llvm/lib/Bitcode/Reader/BitcodeAnalyzer.cpp

   1 //===- BitcodeAnalyzer.cpp - Internal BitcodeAnalyzer implementation ------===//
   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/Bitcode/BitcodeAnalyzer.h"
  10 #include "llvm/Bitcode/BitcodeReader.h"
  11 #include "llvm/Bitcode/LLVMBitCodes.h"
  12 #include "llvm/Bitstream/BitCodes.h"
  13 #include "llvm/Bitstream/BitstreamReader.h"
  14 #include "llvm/Support/Format.h"
  15 #include "llvm/Support/SHA1.h"
  16 #include <optional>
  17
  18 using namespace llvm;
  19
  20 static Error reportError(StringRef Message) {
  21   return createStringError(std::errc::illegal_byte_sequence, Message.data());
  22 }
  23
  24 /// Return a symbolic block name if known, otherwise return null.
  25 static std::optional<const char *>
  26 GetBlockName(unsigned BlockID, const BitstreamBlockInfo &BlockInfo,
  27              CurStreamTypeType CurStreamType) {
  28   // Standard blocks for all bitcode files.
  29   if (BlockID < bitc::FIRST_APPLICATION_BLOCKID) {
  30     if (BlockID == bitc::BLOCKINFO_BLOCK_ID)
  31       return "BLOCKINFO_BLOCK";
  32     return std::nullopt;
  33   }
  34
  35   // Check to see if we have a blockinfo record for this block, with a name.
  36   if (const BitstreamBlockInfo::BlockInfo *Info =
  37           BlockInfo.getBlockInfo(BlockID)) {
  38     if (!Info->Name.empty())
  39       return Info->Name.c_str();
  40   }
  41
  42   if (CurStreamType != LLVMIRBitstream)
  43     return std::nullopt;
  44
  45   switch (BlockID) {
  46   default:
  47     return std::nullopt;
  48   case bitc::OPERAND_BUNDLE_TAGS_BLOCK_ID:
  49     return "OPERAND_BUNDLE_TAGS_BLOCK";
  50   case bitc::MODULE_BLOCK_ID:
  51     return "MODULE_BLOCK";
  52   case bitc::PARAMATTR_BLOCK_ID:
  53     return "PARAMATTR_BLOCK";
  54   case bitc::PARAMATTR_GROUP_BLOCK_ID:
  55     return "PARAMATTR_GROUP_BLOCK_ID";
  56   case bitc::TYPE_BLOCK_ID_NEW:
  57     return "TYPE_BLOCK_ID";
  58   case bitc::CONSTANTS_BLOCK_ID:
  59     return "CONSTANTS_BLOCK";
  60   case bitc::FUNCTION_BLOCK_ID:
  61     return "FUNCTION_BLOCK";
  62   case bitc::IDENTIFICATION_BLOCK_ID:
  63     return "IDENTIFICATION_BLOCK_ID";
  64   case bitc::VALUE_SYMTAB_BLOCK_ID:
  65     return "VALUE_SYMTAB";
  66   case bitc::METADATA_BLOCK_ID:
  67     return "METADATA_BLOCK";
  68   case bitc::METADATA_KIND_BLOCK_ID:
  69     return "METADATA_KIND_BLOCK";
  70   case bitc::METADATA_ATTACHMENT_ID:
  71     return "METADATA_ATTACHMENT_BLOCK";
  72   case bitc::USELIST_BLOCK_ID:
  73     return "USELIST_BLOCK_ID";
  74   case bitc::GLOBALVAL_SUMMARY_BLOCK_ID:
  75     return "GLOBALVAL_SUMMARY_BLOCK";
  76   case bitc::FULL_LTO_GLOBALVAL_SUMMARY_BLOCK_ID:
  77     return "FULL_LTO_GLOBALVAL_SUMMARY_BLOCK";
  78   case bitc::MODULE_STRTAB_BLOCK_ID:
  79     return "MODULE_STRTAB_BLOCK";
  80   case bitc::STRTAB_BLOCK_ID:
  81     return "STRTAB_BLOCK";
  82   case bitc::SYMTAB_BLOCK_ID:
  83     return "SYMTAB_BLOCK";
  84   }
  85 }
  86
  87 /// Return a symbolic code name if known, otherwise return null.
  88 static std::optional<const char *>
  89 GetCodeName(unsigned CodeID, unsigned BlockID,
  90             const BitstreamBlockInfo &BlockInfo,
  91             CurStreamTypeType CurStreamType) {
  92   // Standard blocks for all bitcode files.
  93   if (BlockID < bitc::FIRST_APPLICATION_BLOCKID) {
  94     if (BlockID == bitc::BLOCKINFO_BLOCK_ID) {
  95       switch (CodeID) {
  96       default:
  97         return std::nullopt;
  98       case bitc::BLOCKINFO_CODE_SETBID:
  99         return "SETBID";
 100       case bitc::BLOCKINFO_CODE_BLOCKNAME:
 101         return "BLOCKNAME";
 102       case bitc::BLOCKINFO_CODE_SETRECORDNAME:
 103         return "SETRECORDNAME";
 104       }
 105     }
 106     return std::nullopt;
 107   }
 108
 109   // Check to see if we have a blockinfo record for this record, with a name.
 110   if (const BitstreamBlockInfo::BlockInfo *Info =
 111           BlockInfo.getBlockInfo(BlockID)) {
 112     for (const std::pair<unsigned, std::string> &RN : Info->RecordNames)
 113       if (RN.first == CodeID)
 114         return RN.second.c_str();
 115   }
 116
 117   if (CurStreamType != LLVMIRBitstream)
 118     return std::nullopt;
 119
 120 #define STRINGIFY_CODE(PREFIX, CODE)                                           \
 121   case bitc::PREFIX##_##CODE:                                                  \
 122     return #CODE;
 123   switch (BlockID) {
 124   default:
 125     return std::nullopt;
 126   case bitc::MODULE_BLOCK_ID:
 127     switch (CodeID) {
 128     default:
 129       return std::nullopt;
 130       STRINGIFY_CODE(MODULE_CODE, VERSION)
 131       STRINGIFY_CODE(MODULE_CODE, TRIPLE)
 132       STRINGIFY_CODE(MODULE_CODE, DATALAYOUT)
 133       STRINGIFY_CODE(MODULE_CODE, ASM)
 134       STRINGIFY_CODE(MODULE_CODE, SECTIONNAME)
 135       STRINGIFY_CODE(MODULE_CODE, DEPLIB) // Deprecated, present in old bitcode
 136       STRINGIFY_CODE(MODULE_CODE, GLOBALVAR)
 137       STRINGIFY_CODE(MODULE_CODE, FUNCTION)
 138       STRINGIFY_CODE(MODULE_CODE, ALIAS)
 139       STRINGIFY_CODE(MODULE_CODE, GCNAME)
 140       STRINGIFY_CODE(MODULE_CODE, COMDAT)
 141       STRINGIFY_CODE(MODULE_CODE, VSTOFFSET)
 142       STRINGIFY_CODE(MODULE_CODE, METADATA_VALUES_UNUSED)
 143       STRINGIFY_CODE(MODULE_CODE, SOURCE_FILENAME)
 144       STRINGIFY_CODE(MODULE_CODE, HASH)
 145     }
 146   case bitc::IDENTIFICATION_BLOCK_ID:
 147     switch (CodeID) {
 148     default:
 149       return std::nullopt;
 150       STRINGIFY_CODE(IDENTIFICATION_CODE, STRING)
 151       STRINGIFY_CODE(IDENTIFICATION_CODE, EPOCH)
 152     }
 153   case bitc::PARAMATTR_BLOCK_ID:
 154     switch (CodeID) {
 155     default:
 156       return std::nullopt;
 157     // FIXME: Should these be different?
 158     case bitc::PARAMATTR_CODE_ENTRY_OLD:
 159       return "ENTRY";
 160     case bitc::PARAMATTR_CODE_ENTRY:
 161       return "ENTRY";
 162     }
 163   case bitc::PARAMATTR_GROUP_BLOCK_ID:
 164     switch (CodeID) {
 165     default:
 166       return std::nullopt;
 167     case bitc::PARAMATTR_GRP_CODE_ENTRY:
 168       return "ENTRY";
 169     }
 170   case bitc::TYPE_BLOCK_ID_NEW:
 171     switch (CodeID) {
 172     default:
 173       return std::nullopt;
 174       STRINGIFY_CODE(TYPE_CODE, NUMENTRY)
 175       STRINGIFY_CODE(TYPE_CODE, VOID)
 176       STRINGIFY_CODE(TYPE_CODE, FLOAT)
 177       STRINGIFY_CODE(TYPE_CODE, DOUBLE)
 178       STRINGIFY_CODE(TYPE_CODE, LABEL)
 179       STRINGIFY_CODE(TYPE_CODE, OPAQUE)
 180       STRINGIFY_CODE(TYPE_CODE, INTEGER)
 181       STRINGIFY_CODE(TYPE_CODE, POINTER)
 182       STRINGIFY_CODE(TYPE_CODE, HALF)
 183       STRINGIFY_CODE(TYPE_CODE, ARRAY)
 184       STRINGIFY_CODE(TYPE_CODE, VECTOR)
 185       STRINGIFY_CODE(TYPE_CODE, X86_FP80)
 186       STRINGIFY_CODE(TYPE_CODE, FP128)
 187       STRINGIFY_CODE(TYPE_CODE, PPC_FP128)
 188       STRINGIFY_CODE(TYPE_CODE, METADATA)
 189       STRINGIFY_CODE(TYPE_CODE, X86_MMX)
 190       STRINGIFY_CODE(TYPE_CODE, STRUCT_ANON)
 191       STRINGIFY_CODE(TYPE_CODE, STRUCT_NAME)
 192       STRINGIFY_CODE(TYPE_CODE, STRUCT_NAMED)
 193       STRINGIFY_CODE(TYPE_CODE, FUNCTION)
 194       STRINGIFY_CODE(TYPE_CODE, TOKEN)
 195       STRINGIFY_CODE(TYPE_CODE, BFLOAT)
 196     }
 197
 198   case bitc::CONSTANTS_BLOCK_ID:
 199     switch (CodeID) {
 200     default:
 201       return std::nullopt;
 202       STRINGIFY_CODE(CST_CODE, SETTYPE)
 203       STRINGIFY_CODE(CST_CODE, NULL)
 204       STRINGIFY_CODE(CST_CODE, UNDEF)
 205       STRINGIFY_CODE(CST_CODE, INTEGER)
 206       STRINGIFY_CODE(CST_CODE, WIDE_INTEGER)
 207       STRINGIFY_CODE(CST_CODE, FLOAT)
 208       STRINGIFY_CODE(CST_CODE, AGGREGATE)
 209       STRINGIFY_CODE(CST_CODE, STRING)
 210       STRINGIFY_CODE(CST_CODE, CSTRING)
 211       STRINGIFY_CODE(CST_CODE, CE_BINOP)
 212       STRINGIFY_CODE(CST_CODE, CE_CAST)
 213       STRINGIFY_CODE(CST_CODE, CE_GEP)
 214       STRINGIFY_CODE(CST_CODE, CE_INBOUNDS_GEP)
 215       STRINGIFY_CODE(CST_CODE, CE_SELECT)
 216       STRINGIFY_CODE(CST_CODE, CE_EXTRACTELT)
 217       STRINGIFY_CODE(CST_CODE, CE_INSERTELT)
 218       STRINGIFY_CODE(CST_CODE, CE_SHUFFLEVEC)
 219       STRINGIFY_CODE(CST_CODE, CE_CMP)
 220       STRINGIFY_CODE(CST_CODE, INLINEASM)
 221       STRINGIFY_CODE(CST_CODE, CE_SHUFVEC_EX)
 222       STRINGIFY_CODE(CST_CODE, CE_UNOP)
 223       STRINGIFY_CODE(CST_CODE, DSO_LOCAL_EQUIVALENT)
 224       STRINGIFY_CODE(CST_CODE, NO_CFI_VALUE)
 225     case bitc::CST_CODE_BLOCKADDRESS:
 226       return "CST_CODE_BLOCKADDRESS";
 227       STRINGIFY_CODE(CST_CODE, DATA)
 228     }
 229   case bitc::FUNCTION_BLOCK_ID:
 230     switch (CodeID) {
 231     default:
 232       return std::nullopt;
 233       STRINGIFY_CODE(FUNC_CODE, DECLAREBLOCKS)
 234       STRINGIFY_CODE(FUNC_CODE, INST_BINOP)
 235       STRINGIFY_CODE(FUNC_CODE, INST_CAST)
 236       STRINGIFY_CODE(FUNC_CODE, INST_GEP_OLD)
 237       STRINGIFY_CODE(FUNC_CODE, INST_INBOUNDS_GEP_OLD)
 238       STRINGIFY_CODE(FUNC_CODE, INST_SELECT)
 239       STRINGIFY_CODE(FUNC_CODE, INST_EXTRACTELT)
 240       STRINGIFY_CODE(FUNC_CODE, INST_INSERTELT)
 241       STRINGIFY_CODE(FUNC_CODE, INST_SHUFFLEVEC)
 242       STRINGIFY_CODE(FUNC_CODE, INST_CMP)
 243       STRINGIFY_CODE(FUNC_CODE, INST_RET)
 244       STRINGIFY_CODE(FUNC_CODE, INST_BR)
 245       STRINGIFY_CODE(FUNC_CODE, INST_SWITCH)
 246       STRINGIFY_CODE(FUNC_CODE, INST_INVOKE)
 247       STRINGIFY_CODE(FUNC_CODE, INST_UNOP)
 248       STRINGIFY_CODE(FUNC_CODE, INST_UNREACHABLE)
 249       STRINGIFY_CODE(FUNC_CODE, INST_CLEANUPRET)
 250       STRINGIFY_CODE(FUNC_CODE, INST_CATCHRET)
 251       STRINGIFY_CODE(FUNC_CODE, INST_CATCHPAD)
 252       STRINGIFY_CODE(FUNC_CODE, INST_PHI)
 253       STRINGIFY_CODE(FUNC_CODE, INST_ALLOCA)
 254       STRINGIFY_CODE(FUNC_CODE, INST_LOAD)
 255       STRINGIFY_CODE(FUNC_CODE, INST_VAARG)
 256       STRINGIFY_CODE(FUNC_CODE, INST_STORE)
 257       STRINGIFY_CODE(FUNC_CODE, INST_EXTRACTVAL)
 258       STRINGIFY_CODE(FUNC_CODE, INST_INSERTVAL)
 259       STRINGIFY_CODE(FUNC_CODE, INST_CMP2)
 260       STRINGIFY_CODE(FUNC_CODE, INST_VSELECT)
 261       STRINGIFY_CODE(FUNC_CODE, DEBUG_LOC_AGAIN)
 262       STRINGIFY_CODE(FUNC_CODE, INST_CALL)
 263       STRINGIFY_CODE(FUNC_CODE, DEBUG_LOC)
 264       STRINGIFY_CODE(FUNC_CODE, INST_GEP)
 265       STRINGIFY_CODE(FUNC_CODE, OPERAND_BUNDLE)
 266       STRINGIFY_CODE(FUNC_CODE, INST_FENCE)
 267       STRINGIFY_CODE(FUNC_CODE, INST_ATOMICRMW)
 268       STRINGIFY_CODE(FUNC_CODE, INST_LOADATOMIC)
 269       STRINGIFY_CODE(FUNC_CODE, INST_STOREATOMIC)
 270       STRINGIFY_CODE(FUNC_CODE, INST_CMPXCHG)
 271       STRINGIFY_CODE(FUNC_CODE, INST_CALLBR)
 272       STRINGIFY_CODE(FUNC_CODE, BLOCKADDR_USERS)
 273     }
 274   case bitc::VALUE_SYMTAB_BLOCK_ID:
 275     switch (CodeID) {
 276     default:
 277       return std::nullopt;
 278       STRINGIFY_CODE(VST_CODE, ENTRY)
 279       STRINGIFY_CODE(VST_CODE, BBENTRY)
 280       STRINGIFY_CODE(VST_CODE, FNENTRY)
 281       STRINGIFY_CODE(VST_CODE, COMBINED_ENTRY)
 282     }
 283   case bitc::MODULE_STRTAB_BLOCK_ID:
 284     switch (CodeID) {
 285     default:
 286       return std::nullopt;
 287       STRINGIFY_CODE(MST_CODE, ENTRY)
 288       STRINGIFY_CODE(MST_CODE, HASH)
 289     }
 290   case bitc::GLOBALVAL_SUMMARY_BLOCK_ID:
 291   case bitc::FULL_LTO_GLOBALVAL_SUMMARY_BLOCK_ID:
 292     switch (CodeID) {
 293     default:
 294       return std::nullopt;
 295       STRINGIFY_CODE(FS, PERMODULE)
 296       STRINGIFY_CODE(FS, PERMODULE_PROFILE)
 297       STRINGIFY_CODE(FS, PERMODULE_RELBF)
 298       STRINGIFY_CODE(FS, PERMODULE_GLOBALVAR_INIT_REFS)
 299       STRINGIFY_CODE(FS, PERMODULE_VTABLE_GLOBALVAR_INIT_REFS)
 300       STRINGIFY_CODE(FS, COMBINED)
 301       STRINGIFY_CODE(FS, COMBINED_PROFILE)
 302       STRINGIFY_CODE(FS, COMBINED_GLOBALVAR_INIT_REFS)
 303       STRINGIFY_CODE(FS, ALIAS)
 304       STRINGIFY_CODE(FS, COMBINED_ALIAS)
 305       STRINGIFY_CODE(FS, COMBINED_ORIGINAL_NAME)
 306       STRINGIFY_CODE(FS, VERSION)
 307       STRINGIFY_CODE(FS, FLAGS)
 308       STRINGIFY_CODE(FS, TYPE_TESTS)
 309       STRINGIFY_CODE(FS, TYPE_TEST_ASSUME_VCALLS)
 310       STRINGIFY_CODE(FS, TYPE_CHECKED_LOAD_VCALLS)
 311       STRINGIFY_CODE(FS, TYPE_TEST_ASSUME_CONST_VCALL)
 312       STRINGIFY_CODE(FS, TYPE_CHECKED_LOAD_CONST_VCALL)
 313       STRINGIFY_CODE(FS, VALUE_GUID)
 314       STRINGIFY_CODE(FS, CFI_FUNCTION_DEFS)
 315       STRINGIFY_CODE(FS, CFI_FUNCTION_DECLS)
 316       STRINGIFY_CODE(FS, TYPE_ID)
 317       STRINGIFY_CODE(FS, TYPE_ID_METADATA)
 318       STRINGIFY_CODE(FS, BLOCK_COUNT)
 319       STRINGIFY_CODE(FS, PARAM_ACCESS)
 320       STRINGIFY_CODE(FS, PERMODULE_CALLSITE_INFO)
 321       STRINGIFY_CODE(FS, PERMODULE_ALLOC_INFO)
 322       STRINGIFY_CODE(FS, COMBINED_CALLSITE_INFO)
 323       STRINGIFY_CODE(FS, COMBINED_ALLOC_INFO)
 324       STRINGIFY_CODE(FS, STACK_IDS)
 325     }
 326   case bitc::METADATA_ATTACHMENT_ID:
 327     switch (CodeID) {
 328     default:
 329       return std::nullopt;
 330       STRINGIFY_CODE(METADATA, ATTACHMENT)
 331     }
 332   case bitc::METADATA_BLOCK_ID:
 333     switch (CodeID) {
 334     default:
 335       return std::nullopt;
 336       STRINGIFY_CODE(METADATA, STRING_OLD)
 337       STRINGIFY_CODE(METADATA, VALUE)
 338       STRINGIFY_CODE(METADATA, NODE)
 339       STRINGIFY_CODE(METADATA, NAME)
 340       STRINGIFY_CODE(METADATA, DISTINCT_NODE)
 341       STRINGIFY_CODE(METADATA, KIND) // Older bitcode has it in a MODULE_BLOCK
 342       STRINGIFY_CODE(METADATA, LOCATION)
 343       STRINGIFY_CODE(METADATA, OLD_NODE)
 344       STRINGIFY_CODE(METADATA, OLD_FN_NODE)
 345       STRINGIFY_CODE(METADATA, NAMED_NODE)
 346       STRINGIFY_CODE(METADATA, GENERIC_DEBUG)
 347       STRINGIFY_CODE(METADATA, SUBRANGE)
 348       STRINGIFY_CODE(METADATA, ENUMERATOR)
 349       STRINGIFY_CODE(METADATA, BASIC_TYPE)
 350       STRINGIFY_CODE(METADATA, FILE)
 351       STRINGIFY_CODE(METADATA, DERIVED_TYPE)
 352       STRINGIFY_CODE(METADATA, COMPOSITE_TYPE)
 353       STRINGIFY_CODE(METADATA, SUBROUTINE_TYPE)
 354       STRINGIFY_CODE(METADATA, COMPILE_UNIT)
 355       STRINGIFY_CODE(METADATA, SUBPROGRAM)
 356       STRINGIFY_CODE(METADATA, LEXICAL_BLOCK)
 357       STRINGIFY_CODE(METADATA, LEXICAL_BLOCK_FILE)
 358       STRINGIFY_CODE(METADATA, NAMESPACE)
 359       STRINGIFY_CODE(METADATA, TEMPLATE_TYPE)
 360       STRINGIFY_CODE(METADATA, TEMPLATE_VALUE)
 361       STRINGIFY_CODE(METADATA, GLOBAL_VAR)
 362       STRINGIFY_CODE(METADATA, LOCAL_VAR)
 363       STRINGIFY_CODE(METADATA, EXPRESSION)
 364       STRINGIFY_CODE(METADATA, OBJC_PROPERTY)
 365       STRINGIFY_CODE(METADATA, IMPORTED_ENTITY)
 366       STRINGIFY_CODE(METADATA, MODULE)
 367       STRINGIFY_CODE(METADATA, MACRO)
 368       STRINGIFY_CODE(METADATA, MACRO_FILE)
 369       STRINGIFY_CODE(METADATA, STRINGS)
 370       STRINGIFY_CODE(METADATA, GLOBAL_DECL_ATTACHMENT)
 371       STRINGIFY_CODE(METADATA, GLOBAL_VAR_EXPR)
 372       STRINGIFY_CODE(METADATA, INDEX_OFFSET)
 373       STRINGIFY_CODE(METADATA, INDEX)
 374       STRINGIFY_CODE(METADATA, ARG_LIST)
 375     }
 376   case bitc::METADATA_KIND_BLOCK_ID:
 377     switch (CodeID) {
 378     default:
 379       return std::nullopt;
 380       STRINGIFY_CODE(METADATA, KIND)
 381     }
 382   case bitc::USELIST_BLOCK_ID:
 383     switch (CodeID) {
 384     default:
 385       return std::nullopt;
 386     case bitc::USELIST_CODE_DEFAULT:
 387       return "USELIST_CODE_DEFAULT";
 388     case bitc::USELIST_CODE_BB:
 389       return "USELIST_CODE_BB";
 390     }
 391
 392   case bitc::OPERAND_BUNDLE_TAGS_BLOCK_ID:
 393     switch (CodeID) {
 394     default:
 395       return std::nullopt;
 396     case bitc::OPERAND_BUNDLE_TAG:
 397       return "OPERAND_BUNDLE_TAG";
 398     }
 399   case bitc::STRTAB_BLOCK_ID:
 400     switch (CodeID) {
 401     default:
 402       return std::nullopt;
 403     case bitc::STRTAB_BLOB:
 404       return "BLOB";
 405     }
 406   case bitc::SYMTAB_BLOCK_ID:
 407     switch (CodeID) {
 408     default:
 409       return std::nullopt;
 410     case bitc::SYMTAB_BLOB:
 411       return "BLOB";
 412     }
 413   }
 414 #undef STRINGIFY_CODE
 415 }
 416
 417 static void printSize(raw_ostream &OS, double Bits) {
 418   OS << format("%.2f/%.2fB/%luW", Bits, Bits / 8, (unsigned long)(Bits / 32));
 419 }
 420 static void printSize(raw_ostream &OS, uint64_t Bits) {
 421   OS << format("%lub/%.2fB/%luW", (unsigned long)Bits, (double)Bits / 8,
 422                (unsigned long)(Bits / 32));
 423 }
 424
 425 static Expected<CurStreamTypeType> ReadSignature(BitstreamCursor &Stream) {
 426   auto tryRead = [&Stream](char &Dest, size_t size) -> Error {
 427     if (Expected<SimpleBitstreamCursor::word_t> MaybeWord = Stream.Read(size))
 428       Dest = MaybeWord.get();
 429     else
 430       return MaybeWord.takeError();
 431     return Error::success();
 432   };
 433
 434   char Signature[6];
 435   if (Error Err = tryRead(Signature[0], 8))
 436     return std::move(Err);
 437   if (Error Err = tryRead(Signature[1], 8))
 438     return std::move(Err);
 439
 440   // Autodetect the file contents, if it is one we know.
 441   if (Signature[0] == 'C' && Signature[1] == 'P') {
 442     if (Error Err = tryRead(Signature[2], 8))
 443       return std::move(Err);
 444     if (Error Err = tryRead(Signature[3], 8))
 445       return std::move(Err);
 446     if (Signature[2] == 'C' && Signature[3] == 'H')
 447       return ClangSerializedASTBitstream;
 448   } else if (Signature[0] == 'D' && Signature[1] == 'I') {
 449     if (Error Err = tryRead(Signature[2], 8))
 450       return std::move(Err);
 451     if (Error Err = tryRead(Signature[3], 8))
 452       return std::move(Err);
 453     if (Signature[2] == 'A' && Signature[3] == 'G')
 454       return ClangSerializedDiagnosticsBitstream;
 455   } else if (Signature[0] == 'R' && Signature[1] == 'M') {
 456     if (Error Err = tryRead(Signature[2], 8))
 457       return std::move(Err);
 458     if (Error Err = tryRead(Signature[3], 8))
 459       return std::move(Err);
 460     if (Signature[2] == 'R' && Signature[3] == 'K')
 461       return LLVMBitstreamRemarks;
 462   } else {
 463     if (Error Err = tryRead(Signature[2], 4))
 464       return std::move(Err);
 465     if (Error Err = tryRead(Signature[3], 4))
 466       return std::move(Err);
 467     if (Error Err = tryRead(Signature[4], 4))
 468       return std::move(Err);
 469     if (Error Err = tryRead(Signature[5], 4))
 470       return std::move(Err);
 471     if (Signature[0] == 'B' && Signature[1] == 'C' && Signature[2] == 0x0 &&
 472         Signature[3] == 0xC && Signature[4] == 0xE && Signature[5] == 0xD)
 473       return LLVMIRBitstream;
 474   }
 475   return UnknownBitstream;
 476 }
 477
 478 static Expected<CurStreamTypeType> analyzeHeader(std::optional<BCDumpOptions> O,
 479                                                  BitstreamCursor &Stream) {
 480   ArrayRef<uint8_t> Bytes = Stream.getBitcodeBytes();
 481   const unsigned char *BufPtr = (const unsigned char *)Bytes.data();
 482   const unsigned char *EndBufPtr = BufPtr + Bytes.size();
 483
 484   // If we have a wrapper header, parse it and ignore the non-bc file
 485   // contents. The magic number is 0x0B17C0DE stored in little endian.
 486   if (isBitcodeWrapper(BufPtr, EndBufPtr)) {
 487     if (Bytes.size() < BWH_HeaderSize)
 488       return reportError("Invalid bitcode wrapper header");
 489
 490     if (O) {
 491       unsigned Magic = support::endian::read32le(&BufPtr[BWH_MagicField]);
 492       unsigned Version = support::endian::read32le(&BufPtr[BWH_VersionField]);
 493       unsigned Offset = support::endian::read32le(&BufPtr[BWH_OffsetField]);
 494       unsigned Size = support::endian::read32le(&BufPtr[BWH_SizeField]);
 495       unsigned CPUType = support::endian::read32le(&BufPtr[BWH_CPUTypeField]);
 496
 497       O->OS << "<BITCODE_WRAPPER_HEADER"
 498             << " Magic=" << format_hex(Magic, 10)
 499             << " Version=" << format_hex(Version, 10)
 500             << " Offset=" << format_hex(Offset, 10)
 501             << " Size=" << format_hex(Size, 10)
 502             << " CPUType=" << format_hex(CPUType, 10) << "/>\n";
 503     }
 504
 505     if (SkipBitcodeWrapperHeader(BufPtr, EndBufPtr, true))
 506       return reportError("Invalid bitcode wrapper header");
 507   }
 508
 509   // Use the cursor modified by skipping the wrapper header.
 510   Stream = BitstreamCursor(ArrayRef<uint8_t>(BufPtr, EndBufPtr));
 511
 512   return ReadSignature(Stream);
 513 }
 514
 515 static bool canDecodeBlob(unsigned Code, unsigned BlockID) {
 516   return BlockID == bitc::METADATA_BLOCK_ID && Code == bitc::METADATA_STRINGS;
 517 }
 518
 519 Error BitcodeAnalyzer::decodeMetadataStringsBlob(StringRef Indent,
 520                                                  ArrayRef<uint64_t> Record,
 521                                                  StringRef Blob,
 522                                                  raw_ostream &OS) {
 523   if (Blob.empty())
 524     return reportError("Cannot decode empty blob.");
 525
 526   if (Record.size() != 2)
 527     return reportError(
 528         "Decoding metadata strings blob needs two record entries.");
 529
 530   unsigned NumStrings = Record[0];
 531   unsigned StringsOffset = Record[1];
 532   OS << " num-strings = " << NumStrings << " {\n";
 533
 534   StringRef Lengths = Blob.slice(0, StringsOffset);
 535   SimpleBitstreamCursor R(Lengths);
 536   StringRef Strings = Blob.drop_front(StringsOffset);
 537   do {
 538     if (R.AtEndOfStream())
 539       return reportError("bad length");
 540
 541     uint32_t Size;
 542     if (Error E = R.ReadVBR(6).moveInto(Size))
 543       return E;
 544     if (Strings.size() < Size)
 545       return reportError("truncated chars");
 546
 547     OS << Indent << "    '";
 548     OS.write_escaped(Strings.slice(0, Size), /*hex=*/true);
 549     OS << "'\n";
 550     Strings = Strings.drop_front(Size);
 551   } while (--NumStrings);
 552
 553   OS << Indent << "  }";
 554   return Error::success();
 555 }
 556
 557 BitcodeAnalyzer::BitcodeAnalyzer(StringRef Buffer,
 558                                  std::optional<StringRef> BlockInfoBuffer)
 559     : Stream(Buffer) {
 560   if (BlockInfoBuffer)
 561     BlockInfoStream.emplace(*BlockInfoBuffer);
 562 }
 563
 564 Error BitcodeAnalyzer::analyze(std::optional<BCDumpOptions> O,
 565                                std::optional<StringRef> CheckHash) {
 566   if (Error E = analyzeHeader(O, Stream).moveInto(CurStreamType))
 567     return E;
 568
 569   Stream.setBlockInfo(&BlockInfo);
 570
 571   // Read block info from BlockInfoStream, if specified.
 572   // The block info must be a top-level block.
 573   if (BlockInfoStream) {
 574     BitstreamCursor BlockInfoCursor(*BlockInfoStream);
 575     if (Error E = analyzeHeader(O, BlockInfoCursor).takeError())
 576       return E;
 577
 578     while (!BlockInfoCursor.AtEndOfStream()) {
 579       Expected<unsigned> MaybeCode = BlockInfoCursor.ReadCode();
 580       if (!MaybeCode)
 581         return MaybeCode.takeError();
 582       if (MaybeCode.get() != bitc::ENTER_SUBBLOCK)
 583         return reportError("Invalid record at top-level in block info file");
 584
 585       Expected<unsigned> MaybeBlockID = BlockInfoCursor.ReadSubBlockID();
 586       if (!MaybeBlockID)
 587         return MaybeBlockID.takeError();
 588       if (MaybeBlockID.get() == bitc::BLOCKINFO_BLOCK_ID) {
 589         std::optional<BitstreamBlockInfo> NewBlockInfo;
 590         if (Error E =
 591                 BlockInfoCursor.ReadBlockInfoBlock(/*ReadBlockInfoNames=*/true)
 592                     .moveInto(NewBlockInfo))
 593           return E;
 594         if (!NewBlockInfo)
 595           return reportError("Malformed BlockInfoBlock in block info file");
 596         BlockInfo = std::move(*NewBlockInfo);
 597         break;
 598       }
 599
 600       if (Error Err = BlockInfoCursor.SkipBlock())
 601         return Err;
 602     }
 603   }
 604
 605   // Parse the top-level structure.  We only allow blocks at the top-level.
 606   while (!Stream.AtEndOfStream()) {
 607     Expected<unsigned> MaybeCode = Stream.ReadCode();
 608     if (!MaybeCode)
 609       return MaybeCode.takeError();
 610     if (MaybeCode.get() != bitc::ENTER_SUBBLOCK)
 611       return reportError("Invalid record at top-level");
 612
 613     Expected<unsigned> MaybeBlockID = Stream.ReadSubBlockID();
 614     if (!MaybeBlockID)
 615       return MaybeBlockID.takeError();
 616
 617     if (Error E = parseBlock(MaybeBlockID.get(), 0, O, CheckHash))
 618       return E;
 619     ++NumTopBlocks;
 620   }
 621
 622   return Error::success();
 623 }
 624
 625 void BitcodeAnalyzer::printStats(BCDumpOptions O,
 626                                  std::optional<StringRef> Filename) {
 627   uint64_t BufferSizeBits = Stream.getBitcodeBytes().size() * CHAR_BIT;
 628   // Print a summary of the read file.
 629   O.OS << "Summary ";
 630   if (Filename)
 631     O.OS << "of " << Filename->data() << ":\n";
 632   O.OS << "         Total size: ";
 633   printSize(O.OS, BufferSizeBits);
 634   O.OS << "\n";
 635   O.OS << "        Stream type: ";
 636   switch (CurStreamType) {
 637   case UnknownBitstream:
 638     O.OS << "unknown\n";
 639     break;
 640   case LLVMIRBitstream:
 641     O.OS << "LLVM IR\n";
 642     break;
 643   case ClangSerializedASTBitstream:
 644     O.OS << "Clang Serialized AST\n";
 645     break;
 646   case ClangSerializedDiagnosticsBitstream:
 647     O.OS << "Clang Serialized Diagnostics\n";
 648     break;
 649   case LLVMBitstreamRemarks:
 650     O.OS << "LLVM Remarks\n";
 651     break;
 652   }
 653   O.OS << "  # Toplevel Blocks: " << NumTopBlocks << "\n";
 654   O.OS << "\n";
 655
 656   // Emit per-block stats.
 657   O.OS << "Per-block Summary:\n";
 658   for (const auto &Stat : BlockIDStats) {
 659     O.OS << "  Block ID #" << Stat.first;
 660     if (std::optional<const char *> BlockName =
 661             GetBlockName(Stat.first, BlockInfo, CurStreamType))
 662       O.OS << " (" << *BlockName << ")";
 663     O.OS << ":\n";
 664
 665     const PerBlockIDStats &Stats = Stat.second;
 666     O.OS << "      Num Instances: " << Stats.NumInstances << "\n";
 667     O.OS << "         Total Size: ";
 668     printSize(O.OS, Stats.NumBits);
 669     O.OS << "\n";
 670     double pct = (Stats.NumBits * 100.0) / BufferSizeBits;
 671     O.OS << "    Percent of file: " << format("%2.4f%%", pct) << "\n";
 672     if (Stats.NumInstances > 1) {
 673       O.OS << "       Average Size: ";
 674       printSize(O.OS, Stats.NumBits / (double)Stats.NumInstances);
 675       O.OS << "\n";
 676       O.OS << "  Tot/Avg SubBlocks: " << Stats.NumSubBlocks << "/"
 677            << Stats.NumSubBlocks / (double)Stats.NumInstances << "\n";
 678       O.OS << "    Tot/Avg Abbrevs: " << Stats.NumAbbrevs << "/"
 679            << Stats.NumAbbrevs / (double)Stats.NumInstances << "\n";
 680       O.OS << "    Tot/Avg Records: " << Stats.NumRecords << "/"
 681            << Stats.NumRecords / (double)Stats.NumInstances << "\n";
 682     } else {
 683       O.OS << "      Num SubBlocks: " << Stats.NumSubBlocks << "\n";
 684       O.OS << "        Num Abbrevs: " << Stats.NumAbbrevs << "\n";
 685       O.OS << "        Num Records: " << Stats.NumRecords << "\n";
 686     }
 687     if (Stats.NumRecords) {
 688       double pct = (Stats.NumAbbreviatedRecords * 100.0) / Stats.NumRecords;
 689       O.OS << "    Percent Abbrevs: " << format("%2.4f%%", pct) << "\n";
 690     }
 691     O.OS << "\n";
 692
 693     // Print a histogram of the codes we see.
 694     if (O.Histogram && !Stats.CodeFreq.empty()) {
 695       std::vector<std::pair<unsigned, unsigned>> FreqPairs; // <freq,code>
 696       for (unsigned i = 0, e = Stats.CodeFreq.size(); i != e; ++i)
 697         if (unsigned Freq = Stats.CodeFreq[i].NumInstances)
 698           FreqPairs.push_back(std::make_pair(Freq, i));
 699       llvm::stable_sort(FreqPairs);
 700       std::reverse(FreqPairs.begin(), FreqPairs.end());
 701
 702       O.OS << "\tRecord Histogram:\n";
 703       O.OS << "\t\t  Count    # Bits     b/Rec   % Abv  Record Kind\n";
 704       for (const auto &FreqPair : FreqPairs) {
 705         const PerRecordStats &RecStats = Stats.CodeFreq[FreqPair.second];
 706
 707         O.OS << format("\t\t%7d %9lu", RecStats.NumInstances,
 708                        (unsigned long)RecStats.TotalBits);
 709
 710         if (RecStats.NumInstances > 1)
 711           O.OS << format(" %9.1f",
 712                          (double)RecStats.TotalBits / RecStats.NumInstances);
 713         else
 714           O.OS << "          ";
 715
 716         if (RecStats.NumAbbrev)
 717           O.OS << format(" %7.2f", (double)RecStats.NumAbbrev /
 718                                        RecStats.NumInstances * 100);
 719         else
 720           O.OS << "        ";
 721
 722         O.OS << "  ";
 723         if (std::optional<const char *> CodeName = GetCodeName(
 724                 FreqPair.second, Stat.first, BlockInfo, CurStreamType))
 725           O.OS << *CodeName << "\n";
 726         else
 727           O.OS << "UnknownCode" << FreqPair.second << "\n";
 728       }
 729       O.OS << "\n";
 730     }
 731   }
 732 }
 733
 734 Error BitcodeAnalyzer::parseBlock(unsigned BlockID, unsigned IndentLevel,
 735                                   std::optional<BCDumpOptions> O,
 736                                   std::optional<StringRef> CheckHash) {
 737   std::string Indent(IndentLevel * 2, ' ');
 738   uint64_t BlockBitStart = Stream.GetCurrentBitNo();
 739
 740   // Get the statistics for this BlockID.
 741   PerBlockIDStats &BlockStats = BlockIDStats[BlockID];
 742
 743   BlockStats.NumInstances++;
 744
 745   // BLOCKINFO is a special part of the stream.
 746   bool DumpRecords = O.has_value();
 747   if (BlockID == bitc::BLOCKINFO_BLOCK_ID) {
 748     if (O && !O->DumpBlockinfo)
 749       O->OS << Indent << "<BLOCKINFO_BLOCK/>\n";
 750     std::optional<BitstreamBlockInfo> NewBlockInfo;
 751     if (Error E = Stream.ReadBlockInfoBlock(/*ReadBlockInfoNames=*/true)
 752                       .moveInto(NewBlockInfo))
 753       return E;
 754     if (!NewBlockInfo)
 755       return reportError("Malformed BlockInfoBlock");
 756     BlockInfo = std::move(*NewBlockInfo);
 757     if (Error Err = Stream.JumpToBit(BlockBitStart))
 758       return Err;
 759     // It's not really interesting to dump the contents of the blockinfo
 760     // block, so only do it if the user explicitly requests it.
 761     DumpRecords = O && O->DumpBlockinfo;
 762   }
 763
 764   unsigned NumWords = 0;
 765   if (Error Err = Stream.EnterSubBlock(BlockID, &NumWords))
 766     return Err;
 767
 768   // Keep it for later, when we see a MODULE_HASH record
 769   uint64_t BlockEntryPos = Stream.getCurrentByteNo();
 770
 771   std::optional<const char *> BlockName;
 772   if (DumpRecords) {
 773     O->OS << Indent << "<";
 774     if ((BlockName = GetBlockName(BlockID, BlockInfo, CurStreamType)))
 775       O->OS << *BlockName;
 776     else
 777       O->OS << "UnknownBlock" << BlockID;
 778
 779     if (!O->Symbolic && BlockName)
 780       O->OS << " BlockID=" << BlockID;
 781
 782     O->OS << " NumWords=" << NumWords
 783           << " BlockCodeSize=" << Stream.getAbbrevIDWidth() << ">\n";
 784   }
 785
 786   SmallVector<uint64_t, 64> Record;
 787
 788   // Keep the offset to the metadata index if seen.
 789   uint64_t MetadataIndexOffset = 0;
 790
 791   // Read all the records for this block.
 792   while (true) {
 793     if (Stream.AtEndOfStream())
 794       return reportError("Premature end of bitstream");
 795
 796     uint64_t RecordStartBit = Stream.GetCurrentBitNo();
 797
 798     BitstreamEntry Entry;
 799     if (Error E = Stream.advance(BitstreamCursor::AF_DontAutoprocessAbbrevs)
 800                       .moveInto(Entry))
 801       return E;
 802
 803     switch (Entry.Kind) {
 804     case BitstreamEntry::Error:
 805       return reportError("malformed bitcode file");
 806     case BitstreamEntry::EndBlock: {
 807       uint64_t BlockBitEnd = Stream.GetCurrentBitNo();
 808       BlockStats.NumBits += BlockBitEnd - BlockBitStart;
 809       if (DumpRecords) {
 810         O->OS << Indent << "</";
 811         if (BlockName)
 812           O->OS << *BlockName << ">\n";
 813         else
 814           O->OS << "UnknownBlock" << BlockID << ">\n";
 815       }
 816       return Error::success();
 817     }
 818
 819     case BitstreamEntry::SubBlock: {
 820       uint64_t SubBlockBitStart = Stream.GetCurrentBitNo();
 821       if (Error E = parseBlock(Entry.ID, IndentLevel + 1, O, CheckHash))
 822         return E;
 823       ++BlockStats.NumSubBlocks;
 824       uint64_t SubBlockBitEnd = Stream.GetCurrentBitNo();
 825
 826       // Don't include subblock sizes in the size of this block.
 827       BlockBitStart += SubBlockBitEnd - SubBlockBitStart;
 828       continue;
 829     }
 830     case BitstreamEntry::Record:
 831       // The interesting case.
 832       break;
 833     }
 834
 835     if (Entry.ID == bitc::DEFINE_ABBREV) {
 836       if (Error Err = Stream.ReadAbbrevRecord())
 837         return Err;
 838       ++BlockStats.NumAbbrevs;
 839       continue;
 840     }
 841
 842     Record.clear();
 843
 844     ++BlockStats.NumRecords;
 845
 846     StringRef Blob;
 847     uint64_t CurrentRecordPos = Stream.GetCurrentBitNo();
 848     unsigned Code;
 849     if (Error E = Stream.readRecord(Entry.ID, Record, &Blob).moveInto(Code))
 850       return E;
 851
 852     // Increment the # occurrences of this code.
 853     if (BlockStats.CodeFreq.size() <= Code)
 854       BlockStats.CodeFreq.resize(Code + 1);
 855     BlockStats.CodeFreq[Code].NumInstances++;
 856     BlockStats.CodeFreq[Code].TotalBits +=
 857         Stream.GetCurrentBitNo() - RecordStartBit;
 858     if (Entry.ID != bitc::UNABBREV_RECORD) {
 859       BlockStats.CodeFreq[Code].NumAbbrev++;
 860       ++BlockStats.NumAbbreviatedRecords;
 861     }
 862
 863     if (DumpRecords) {
 864       O->OS << Indent << "  <";
 865       std::optional<const char *> CodeName =
 866           GetCodeName(Code, BlockID, BlockInfo, CurStreamType);
 867       if (CodeName)
 868         O->OS << *CodeName;
 869       else
 870         O->OS << "UnknownCode" << Code;
 871       if (!O->Symbolic && CodeName)
 872         O->OS << " codeid=" << Code;
 873       const BitCodeAbbrev *Abbv = nullptr;
 874       if (Entry.ID != bitc::UNABBREV_RECORD) {
 875         Expected<const BitCodeAbbrev *> MaybeAbbv = Stream.getAbbrev(Entry.ID);
 876         if (!MaybeAbbv)
 877           return MaybeAbbv.takeError();
 878         Abbv = MaybeAbbv.get();
 879         O->OS << " abbrevid=" << Entry.ID;
 880       }
 881
 882       for (unsigned i = 0, e = Record.size(); i != e; ++i)
 883         O->OS << " op" << i << "=" << (int64_t)Record[i];
 884
 885       // If we found a metadata index, let's verify that we had an offset
 886       // before and validate its forward reference offset was correct!
 887       if (BlockID == bitc::METADATA_BLOCK_ID) {
 888         if (Code == bitc::METADATA_INDEX_OFFSET) {
 889           if (Record.size() != 2)
 890             O->OS << "(Invalid record)";
 891           else {
 892             auto Offset = Record[0] + (Record[1] << 32);
 893             MetadataIndexOffset = Stream.GetCurrentBitNo() + Offset;
 894           }
 895         }
 896         if (Code == bitc::METADATA_INDEX) {
 897           O->OS << " (offset ";
 898           if (MetadataIndexOffset == RecordStartBit)
 899             O->OS << "match)";
 900           else
 901             O->OS << "mismatch: " << MetadataIndexOffset << " vs "
 902                   << RecordStartBit << ")";
 903         }
 904       }
 905
 906       // If we found a module hash, let's verify that it matches!
 907       if (BlockID == bitc::MODULE_BLOCK_ID && Code == bitc::MODULE_CODE_HASH &&
 908           CheckHash) {
 909         if (Record.size() != 5)
 910           O->OS << " (invalid)";
 911         else {
 912           // Recompute the hash and compare it to the one in the bitcode
 913           SHA1 Hasher;
 914           std::array<uint8_t, 20> Hash;
 915           Hasher.update(*CheckHash);
 916           {
 917             int BlockSize = (CurrentRecordPos / 8) - BlockEntryPos;
 918             auto Ptr = Stream.getPointerToByte(BlockEntryPos, BlockSize);
 919             Hasher.update(ArrayRef<uint8_t>(Ptr, BlockSize));
 920             Hash = Hasher.result();
 921           }
 922           std::array<uint8_t, 20> RecordedHash;
 923           int Pos = 0;
 924           for (auto &Val : Record) {
 925             assert(!(Val >> 32) && "Unexpected high bits set");
 926             support::endian::write32be(&RecordedHash[Pos], Val);
 927             Pos += 4;
 928           }
 929           if (Hash == RecordedHash)
 930             O->OS << " (match)";
 931           else
 932             O->OS << " (!mismatch!)";
 933         }
 934       }
 935
 936       O->OS << "/>";
 937
 938       if (Abbv) {
 939         for (unsigned i = 1, e = Abbv->getNumOperandInfos(); i != e; ++i) {
 940           const BitCodeAbbrevOp &Op = Abbv->getOperandInfo(i);
 941           if (!Op.isEncoding() || Op.getEncoding() != BitCodeAbbrevOp::Array)
 942             continue;
 943           assert(i + 2 == e && "Array op not second to last");
 944           std::string Str;
 945           bool ArrayIsPrintable = true;
 946           for (unsigned j = i - 1, je = Record.size(); j != je; ++j) {
 947             if (!isPrint(static_cast<unsigned char>(Record[j]))) {
 948               ArrayIsPrintable = false;
 949               break;
 950             }
 951             Str += (char)Record[j];
 952           }
 953           if (ArrayIsPrintable)
 954             O->OS << " record string = '" << Str << "'";
 955           break;
 956         }
 957       }
 958
 959       if (Blob.data()) {
 960         if (canDecodeBlob(Code, BlockID)) {
 961           if (Error E = decodeMetadataStringsBlob(Indent, Record, Blob, O->OS))
 962             return E;
 963         } else {
 964           O->OS << " blob data = ";
 965           if (O->ShowBinaryBlobs) {
 966             O->OS << "'";
 967             O->OS.write_escaped(Blob, /*hex=*/true) << "'";
 968           } else {
 969             bool BlobIsPrintable = true;
 970             for (char C : Blob)
 971               if (!isPrint(static_cast<unsigned char>(C))) {
 972                 BlobIsPrintable = false;
 973                 break;
 974               }
 975
 976             if (BlobIsPrintable)
 977               O->OS << "'" << Blob << "'";
 978             else
 979               O->OS << "unprintable, " << Blob.size() << " bytes.";
 980           }
 981         }
 982       }
 983
 984       O->OS << "\n";
 985     }
 986
 987     // Make sure that we can skip the current record.
 988     if (Error Err = Stream.JumpToBit(CurrentRecordPos))
 989       return Err;
 990     if (Expected<unsigned> Skipped = Stream.skipRecord(Entry.ID))
 991       ; // Do nothing.
 992     else
 993       return Skipped.takeError();
 994   }
 995 }
 996