LLVM  12.0.0git
BitstreamReader.h
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1 //===- BitstreamReader.h - Low-level bitstream reader interface -*- 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 // This header defines the BitstreamReader class. This class can be used to
10 // read an arbitrary bitstream, regardless of its contents.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #ifndef LLVM_BITSTREAM_BITSTREAMREADER_H
15 #define LLVM_BITSTREAM_BITSTREAMREADER_H
16 
17 #include "llvm/ADT/ArrayRef.h"
18 #include "llvm/ADT/SmallVector.h"
20 #include "llvm/Support/Endian.h"
21 #include "llvm/Support/Error.h"
25 #include <algorithm>
26 #include <cassert>
27 #include <climits>
28 #include <cstddef>
29 #include <cstdint>
30 #include <memory>
31 #include <string>
32 #include <utility>
33 #include <vector>
34 
35 namespace llvm {
36 
37 /// This class maintains the abbreviations read from a block info block.
39 public:
40  /// This contains information emitted to BLOCKINFO_BLOCK blocks. These
41  /// describe abbreviations that all blocks of the specified ID inherit.
42  struct BlockInfo {
43  unsigned BlockID = 0;
44  std::vector<std::shared_ptr<BitCodeAbbrev>> Abbrevs;
45  std::string Name;
46  std::vector<std::pair<unsigned, std::string>> RecordNames;
47  };
48 
49 private:
50  std::vector<BlockInfo> BlockInfoRecords;
51 
52 public:
53  /// If there is block info for the specified ID, return it, otherwise return
54  /// null.
55  const BlockInfo *getBlockInfo(unsigned BlockID) const {
56  // Common case, the most recent entry matches BlockID.
57  if (!BlockInfoRecords.empty() && BlockInfoRecords.back().BlockID == BlockID)
58  return &BlockInfoRecords.back();
59 
60  for (unsigned i = 0, e = static_cast<unsigned>(BlockInfoRecords.size());
61  i != e; ++i)
62  if (BlockInfoRecords[i].BlockID == BlockID)
63  return &BlockInfoRecords[i];
64  return nullptr;
65  }
66 
68  if (const BlockInfo *BI = getBlockInfo(BlockID))
69  return *const_cast<BlockInfo*>(BI);
70 
71  // Otherwise, add a new record.
72  BlockInfoRecords.emplace_back();
73  BlockInfoRecords.back().BlockID = BlockID;
74  return BlockInfoRecords.back();
75  }
76 };
77 
78 /// This represents a position within a bitstream. There may be multiple
79 /// independent cursors reading within one bitstream, each maintaining their
80 /// own local state.
82  ArrayRef<uint8_t> BitcodeBytes;
83  size_t NextChar = 0;
84 
85 public:
86  /// This is the current data we have pulled from the stream but have not
87  /// returned to the client. This is specifically and intentionally defined to
88  /// follow the word size of the host machine for efficiency. We use word_t in
89  /// places that are aware of this to make it perfectly explicit what is going
90  /// on.
91  using word_t = size_t;
92 
93 private:
94  word_t CurWord = 0;
95 
96  /// This is the number of bits in CurWord that are valid. This is always from
97  /// [0...bits_of(size_t)-1] inclusive.
98  unsigned BitsInCurWord = 0;
99 
100 public:
101  static const constexpr size_t MaxChunkSize = sizeof(word_t) * 8;
102 
103  SimpleBitstreamCursor() = default;
105  : BitcodeBytes(BitcodeBytes) {}
106  explicit SimpleBitstreamCursor(StringRef BitcodeBytes)
107  : BitcodeBytes(arrayRefFromStringRef(BitcodeBytes)) {}
108  explicit SimpleBitstreamCursor(MemoryBufferRef BitcodeBytes)
109  : SimpleBitstreamCursor(BitcodeBytes.getBuffer()) {}
110 
111  bool canSkipToPos(size_t pos) const {
112  // pos can be skipped to if it is a valid address or one byte past the end.
113  return pos <= BitcodeBytes.size();
114  }
115 
116  bool AtEndOfStream() {
117  return BitsInCurWord == 0 && BitcodeBytes.size() <= NextChar;
118  }
119 
120  /// Return the bit # of the bit we are reading.
121  uint64_t GetCurrentBitNo() const {
122  return NextChar*CHAR_BIT - BitsInCurWord;
123  }
124 
125  // Return the byte # of the current bit.
126  uint64_t getCurrentByteNo() const { return GetCurrentBitNo() / 8; }
127 
128  ArrayRef<uint8_t> getBitcodeBytes() const { return BitcodeBytes; }
129 
130  /// Reset the stream to the specified bit number.
131  Error JumpToBit(uint64_t BitNo) {
132  size_t ByteNo = size_t(BitNo/8) & ~(sizeof(word_t)-1);
133  unsigned WordBitNo = unsigned(BitNo & (sizeof(word_t)*8-1));
134  assert(canSkipToPos(ByteNo) && "Invalid location");
135 
136  // Move the cursor to the right word.
137  NextChar = ByteNo;
138  BitsInCurWord = 0;
139 
140  // Skip over any bits that are already consumed.
141  if (WordBitNo) {
142  if (Expected<word_t> Res = Read(WordBitNo))
143  return Error::success();
144  else
145  return Res.takeError();
146  }
147 
148  return Error::success();
149  }
150 
151  /// Get a pointer into the bitstream at the specified byte offset.
152  const uint8_t *getPointerToByte(uint64_t ByteNo, uint64_t NumBytes) {
153  return BitcodeBytes.data() + ByteNo;
154  }
155 
156  /// Get a pointer into the bitstream at the specified bit offset.
157  ///
158  /// The bit offset must be on a byte boundary.
159  const uint8_t *getPointerToBit(uint64_t BitNo, uint64_t NumBytes) {
160  assert(!(BitNo % 8) && "Expected bit on byte boundary");
161  return getPointerToByte(BitNo / 8, NumBytes);
162  }
163 
165  if (NextChar >= BitcodeBytes.size())
166  return createStringError(std::errc::io_error,
167  "Unexpected end of file reading %u of %u bytes",
168  NextChar, BitcodeBytes.size());
169 
170  // Read the next word from the stream.
171  const uint8_t *NextCharPtr = BitcodeBytes.data() + NextChar;
172  unsigned BytesRead;
173  if (BitcodeBytes.size() >= NextChar + sizeof(word_t)) {
174  BytesRead = sizeof(word_t);
175  CurWord =
176  support::endian::read<word_t, support::little, support::unaligned>(
177  NextCharPtr);
178  } else {
179  // Short read.
180  BytesRead = BitcodeBytes.size() - NextChar;
181  CurWord = 0;
182  for (unsigned B = 0; B != BytesRead; ++B)
183  CurWord |= uint64_t(NextCharPtr[B]) << (B * 8);
184  }
185  NextChar += BytesRead;
186  BitsInCurWord = BytesRead * 8;
187  return Error::success();
188  }
189 
190  Expected<word_t> Read(unsigned NumBits) {
191  static const unsigned BitsInWord = MaxChunkSize;
192 
193  assert(NumBits && NumBits <= BitsInWord &&
194  "Cannot return zero or more than BitsInWord bits!");
195 
196  static const unsigned Mask = sizeof(word_t) > 4 ? 0x3f : 0x1f;
197 
198  // If the field is fully contained by CurWord, return it quickly.
199  if (BitsInCurWord >= NumBits) {
200  word_t R = CurWord & (~word_t(0) >> (BitsInWord - NumBits));
201 
202  // Use a mask to avoid undefined behavior.
203  CurWord >>= (NumBits & Mask);
204 
205  BitsInCurWord -= NumBits;
206  return R;
207  }
208 
209  word_t R = BitsInCurWord ? CurWord : 0;
210  unsigned BitsLeft = NumBits - BitsInCurWord;
211 
212  if (Error fillResult = fillCurWord())
213  return std::move(fillResult);
214 
215  // If we run out of data, abort.
216  if (BitsLeft > BitsInCurWord)
217  return createStringError(std::errc::io_error,
218  "Unexpected end of file reading %u of %u bits",
219  BitsInCurWord, BitsLeft);
220 
221  word_t R2 = CurWord & (~word_t(0) >> (BitsInWord - BitsLeft));
222 
223  // Use a mask to avoid undefined behavior.
224  CurWord >>= (BitsLeft & Mask);
225 
226  BitsInCurWord -= BitsLeft;
227 
228  R |= R2 << (NumBits - BitsLeft);
229 
230  return R;
231  }
232 
233  Expected<uint32_t> ReadVBR(unsigned NumBits) {
234  Expected<unsigned> MaybeRead = Read(NumBits);
235  if (!MaybeRead)
236  return MaybeRead;
237  uint32_t Piece = MaybeRead.get();
238 
239  if ((Piece & (1U << (NumBits-1))) == 0)
240  return Piece;
241 
242  uint32_t Result = 0;
243  unsigned NextBit = 0;
244  while (true) {
245  Result |= (Piece & ((1U << (NumBits-1))-1)) << NextBit;
246 
247  if ((Piece & (1U << (NumBits-1))) == 0)
248  return Result;
249 
250  NextBit += NumBits-1;
251  MaybeRead = Read(NumBits);
252  if (!MaybeRead)
253  return MaybeRead;
254  Piece = MaybeRead.get();
255  }
256  }
257 
258  // Read a VBR that may have a value up to 64-bits in size. The chunk size of
259  // the VBR must still be <= 32 bits though.
260  Expected<uint64_t> ReadVBR64(unsigned NumBits) {
261  Expected<uint64_t> MaybeRead = Read(NumBits);
262  if (!MaybeRead)
263  return MaybeRead;
264  uint32_t Piece = MaybeRead.get();
265 
266  if ((Piece & (1U << (NumBits-1))) == 0)
267  return uint64_t(Piece);
268 
269  uint64_t Result = 0;
270  unsigned NextBit = 0;
271  while (true) {
272  Result |= uint64_t(Piece & ((1U << (NumBits-1))-1)) << NextBit;
273 
274  if ((Piece & (1U << (NumBits-1))) == 0)
275  return Result;
276 
277  NextBit += NumBits-1;
278  MaybeRead = Read(NumBits);
279  if (!MaybeRead)
280  return MaybeRead;
281  Piece = MaybeRead.get();
282  }
283  }
284 
286  // If word_t is 64-bits and if we've read less than 32 bits, just dump
287  // the bits we have up to the next 32-bit boundary.
288  if (sizeof(word_t) > 4 &&
289  BitsInCurWord >= 32) {
290  CurWord >>= BitsInCurWord-32;
291  BitsInCurWord = 32;
292  return;
293  }
294 
295  BitsInCurWord = 0;
296  }
297 
298  /// Return the size of the stream in bytes.
299  size_t SizeInBytes() const { return BitcodeBytes.size(); }
300 
301  /// Skip to the end of the file.
302  void skipToEnd() { NextChar = BitcodeBytes.size(); }
303 };
304 
305 /// When advancing through a bitstream cursor, each advance can discover a few
306 /// different kinds of entries:
308  enum {
309  Error, // Malformed bitcode was found.
310  EndBlock, // We've reached the end of the current block, (or the end of the
311  // file, which is treated like a series of EndBlock records.
312  SubBlock, // This is the start of a new subblock of a specific ID.
313  Record // This is a record with a specific AbbrevID.
314  } Kind;
315 
316  unsigned ID;
317 
319  BitstreamEntry E; E.Kind = Error; return E;
320  }
321 
323  BitstreamEntry E; E.Kind = EndBlock; return E;
324  }
325 
326  static BitstreamEntry getSubBlock(unsigned ID) {
327  BitstreamEntry E; E.Kind = SubBlock; E.ID = ID; return E;
328  }
329 
330  static BitstreamEntry getRecord(unsigned AbbrevID) {
331  BitstreamEntry E; E.Kind = Record; E.ID = AbbrevID; return E;
332  }
333 };
334 
335 /// This represents a position within a bitcode file, implemented on top of a
336 /// SimpleBitstreamCursor.
337 ///
338 /// Unlike iterators, BitstreamCursors are heavy-weight objects that should not
339 /// be passed by value.
341  // This is the declared size of code values used for the current block, in
342  // bits.
343  unsigned CurCodeSize = 2;
344 
345  /// Abbrevs installed at in this block.
346  std::vector<std::shared_ptr<BitCodeAbbrev>> CurAbbrevs;
347 
348  struct Block {
349  unsigned PrevCodeSize;
350  std::vector<std::shared_ptr<BitCodeAbbrev>> PrevAbbrevs;
351 
352  explicit Block(unsigned PCS) : PrevCodeSize(PCS) {}
353  };
354 
355  /// This tracks the codesize of parent blocks.
356  SmallVector<Block, 8> BlockScope;
357 
358  BitstreamBlockInfo *BlockInfo = nullptr;
359 
360 public:
361  static const size_t MaxChunkSize = sizeof(word_t) * 8;
362 
363  BitstreamCursor() = default;
364  explicit BitstreamCursor(ArrayRef<uint8_t> BitcodeBytes)
365  : SimpleBitstreamCursor(BitcodeBytes) {}
366  explicit BitstreamCursor(StringRef BitcodeBytes)
367  : SimpleBitstreamCursor(BitcodeBytes) {}
368  explicit BitstreamCursor(MemoryBufferRef BitcodeBytes)
369  : SimpleBitstreamCursor(BitcodeBytes) {}
370 
384 
385  /// Return the number of bits used to encode an abbrev #.
386  unsigned getAbbrevIDWidth() const { return CurCodeSize; }
387 
388  /// Flags that modify the behavior of advance().
389  enum {
390  /// If this flag is used, the advance() method does not automatically pop
391  /// the block scope when the end of a block is reached.
392  AF_DontPopBlockAtEnd = 1,
393 
394  /// If this flag is used, abbrev entries are returned just like normal
395  /// records.
396  AF_DontAutoprocessAbbrevs = 2
397  };
398 
399  /// Advance the current bitstream, returning the next entry in the stream.
400  Expected<BitstreamEntry> advance(unsigned Flags = 0) {
401  while (true) {
402  if (AtEndOfStream())
403  return BitstreamEntry::getError();
404 
405  Expected<unsigned> MaybeCode = ReadCode();
406  if (!MaybeCode)
407  return MaybeCode.takeError();
408  unsigned Code = MaybeCode.get();
409 
410  if (Code == bitc::END_BLOCK) {
411  // Pop the end of the block unless Flags tells us not to.
412  if (!(Flags & AF_DontPopBlockAtEnd) && ReadBlockEnd())
413  return BitstreamEntry::getError();
415  }
416 
417  if (Code == bitc::ENTER_SUBBLOCK) {
418  if (Expected<unsigned> MaybeSubBlock = ReadSubBlockID())
419  return BitstreamEntry::getSubBlock(MaybeSubBlock.get());
420  else
421  return MaybeSubBlock.takeError();
422  }
423 
424  if (Code == bitc::DEFINE_ABBREV &&
425  !(Flags & AF_DontAutoprocessAbbrevs)) {
426  // We read and accumulate abbrev's, the client can't do anything with
427  // them anyway.
428  if (Error Err = ReadAbbrevRecord())
429  return std::move(Err);
430  continue;
431  }
432 
433  return BitstreamEntry::getRecord(Code);
434  }
435  }
436 
437  /// This is a convenience function for clients that don't expect any
438  /// subblocks. This just skips over them automatically.
440  while (true) {
441  // If we found a normal entry, return it.
442  Expected<BitstreamEntry> MaybeEntry = advance(Flags);
443  if (!MaybeEntry)
444  return MaybeEntry;
445  BitstreamEntry Entry = MaybeEntry.get();
446 
447  if (Entry.Kind != BitstreamEntry::SubBlock)
448  return Entry;
449 
450  // If we found a sub-block, just skip over it and check the next entry.
451  if (Error Err = SkipBlock())
452  return std::move(Err);
453  }
454  }
455 
456  Expected<unsigned> ReadCode() { return Read(CurCodeSize); }
457 
458  // Block header:
459  // [ENTER_SUBBLOCK, blockid, newcodelen, <align4bytes>, blocklen]
460 
461  /// Having read the ENTER_SUBBLOCK code, read the BlockID for the block.
463 
464  /// Having read the ENTER_SUBBLOCK abbrevid and a BlockID, skip over the body
465  /// of this block.
467  // Read and ignore the codelen value.
468  if (Expected<uint32_t> Res = ReadVBR(bitc::CodeLenWidth))
469  ; // Since we are skipping this block, we don't care what code widths are
470  // used inside of it.
471  else
472  return Res.takeError();
473 
474  SkipToFourByteBoundary();
475  Expected<unsigned> MaybeNum = Read(bitc::BlockSizeWidth);
476  if (!MaybeNum)
477  return MaybeNum.takeError();
478  size_t NumFourBytes = MaybeNum.get();
479 
480  // Check that the block wasn't partially defined, and that the offset isn't
481  // bogus.
482  size_t SkipTo = GetCurrentBitNo() + NumFourBytes * 4 * 8;
483  if (AtEndOfStream())
484  return createStringError(std::errc::illegal_byte_sequence,
485  "can't skip block: already at end of stream");
486  if (!canSkipToPos(SkipTo / 8))
487  return createStringError(std::errc::illegal_byte_sequence,
488  "can't skip to bit %zu from %" PRIu64, SkipTo,
489  GetCurrentBitNo());
490 
491  if (Error Res = JumpToBit(SkipTo))
492  return Res;
493 
494  return Error::success();
495  }
496 
497  /// Having read the ENTER_SUBBLOCK abbrevid, and enter the block.
498  Error EnterSubBlock(unsigned BlockID, unsigned *NumWordsP = nullptr);
499 
500  bool ReadBlockEnd() {
501  if (BlockScope.empty()) return true;
502 
503  // Block tail:
504  // [END_BLOCK, <align4bytes>]
505  SkipToFourByteBoundary();
506 
507  popBlockScope();
508  return false;
509  }
510 
511 private:
512  void popBlockScope() {
513  CurCodeSize = BlockScope.back().PrevCodeSize;
514 
515  CurAbbrevs = std::move(BlockScope.back().PrevAbbrevs);
516  BlockScope.pop_back();
517  }
518 
519  //===--------------------------------------------------------------------===//
520  // Record Processing
521  //===--------------------------------------------------------------------===//
522 
523 public:
524  /// Return the abbreviation for the specified AbbrevId.
525  const BitCodeAbbrev *getAbbrev(unsigned AbbrevID) {
526  unsigned AbbrevNo = AbbrevID - bitc::FIRST_APPLICATION_ABBREV;
527  if (AbbrevNo >= CurAbbrevs.size())
528  report_fatal_error("Invalid abbrev number");
529  return CurAbbrevs[AbbrevNo].get();
530  }
531 
532  /// Read the current record and discard it, returning the code for the record.
533  Expected<unsigned> skipRecord(unsigned AbbrevID);
534 
535  Expected<unsigned> readRecord(unsigned AbbrevID,
537  StringRef *Blob = nullptr);
538 
539  //===--------------------------------------------------------------------===//
540  // Abbrev Processing
541  //===--------------------------------------------------------------------===//
542  Error ReadAbbrevRecord();
543 
544  /// Read and return a block info block from the bitstream. If an error was
545  /// encountered, return None.
546  ///
547  /// \param ReadBlockInfoNames Whether to read block/record name information in
548  /// the BlockInfo block. Only llvm-bcanalyzer uses this.
550  ReadBlockInfoBlock(bool ReadBlockInfoNames = false);
551 
552  /// Set the block info to be used by this BitstreamCursor to interpret
553  /// abbreviated records.
554  void setBlockInfo(BitstreamBlockInfo *BI) { BlockInfo = BI; }
555 };
556 
557 } // end llvm namespace
558 
559 #endif // LLVM_BITSTREAM_BITSTREAMREADER_H
This contains information emitted to BLOCKINFO_BLOCK blocks.
const BitCodeAbbrev * getAbbrev(unsigned AbbrevID)
Return the abbreviation for the specified AbbrevId.
BlockInfo & getOrCreateBlockInfo(unsigned BlockID)
LLVM_ATTRIBUTE_NORETURN void report_fatal_error(Error Err, bool gen_crash_diag=true)
Report a serious error, calling any installed error handler.
Definition: Error.cpp:140
This class represents lattice values for constants.
Definition: AllocatorList.h:23
uint64_t GetCurrentBitNo() const
Return the bit # of the bit we are reading.
LLVM_NODISCARD bool empty() const
Definition: SmallVector.h:75
const uint8_t * getPointerToByte(uint64_t ByteNo, uint64_t NumBytes)
Get a pointer into the bitstream at the specified byte offset.
BitCodeAbbrev - This class represents an abbreviation record.
Definition: BitCodes.h:167
const uint8_t * getPointerToBit(uint64_t BitNo, uint64_t NumBytes)
Get a pointer into the bitstream at the specified bit offset.
Expected< uint32_t > ReadVBR(unsigned NumBits)
ArrayRef< uint8_t > arrayRefFromStringRef(StringRef Input)
Construct a string ref from an array ref of unsigned chars.
Definition: StringExtras.h:60
BitstreamCursor(MemoryBufferRef BitcodeBytes)
#define R2(n)
Error takeError()
Take ownership of the stored error.
Definition: Error.h:557
SimpleBitstreamCursor(ArrayRef< uint8_t > BitcodeBytes)
std::vector< std::pair< unsigned, std::string > > RecordNames
void setBlockInfo(BitstreamBlockInfo *BI)
Set the block info to be used by this BitstreamCursor to interpret abbreviated records.
bool canSkipToPos(size_t pos) const
Expected< BitstreamEntry > advance(unsigned Flags=0)
Advance the current bitstream, returning the next entry in the stream.
This class consists of common code factored out of the SmallVector class to reduce code duplication b...
Definition: APFloat.h:43
enum llvm::BitstreamEntry::@162 Kind
Error SkipBlock()
Having read the ENTER_SUBBLOCK abbrevid and a BlockID, skip over the body of this block...
Tagged union holding either a T or a Error.
Definition: APFloat.h:42
std::underlying_type_t< E > Mask()
Get a bitmask with 1s in all places up to the high-order bit of E&#39;s largest value.
Definition: BitmaskEnum.h:80
void skipToEnd()
Skip to the end of the file.
Expected< unsigned > ReadCode()
static BitstreamEntry getSubBlock(unsigned ID)
ArrayRef< uint8_t > getBitcodeBytes() const
size_t SizeInBytes() const
Return the size of the stream in bytes.
static GCRegistry::Add< OcamlGC > B("ocaml", "ocaml 3.10-compatible GC")
uint64_t getCurrentByteNo() const
size_t size() const
size - Get the array size.
Definition: ArrayRef.h:156
static GCRegistry::Add< CoreCLRGC > E("coreclr", "CoreCLR-compatible GC")
This represents a position within a bitcode file, implemented on top of a SimpleBitstreamCursor.
Expected< uint64_t > ReadVBR64(unsigned NumBits)
constexpr double e
Definition: MathExtras.h:58
const BlockInfo * getBlockInfo(unsigned BlockID) const
If there is block info for the specified ID, return it, otherwise return null.
unsigned getAbbrevIDWidth() const
Return the number of bits used to encode an abbrev #.
Expected< unsigned > ReadSubBlockID()
Having read the ENTER_SUBBLOCK code, read the BlockID for the block.
const T * data() const
Definition: ArrayRef.h:153
std::vector< std::shared_ptr< BitCodeAbbrev > > Abbrevs
Error JumpToBit(uint64_t BitNo)
Reset the stream to the specified bit number.
SimpleBitstreamCursor(MemoryBufferRef BitcodeBytes)
static ErrorSuccess success()
Create a success value.
Definition: Error.h:332
When advancing through a bitstream cursor, each advance can discover a few different kinds of entries...
BitstreamCursor(ArrayRef< uint8_t > BitcodeBytes)
This class maintains the abbreviations read from a block info block.
reference get()
Returns a reference to the stored T value.
Definition: Error.h:537
DEFINE_ABBREV - Defines an abbrev for the current block.
Definition: BitCodes.h:54
static BitstreamEntry getEndBlock()
static BitstreamEntry getRecord(unsigned AbbrevID)
Expected< BitstreamEntry > advanceSkippingSubblocks(unsigned Flags=0)
This is a convenience function for clients that don&#39;t expect any subblocks.
SimpleBitstreamCursor(StringRef BitcodeBytes)
static BitstreamEntry getError()
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
Lightweight error class with error context and mandatory checking.
Definition: Error.h:157
OutputIt move(R &&Range, OutputIt Out)
Provide wrappers to std::move which take ranges instead of having to pass begin/end explicitly...
Definition: STLExtras.h:1556
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:57
This represents a position within a bitstream.
Expected< word_t > Read(unsigned NumBits)
Error createStringError(std::error_code EC, char const *Fmt, const Ts &... Vals)
Create formatted StringError object.
Definition: Error.h:1202
BitstreamCursor(StringRef BitcodeBytes)