| //===- 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/StreamableMemoryObject.h" |
| #include <climits> |
| #include <string> |
| #include <vector> |
| |
| namespace llvm { |
| |
| class Deserializer; |
| |
| /// BitstreamReader - 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: |
| /// 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<BitCodeAbbrev*> Abbrevs; |
| std::string Name; |
| |
| std::vector<std::pair<unsigned, std::string> > RecordNames; |
| }; |
| private: |
| std::unique_ptr<StreamableMemoryObject> BitcodeBytes; |
| |
| std::vector<BlockInfo> BlockInfoRecords; |
| |
| /// IgnoreBlockInfoNames - 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&) LLVM_DELETED_FUNCTION; |
| void operator=(const BitstreamReader&) LLVM_DELETED_FUNCTION; |
| public: |
| BitstreamReader() : IgnoreBlockInfoNames(true) { |
| } |
| |
| BitstreamReader(const unsigned char *Start, const unsigned char *End) { |
| IgnoreBlockInfoNames = true; |
| init(Start, End); |
| } |
| |
| BitstreamReader(StreamableMemoryObject *bytes) { |
| BitcodeBytes.reset(bytes); |
| } |
| |
| 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)); |
| } |
| |
| StreamableMemoryObject &getBitcodeBytes() { return *BitcodeBytes; } |
| |
| ~BitstreamReader() { |
| // Free the BlockInfoRecords. |
| while (!BlockInfoRecords.empty()) { |
| BlockInfo &Info = BlockInfoRecords.back(); |
| // Free blockinfo abbrev info. |
| for (unsigned i = 0, e = static_cast<unsigned>(Info.Abbrevs.size()); |
| i != e; ++i) |
| Info.Abbrevs[i]->dropRef(); |
| BlockInfoRecords.pop_back(); |
| } |
| } |
| |
| /// CollectBlockInfoNames - This is called by clients that want block/record |
| /// name information. |
| void CollectBlockInfoNames() { IgnoreBlockInfoNames = false; } |
| bool isIgnoringBlockInfoNames() { return IgnoreBlockInfoNames; } |
| |
| //===--------------------------------------------------------------------===// |
| // Block Manipulation |
| //===--------------------------------------------------------------------===// |
| |
| /// hasBlockInfoRecords - 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(); } |
| |
| /// getBlockInfo - 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.push_back(BlockInfo()); |
| BlockInfoRecords.back().BlockID = BlockID; |
| return BlockInfoRecords.back(); |
| } |
| }; |
| |
| |
| /// BitstreamEntry - When advancing through a bitstream cursor, each advance can |
| /// discover a few different kinds of entries: |
| /// 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. |
| /// |
| struct BitstreamEntry { |
| enum { |
| Error, |
| EndBlock, |
| SubBlock, |
| Record |
| } 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; |
| } |
| }; |
| |
| /// BitstreamCursor - 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 { |
| friend class Deserializer; |
| BitstreamReader *BitStream; |
| size_t NextChar; |
| |
| |
| /// CurWord/word_t - 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 uint32_t word_t; |
| word_t CurWord; |
| |
| /// BitsInCurWord - This is the number of bits in CurWord that are valid. This |
| /// is always from [0...31/63] inclusive (depending on word size). |
| unsigned BitsInCurWord; |
| |
| // CurCodeSize - This is the declared size of code values used for the current |
| // block, in bits. |
| unsigned CurCodeSize; |
| |
| /// CurAbbrevs - Abbrevs installed at in this block. |
| std::vector<BitCodeAbbrev*> CurAbbrevs; |
| |
| struct Block { |
| unsigned PrevCodeSize; |
| std::vector<BitCodeAbbrev*> PrevAbbrevs; |
| explicit Block(unsigned PCS) : PrevCodeSize(PCS) {} |
| }; |
| |
| /// BlockScope - This tracks the codesize of parent blocks. |
| SmallVector<Block, 8> BlockScope; |
| |
| |
| public: |
| BitstreamCursor() : BitStream(nullptr), NextChar(0) {} |
| BitstreamCursor(const BitstreamCursor &RHS) |
| : BitStream(nullptr), NextChar(0) { |
| operator=(RHS); |
| } |
| |
| explicit BitstreamCursor(BitstreamReader &R) : BitStream(&R) { |
| NextChar = 0; |
| CurWord = 0; |
| BitsInCurWord = 0; |
| CurCodeSize = 2; |
| } |
| |
| void init(BitstreamReader &R) { |
| freeState(); |
| |
| BitStream = &R; |
| NextChar = 0; |
| CurWord = 0; |
| BitsInCurWord = 0; |
| CurCodeSize = 2; |
| } |
| |
| ~BitstreamCursor() { |
| freeState(); |
| } |
| |
| void operator=(const BitstreamCursor &RHS); |
| |
| void freeState(); |
| |
| bool isEndPos(size_t pos) { |
| return BitStream->getBitcodeBytes().isObjectEnd(static_cast<uint64_t>(pos)); |
| } |
| |
| 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)); |
| } |
| |
| uint32_t getWord(size_t pos) { |
| uint8_t buf[4] = { 0xFF, 0xFF, 0xFF, 0xFF }; |
| BitStream->getBitcodeBytes().readBytes(pos, sizeof(buf), buf); |
| return *reinterpret_cast<support::ulittle32_t *>(buf); |
| } |
| |
| bool AtEndOfStream() { |
| return BitsInCurWord == 0 && isEndPos(NextChar); |
| } |
| |
| /// getAbbrevIDWidth - Return the number of bits used to encode an abbrev #. |
| unsigned getAbbrevIDWidth() const { return CurCodeSize; } |
| |
| /// GetCurrentBitNo - 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 { |
| /// AF_DontPopBlockAtEnd - 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, |
| |
| /// AF_DontAutoprocessAbbrevs - If this flag is used, abbrev entries are |
| /// returned just like normal records. |
| AF_DontAutoprocessAbbrevs = 2 |
| }; |
| |
| /// advance - 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); |
| } |
| } |
| |
| /// advanceSkippingSubblocks - 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(); |
| } |
| } |
| |
| /// JumpToBit - Reset the stream to the specified bit number. |
| void JumpToBit(uint64_t BitNo) { |
| uintptr_t ByteNo = uintptr_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; |
| CurWord = 0; |
| |
| // Skip over any bits that are already consumed. |
| if (WordBitNo) { |
| if (sizeof(word_t) > 4) |
| Read64(WordBitNo); |
| else |
| Read(WordBitNo); |
| } |
| } |
| |
| |
| uint32_t Read(unsigned NumBits) { |
| assert(NumBits && NumBits <= 32 && |
| "Cannot return zero or more than 32 bits!"); |
| |
| // If the field is fully contained by CurWord, return it quickly. |
| if (BitsInCurWord >= NumBits) { |
| uint32_t R = uint32_t(CurWord) & (~0U >> (32-NumBits)); |
| CurWord >>= NumBits; |
| BitsInCurWord -= NumBits; |
| return R; |
| } |
| |
| // If we run out of data, stop at the end of the stream. |
| if (isEndPos(NextChar)) { |
| CurWord = 0; |
| BitsInCurWord = 0; |
| return 0; |
| } |
| |
| uint32_t R = uint32_t(CurWord); |
| |
| // Read the next word from the stream. |
| uint8_t Array[sizeof(word_t)] = {0}; |
| |
| BitStream->getBitcodeBytes().readBytes(NextChar, sizeof(Array), Array); |
| |
| // Handle big-endian byte-swapping if necessary. |
| support::detail::packed_endian_specific_integral |
| <word_t, support::little, support::unaligned> EndianValue; |
| memcpy(&EndianValue, Array, sizeof(Array)); |
| |
| CurWord = EndianValue; |
| |
| NextChar += sizeof(word_t); |
| |
| // Extract NumBits-BitsInCurWord from what we just read. |
| unsigned BitsLeft = NumBits-BitsInCurWord; |
| |
| // Be careful here, BitsLeft is in the range [1..32]/[1..64] inclusive. |
| R |= uint32_t((CurWord & (word_t(~0ULL) >> (sizeof(word_t)*8-BitsLeft))) |
| << BitsInCurWord); |
| |
| // BitsLeft bits have just been used up from CurWord. BitsLeft is in the |
| // range [1..32]/[1..64] so be careful how we shift. |
| if (BitsLeft != sizeof(word_t)*8) |
| CurWord >>= BitsLeft; |
| else |
| CurWord = 0; |
| BitsInCurWord = sizeof(word_t)*8-BitsLeft; |
| return R; |
| } |
| |
| uint64_t Read64(unsigned NumBits) { |
| if (NumBits <= 32) return Read(NumBits); |
| |
| uint64_t V = Read(32); |
| return V | (uint64_t)Read(NumBits-32) << 32; |
| } |
| |
| 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); |
| } |
| } |
| |
| // ReadVBR64 - 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; |
| CurWord = 0; |
| } |
| public: |
| |
| unsigned ReadCode() { |
| return Read(CurCodeSize); |
| } |
| |
| |
| // Block header: |
| // [ENTER_SUBBLOCK, blockid, newcodelen, <align4bytes>, blocklen] |
| |
| /// ReadSubBlockID - Having read the ENTER_SUBBLOCK code, read the BlockID for |
| /// the block. |
| unsigned ReadSubBlockID() { |
| return ReadVBR(bitc::BlockIDWidth); |
| } |
| |
| /// SkipBlock - 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; |
| } |
| |
| /// EnterSubBlock - 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; |
| |
| // Delete abbrevs from popped scope. |
| for (unsigned i = 0, e = static_cast<unsigned>(CurAbbrevs.size()); |
| i != e; ++i) |
| CurAbbrevs[i]->dropRef(); |
| |
| BlockScope.back().PrevAbbrevs.swap(CurAbbrevs); |
| BlockScope.pop_back(); |
| } |
| |
| //===--------------------------------------------------------------------===// |
| // Record Processing |
| //===--------------------------------------------------------------------===// |
| |
| private: |
| void readAbbreviatedLiteral(const BitCodeAbbrevOp &Op, |
| SmallVectorImpl<uint64_t> &Vals); |
| void readAbbreviatedField(const BitCodeAbbrevOp &Op, |
| SmallVectorImpl<uint64_t> &Vals); |
| void skipAbbreviatedField(const BitCodeAbbrevOp &Op); |
| |
| public: |
| |
| /// getAbbrev - Return the abbreviation for the specified AbbrevId. |
| const BitCodeAbbrev *getAbbrev(unsigned AbbrevID) { |
| unsigned AbbrevNo = AbbrevID-bitc::FIRST_APPLICATION_ABBREV; |
| assert(AbbrevNo < CurAbbrevs.size() && "Invalid abbrev #!"); |
| return CurAbbrevs[AbbrevNo]; |
| } |
| |
| /// skipRecord - 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 |