lib/Bitcode/Reader/BitstreamReader.cpp - llvm - Git at Google

 //===- BitstreamReader.cpp - BitstreamReader implementation ---------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//

 #include "llvm/Bitcode/BitstreamReader.h"

 using namespace llvm;

 //===----------------------------------------------------------------------===//
 //  BitstreamCursor implementation
 //===----------------------------------------------------------------------===//

 void BitstreamCursor::operator=(const BitstreamCursor &RHS) {
   freeState();

   BitStream = RHS.BitStream;
   NextChar = RHS.NextChar;
   CurWord = RHS.CurWord;
   BitsInCurWord = RHS.BitsInCurWord;
   CurCodeSize = RHS.CurCodeSize;

   // Copy abbreviations, and bump ref counts.
   CurAbbrevs = RHS.CurAbbrevs;
   for (size_t i = 0, e = CurAbbrevs.size(); i != e; ++i)
     CurAbbrevs[i]->addRef();

   // Copy block scope and bump ref counts.
   BlockScope = RHS.BlockScope;
   for (size_t S = 0, e = BlockScope.size(); S != e; ++S) {
     std::vector<BitCodeAbbrev*> &Abbrevs = BlockScope[S].PrevAbbrevs;
     for (size_t i = 0, e = Abbrevs.size(); i != e; ++i)
       Abbrevs[i]->addRef();
   }
 }

 void BitstreamCursor::freeState() {
   // Free all the Abbrevs.
   for (size_t i = 0, e = CurAbbrevs.size(); i != e; ++i)
     CurAbbrevs[i]->dropRef();
   CurAbbrevs.clear();

   // Free all the Abbrevs in the block scope.
   for (size_t S = 0, e = BlockScope.size(); S != e; ++S) {
     std::vector<BitCodeAbbrev*> &Abbrevs = BlockScope[S].PrevAbbrevs;
     for (size_t i = 0, e = Abbrevs.size(); i != e; ++i)
       Abbrevs[i]->dropRef();
   }
   BlockScope.clear();
 }

 /// EnterSubBlock - Having read the ENTER_SUBBLOCK abbrevid, enter
 /// the block, and return true if the block has an error.
 bool BitstreamCursor::EnterSubBlock(unsigned BlockID, unsigned *NumWordsP) {
   // Save the current block's state on BlockScope.
   BlockScope.push_back(Block(CurCodeSize));
   BlockScope.back().PrevAbbrevs.swap(CurAbbrevs);

   // Add the abbrevs specific to this block to the CurAbbrevs list.
   if (const BitstreamReader::BlockInfo *Info =
       BitStream->getBlockInfo(BlockID)) {
     for (size_t i = 0, e = Info->Abbrevs.size(); i != e; ++i) {
       CurAbbrevs.push_back(Info->Abbrevs[i]);
       CurAbbrevs.back()->addRef();
     }
   }

   // Get the codesize of this block.
   CurCodeSize = ReadVBR(bitc::CodeLenWidth);
   SkipToFourByteBoundary();
   unsigned NumWords = Read(bitc::BlockSizeWidth);
   if (NumWordsP) *NumWordsP = NumWords;

   // Validate that this block is sane.
   if (CurCodeSize == 0 || AtEndOfStream())
     return true;

   return false;
 }

 void BitstreamCursor::readAbbreviatedLiteral(const BitCodeAbbrevOp &Op,
                                              SmallVectorImpl<uint64_t> &Vals) {
   assert(Op.isLiteral() && "Not a literal");
   // If the abbrev specifies the literal value to use, use it.
   Vals.push_back(Op.getLiteralValue());
 }

 void BitstreamCursor::readAbbreviatedField(const BitCodeAbbrevOp &Op,
                                            SmallVectorImpl<uint64_t> &Vals) {
   assert(!Op.isLiteral() && "Use ReadAbbreviatedLiteral for literals!");

   // Decode the value as we are commanded.
   switch (Op.getEncoding()) {
   case BitCodeAbbrevOp::Array:
   case BitCodeAbbrevOp::Blob:
     assert(0 && "Should not reach here");
   case BitCodeAbbrevOp::Fixed:
     Vals.push_back(Read((unsigned)Op.getEncodingData()));
     break;
   case BitCodeAbbrevOp::VBR:
     Vals.push_back(ReadVBR64((unsigned)Op.getEncodingData()));
     break;
   case BitCodeAbbrevOp::Char6:
     Vals.push_back(BitCodeAbbrevOp::DecodeChar6(Read(6)));
     break;
   }
 }

 void BitstreamCursor::skipAbbreviatedField(const BitCodeAbbrevOp &Op) {
   assert(!Op.isLiteral() && "Use ReadAbbreviatedLiteral for literals!");

   // Decode the value as we are commanded.
   switch (Op.getEncoding()) {
   case BitCodeAbbrevOp::Array:
   case BitCodeAbbrevOp::Blob:
     assert(0 && "Should not reach here");
   case BitCodeAbbrevOp::Fixed:
     (void)Read((unsigned)Op.getEncodingData());
     break;
   case BitCodeAbbrevOp::VBR:
     (void)ReadVBR64((unsigned)Op.getEncodingData());
     break;
   case BitCodeAbbrevOp::Char6:
     (void)Read(6);
     break;
   }
 }


 /// skipRecord - Read the current record and discard it.
 void BitstreamCursor::skipRecord(unsigned AbbrevID) {
   // Skip unabbreviated records by reading past their entries.
   if (AbbrevID == bitc::UNABBREV_RECORD) {
     unsigned Code = ReadVBR(6);
     (void)Code;
     unsigned NumElts = ReadVBR(6);
     for (unsigned i = 0; i != NumElts; ++i)
       (void)ReadVBR64(6);
     return;
   }

   const BitCodeAbbrev *Abbv = getAbbrev(AbbrevID);

   for (unsigned i = 0, e = Abbv->getNumOperandInfos(); i != e; ++i) {
     const BitCodeAbbrevOp &Op = Abbv->getOperandInfo(i);
     if (Op.isLiteral())
       continue;

     if (Op.getEncoding() != BitCodeAbbrevOp::Array &&
         Op.getEncoding() != BitCodeAbbrevOp::Blob) {
       skipAbbreviatedField(Op);
       continue;
     }

     if (Op.getEncoding() == BitCodeAbbrevOp::Array) {
       // Array case.  Read the number of elements as a vbr6.
       unsigned NumElts = ReadVBR(6);

       // Get the element encoding.
       assert(i+2 == e && "array op not second to last?");
       const BitCodeAbbrevOp &EltEnc = Abbv->getOperandInfo(++i);

       // Read all the elements.
       for (; NumElts; --NumElts)
         skipAbbreviatedField(EltEnc);
       continue;
     }

     assert(Op.getEncoding() == BitCodeAbbrevOp::Blob);
     // Blob case.  Read the number of bytes as a vbr6.
     unsigned NumElts = ReadVBR(6);
     SkipToFourByteBoundary();  // 32-bit alignment

     // Figure out where the end of this blob will be including tail padding.
     size_t NewEnd = GetCurrentBitNo()+((NumElts+3)&~3)*8;

     // If this would read off the end of the bitcode file, just set the
     // record to empty and return.
     if (!canSkipToPos(NewEnd/8)) {
       NextChar = BitStream->getBitcodeBytes().getExtent();
       break;
     }

     // Skip over the blob.
     JumpToBit(NewEnd);
   }
 }

 unsigned BitstreamCursor::readRecord(unsigned AbbrevID,
                                      SmallVectorImpl<uint64_t> &Vals,
                                      StringRef *Blob) {
   if (AbbrevID == bitc::UNABBREV_RECORD) {
     unsigned Code = ReadVBR(6);
     unsigned NumElts = ReadVBR(6);
     for (unsigned i = 0; i != NumElts; ++i)
       Vals.push_back(ReadVBR64(6));
     return Code;
   }

   const BitCodeAbbrev *Abbv = getAbbrev(AbbrevID);

   for (unsigned i = 0, e = Abbv->getNumOperandInfos(); i != e; ++i) {
     const BitCodeAbbrevOp &Op = Abbv->getOperandInfo(i);
     if (Op.isLiteral()) {
       readAbbreviatedLiteral(Op, Vals);
       continue;
     }

     if (Op.getEncoding() != BitCodeAbbrevOp::Array &&
         Op.getEncoding() != BitCodeAbbrevOp::Blob) {
       readAbbreviatedField(Op, Vals);
       continue;
     }

     if (Op.getEncoding() == BitCodeAbbrevOp::Array) {
       // Array case.  Read the number of elements as a vbr6.
       unsigned NumElts = ReadVBR(6);

       // Get the element encoding.
       assert(i+2 == e && "array op not second to last?");
       const BitCodeAbbrevOp &EltEnc = Abbv->getOperandInfo(++i);

       // Read all the elements.
       for (; NumElts; --NumElts)
         readAbbreviatedField(EltEnc, Vals);
       continue;
     }

     assert(Op.getEncoding() == BitCodeAbbrevOp::Blob);
     // Blob case.  Read the number of bytes as a vbr6.
     unsigned NumElts = ReadVBR(6);
     SkipToFourByteBoundary();  // 32-bit alignment

     // Figure out where the end of this blob will be including tail padding.
     size_t CurBitPos = GetCurrentBitNo();
     size_t NewEnd = CurBitPos+((NumElts+3)&~3)*8;

     // If this would read off the end of the bitcode file, just set the
     // record to empty and return.
     if (!canSkipToPos(NewEnd/8)) {
       Vals.append(NumElts, 0);
       NextChar = BitStream->getBitcodeBytes().getExtent();
       break;
     }

     // Otherwise, inform the streamer that we need these bytes in memory.
     const char *Ptr = (const char*)
       BitStream->getBitcodeBytes().getPointer(CurBitPos/8, NumElts);

     // If we can return a reference to the data, do so to avoid copying it.
     if (Blob) {
       *Blob = StringRef(Ptr, NumElts);
     } else {
       // Otherwise, unpack into Vals with zero extension.
       for (; NumElts; --NumElts)
         Vals.push_back((unsigned char)*Ptr++);
     }
     // Skip over tail padding.
     JumpToBit(NewEnd);
   }

   unsigned Code = (unsigned)Vals[0];
   Vals.erase(Vals.begin());
   return Code;
 }


 void BitstreamCursor::ReadAbbrevRecord() {
   BitCodeAbbrev *Abbv = new BitCodeAbbrev();
   unsigned NumOpInfo = ReadVBR(5);
   for (unsigned i = 0; i != NumOpInfo; ++i) {
     bool IsLiteral = Read(1) ? true : false;
     if (IsLiteral) {
       Abbv->Add(BitCodeAbbrevOp(ReadVBR64(8)));
       continue;
     }

     BitCodeAbbrevOp::Encoding E = (BitCodeAbbrevOp::Encoding)Read(3);
     if (BitCodeAbbrevOp::hasEncodingData(E)) {
       unsigned Data = ReadVBR64(5);

       // As a special case, handle fixed(0) (i.e., a fixed field with zero bits)
       // and vbr(0) as a literal zero.  This is decoded the same way, and avoids
       // a slow path in Read() to have to handle reading zero bits.
       if ((E == BitCodeAbbrevOp::Fixed || E == BitCodeAbbrevOp::VBR) &&
           Data == 0) {
         Abbv->Add(BitCodeAbbrevOp(0));
         continue;
       }

       Abbv->Add(BitCodeAbbrevOp(E, Data));
     } else
       Abbv->Add(BitCodeAbbrevOp(E));
   }
   CurAbbrevs.push_back(Abbv);
 }

 bool BitstreamCursor::ReadBlockInfoBlock() {
   // If this is the second stream to get to the block info block, skip it.
   if (BitStream->hasBlockInfoRecords())
     return SkipBlock();

   if (EnterSubBlock(bitc::BLOCKINFO_BLOCK_ID)) return true;

   SmallVector<uint64_t, 64> Record;
   BitstreamReader::BlockInfo *CurBlockInfo = 0;

   // Read all the records for this module.
   while (1) {
     BitstreamEntry Entry = advanceSkippingSubblocks(AF_DontAutoprocessAbbrevs);

     switch (Entry.Kind) {
     case llvm::BitstreamEntry::SubBlock: // Handled for us already.
     case llvm::BitstreamEntry::Error:
       return true;
     case llvm::BitstreamEntry::EndBlock:
       return false;
     case llvm::BitstreamEntry::Record:
       // The interesting case.
       break;
     }

     // Read abbrev records, associate them with CurBID.
     if (Entry.ID == bitc::DEFINE_ABBREV) {
       if (!CurBlockInfo) return true;
       ReadAbbrevRecord();

       // ReadAbbrevRecord installs the abbrev in CurAbbrevs.  Move it to the
       // appropriate BlockInfo.
       BitCodeAbbrev *Abbv = CurAbbrevs.back();
       CurAbbrevs.pop_back();
       CurBlockInfo->Abbrevs.push_back(Abbv);
       continue;
     }

     // Read a record.
     Record.clear();
     switch (readRecord(Entry.ID, Record)) {
       default: break;  // Default behavior, ignore unknown content.
       case bitc::BLOCKINFO_CODE_SETBID:
         if (Record.size() < 1) return true;
         CurBlockInfo = &BitStream->getOrCreateBlockInfo((unsigned)Record[0]);
         break;
       case bitc::BLOCKINFO_CODE_BLOCKNAME: {
         if (!CurBlockInfo) return true;
         if (BitStream->isIgnoringBlockInfoNames()) break;  // Ignore name.
         std::string Name;
         for (unsigned i = 0, e = Record.size(); i != e; ++i)
           Name += (char)Record[i];
         CurBlockInfo->Name = Name;
         break;
       }
       case bitc::BLOCKINFO_CODE_SETRECORDNAME: {
         if (!CurBlockInfo) return true;
         if (BitStream->isIgnoringBlockInfoNames()) break;  // Ignore name.
         std::string Name;
         for (unsigned i = 1, e = Record.size(); i != e; ++i)
           Name += (char)Record[i];
         CurBlockInfo->RecordNames.push_back(std::make_pair((unsigned)Record[0],
                                                            Name));
         break;
       }
     }
   }
 }
	//===- BitstreamReader.cpp - BitstreamReader implementation ---------------===//
	//
	// The LLVM Compiler Infrastructure
	//
	// This file is distributed under the University of Illinois Open Source
	// License. See LICENSE.TXT for details.
	//
	//===----------------------------------------------------------------------===//

	#include "llvm/Bitcode/BitstreamReader.h"

	using namespace llvm;

	//===----------------------------------------------------------------------===//
	// BitstreamCursor implementation
	//===----------------------------------------------------------------------===//

	void BitstreamCursor::operator=(const BitstreamCursor &RHS) {
	freeState();

	BitStream = RHS.BitStream;
	NextChar = RHS.NextChar;
	CurWord = RHS.CurWord;
	BitsInCurWord = RHS.BitsInCurWord;
	CurCodeSize = RHS.CurCodeSize;

	// Copy abbreviations, and bump ref counts.
	CurAbbrevs = RHS.CurAbbrevs;
	for (size_t i = 0, e = CurAbbrevs.size(); i != e; ++i)
	CurAbbrevs[i]->addRef();

	// Copy block scope and bump ref counts.
	BlockScope = RHS.BlockScope;
	for (size_t S = 0, e = BlockScope.size(); S != e; ++S) {
	std::vector<BitCodeAbbrev*> &Abbrevs = BlockScope[S].PrevAbbrevs;
	for (size_t i = 0, e = Abbrevs.size(); i != e; ++i)
	Abbrevs[i]->addRef();
	}
	}

	void BitstreamCursor::freeState() {
	// Free all the Abbrevs.
	for (size_t i = 0, e = CurAbbrevs.size(); i != e; ++i)
	CurAbbrevs[i]->dropRef();
	CurAbbrevs.clear();

	// Free all the Abbrevs in the block scope.
	for (size_t S = 0, e = BlockScope.size(); S != e; ++S) {
	std::vector<BitCodeAbbrev*> &Abbrevs = BlockScope[S].PrevAbbrevs;
	for (size_t i = 0, e = Abbrevs.size(); i != e; ++i)
	Abbrevs[i]->dropRef();
	}
	BlockScope.clear();
	}

	/// EnterSubBlock - Having read the ENTER_SUBBLOCK abbrevid, enter
	/// the block, and return true if the block has an error.
	bool BitstreamCursor::EnterSubBlock(unsigned BlockID, unsigned *NumWordsP) {
	// Save the current block's state on BlockScope.
	BlockScope.push_back(Block(CurCodeSize));
	BlockScope.back().PrevAbbrevs.swap(CurAbbrevs);

	// Add the abbrevs specific to this block to the CurAbbrevs list.
	if (const BitstreamReader::BlockInfo *Info =
	BitStream->getBlockInfo(BlockID)) {
	for (size_t i = 0, e = Info->Abbrevs.size(); i != e; ++i) {
	CurAbbrevs.push_back(Info->Abbrevs[i]);
	CurAbbrevs.back()->addRef();
	}
	}

	// Get the codesize of this block.
	CurCodeSize = ReadVBR(bitc::CodeLenWidth);
	SkipToFourByteBoundary();
	unsigned NumWords = Read(bitc::BlockSizeWidth);
	if (NumWordsP) *NumWordsP = NumWords;

	// Validate that this block is sane.
	if (CurCodeSize == 0 \|\| AtEndOfStream())
	return true;

	return false;
	}

	void BitstreamCursor::readAbbreviatedLiteral(const BitCodeAbbrevOp &Op,
	SmallVectorImpl<uint64_t> &Vals) {
	assert(Op.isLiteral() && "Not a literal");
	// If the abbrev specifies the literal value to use, use it.
	Vals.push_back(Op.getLiteralValue());
	}

	void BitstreamCursor::readAbbreviatedField(const BitCodeAbbrevOp &Op,
	SmallVectorImpl<uint64_t> &Vals) {
	assert(!Op.isLiteral() && "Use ReadAbbreviatedLiteral for literals!");

	// Decode the value as we are commanded.
	switch (Op.getEncoding()) {
	case BitCodeAbbrevOp::Array:
	case BitCodeAbbrevOp::Blob:
	assert(0 && "Should not reach here");
	case BitCodeAbbrevOp::Fixed:
	Vals.push_back(Read((unsigned)Op.getEncodingData()));
	break;
	case BitCodeAbbrevOp::VBR:
	Vals.push_back(ReadVBR64((unsigned)Op.getEncodingData()));
	break;
	case BitCodeAbbrevOp::Char6:
	Vals.push_back(BitCodeAbbrevOp::DecodeChar6(Read(6)));
	break;
	}
	}

	void BitstreamCursor::skipAbbreviatedField(const BitCodeAbbrevOp &Op) {
	assert(!Op.isLiteral() && "Use ReadAbbreviatedLiteral for literals!");

	// Decode the value as we are commanded.
	switch (Op.getEncoding()) {
	case BitCodeAbbrevOp::Array:
	case BitCodeAbbrevOp::Blob:
	assert(0 && "Should not reach here");
	case BitCodeAbbrevOp::Fixed:
	(void)Read((unsigned)Op.getEncodingData());
	break;
	case BitCodeAbbrevOp::VBR:
	(void)ReadVBR64((unsigned)Op.getEncodingData());
	break;
	case BitCodeAbbrevOp::Char6:
	(void)Read(6);
	break;
	}
	}



	/// skipRecord - Read the current record and discard it.
	void BitstreamCursor::skipRecord(unsigned AbbrevID) {
	// Skip unabbreviated records by reading past their entries.
	if (AbbrevID == bitc::UNABBREV_RECORD) {
	unsigned Code = ReadVBR(6);
	(void)Code;
	unsigned NumElts = ReadVBR(6);
	for (unsigned i = 0; i != NumElts; ++i)
	(void)ReadVBR64(6);
	return;
	}

	const BitCodeAbbrev *Abbv = getAbbrev(AbbrevID);

	for (unsigned i = 0, e = Abbv->getNumOperandInfos(); i != e; ++i) {
	const BitCodeAbbrevOp &Op = Abbv->getOperandInfo(i);
	if (Op.isLiteral())
	continue;

	if (Op.getEncoding() != BitCodeAbbrevOp::Array &&
	Op.getEncoding() != BitCodeAbbrevOp::Blob) {
	skipAbbreviatedField(Op);
	continue;
	}

	if (Op.getEncoding() == BitCodeAbbrevOp::Array) {
	// Array case. Read the number of elements as a vbr6.
	unsigned NumElts = ReadVBR(6);

	// Get the element encoding.
	assert(i+2 == e && "array op not second to last?");
	const BitCodeAbbrevOp &EltEnc = Abbv->getOperandInfo(++i);

	// Read all the elements.
	for (; NumElts; --NumElts)
	skipAbbreviatedField(EltEnc);
	continue;
	}

	assert(Op.getEncoding() == BitCodeAbbrevOp::Blob);
	// Blob case. Read the number of bytes as a vbr6.
	unsigned NumElts = ReadVBR(6);
	SkipToFourByteBoundary(); // 32-bit alignment

	// Figure out where the end of this blob will be including tail padding.
	size_t NewEnd = GetCurrentBitNo()+((NumElts+3)&~3)*8;

	// If this would read off the end of the bitcode file, just set the
	// record to empty and return.
	if (!canSkipToPos(NewEnd/8)) {
	NextChar = BitStream->getBitcodeBytes().getExtent();
	break;
	}

	// Skip over the blob.
	JumpToBit(NewEnd);
	}
	}

	unsigned BitstreamCursor::readRecord(unsigned AbbrevID,
	SmallVectorImpl<uint64_t> &Vals,
	StringRef *Blob) {
	if (AbbrevID == bitc::UNABBREV_RECORD) {
	unsigned Code = ReadVBR(6);
	unsigned NumElts = ReadVBR(6);
	for (unsigned i = 0; i != NumElts; ++i)
	Vals.push_back(ReadVBR64(6));
	return Code;
	}

	const BitCodeAbbrev *Abbv = getAbbrev(AbbrevID);

	for (unsigned i = 0, e = Abbv->getNumOperandInfos(); i != e; ++i) {
	const BitCodeAbbrevOp &Op = Abbv->getOperandInfo(i);
	if (Op.isLiteral()) {
	readAbbreviatedLiteral(Op, Vals);
	continue;
	}

	if (Op.getEncoding() != BitCodeAbbrevOp::Array &&
	Op.getEncoding() != BitCodeAbbrevOp::Blob) {
	readAbbreviatedField(Op, Vals);
	continue;
	}

	if (Op.getEncoding() == BitCodeAbbrevOp::Array) {
	// Array case. Read the number of elements as a vbr6.
	unsigned NumElts = ReadVBR(6);

	// Get the element encoding.
	assert(i+2 == e && "array op not second to last?");
	const BitCodeAbbrevOp &EltEnc = Abbv->getOperandInfo(++i);

	// Read all the elements.
	for (; NumElts; --NumElts)
	readAbbreviatedField(EltEnc, Vals);
	continue;
	}

	assert(Op.getEncoding() == BitCodeAbbrevOp::Blob);
	// Blob case. Read the number of bytes as a vbr6.
	unsigned NumElts = ReadVBR(6);
	SkipToFourByteBoundary(); // 32-bit alignment

	// Figure out where the end of this blob will be including tail padding.
	size_t CurBitPos = GetCurrentBitNo();
	size_t NewEnd = CurBitPos+((NumElts+3)&~3)*8;

	// If this would read off the end of the bitcode file, just set the
	// record to empty and return.
	if (!canSkipToPos(NewEnd/8)) {
	Vals.append(NumElts, 0);
	NextChar = BitStream->getBitcodeBytes().getExtent();
	break;
	}

	// Otherwise, inform the streamer that we need these bytes in memory.
	const char Ptr = (const char)
	BitStream->getBitcodeBytes().getPointer(CurBitPos/8, NumElts);

	// If we can return a reference to the data, do so to avoid copying it.
	if (Blob) {
	*Blob = StringRef(Ptr, NumElts);
	} else {
	// Otherwise, unpack into Vals with zero extension.
	for (; NumElts; --NumElts)
	Vals.push_back((unsigned char)*Ptr++);
	}
	// Skip over tail padding.
	JumpToBit(NewEnd);
	}

	unsigned Code = (unsigned)Vals[0];
	Vals.erase(Vals.begin());
	return Code;
	}


	void BitstreamCursor::ReadAbbrevRecord() {
	BitCodeAbbrev *Abbv = new BitCodeAbbrev();
	unsigned NumOpInfo = ReadVBR(5);
	for (unsigned i = 0; i != NumOpInfo; ++i) {
	bool IsLiteral = Read(1) ? true : false;
	if (IsLiteral) {
	Abbv->Add(BitCodeAbbrevOp(ReadVBR64(8)));
	continue;
	}

	BitCodeAbbrevOp::Encoding E = (BitCodeAbbrevOp::Encoding)Read(3);
	if (BitCodeAbbrevOp::hasEncodingData(E)) {
	unsigned Data = ReadVBR64(5);

	// As a special case, handle fixed(0) (i.e., a fixed field with zero bits)
	// and vbr(0) as a literal zero. This is decoded the same way, and avoids
	// a slow path in Read() to have to handle reading zero bits.
	if ((E == BitCodeAbbrevOp::Fixed \|\| E == BitCodeAbbrevOp::VBR) &&
	Data == 0) {
	Abbv->Add(BitCodeAbbrevOp(0));
	continue;
	}

	Abbv->Add(BitCodeAbbrevOp(E, Data));
	} else
	Abbv->Add(BitCodeAbbrevOp(E));
	}
	CurAbbrevs.push_back(Abbv);
	}

	bool BitstreamCursor::ReadBlockInfoBlock() {
	// If this is the second stream to get to the block info block, skip it.
	if (BitStream->hasBlockInfoRecords())
	return SkipBlock();

	if (EnterSubBlock(bitc::BLOCKINFO_BLOCK_ID)) return true;

	SmallVector<uint64_t, 64> Record;
	BitstreamReader::BlockInfo *CurBlockInfo = 0;

	// Read all the records for this module.
	while (1) {
	BitstreamEntry Entry = advanceSkippingSubblocks(AF_DontAutoprocessAbbrevs);

	switch (Entry.Kind) {
	case llvm::BitstreamEntry::SubBlock: // Handled for us already.
	case llvm::BitstreamEntry::Error:
	return true;
	case llvm::BitstreamEntry::EndBlock:
	return false;
	case llvm::BitstreamEntry::Record:
	// The interesting case.
	break;
	}

	// Read abbrev records, associate them with CurBID.
	if (Entry.ID == bitc::DEFINE_ABBREV) {
	if (!CurBlockInfo) return true;
	ReadAbbrevRecord();

	// ReadAbbrevRecord installs the abbrev in CurAbbrevs. Move it to the
	// appropriate BlockInfo.
	BitCodeAbbrev *Abbv = CurAbbrevs.back();
	CurAbbrevs.pop_back();
	CurBlockInfo->Abbrevs.push_back(Abbv);
	continue;
	}

	// Read a record.
	Record.clear();
	switch (readRecord(Entry.ID, Record)) {
	default: break; // Default behavior, ignore unknown content.
	case bitc::BLOCKINFO_CODE_SETBID:
	if (Record.size() < 1) return true;
	CurBlockInfo = &BitStream->getOrCreateBlockInfo((unsigned)Record[0]);
	break;
	case bitc::BLOCKINFO_CODE_BLOCKNAME: {
	if (!CurBlockInfo) return true;
	if (BitStream->isIgnoringBlockInfoNames()) break; // Ignore name.
	std::string Name;
	for (unsigned i = 0, e = Record.size(); i != e; ++i)
	Name += (char)Record[i];
	CurBlockInfo->Name = Name;
	break;
	}
	case bitc::BLOCKINFO_CODE_SETRECORDNAME: {
	if (!CurBlockInfo) return true;
	if (BitStream->isIgnoringBlockInfoNames()) break; // Ignore name.
	std::string Name;
	for (unsigned i = 1, e = Record.size(); i != e; ++i)
	Name += (char)Record[i];
	CurBlockInfo->RecordNames.push_back(std::make_pair((unsigned)Record[0],
	Name));
	break;
	}
	}
	}
	}