   ++NumBadIndices;
 233
 234   // This type index is invalid. Remap this to "not translated by cvpack",
 235   // and return failure.
 236   Idx = Untranslated;
 237   return false;
 238 }
 239
 240 // Local hashing entry points
 241 Error TypeStreamMerger::mergeTypeRecords(MergingTypeTableBuilder &Dest,
 242                                          const CVTypeArray &Types) {
 243   DestTypeStream = &Dest;
 244   UseGlobalHashes = false;
 245
 246   return doit(Types);
 247 }
 248
 249 Error TypeStreamMerger::mergeIdRecords(MergingTypeTableBuilder &Dest,
 250                                        ArrayRef<TypeIndex> TypeSourceToDest,
 251                                        const CVTypeArray &Ids) {
 252   DestIdStream = &Dest;
 253   TypeLookup = TypeSourceToDest;
 254   UseGlobalHashes = false;
 255
 256   return doit(Ids);
 257 }
 258
 259 Error TypeStreamMerger::mergeTypesAndIds(MergingTypeTableBuilder &DestIds,
 260                                          MergingTypeTableBuilder &DestTypes,
 261                                          const CVTypeArray &IdsAndTypes,
 262                                          Optional<uint32_t> &S) {
 263   DestIdStream = &DestIds;
 264   DestTypeStream = &DestTypes;
 265   UseGlobalHashes = false;
 266   auto Err = doit(IdsAndTypes);
 267   S = PCHSignature;
 268   return Err;
 269 }
 270
 271 // Global hashing entry points
 272 Error TypeStreamMerger::mergeTypeRecords(GlobalTypeTableBuilder &Dest,
 273                                          const CVTypeArray &Types,
 274                                          ArrayRef<GloballyHashedType> Hashes,
 275                                          Optional<uint32_t> &S) {
 276   DestGlobalTypeStream = &Dest;
 277   UseGlobalHashes = true;
 278   GlobalHashes = Hashes;
 279   auto Err = doit(Types);
 280   S = PCHSignature;
 281   return Err;
 282 }
 283
 284 Error TypeStreamMerger::mergeIdRecords(GlobalTypeTableBuilder &Dest,
 285                                        ArrayRef<TypeIndex> TypeSourceToDest,
 286                                        const CVTypeArray &Ids,
 287                                        ArrayRef<GloballyHashedType> Hashes) {
 288   DestGlobalIdStream = &Dest;
 289   TypeLookup = TypeSourceToDest;
 290   UseGlobalHashes = true;
 291   GlobalHashes = Hashes;
 292
 293   return doit(Ids);
 294 }
 295
 296 Error TypeStreamMerger::mergeTypesAndIds(GlobalTypeTableBuilder &DestIds,
 297                                          GlobalTypeTableBuilder &DestTypes,
 298                                          const CVTypeArray &IdsAndTypes,
 299                                          ArrayRef<GloballyHashedType> Hashes,
 300                                          Optional<uint32_t> &S) {
 301   DestGlobalIdStream = &DestIds;
 302   DestGlobalTypeStream = &DestTypes;
 303   UseGlobalHashes = true;
 304   GlobalHashes = Hashes;
 305   auto Err = doit(IdsAndTypes);
 306   S = PCHSignature;
 307   return Err;
 308 }
 309
 310 Error TypeStreamMerger::doit(const CVTypeArray &Types) {
 311   if (auto EC = remapAllTypes(Types))
 312     return EC;
 313
 314   // If we found bad indices but no other errors, try doing another pass and see
 315   // if we can resolve the indices that weren't in the map on the first pass.
 316   // This may require multiple passes, but we should always make progress. MASM
 317   // is the only known CodeView producer that makes type streams that aren't
 318   // topologically sorted. The standard library contains MASM-produced objects,
 319   // so this is important to handle correctly, but we don't have to be too
 320   // efficient. MASM type streams are usually very small.
 321   while (!LastError && NumBadIndices > 0) {
 322     unsigned BadIndicesRemaining = NumBadIndices;
 323     IsSecondPass = true;
 324     NumBadIndices = 0;
 325     CurIndex = TypeIndex(TypeIndex::FirstNonSimpleIndex);
 326
 327     if (auto EC = remapAllTypes(Types))
 328       return EC;
 329
 330     assert(NumBadIndices <= BadIndicesRemaining &&
 331            "second pass found more bad indices");
 332     if (!LastError && NumBadIndices == BadIndicesRemaining) {
 333       return llvm::make_error<CodeViewError>(
 334           cv_error_code::corrupt_record, "Input type graph contains cycles");
 335     }
 336   }
 337
 338   if (LastError)
 339     return std::move(*LastError);
 340   return Error::success();
 341 }
 342
 343 Error TypeStreamMerger::remapAllTypes(const CVTypeArray &Types) {
 344   BinaryStreamRef Stream = Types.getUnderlyingStream();
 345   ArrayRef<uint8_t> Buffer;
 346   cantFail(Stream.readBytes(0, Stream.getLength(), Buffer));
 347
 348   return forEachCodeViewRecord<CVType>(
 349       Buffer, [this](const CVType &T) { return remapType(T); });
 350 }
 351
 352 Error TypeStreamMerger::remapType(const CVType &Type) {
 353   auto R = shouldRemapType(Type);
 354   if (!R)
 355     return R.takeError();
 356
 357   TypeIndex DestIdx = Untranslated;
 358   if (*R) {
 359     auto DoSerialize =
 360         [this, Type](MutableArrayRef<uint8_t> Storage) -> ArrayRef<uint8_t> {
 361       return remapIndices(Type, Storage);
 362     };
 363     unsigned AlignedSize = alignTo(Type.RecordData.size(), 4);
 364
 365     if (LLVM_LIKELY(UseGlobalHashes)) {
 366       GlobalTypeTableBuilder &Dest =
 367           isIdRecord(Type.kind()) ? *DestGlobalIdStream : *DestGlobalTypeStream;
 368       GloballyHashedType H = GlobalHashes[CurIndex.toArrayIndex()];
 369       DestIdx = Dest.insertRecordAs(H, AlignedSize, DoSerialize);
 370     } else {
 371       MergingTypeTableBuilder &Dest =
 372           isIdRecord(Type.kind()) ? *DestIdStream : *DestTypeStream;
 373
 374       RemapStorage.resize(AlignedSize);
 375       ArrayRef<uint8_t> Result = DoSerialize(RemapStorage);
 376       if (!Result.empty())
 377         DestIdx = Dest.insertRecordBytes(Result);
 378     }
 379   }
 380   addMapping(DestIdx);
 381
 382   ++CurIndex;
 383   assert((IsSecondPass || IndexMap.size() == slotForIndex(CurIndex)) &&
 384          "visitKnownRecord should add one index map entry");
 385   return Error::success();
 386 }
 387
 388 ArrayRef<uint8_t>
 389 TypeStreamMerger::remapIndices(const CVType &OriginalType,
 390                                MutableArrayRef<uint8_t> Storage) {
 391   unsigned Align = OriginalType.RecordData.size() & 3;
 392   assert(Storage.size() == alignTo(OriginalType.RecordData.size(), 4) &&
 393          "The storage buffer size is not a multiple of 4 bytes which will "
 394          "cause misalignment in the output TPI stream!");
 395
 396   SmallVector<TiReference, 4> Refs;
 397   discoverTypeIndices(OriginalType.RecordData, Refs);
 398   if (Refs.empty() && Align == 0)
 399     return OriginalType.RecordData;
 400
 401   ::memcpy(Storage.data(), OriginalType.RecordData.data(),
 402            OriginalType.RecordData.size());
 403
 404   uint8_t *DestContent = Storage.data() + sizeof(RecordPrefix);
 405
 406   for (auto &Ref : Refs) {
 407     TypeIndex *DestTIs =
 408         reinterpret_cast<TypeIndex *>(DestContent + Ref.Offset);
 409
 410     for (size_t I = 0; I < Ref.Count; ++I) {
 411       TypeIndex &TI = DestTIs[I];
 412       bool Success = (Ref.Kind == TiRefKind::IndexRef) ? remapItemIndex(TI)
 413                                                        : remapTypeIndex(TI);
 414       if (LLVM_UNLIKELY(!Success))
 415         return {};
 416     }
 417   }
 418
 419   if (Align > 0) {
 420     RecordPrefix *StorageHeader =
 421         reinterpret_cast<RecordPrefix *>(Storage.data());
 422     StorageHeader->RecordLen += 4 - Align;
 423
 424     DestContent = Storage.data() + OriginalType.RecordData.size();
 425     for (; Align < 4; ++Align)
 426       *DestContent++ = LF_PAD4 - Align;
 427   }
 428   return Storage;
 429 }
 430
 431 Error llvm::codeview::mergeTypeRecords(MergingTypeTableBuilder &Dest,
 432                                        SmallVectorImpl<TypeIndex> &SourceToDest,
 433                                        const CVTypeArray &Types) {
 434   TypeStreamMerger M(SourceToDest);
 435   return M.mergeTypeRecords(Dest, Types);
 436 }
 437
 438 Error llvm::codeview::mergeIdRecords(MergingTypeTableBuilder &Dest,
 439                                      ArrayRef<TypeIndex> TypeSourceToDest,
 440                                      SmallVectorImpl<TypeIndex> &SourceToDest,
 441                                      const CVTypeArray &Ids) {
 442   TypeStreamMerger M(SourceToDest);
 443   return M.mergeIdRecords(Dest, TypeSourceToDest, Ids);
 444 }
 445
 446 Error llvm::codeview::mergeTypeAndIdRecords(
 447     MergingTypeTableBuilder &DestIds, MergingTypeTableBuilder &DestTypes,
 448     SmallVectorImpl<TypeIndex> &SourceToDest, const CVTypeArray &IdsAndTypes,
 449     Optional<uint32_t> &PCHSignature) {
 450   TypeStreamMerger M(SourceToDest);
 451   return M.mergeTypesAndIds(DestIds, DestTypes, IdsAndTypes, PCHSignature);
 452 }
 453
 454 Error llvm::codeview::mergeTypeAndIdRecords(
 455     GlobalTypeTableBuilder &DestIds, GlobalTypeTableBuilder &DestTypes,
 456     SmallVectorImpl<TypeIndex> &SourceToDest, const CVTypeArray &IdsAndTypes,
 457     ArrayRef<GloballyHashedType> Hashes, Optional<uint32_t> &PCHSignature) {
 458   TypeStreamMerger M(SourceToDest);
 459   return M.mergeTypesAndIds(DestIds, DestTypes, IdsAndTypes, Hashes,
 460                             PCHSignature);
 461 }
 462
 463 Error llvm::codeview::mergeTypeRecords(GlobalTypeTableBuilder &Dest,
 464                                        SmallVectorImpl<TypeIndex> &SourceToDest,
 465                                        const CVTypeArray &Types,
 466                                        ArrayRef<GloballyHashedType> Hashes,
 467                                        Optional<uint32_t> &PCHSignature) {
 468   TypeStreamMerger M(SourceToDest);
 469   return M.mergeTypeRecords(Dest, Types, Hashes, PCHSignature);
 470 }
 471
 472 Error llvm::codeview::mergeIdRecords(GlobalTypeTableBuilder &Dest,
 473                                      ArrayRef<TypeIndex> Types,
 474                                      SmallVectorImpl<TypeIndex> &SourceToDest,
 475                                      const CVTypeArray &Ids,
 476                                      ArrayRef<GloballyHashedType> Hashes) {
 477   TypeStreamMerger M(SourceToDest);
 478   return M.mergeIdRecords(Dest, Types, Ids, Hashes);
 479 }
 480
 481 Expected<bool> TypeStreamMerger::shouldRemapType(const CVType &Type) {
 482   // For object files containing precompiled types, we need to extract the
 483   // signature, through EndPrecompRecord. This is done here for performance
 484   // reasons, to avoid re-parsing the Types stream.
 485   if (Type.kind() == LF_ENDPRECOMP) {
 486     EndPrecompRecord EP;
 487     if (auto EC = TypeDeserializer::deserializeAs(const_cast<CVType &>(Type),
 488                                                   EP))
 489       return joinErrors(std::move(EC), errorCorruptRecord());
 490     if (PCHSignature.hasValue())
 491       return errorCorruptRecord();
 492     PCHSignature.emplace(EP.getSignature());
 493     return false;
 494   }
 495   return true;
 496 }