vendor/llvm/llvm-trunk-r366426

3 files changed, 1288 insertions, 0 deletions

diff --git a/include/llvm/Bitstream/BitCodes.h b/include/llvm/Bitstream/BitCodes.h
new file mode 100644
index 000000000000..adf54ba96396
--- /dev/null
+++ b/include/llvm/Bitstream/BitCodes.h
@@ -0,0 +1,184 @@
+//===- BitCodes.h - Enum values for the bitstream format --------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This header defines bitstream enum values.
+//
+// The enum values defined in this file should be considered permanent.  If
+// new features are added, they should have values added at the end of the
+// respective lists.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_BITSTREAM_BITCODES_H
+#define LLVM_BITSTREAM_BITCODES_H
+
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/Support/DataTypes.h"
+#include "llvm/Support/ErrorHandling.h"
+#include <cassert>
+
+namespace llvm {
+/// Offsets of the 32-bit fields of bitstream wrapper header.
+enum BitstreamWrapperHeader : unsigned {
+  BWH_MagicField   = 0 * 4,
+  BWH_VersionField = 1 * 4,
+  BWH_OffsetField  = 2 * 4,
+  BWH_SizeField    = 3 * 4,
+  BWH_CPUTypeField = 4 * 4,
+  BWH_HeaderSize   = 5 * 4
+};
+
+namespace bitc {
+  enum StandardWidths {
+    BlockIDWidth   = 8,  // We use VBR-8 for block IDs.
+    CodeLenWidth   = 4,  // Codelen are VBR-4.
+    BlockSizeWidth = 32  // BlockSize up to 2^32 32-bit words = 16GB per block.
+  };
+
+  // The standard abbrev namespace always has a way to exit a block, enter a
+  // nested block, define abbrevs, and define an unabbreviated record.
+  enum FixedAbbrevIDs {
+    END_BLOCK = 0,  // Must be zero to guarantee termination for broken bitcode.
+    ENTER_SUBBLOCK = 1,
+
+    /// DEFINE_ABBREV - Defines an abbrev for the current block.  It consists
+    /// of a vbr5 for # operand infos.  Each operand info is emitted with a
+    /// single bit to indicate if it is a literal encoding.  If so, the value is
+    /// emitted with a vbr8.  If not, the encoding is emitted as 3 bits followed
+    /// by the info value as a vbr5 if needed.
+    DEFINE_ABBREV = 2,
+
+    // UNABBREV_RECORDs are emitted with a vbr6 for the record code, followed by
+    // a vbr6 for the # operands, followed by vbr6's for each operand.
+    UNABBREV_RECORD = 3,
+
+    // This is not a code, this is a marker for the first abbrev assignment.
+    FIRST_APPLICATION_ABBREV = 4
+  };
+
+  /// StandardBlockIDs - All bitcode files can optionally include a BLOCKINFO
+  /// block, which contains metadata about other blocks in the file.
+  enum StandardBlockIDs {
+    /// BLOCKINFO_BLOCK is used to define metadata about blocks, for example,
+    /// standard abbrevs that should be available to all blocks of a specified
+    /// ID.
+    BLOCKINFO_BLOCK_ID = 0,
+
+    // Block IDs 1-7 are reserved for future expansion.
+    FIRST_APPLICATION_BLOCKID = 8
+  };
+
+  /// BlockInfoCodes - The blockinfo block contains metadata about user-defined
+  /// blocks.
+  enum BlockInfoCodes {
+    // DEFINE_ABBREV has magic semantics here, applying to the current SETBID'd
+    // block, instead of the BlockInfo block.
+
+    BLOCKINFO_CODE_SETBID        = 1, // SETBID: [blockid#]
+    BLOCKINFO_CODE_BLOCKNAME     = 2, // BLOCKNAME: [name]
+    BLOCKINFO_CODE_SETRECORDNAME = 3  // BLOCKINFO_CODE_SETRECORDNAME:
+                                      //                             [id, name]
+  };
+
+} // End bitc namespace
+
+/// BitCodeAbbrevOp - This describes one or more operands in an abbreviation.
+/// This is actually a union of two different things:
+///   1. It could be a literal integer value ("the operand is always 17").
+///   2. It could be an encoding specification ("this operand encoded like so").
+///
+class BitCodeAbbrevOp {
+  uint64_t Val;           // A literal value or data for an encoding.
+  bool IsLiteral : 1;     // Indicate whether this is a literal value or not.
+  unsigned Enc   : 3;     // The encoding to use.
+public:
+  enum Encoding {
+    Fixed = 1,  // A fixed width field, Val specifies number of bits.
+    VBR   = 2,  // A VBR field where Val specifies the width of each chunk.
+    Array = 3,  // A sequence of fields, next field species elt encoding.
+    Char6 = 4,  // A 6-bit fixed field which maps to [a-zA-Z0-9._].
+    Blob  = 5   // 32-bit aligned array of 8-bit characters.
+  };
+
+  explicit BitCodeAbbrevOp(uint64_t V) :  Val(V), IsLiteral(true) {}
+  explicit BitCodeAbbrevOp(Encoding E, uint64_t Data = 0)
+    : Val(Data), IsLiteral(false), Enc(E) {}
+
+  bool isLiteral() const  { return IsLiteral; }
+  bool isEncoding() const { return !IsLiteral; }
+
+  // Accessors for literals.
+  uint64_t getLiteralValue() const { assert(isLiteral()); return Val; }
+
+  // Accessors for encoding info.
+  Encoding getEncoding() const { assert(isEncoding()); return (Encoding)Enc; }
+  uint64_t getEncodingData() const {
+    assert(isEncoding() && hasEncodingData());
+    return Val;
+  }
+
+  bool hasEncodingData() const { return hasEncodingData(getEncoding()); }
+  static bool hasEncodingData(Encoding E) {
+    switch (E) {
+    case Fixed:
+    case VBR:
+      return true;
+    case Array:
+    case Char6:
+    case Blob:
+      return false;
+    }
+    report_fatal_error("Invalid encoding");
+  }
+
+  /// isChar6 - Return true if this character is legal in the Char6 encoding.
+  static bool isChar6(char C) {
+    if (C >= 'a' && C <= 'z') return true;
+    if (C >= 'A' && C <= 'Z') return true;
+    if (C >= '0' && C <= '9') return true;
+    if (C == '.' || C == '_') return true;
+    return false;
+  }
+  static unsigned EncodeChar6(char C) {
+    if (C >= 'a' && C <= 'z') return C-'a';
+    if (C >= 'A' && C <= 'Z') return C-'A'+26;
+    if (C >= '0' && C <= '9') return C-'0'+26+26;
+    if (C == '.')             return 62;
+    if (C == '_')             return 63;
+    llvm_unreachable("Not a value Char6 character!");
+  }
+
+  static char DecodeChar6(unsigned V) {
+    assert((V & ~63) == 0 && "Not a Char6 encoded character!");
+    return "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789._"
+        [V];
+  }
+
+};
+
+/// BitCodeAbbrev - This class represents an abbreviation record.  An
+/// abbreviation allows a complex record that has redundancy to be stored in a
+/// specialized format instead of the fully-general, fully-vbr, format.
+class BitCodeAbbrev {
+  SmallVector<BitCodeAbbrevOp, 32> OperandList;
+
+public:
+  unsigned getNumOperandInfos() const {
+    return static_cast<unsigned>(OperandList.size());
+  }
+  const BitCodeAbbrevOp &getOperandInfo(unsigned N) const {
+    return OperandList[N];
+  }
+
+  void Add(const BitCodeAbbrevOp &OpInfo) {
+    OperandList.push_back(OpInfo);
+  }
+};
+} // End llvm namespace
+
+#endif
diff --git a/include/llvm/Bitstream/BitstreamReader.h b/include/llvm/Bitstream/BitstreamReader.h
new file mode 100644
index 000000000000..ee82e7ec1ba2
--- /dev/null
+++ b/include/llvm/Bitstream/BitstreamReader.h
@@ -0,0 +1,557 @@
+//===- BitstreamReader.h - Low-level bitstream reader interface -*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This header defines the BitstreamReader class.  This class can be used to
+// read an arbitrary bitstream, regardless of its contents.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_BITSTREAM_BITSTREAMREADER_H
+#define LLVM_BITSTREAM_BITSTREAMREADER_H
+
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/Bitstream/BitCodes.h"
+#include "llvm/Support/Endian.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/MathExtras.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include <algorithm>
+#include <cassert>
+#include <climits>
+#include <cstddef>
+#include <cstdint>
+#include <memory>
+#include <string>
+#include <utility>
+#include <vector>
+
+namespace llvm {
+
+/// This class maintains the abbreviations read from a block info block.
+class BitstreamBlockInfo {
+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<std::shared_ptr<BitCodeAbbrev>> Abbrevs;
+    std::string Name;
+    std::vector<std::pair<unsigned, std::string>> RecordNames;
+  };
+
+private:
+  std::vector<BlockInfo> BlockInfoRecords;
+
+public:
+  /// 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();
+  }
+};
+
+/// This represents a position within a bitstream. There may be multiple
+/// independent cursors reading within one bitstream, each maintaining their
+/// own local state.
+class SimpleBitstreamCursor {
+  ArrayRef<uint8_t> BitcodeBytes;
+  size_t NextChar = 0;
+
+public:
+  /// 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.
+  using word_t = size_t;
+
+private:
+  word_t CurWord = 0;
+
+  /// This is the number of bits in CurWord that are valid. This is always from
+  /// [0...bits_of(size_t)-1] inclusive.
+  unsigned BitsInCurWord = 0;
+
+public:
+  static const constexpr size_t MaxChunkSize = sizeof(word_t) * 8;
+
+  SimpleBitstreamCursor() = default;
+  explicit SimpleBitstreamCursor(ArrayRef<uint8_t> BitcodeBytes)
+      : BitcodeBytes(BitcodeBytes) {}
+  explicit SimpleBitstreamCursor(StringRef BitcodeBytes)
+      : BitcodeBytes(arrayRefFromStringRef(BitcodeBytes)) {}
+  explicit SimpleBitstreamCursor(MemoryBufferRef BitcodeBytes)
+      : SimpleBitstreamCursor(BitcodeBytes.getBuffer()) {}
+
+  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 <= BitcodeBytes.size();
+  }
+
+  bool AtEndOfStream() {
+    return BitsInCurWord == 0 && BitcodeBytes.size() <= NextChar;
+  }
+
+  /// Return the bit # of the bit we are reading.
+  uint64_t GetCurrentBitNo() const {
+    return NextChar*CHAR_BIT - BitsInCurWord;
+  }
+
+  // Return the byte # of the current bit.
+  uint64_t getCurrentByteNo() const { return GetCurrentBitNo() / 8; }
+
+  ArrayRef<uint8_t> getBitcodeBytes() const { return BitcodeBytes; }
+
+  /// Reset the stream to the specified bit number.
+  Error 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) {
+      if (Expected<word_t> Res = Read(WordBitNo))
+        return Error::success();
+      else
+        return Res.takeError();
+    }
+
+    return Error::success();
+  }
+
+  /// Get a pointer into the bitstream at the specified byte offset.
+  const uint8_t *getPointerToByte(uint64_t ByteNo, uint64_t NumBytes) {
+    return BitcodeBytes.data() + ByteNo;
+  }
+
+  /// Get a pointer into the bitstream at the specified bit offset.
+  ///
+  /// The bit offset must be on a byte boundary.
+  const uint8_t *getPointerToBit(uint64_t BitNo, uint64_t NumBytes) {
+    assert(!(BitNo % 8) && "Expected bit on byte boundary");
+    return getPointerToByte(BitNo / 8, NumBytes);
+  }
+
+  Error fillCurWord() {
+    if (NextChar >= BitcodeBytes.size())
+      return createStringError(std::errc::io_error,
+                               "Unexpected end of file reading %u of %u bytes",
+                               NextChar, BitcodeBytes.size());
+
+    // Read the next word from the stream.
+    const uint8_t *NextCharPtr = BitcodeBytes.data() + NextChar;
+    unsigned BytesRead;
+    if (BitcodeBytes.size() >= NextChar + sizeof(word_t)) {
+      BytesRead = sizeof(word_t);
+      CurWord =
+          support::endian::read<word_t, support::little, support::unaligned>(
+              NextCharPtr);
+    } else {
+      // Short read.
+      BytesRead = BitcodeBytes.size() - NextChar;
+      CurWord = 0;
+      for (unsigned B = 0; B != BytesRead; ++B)
+        CurWord |= uint64_t(NextCharPtr[B]) << (B * 8);
+    }
+    NextChar += BytesRead;
+    BitsInCurWord = BytesRead * 8;
+    return Error::success();
+  }
+
+  Expected<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;
+
+    if (Error fillResult = fillCurWord())
+      return std::move(fillResult);
+
+    // If we run out of data, abort.
+    if (BitsLeft > BitsInCurWord)
+      return createStringError(std::errc::io_error,
+                               "Unexpected end of file reading %u of %u bits",
+                               BitsInCurWord, BitsLeft);
+
+    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;
+  }
+
+  Expected<uint32_t> ReadVBR(unsigned NumBits) {
+    Expected<unsigned> MaybeRead = Read(NumBits);
+    if (!MaybeRead)
+      return MaybeRead;
+    uint32_t Piece = MaybeRead.get();
+
+    if ((Piece & (1U << (NumBits-1))) == 0)
+      return Piece;
+
+    uint32_t Result = 0;
+    unsigned NextBit = 0;
+    while (true) {
+      Result |= (Piece & ((1U << (NumBits-1))-1)) << NextBit;
+
+      if ((Piece & (1U << (NumBits-1))) == 0)
+        return Result;
+
+      NextBit += NumBits-1;
+      MaybeRead = Read(NumBits);
+      if (!MaybeRead)
+        return MaybeRead;
+      Piece = MaybeRead.get();
+    }
+  }
+
+  // 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.
+  Expected<uint64_t> ReadVBR64(unsigned NumBits) {
+    Expected<uint64_t> MaybeRead = Read(NumBits);
+    if (!MaybeRead)
+      return MaybeRead;
+    uint32_t Piece = MaybeRead.get();
+
+    if ((Piece & (1U << (NumBits-1))) == 0)
+      return uint64_t(Piece);
+
+    uint64_t Result = 0;
+    unsigned NextBit = 0;
+    while (true) {
+      Result |= uint64_t(Piece & ((1U << (NumBits-1))-1)) << NextBit;
+
+      if ((Piece & (1U << (NumBits-1))) == 0)
+        return Result;
+
+      NextBit += NumBits-1;
+      MaybeRead = Read(NumBits);
+      if (!MaybeRead)
+        return MaybeRead;
+      Piece = MaybeRead.get();
+    }
+  }
+
+  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;
+  }
+
+  /// Return the size of the stream in bytes.
+  size_t SizeInBytes() const { return BitcodeBytes.size(); }
+
+  /// Skip to the end of the file.
+  void skipToEnd() { NextChar = BitcodeBytes.size(); }
+};
+
+/// 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, implemented on top of a
+/// SimpleBitstreamCursor.
+///
+/// Unlike iterators, BitstreamCursors are heavy-weight objects that should not
+/// be passed by value.
+class BitstreamCursor : SimpleBitstreamCursor {
+  // This is the declared size of code values used for the current block, in
+  // bits.
+  unsigned CurCodeSize = 2;
+
+  /// Abbrevs installed at in this block.
+  std::vector<std::shared_ptr<BitCodeAbbrev>> CurAbbrevs;
+
+  struct Block {
+    unsigned PrevCodeSize;
+    std::vector<std::shared_ptr<BitCodeAbbrev>> PrevAbbrevs;
+
+    explicit Block(unsigned PCS) : PrevCodeSize(PCS) {}
+  };
+
+  /// This tracks the codesize of parent blocks.
+  SmallVector<Block, 8> BlockScope;
+
+  BitstreamBlockInfo *BlockInfo = nullptr;
+
+public:
+  static const size_t MaxChunkSize = sizeof(word_t) * 8;
+
+  BitstreamCursor() = default;
+  explicit BitstreamCursor(ArrayRef<uint8_t> BitcodeBytes)
+      : SimpleBitstreamCursor(BitcodeBytes) {}
+  explicit BitstreamCursor(StringRef BitcodeBytes)
+      : SimpleBitstreamCursor(BitcodeBytes) {}
+  explicit BitstreamCursor(MemoryBufferRef BitcodeBytes)
+      : SimpleBitstreamCursor(BitcodeBytes) {}
+
+  using SimpleBitstreamCursor::AtEndOfStream;
+  using SimpleBitstreamCursor::canSkipToPos;
+  using SimpleBitstreamCursor::fillCurWord;
+  using SimpleBitstreamCursor::getBitcodeBytes;
+  using SimpleBitstreamCursor::GetCurrentBitNo;
+  using SimpleBitstreamCursor::getCurrentByteNo;
+  using SimpleBitstreamCursor::getPointerToByte;
+  using SimpleBitstreamCursor::JumpToBit;
+  using SimpleBitstreamCursor::Read;
+  using SimpleBitstreamCursor::ReadVBR;
+  using SimpleBitstreamCursor::ReadVBR64;
+  using SimpleBitstreamCursor::SizeInBytes;
+
+  /// Return the number of bits used to encode an abbrev #.
+  unsigned getAbbrevIDWidth() const { return CurCodeSize; }
+
+  /// 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.
+  Expected<BitstreamEntry> advance(unsigned Flags = 0) {
+    while (true) {
+      if (AtEndOfStream())
+        return BitstreamEntry::getError();
+
+      Expected<unsigned> MaybeCode = ReadCode();
+      if (!MaybeCode)
+        return MaybeCode.takeError();
+      unsigned Code = MaybeCode.get();
+
+      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) {
+        if (Expected<unsigned> MaybeSubBlock = ReadSubBlockID())
+          return BitstreamEntry::getSubBlock(MaybeSubBlock.get());
+        else
+          return MaybeSubBlock.takeError();
+      }
+
+      if (Code == bitc::DEFINE_ABBREV &&
+          !(Flags & AF_DontAutoprocessAbbrevs)) {
+        // We read and accumulate abbrev's, the client can't do anything with
+        // them anyway.
+        if (Error Err = ReadAbbrevRecord())
+          return std::move(Err);
+        continue;
+      }
+
+      return BitstreamEntry::getRecord(Code);
+    }
+  }
+
+  /// This is a convenience function for clients that don't expect any
+  /// subblocks. This just skips over them automatically.
+  Expected<BitstreamEntry> advanceSkippingSubblocks(unsigned Flags = 0) {
+    while (true) {
+      // If we found a normal entry, return it.
+      Expected<BitstreamEntry> MaybeEntry = advance(Flags);
+      if (!MaybeEntry)
+        return MaybeEntry;
+      BitstreamEntry Entry = MaybeEntry.get();
+
+      if (Entry.Kind != BitstreamEntry::SubBlock)
+        return Entry;
+
+      // If we found a sub-block, just skip over it and check the next entry.
+      if (Error Err = SkipBlock())
+        return std::move(Err);
+    }
+  }
+
+  Expected<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.
+  Expected<unsigned> ReadSubBlockID() { return ReadVBR(bitc::BlockIDWidth); }
+
+  /// Having read the ENTER_SUBBLOCK abbrevid and a BlockID, skip over the body
+  /// of this block.
+  Error SkipBlock() {
+    // Read and ignore the codelen value.
+    if (Expected<uint32_t> Res = ReadVBR(bitc::CodeLenWidth))
+      ; // Since we are skipping this block, we don't care what code widths are
+        // used inside of it.
+    else
+      return Res.takeError();
+
+    SkipToFourByteBoundary();
+    Expected<unsigned> MaybeNum = Read(bitc::BlockSizeWidth);
+    if (!MaybeNum)
+      return MaybeNum.takeError();
+    size_t NumFourBytes = MaybeNum.get();
+
+    // Check that the block wasn't partially defined, and that the offset isn't
+    // bogus.
+    size_t SkipTo = GetCurrentBitNo() + NumFourBytes * 4 * 8;
+    if (AtEndOfStream())
+      return createStringError(std::errc::illegal_byte_sequence,
+                               "can't skip block: already at end of stream");
+    if (!canSkipToPos(SkipTo / 8))
+      return createStringError(std::errc::illegal_byte_sequence,
+                               "can't skip to bit %zu from %" PRIu64, SkipTo,
+                               GetCurrentBitNo());
+
+    if (Error Res = JumpToBit(SkipTo))
+      return Res;
+
+    return Error::success();
+  }
+
+  /// Having read the ENTER_SUBBLOCK abbrevid, and enter the block.
+  Error 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, returning the code for the record.
+  Expected<unsigned> skipRecord(unsigned AbbrevID);
+
+  Expected<unsigned> readRecord(unsigned AbbrevID,
+                                SmallVectorImpl<uint64_t> &Vals,
+                                StringRef *Blob = nullptr);
+
+  //===--------------------------------------------------------------------===//
+  // Abbrev Processing
+  //===--------------------------------------------------------------------===//
+  Error ReadAbbrevRecord();
+
+  /// Read and return a block info block from the bitstream. If an error was
+  /// encountered, return None.
+  ///
+  /// \param ReadBlockInfoNames Whether to read block/record name information in
+  /// the BlockInfo block. Only llvm-bcanalyzer uses this.
+  Expected<Optional<BitstreamBlockInfo>>
+  ReadBlockInfoBlock(bool ReadBlockInfoNames = false);
+
+  /// Set the block info to be used by this BitstreamCursor to interpret
+  /// abbreviated records.
+  void setBlockInfo(BitstreamBlockInfo *BI) { BlockInfo = BI; }
+};
+
+} // end llvm namespace
+
+#endif // LLVM_BITSTREAM_BITSTREAMREADER_H
diff --git a/include/llvm/Bitstream/BitstreamWriter.h b/include/llvm/Bitstream/BitstreamWriter.h
new file mode 100644
index 000000000000..c0ead19dc71d
--- /dev/null
+++ b/include/llvm/Bitstream/BitstreamWriter.h
@@ -0,0 +1,547 @@
+//===- BitstreamWriter.h - Low-level bitstream writer interface -*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This header defines the BitstreamWriter class.  This class can be used to
+// write an arbitrary bitstream, regardless of its contents.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_BITSTREAM_BITSTREAMWRITER_H
+#define LLVM_BITSTREAM_BITSTREAMWRITER_H
+
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/Optional.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/StringRef.h"
+#include "llvm/Bitstream/BitCodes.h"
+#include "llvm/Support/Endian.h"
+#include <vector>
+
+namespace llvm {
+
+class BitstreamWriter {
+  SmallVectorImpl<char> &Out;
+
+  /// CurBit - Always between 0 and 31 inclusive, specifies the next bit to use.
+  unsigned CurBit;
+
+  /// CurValue - The current value.  Only bits < CurBit are valid.
+  uint32_t CurValue;
+
+  /// CurCodeSize - This is the declared size of code values used for the
+  /// current block, in bits.
+  unsigned CurCodeSize;
+
+  /// BlockInfoCurBID - When emitting a BLOCKINFO_BLOCK, this is the currently
+  /// selected BLOCK ID.
+  unsigned BlockInfoCurBID;
+
+  /// CurAbbrevs - Abbrevs installed at in this block.
+  std::vector<std::shared_ptr<BitCodeAbbrev>> CurAbbrevs;
+
+  struct Block {
+    unsigned PrevCodeSize;
+    size_t StartSizeWord;
+    std::vector<std::shared_ptr<BitCodeAbbrev>> PrevAbbrevs;
+    Block(unsigned PCS, size_t SSW) : PrevCodeSize(PCS), StartSizeWord(SSW) {}
+  };
+
+  /// BlockScope - This tracks the current blocks that we have entered.
+  std::vector<Block> BlockScope;
+
+  /// BlockInfo - 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<std::shared_ptr<BitCodeAbbrev>> Abbrevs;
+  };
+  std::vector<BlockInfo> BlockInfoRecords;
+
+  void WriteByte(unsigned char Value) {
+    Out.push_back(Value);
+  }
+
+  void WriteWord(unsigned Value) {
+    Value = support::endian::byte_swap<uint32_t, support::little>(Value);
+    Out.append(reinterpret_cast<const char *>(&Value),
+               reinterpret_cast<const char *>(&Value + 1));
+  }
+
+  size_t GetBufferOffset() const { return Out.size(); }
+
+  size_t GetWordIndex() const {
+    size_t Offset = GetBufferOffset();
+    assert((Offset & 3) == 0 && "Not 32-bit aligned");
+    return Offset / 4;
+  }
+
+public:
+  explicit BitstreamWriter(SmallVectorImpl<char> &O)
+    : Out(O), CurBit(0), CurValue(0), CurCodeSize(2) {}
+
+  ~BitstreamWriter() {
+    assert(CurBit == 0 && "Unflushed data remaining");
+    assert(BlockScope.empty() && CurAbbrevs.empty() && "Block imbalance");
+  }
+
+  /// Retrieve the current position in the stream, in bits.
+  uint64_t GetCurrentBitNo() const { return GetBufferOffset() * 8 + CurBit; }
+
+  /// Retrieve the number of bits currently used to encode an abbrev ID.
+  unsigned GetAbbrevIDWidth() const { return CurCodeSize; }
+
+  //===--------------------------------------------------------------------===//
+  // Basic Primitives for emitting bits to the stream.
+  //===--------------------------------------------------------------------===//
+
+  /// Backpatch a 32-bit word in the output at the given bit offset
+  /// with the specified value.
+  void BackpatchWord(uint64_t BitNo, unsigned NewWord) {
+    using namespace llvm::support;
+    unsigned ByteNo = BitNo / 8;
+    assert((!endian::readAtBitAlignment<uint32_t, little, unaligned>(
+               &Out[ByteNo], BitNo & 7)) &&
+           "Expected to be patching over 0-value placeholders");
+    endian::writeAtBitAlignment<uint32_t, little, unaligned>(
+        &Out[ByteNo], NewWord, BitNo & 7);
+  }
+
+  void BackpatchWord64(uint64_t BitNo, uint64_t Val) {
+    BackpatchWord(BitNo, (uint32_t)Val);
+    BackpatchWord(BitNo + 32, (uint32_t)(Val >> 32));
+  }
+
+  void Emit(uint32_t Val, unsigned NumBits) {
+    assert(NumBits && NumBits <= 32 && "Invalid value size!");
+    assert((Val & ~(~0U >> (32-NumBits))) == 0 && "High bits set!");
+    CurValue |= Val << CurBit;
+    if (CurBit + NumBits < 32) {
+      CurBit += NumBits;
+      return;
+    }
+
+    // Add the current word.
+    WriteWord(CurValue);
+
+    if (CurBit)
+      CurValue = Val >> (32-CurBit);
+    else
+      CurValue = 0;
+    CurBit = (CurBit+NumBits) & 31;
+  }
+
+  void FlushToWord() {
+    if (CurBit) {
+      WriteWord(CurValue);
+      CurBit = 0;
+      CurValue = 0;
+    }
+  }
+
+  void EmitVBR(uint32_t Val, unsigned NumBits) {
+    assert(NumBits <= 32 && "Too many bits to emit!");
+    uint32_t Threshold = 1U << (NumBits-1);
+
+    // Emit the bits with VBR encoding, NumBits-1 bits at a time.
+    while (Val >= Threshold) {
+      Emit((Val & ((1 << (NumBits-1))-1)) | (1 << (NumBits-1)), NumBits);
+      Val >>= NumBits-1;
+    }
+
+    Emit(Val, NumBits);
+  }
+
+  void EmitVBR64(uint64_t Val, unsigned NumBits) {
+    assert(NumBits <= 32 && "Too many bits to emit!");
+    if ((uint32_t)Val == Val)
+      return EmitVBR((uint32_t)Val, NumBits);
+
+    uint32_t Threshold = 1U << (NumBits-1);
+
+    // Emit the bits with VBR encoding, NumBits-1 bits at a time.
+    while (Val >= Threshold) {
+      Emit(((uint32_t)Val & ((1 << (NumBits-1))-1)) |
+           (1 << (NumBits-1)), NumBits);
+      Val >>= NumBits-1;
+    }
+
+    Emit((uint32_t)Val, NumBits);
+  }
+
+  /// EmitCode - Emit the specified code.
+  void EmitCode(unsigned Val) {
+    Emit(Val, CurCodeSize);
+  }
+
+  //===--------------------------------------------------------------------===//
+  // Block Manipulation
+  //===--------------------------------------------------------------------===//
+
+  /// getBlockInfo - If there is block info for the specified ID, return it,
+  /// otherwise return null.
+  BlockInfo *getBlockInfo(unsigned BlockID) {
+    // 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;
+  }
+
+  void EnterSubblock(unsigned BlockID, unsigned CodeLen) {
+    // Block header:
+    //    [ENTER_SUBBLOCK, blockid, newcodelen, <align4bytes>, blocklen]
+    EmitCode(bitc::ENTER_SUBBLOCK);
+    EmitVBR(BlockID, bitc::BlockIDWidth);
+    EmitVBR(CodeLen, bitc::CodeLenWidth);
+    FlushToWord();
+
+    size_t BlockSizeWordIndex = GetWordIndex();
+    unsigned OldCodeSize = CurCodeSize;
+
+    // Emit a placeholder, which will be replaced when the block is popped.
+    Emit(0, bitc::BlockSizeWidth);
+
+    CurCodeSize = CodeLen;
+
+    // Push the outer block's abbrev set onto the stack, start out with an
+    // empty abbrev set.
+    BlockScope.emplace_back(OldCodeSize, BlockSizeWordIndex);
+    BlockScope.back().PrevAbbrevs.swap(CurAbbrevs);
+
+    // If there is a blockinfo for this BlockID, add all the predefined abbrevs
+    // to the abbrev list.
+    if (BlockInfo *Info = getBlockInfo(BlockID)) {
+      CurAbbrevs.insert(CurAbbrevs.end(), Info->Abbrevs.begin(),
+                        Info->Abbrevs.end());
+    }
+  }
+
+  void ExitBlock() {
+    assert(!BlockScope.empty() && "Block scope imbalance!");
+    const Block &B = BlockScope.back();
+
+    // Block tail:
+    //    [END_BLOCK, <align4bytes>]
+    EmitCode(bitc::END_BLOCK);
+    FlushToWord();
+
+    // Compute the size of the block, in words, not counting the size field.
+    size_t SizeInWords = GetWordIndex() - B.StartSizeWord - 1;
+    uint64_t BitNo = uint64_t(B.StartSizeWord) * 32;
+
+    // Update the block size field in the header of this sub-block.
+    BackpatchWord(BitNo, SizeInWords);
+
+    // Restore the inner block's code size and abbrev table.
+    CurCodeSize = B.PrevCodeSize;
+    CurAbbrevs = std::move(B.PrevAbbrevs);
+    BlockScope.pop_back();
+  }
+
+  //===--------------------------------------------------------------------===//
+  // Record Emission
+  //===--------------------------------------------------------------------===//
+
+private:
+  /// EmitAbbreviatedLiteral - Emit a literal value according to its abbrev
+  /// record.  This is a no-op, since the abbrev specifies the literal to use.
+  template<typename uintty>
+  void EmitAbbreviatedLiteral(const BitCodeAbbrevOp &Op, uintty V) {
+    assert(Op.isLiteral() && "Not a literal");
+    // If the abbrev specifies the literal value to use, don't emit
+    // anything.
+    assert(V == Op.getLiteralValue() &&
+           "Invalid abbrev for record!");
+  }
+
+  /// EmitAbbreviatedField - Emit a single scalar field value with the specified
+  /// encoding.
+  template<typename uintty>
+  void EmitAbbreviatedField(const BitCodeAbbrevOp &Op, uintty V) {
+    assert(!Op.isLiteral() && "Literals should use EmitAbbreviatedLiteral!");
+
+    // Encode the value as we are commanded.
+    switch (Op.getEncoding()) {
+    default: llvm_unreachable("Unknown encoding!");
+    case BitCodeAbbrevOp::Fixed:
+      if (Op.getEncodingData())
+        Emit((unsigned)V, (unsigned)Op.getEncodingData());
+      break;
+    case BitCodeAbbrevOp::VBR:
+      if (Op.getEncodingData())
+        EmitVBR64(V, (unsigned)Op.getEncodingData());
+      break;
+    case BitCodeAbbrevOp::Char6:
+      Emit(BitCodeAbbrevOp::EncodeChar6((char)V), 6);
+      break;
+    }
+  }
+
+  /// EmitRecordWithAbbrevImpl - This is the core implementation of the record
+  /// emission code.  If BlobData is non-null, then it specifies an array of
+  /// data that should be emitted as part of the Blob or Array operand that is
+  /// known to exist at the end of the record. If Code is specified, then
+  /// it is the record code to emit before the Vals, which must not contain
+  /// the code.
+  template <typename uintty>
+  void EmitRecordWithAbbrevImpl(unsigned Abbrev, ArrayRef<uintty> Vals,
+                                StringRef Blob, Optional<unsigned> Code) {
+    const char *BlobData = Blob.data();
+    unsigned BlobLen = (unsigned) Blob.size();
+    unsigned AbbrevNo = Abbrev-bitc::FIRST_APPLICATION_ABBREV;
+    assert(AbbrevNo < CurAbbrevs.size() && "Invalid abbrev #!");
+    const BitCodeAbbrev *Abbv = CurAbbrevs[AbbrevNo].get();
+
+    EmitCode(Abbrev);
+
+    unsigned i = 0, e = static_cast<unsigned>(Abbv->getNumOperandInfos());
+    if (Code) {
+      assert(e && "Expected non-empty abbreviation");
+      const BitCodeAbbrevOp &Op = Abbv->getOperandInfo(i++);
+
+      if (Op.isLiteral())
+        EmitAbbreviatedLiteral(Op, Code.getValue());
+      else {
+        assert(Op.getEncoding() != BitCodeAbbrevOp::Array &&
+               Op.getEncoding() != BitCodeAbbrevOp::Blob &&
+               "Expected literal or scalar");
+        EmitAbbreviatedField(Op, Code.getValue());
+      }
+    }
+
+    unsigned RecordIdx = 0;
+    for (; i != e; ++i) {
+      const BitCodeAbbrevOp &Op = Abbv->getOperandInfo(i);
+      if (Op.isLiteral()) {
+        assert(RecordIdx < Vals.size() && "Invalid abbrev/record");
+        EmitAbbreviatedLiteral(Op, Vals[RecordIdx]);
+        ++RecordIdx;
+      } else if (Op.getEncoding() == BitCodeAbbrevOp::Array) {
+        // Array case.
+        assert(i + 2 == e && "array op not second to last?");
+        const BitCodeAbbrevOp &EltEnc = Abbv->getOperandInfo(++i);
+
+        // If this record has blob data, emit it, otherwise we must have record
+        // entries to encode this way.
+        if (BlobData) {
+          assert(RecordIdx == Vals.size() &&
+                 "Blob data and record entries specified for array!");
+          // Emit a vbr6 to indicate the number of elements present.
+          EmitVBR(static_cast<uint32_t>(BlobLen), 6);
+
+          // Emit each field.
+          for (unsigned i = 0; i != BlobLen; ++i)
+            EmitAbbreviatedField(EltEnc, (unsigned char)BlobData[i]);
+
+          // Know that blob data is consumed for assertion below.
+          BlobData = nullptr;
+        } else {
+          // Emit a vbr6 to indicate the number of elements present.
+          EmitVBR(static_cast<uint32_t>(Vals.size()-RecordIdx), 6);
+
+          // Emit each field.
+          for (unsigned e = Vals.size(); RecordIdx != e; ++RecordIdx)
+            EmitAbbreviatedField(EltEnc, Vals[RecordIdx]);
+        }
+      } else if (Op.getEncoding() == BitCodeAbbrevOp::Blob) {
+        // If this record has blob data, emit it, otherwise we must have record
+        // entries to encode this way.
+
+        if (BlobData) {
+          assert(RecordIdx == Vals.size() &&
+                 "Blob data and record entries specified for blob operand!");
+
+          assert(Blob.data() == BlobData && "BlobData got moved");
+          assert(Blob.size() == BlobLen && "BlobLen got changed");
+          emitBlob(Blob);
+          BlobData = nullptr;
+        } else {
+          emitBlob(Vals.slice(RecordIdx));
+        }
+      } else {  // Single scalar field.
+        assert(RecordIdx < Vals.size() && "Invalid abbrev/record");
+        EmitAbbreviatedField(Op, Vals[RecordIdx]);
+        ++RecordIdx;
+      }
+    }
+    assert(RecordIdx == Vals.size() && "Not all record operands emitted!");
+    assert(BlobData == nullptr &&
+           "Blob data specified for record that doesn't use it!");
+  }
+
+public:
+  /// Emit a blob, including flushing before and tail-padding.
+  template <class UIntTy>
+  void emitBlob(ArrayRef<UIntTy> Bytes, bool ShouldEmitSize = true) {
+    // Emit a vbr6 to indicate the number of elements present.
+    if (ShouldEmitSize)
+      EmitVBR(static_cast<uint32_t>(Bytes.size()), 6);
+
+    // Flush to a 32-bit alignment boundary.
+    FlushToWord();
+
+    // Emit literal bytes.
+    for (const auto &B : Bytes) {
+      assert(isUInt<8>(B) && "Value too large to emit as byte");
+      WriteByte((unsigned char)B);
+    }
+
+    // Align end to 32-bits.
+    while (GetBufferOffset() & 3)
+      WriteByte(0);
+  }
+  void emitBlob(StringRef Bytes, bool ShouldEmitSize = true) {
+    emitBlob(makeArrayRef((const uint8_t *)Bytes.data(), Bytes.size()),
+             ShouldEmitSize);
+  }
+
+  /// EmitRecord - Emit the specified record to the stream, using an abbrev if
+  /// we have one to compress the output.
+  template <typename Container>
+  void EmitRecord(unsigned Code, const Container &Vals, unsigned Abbrev = 0) {
+    if (!Abbrev) {
+      // If we don't have an abbrev to use, emit this in its fully unabbreviated
+      // form.
+      auto Count = static_cast<uint32_t>(makeArrayRef(Vals).size());
+      EmitCode(bitc::UNABBREV_RECORD);
+      EmitVBR(Code, 6);
+      EmitVBR(Count, 6);
+      for (unsigned i = 0, e = Count; i != e; ++i)
+        EmitVBR64(Vals[i], 6);
+      return;
+    }
+
+    EmitRecordWithAbbrevImpl(Abbrev, makeArrayRef(Vals), StringRef(), Code);
+  }
+
+  /// EmitRecordWithAbbrev - Emit a record with the specified abbreviation.
+  /// Unlike EmitRecord, the code for the record should be included in Vals as
+  /// the first entry.
+  template <typename Container>
+  void EmitRecordWithAbbrev(unsigned Abbrev, const Container &Vals) {
+    EmitRecordWithAbbrevImpl(Abbrev, makeArrayRef(Vals), StringRef(), None);
+  }
+
+  /// EmitRecordWithBlob - Emit the specified record to the stream, using an
+  /// abbrev that includes a blob at the end.  The blob data to emit is
+  /// specified by the pointer and length specified at the end.  In contrast to
+  /// EmitRecord, this routine expects that the first entry in Vals is the code
+  /// of the record.
+  template <typename Container>
+  void EmitRecordWithBlob(unsigned Abbrev, const Container &Vals,
+                          StringRef Blob) {
+    EmitRecordWithAbbrevImpl(Abbrev, makeArrayRef(Vals), Blob, None);
+  }
+  template <typename Container>
+  void EmitRecordWithBlob(unsigned Abbrev, const Container &Vals,
+                          const char *BlobData, unsigned BlobLen) {
+    return EmitRecordWithAbbrevImpl(Abbrev, makeArrayRef(Vals),
+                                    StringRef(BlobData, BlobLen), None);
+  }
+
+  /// EmitRecordWithArray - Just like EmitRecordWithBlob, works with records
+  /// that end with an array.
+  template <typename Container>
+  void EmitRecordWithArray(unsigned Abbrev, const Container &Vals,
+                           StringRef Array) {
+    EmitRecordWithAbbrevImpl(Abbrev, makeArrayRef(Vals), Array, None);
+  }
+  template <typename Container>
+  void EmitRecordWithArray(unsigned Abbrev, const Container &Vals,
+                           const char *ArrayData, unsigned ArrayLen) {
+    return EmitRecordWithAbbrevImpl(Abbrev, makeArrayRef(Vals),
+                                    StringRef(ArrayData, ArrayLen), None);
+  }
+
+  //===--------------------------------------------------------------------===//
+  // Abbrev Emission
+  //===--------------------------------------------------------------------===//
+
+private:
+  // Emit the abbreviation as a DEFINE_ABBREV record.
+  void EncodeAbbrev(const BitCodeAbbrev &Abbv) {
+    EmitCode(bitc::DEFINE_ABBREV);
+    EmitVBR(Abbv.getNumOperandInfos(), 5);
+    for (unsigned i = 0, e = static_cast<unsigned>(Abbv.getNumOperandInfos());
+         i != e; ++i) {
+      const BitCodeAbbrevOp &Op = Abbv.getOperandInfo(i);
+      Emit(Op.isLiteral(), 1);
+      if (Op.isLiteral()) {
+        EmitVBR64(Op.getLiteralValue(), 8);
+      } else {
+        Emit(Op.getEncoding(), 3);
+        if (Op.hasEncodingData())
+          EmitVBR64(Op.getEncodingData(), 5);
+      }
+    }
+  }
+public:
+
+  /// Emits the abbreviation \p Abbv to the stream.
+  unsigned EmitAbbrev(std::shared_ptr<BitCodeAbbrev> Abbv) {
+    EncodeAbbrev(*Abbv);
+    CurAbbrevs.push_back(std::move(Abbv));
+    return static_cast<unsigned>(CurAbbrevs.size())-1 +
+      bitc::FIRST_APPLICATION_ABBREV;
+  }
+
+  //===--------------------------------------------------------------------===//
+  // BlockInfo Block Emission
+  //===--------------------------------------------------------------------===//
+
+  /// EnterBlockInfoBlock - Start emitting the BLOCKINFO_BLOCK.
+  void EnterBlockInfoBlock() {
+    EnterSubblock(bitc::BLOCKINFO_BLOCK_ID, 2);
+    BlockInfoCurBID = ~0U;
+    BlockInfoRecords.clear();
+  }
+private:
+  /// SwitchToBlockID - If we aren't already talking about the specified block
+  /// ID, emit a BLOCKINFO_CODE_SETBID record.
+  void SwitchToBlockID(unsigned BlockID) {
+    if (BlockInfoCurBID == BlockID) return;
+    SmallVector<unsigned, 2> V;
+    V.push_back(BlockID);
+    EmitRecord(bitc::BLOCKINFO_CODE_SETBID, V);
+    BlockInfoCurBID = BlockID;
+  }
+
+  BlockInfo &getOrCreateBlockInfo(unsigned BlockID) {
+    if (BlockInfo *BI = getBlockInfo(BlockID))
+      return *BI;
+
+    // Otherwise, add a new record.
+    BlockInfoRecords.emplace_back();
+    BlockInfoRecords.back().BlockID = BlockID;
+    return BlockInfoRecords.back();
+  }
+
+public:
+
+  /// EmitBlockInfoAbbrev - Emit a DEFINE_ABBREV record for the specified
+  /// BlockID.
+  unsigned EmitBlockInfoAbbrev(unsigned BlockID, std::shared_ptr<BitCodeAbbrev> Abbv) {
+    SwitchToBlockID(BlockID);
+    EncodeAbbrev(*Abbv);
+
+    // Add the abbrev to the specified block record.
+    BlockInfo &Info = getOrCreateBlockInfo(BlockID);
+    Info.Abbrevs.push_back(std::move(Abbv));
+
+    return Info.Abbrevs.size()-1+bitc::FIRST_APPLICATION_ABBREV;
+  }
+};
+
+
+} // End llvm namespace
+
+#endif