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diff --git a/contrib/llvm/include/llvm/Bitcode/BitstreamReader.h b/contrib/llvm/include/llvm/Bitcode/BitstreamReader.h
new file mode 100644
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--- /dev/null
+++ b/contrib/llvm/include/llvm/Bitcode/BitstreamReader.h
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+//===- BitstreamReader.h - Low-level bitstream reader interface -*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This header defines the BitstreamReader class.  This class can be used to
+// read an arbitrary bitstream, regardless of its contents.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_BITCODE_BITSTREAMREADER_H
+#define LLVM_BITCODE_BITSTREAMREADER_H
+
+#include "llvm/Bitcode/BitCodes.h"
+#include "llvm/Support/Endian.h"
+#include "llvm/Support/StreamingMemoryObject.h"
+#include <climits>
+#include <string>
+#include <vector>
+
+namespace llvm {
+
+/// This class is used to read from an LLVM bitcode stream, maintaining
+/// information that is global to decoding the entire file. While a file is
+/// being read, multiple cursors can be independently advanced or skipped around
+/// within the file.  These are represented by the BitstreamCursor class.
+class BitstreamReader {
+public:
+  /// This contains information emitted to BLOCKINFO_BLOCK blocks. These
+  /// describe abbreviations that all blocks of the specified ID inherit.
+  struct BlockInfo {
+    unsigned BlockID;
+    std::vector<IntrusiveRefCntPtr<BitCodeAbbrev>> Abbrevs;
+    std::string Name;
+
+    std::vector<std::pair<unsigned, std::string> > RecordNames;
+  };
+private:
+  std::unique_ptr<MemoryObject> BitcodeBytes;
+
+  std::vector<BlockInfo> BlockInfoRecords;
+
+  /// This is set to true if we don't care about the block/record name
+  /// information in the BlockInfo block. Only llvm-bcanalyzer uses this.
+  bool IgnoreBlockInfoNames;
+
+  BitstreamReader(const BitstreamReader&) = delete;
+  void operator=(const BitstreamReader&) = delete;
+public:
+  BitstreamReader() : IgnoreBlockInfoNames(true) {
+  }
+
+  BitstreamReader(const unsigned char *Start, const unsigned char *End)
+      : IgnoreBlockInfoNames(true) {
+    init(Start, End);
+  }
+
+  BitstreamReader(std::unique_ptr<MemoryObject> BitcodeBytes)
+      : BitcodeBytes(std::move(BitcodeBytes)), IgnoreBlockInfoNames(true) {}
+
+  BitstreamReader(BitstreamReader &&Other) {
+    *this = std::move(Other);
+  }
+
+  BitstreamReader &operator=(BitstreamReader &&Other) {
+    BitcodeBytes = std::move(Other.BitcodeBytes);
+    // Explicitly swap block info, so that nothing gets destroyed twice.
+    std::swap(BlockInfoRecords, Other.BlockInfoRecords);
+    IgnoreBlockInfoNames = Other.IgnoreBlockInfoNames;
+    return *this;
+  }
+
+  void init(const unsigned char *Start, const unsigned char *End) {
+    assert(((End-Start) & 3) == 0 &&"Bitcode stream not a multiple of 4 bytes");
+    BitcodeBytes.reset(getNonStreamedMemoryObject(Start, End));
+  }
+
+  MemoryObject &getBitcodeBytes() { return *BitcodeBytes; }
+
+  /// This is called by clients that want block/record name information.
+  void CollectBlockInfoNames() { IgnoreBlockInfoNames = false; }
+  bool isIgnoringBlockInfoNames() { return IgnoreBlockInfoNames; }
+
+  //===--------------------------------------------------------------------===//
+  // Block Manipulation
+  //===--------------------------------------------------------------------===//
+
+  /// Return true if we've already read and processed the block info block for
+  /// this Bitstream. We only process it for the first cursor that walks over
+  /// it.
+  bool hasBlockInfoRecords() const { return !BlockInfoRecords.empty(); }
+
+  /// If there is block info for the specified ID, return it, otherwise return
+  /// null.
+  const BlockInfo *getBlockInfo(unsigned BlockID) const {
+    // Common case, the most recent entry matches BlockID.
+    if (!BlockInfoRecords.empty() && BlockInfoRecords.back().BlockID == BlockID)
+      return &BlockInfoRecords.back();
+
+    for (unsigned i = 0, e = static_cast<unsigned>(BlockInfoRecords.size());
+         i != e; ++i)
+      if (BlockInfoRecords[i].BlockID == BlockID)
+        return &BlockInfoRecords[i];
+    return nullptr;
+  }
+
+  BlockInfo &getOrCreateBlockInfo(unsigned BlockID) {
+    if (const BlockInfo *BI = getBlockInfo(BlockID))
+      return *const_cast<BlockInfo*>(BI);
+
+    // Otherwise, add a new record.
+    BlockInfoRecords.emplace_back();
+    BlockInfoRecords.back().BlockID = BlockID;
+    return BlockInfoRecords.back();
+  }
+
+  /// Takes block info from the other bitstream reader.
+  ///
+  /// This is a "take" operation because BlockInfo records are non-trivial, and
+  /// indeed rather expensive.
+  void takeBlockInfo(BitstreamReader &&Other) {
+    assert(!hasBlockInfoRecords());
+    BlockInfoRecords = std::move(Other.BlockInfoRecords);
+  }
+};
+
+/// When advancing through a bitstream cursor, each advance can discover a few
+/// different kinds of entries:
+struct BitstreamEntry {
+  enum {
+    Error,    // Malformed bitcode was found.
+    EndBlock, // We've reached the end of the current block, (or the end of the
+              // file, which is treated like a series of EndBlock records.
+    SubBlock, // This is the start of a new subblock of a specific ID.
+    Record    // This is a record with a specific AbbrevID.
+  } Kind;
+
+  unsigned ID;
+
+  static BitstreamEntry getError() {
+    BitstreamEntry E; E.Kind = Error; return E;
+  }
+  static BitstreamEntry getEndBlock() {
+    BitstreamEntry E; E.Kind = EndBlock; return E;
+  }
+  static BitstreamEntry getSubBlock(unsigned ID) {
+    BitstreamEntry E; E.Kind = SubBlock; E.ID = ID; return E;
+  }
+  static BitstreamEntry getRecord(unsigned AbbrevID) {
+    BitstreamEntry E; E.Kind = Record; E.ID = AbbrevID; return E;
+  }
+};
+
+/// This represents a position within a bitcode file. There may be multiple
+/// independent cursors reading within one bitstream, each maintaining their own
+/// local state.
+///
+/// Unlike iterators, BitstreamCursors are heavy-weight objects that should not
+/// be passed by value.
+class BitstreamCursor {
+  BitstreamReader *BitStream;
+  size_t NextChar;
+
+  // The size of the bicode. 0 if we don't know it yet.
+  size_t Size;
+
+  /// This is the current data we have pulled from the stream but have not
+  /// returned to the client. This is specifically and intentionally defined to
+  /// follow the word size of the host machine for efficiency. We use word_t in
+  /// places that are aware of this to make it perfectly explicit what is going
+  /// on.
+  typedef size_t word_t;
+  word_t CurWord;
+
+  /// This is the number of bits in CurWord that are valid. This is always from
+  /// [0...bits_of(size_t)-1] inclusive.
+  unsigned BitsInCurWord;
+
+  // This is the declared size of code values used for the current block, in
+  // bits.
+  unsigned CurCodeSize;
+
+  /// Abbrevs installed at in this block.
+  std::vector<IntrusiveRefCntPtr<BitCodeAbbrev>> CurAbbrevs;
+
+  struct Block {
+    unsigned PrevCodeSize;
+    std::vector<IntrusiveRefCntPtr<BitCodeAbbrev>> PrevAbbrevs;
+    explicit Block(unsigned PCS) : PrevCodeSize(PCS) {}
+  };
+
+  /// This tracks the codesize of parent blocks.
+  SmallVector<Block, 8> BlockScope;
+
+
+public:
+  static const size_t MaxChunkSize = sizeof(word_t) * 8;
+
+  BitstreamCursor() { init(nullptr); }
+
+  explicit BitstreamCursor(BitstreamReader &R) { init(&R); }
+
+  void init(BitstreamReader *R) {
+    freeState();
+
+    BitStream = R;
+    NextChar = 0;
+    Size = 0;
+    BitsInCurWord = 0;
+    CurCodeSize = 2;
+  }
+
+  void freeState();
+
+  bool canSkipToPos(size_t pos) const {
+    // pos can be skipped to if it is a valid address or one byte past the end.
+    return pos == 0 || BitStream->getBitcodeBytes().isValidAddress(
+        static_cast<uint64_t>(pos - 1));
+  }
+
+  bool AtEndOfStream() {
+    if (BitsInCurWord != 0)
+      return false;
+    if (Size != 0)
+      return Size == NextChar;
+    fillCurWord();
+    return BitsInCurWord == 0;
+  }
+
+  /// Return the number of bits used to encode an abbrev #.
+  unsigned getAbbrevIDWidth() const { return CurCodeSize; }
+
+  /// Return the bit # of the bit we are reading.
+  uint64_t GetCurrentBitNo() const {
+    return NextChar*CHAR_BIT - BitsInCurWord;
+  }
+
+  BitstreamReader *getBitStreamReader() {
+    return BitStream;
+  }
+  const BitstreamReader *getBitStreamReader() const {
+    return BitStream;
+  }
+
+  /// Flags that modify the behavior of advance().
+  enum {
+    /// If this flag is used, the advance() method does not automatically pop
+    /// the block scope when the end of a block is reached.
+    AF_DontPopBlockAtEnd = 1,
+
+    /// If this flag is used, abbrev entries are returned just like normal
+    /// records.
+    AF_DontAutoprocessAbbrevs = 2
+  };
+
+  /// Advance the current bitstream, returning the next entry in the stream.
+  BitstreamEntry advance(unsigned Flags = 0) {
+    while (1) {
+      unsigned Code = ReadCode();
+      if (Code == bitc::END_BLOCK) {
+        // Pop the end of the block unless Flags tells us not to.
+        if (!(Flags & AF_DontPopBlockAtEnd) && ReadBlockEnd())
+          return BitstreamEntry::getError();
+        return BitstreamEntry::getEndBlock();
+      }
+
+      if (Code == bitc::ENTER_SUBBLOCK)
+        return BitstreamEntry::getSubBlock(ReadSubBlockID());
+
+      if (Code == bitc::DEFINE_ABBREV &&
+          !(Flags & AF_DontAutoprocessAbbrevs)) {
+        // We read and accumulate abbrev's, the client can't do anything with
+        // them anyway.
+        ReadAbbrevRecord();
+        continue;
+      }
+
+      return BitstreamEntry::getRecord(Code);
+    }
+  }
+
+  /// This is a convenience function for clients that don't expect any
+  /// subblocks. This just skips over them automatically.
+  BitstreamEntry advanceSkippingSubblocks(unsigned Flags = 0) {
+    while (1) {
+      // If we found a normal entry, return it.
+      BitstreamEntry Entry = advance(Flags);
+      if (Entry.Kind != BitstreamEntry::SubBlock)
+        return Entry;
+
+      // If we found a sub-block, just skip over it and check the next entry.
+      if (SkipBlock())
+        return BitstreamEntry::getError();
+    }
+  }
+
+  /// Reset the stream to the specified bit number.
+  void JumpToBit(uint64_t BitNo) {
+    size_t ByteNo = size_t(BitNo/8) & ~(sizeof(word_t)-1);
+    unsigned WordBitNo = unsigned(BitNo & (sizeof(word_t)*8-1));
+    assert(canSkipToPos(ByteNo) && "Invalid location");
+
+    // Move the cursor to the right word.
+    NextChar = ByteNo;
+    BitsInCurWord = 0;
+
+    // Skip over any bits that are already consumed.
+    if (WordBitNo)
+      Read(WordBitNo);
+  }
+
+  void fillCurWord() {
+    if (Size != 0 && NextChar >= Size)
+      report_fatal_error("Unexpected end of file");
+
+    // Read the next word from the stream.
+    uint8_t Array[sizeof(word_t)] = {0};
+
+    uint64_t BytesRead =
+        BitStream->getBitcodeBytes().readBytes(Array, sizeof(Array), NextChar);
+
+    // If we run out of data, stop at the end of the stream.
+    if (BytesRead == 0) {
+      Size = NextChar;
+      return;
+    }
+
+    CurWord =
+        support::endian::read<word_t, support::little, support::unaligned>(
+            Array);
+    NextChar += BytesRead;
+    BitsInCurWord = BytesRead * 8;
+  }
+
+  word_t Read(unsigned NumBits) {
+    static const unsigned BitsInWord = MaxChunkSize;
+
+    assert(NumBits && NumBits <= BitsInWord &&
+           "Cannot return zero or more than BitsInWord bits!");
+
+    static const unsigned Mask = sizeof(word_t) > 4 ? 0x3f : 0x1f;
+
+    // If the field is fully contained by CurWord, return it quickly.
+    if (BitsInCurWord >= NumBits) {
+      word_t R = CurWord & (~word_t(0) >> (BitsInWord - NumBits));
+
+      // Use a mask to avoid undefined behavior.
+      CurWord >>= (NumBits & Mask);
+
+      BitsInCurWord -= NumBits;
+      return R;
+    }
+
+    word_t R = BitsInCurWord ? CurWord : 0;
+    unsigned BitsLeft = NumBits - BitsInCurWord;
+
+    fillCurWord();
+
+    // If we run out of data, stop at the end of the stream.
+    if (BitsLeft > BitsInCurWord)
+      return 0;
+
+    word_t R2 = CurWord & (~word_t(0) >> (BitsInWord - BitsLeft));
+
+    // Use a mask to avoid undefined behavior.
+    CurWord >>= (BitsLeft & Mask);
+
+    BitsInCurWord -= BitsLeft;
+
+    R |= R2 << (NumBits - BitsLeft);
+
+    return R;
+  }
+
+  uint32_t ReadVBR(unsigned NumBits) {
+    uint32_t Piece = Read(NumBits);
+    if ((Piece & (1U << (NumBits-1))) == 0)
+      return Piece;
+
+    uint32_t Result = 0;
+    unsigned NextBit = 0;
+    while (1) {
+      Result |= (Piece & ((1U << (NumBits-1))-1)) << NextBit;
+
+      if ((Piece & (1U << (NumBits-1))) == 0)
+        return Result;
+
+      NextBit += NumBits-1;
+      Piece = Read(NumBits);
+    }
+  }
+
+  // Read a VBR that may have a value up to 64-bits in size. The chunk size of
+  // the VBR must still be <= 32 bits though.
+  uint64_t ReadVBR64(unsigned NumBits) {
+    uint32_t Piece = Read(NumBits);
+    if ((Piece & (1U << (NumBits-1))) == 0)
+      return uint64_t(Piece);
+
+    uint64_t Result = 0;
+    unsigned NextBit = 0;
+    while (1) {
+      Result |= uint64_t(Piece & ((1U << (NumBits-1))-1)) << NextBit;
+
+      if ((Piece & (1U << (NumBits-1))) == 0)
+        return Result;
+
+      NextBit += NumBits-1;
+      Piece = Read(NumBits);
+    }
+  }
+
+private:
+  void SkipToFourByteBoundary() {
+    // If word_t is 64-bits and if we've read less than 32 bits, just dump
+    // the bits we have up to the next 32-bit boundary.
+    if (sizeof(word_t) > 4 &&
+        BitsInCurWord >= 32) {
+      CurWord >>= BitsInCurWord-32;
+      BitsInCurWord = 32;
+      return;
+    }
+
+    BitsInCurWord = 0;
+  }
+public:
+
+  unsigned ReadCode() {
+    return Read(CurCodeSize);
+  }
+
+
+  // Block header:
+  //    [ENTER_SUBBLOCK, blockid, newcodelen, <align4bytes>, blocklen]
+
+  /// Having read the ENTER_SUBBLOCK code, read the BlockID for the block.
+  unsigned ReadSubBlockID() {
+    return ReadVBR(bitc::BlockIDWidth);
+  }
+
+  /// Having read the ENTER_SUBBLOCK abbrevid and a BlockID, skip over the body
+  /// of this block. If the block record is malformed, return true.
+  bool SkipBlock() {
+    // Read and ignore the codelen value.  Since we are skipping this block, we
+    // don't care what code widths are used inside of it.
+    ReadVBR(bitc::CodeLenWidth);
+    SkipToFourByteBoundary();
+    unsigned NumFourBytes = Read(bitc::BlockSizeWidth);
+
+    // Check that the block wasn't partially defined, and that the offset isn't
+    // bogus.
+    size_t SkipTo = GetCurrentBitNo() + NumFourBytes*4*8;
+    if (AtEndOfStream() || !canSkipToPos(SkipTo/8))
+      return true;
+
+    JumpToBit(SkipTo);
+    return false;
+  }
+
+  /// Having read the ENTER_SUBBLOCK abbrevid, enter the block, and return true
+  /// if the block has an error.
+  bool EnterSubBlock(unsigned BlockID, unsigned *NumWordsP = nullptr);
+
+  bool ReadBlockEnd() {
+    if (BlockScope.empty()) return true;
+
+    // Block tail:
+    //    [END_BLOCK, <align4bytes>]
+    SkipToFourByteBoundary();
+
+    popBlockScope();
+    return false;
+  }
+
+private:
+
+  void popBlockScope() {
+    CurCodeSize = BlockScope.back().PrevCodeSize;
+
+    CurAbbrevs = std::move(BlockScope.back().PrevAbbrevs);
+    BlockScope.pop_back();
+  }
+
+  //===--------------------------------------------------------------------===//
+  // Record Processing
+  //===--------------------------------------------------------------------===//
+
+public:
+  /// Return the abbreviation for the specified AbbrevId.
+  const BitCodeAbbrev *getAbbrev(unsigned AbbrevID) {
+    unsigned AbbrevNo = AbbrevID - bitc::FIRST_APPLICATION_ABBREV;
+    if (AbbrevNo >= CurAbbrevs.size())
+      report_fatal_error("Invalid abbrev number");
+    return CurAbbrevs[AbbrevNo].get();
+  }
+
+  /// Read the current record and discard it.
+  void skipRecord(unsigned AbbrevID);
+
+  unsigned readRecord(unsigned AbbrevID, SmallVectorImpl<uint64_t> &Vals,
+                      StringRef *Blob = nullptr);
+
+  //===--------------------------------------------------------------------===//
+  // Abbrev Processing
+  //===--------------------------------------------------------------------===//
+  void ReadAbbrevRecord();
+
+  bool ReadBlockInfoBlock();
+};
+
+} // End llvm namespace
+
+#endif