| //===- NaClBitstreamReader.h -----------------------------------*- C++ -*-===// |
| // Low-level bitstream reader interface |
| // |
| // 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_NACL_NACLBITSTREAMREADER_H |
| #define LLVM_BITCODE_NACL_NACLBITSTREAMREADER_H |
| |
| #include "llvm/ADT/SmallVector.h" |
| #include "llvm/Bitcode/NaCl/NaClBitcodeHeader.h" |
| #include "llvm/Bitcode/NaCl/NaClLLVMBitCodes.h" |
| #include "llvm/Support/Endian.h" |
| #include "llvm/Support/StreamingMemoryObject.h" |
| #include <atomic> |
| #include <climits> |
| #include <mutex> |
| #include <unordered_map> |
| #include <vector> |
| |
| namespace llvm { |
| |
| class Deserializer; |
| class NaClBitstreamCursor; |
| |
| namespace naclbitc { |
| |
| /// Returns the Bit as a Byte:BitInByte string. |
| std::string getBitAddress(uint64_t Bit); |
| |
| /// Severity levels for reporting errors. |
| enum ErrorLevel { |
| Warning, |
| Error, |
| Fatal |
| }; |
| |
| // Basic printing routine to generate the beginning of an error |
| // message. BitPosition is the bit position the error was found. |
| // Level is the severity of the error. |
| raw_ostream &ErrorAt(raw_ostream &Out, ErrorLevel Level, |
| uint64_t BitPosition); |
| |
| } // End namespace naclbitc. |
| |
| /// This class is used to read from a NaCl bitcode wire format 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 NaClBitstreamCursor class. |
| class NaClBitstreamReader { |
| public: |
| // Models a raw list of abbreviations. |
| static const size_t DefaultAbbrevListSize = 12; |
| using AbbrevListVector = SmallVector<NaClBitCodeAbbrev *, |
| DefaultAbbrevListSize>; |
| |
| // Models and maintains a list of abbreviations. In particular, it maintains |
| // updating reference counts of abbreviation operators within the abbreviation |
| // list. |
| class AbbrevList { |
| public: |
| AbbrevList() = default; |
| explicit AbbrevList(const AbbrevList &NewAbbrevs) { |
| appendList(NewAbbrevs); |
| } |
| AbbrevList &operator=(const AbbrevList &Rhs) { |
| clear(); |
| appendList(Rhs); |
| return *this; |
| } |
| // Creates a new (empty) abbreviation, appends it to this, and then returns |
| // the new abbreviation. |
| NaClBitCodeAbbrev *appendCreate() { |
| NaClBitCodeAbbrev *Abbv = new NaClBitCodeAbbrev(); |
| Abbrevs.push_back(Abbv); |
| return Abbv; |
| } |
| // Appends the given abbreviation to this. |
| void append(NaClBitCodeAbbrev *Abbrv) { |
| Abbrv->addRef(); |
| Abbrevs.push_back(Abbrv); |
| } |
| // Appends the contents of NewAbbrevs to this. |
| void appendList(const AbbrevList &NewAbbrevs) { |
| for (NaClBitCodeAbbrev *Abbrv : NewAbbrevs.Abbrevs) |
| append(Abbrv); |
| } |
| // Returns last abbreviation on list. |
| NaClBitCodeAbbrev *last() { return Abbrevs.back(); } |
| // Removes the last element of the list. |
| void popLast() { |
| Abbrevs.back()->dropRef(); |
| Abbrevs.pop_back(); |
| } |
| // Empties abbreviation list. |
| void clear() { |
| while(!Abbrevs.empty()) |
| popLast(); |
| } |
| // Allow read access to vector defining list. |
| const AbbrevListVector &getVector() const { return Abbrevs; } |
| ~AbbrevList() { clear(); } |
| private: |
| AbbrevListVector Abbrevs; |
| }; |
| |
| /// This contains information about abbreviations in blocks defined in the |
| /// BLOCKINFO_BLOCK block. These describe global abbreviations that apply to |
| /// all succeeding blocks of the specified ID. |
| class BlockInfo { |
| BlockInfo &operator=(const BlockInfo&) = delete; |
| public: |
| BlockInfo() = default; |
| explicit BlockInfo(unsigned BlockID) |
| : BlockID(BlockID), Abbrevs() {} |
| BlockInfo(const BlockInfo&) = default; |
| unsigned getBlockID() const { return BlockID; } |
| void setBlockID(unsigned ID) { BlockID = ID; } |
| AbbrevList &getAbbrevs() { return Abbrevs; } |
| ~BlockInfo() {} |
| private: |
| unsigned BlockID; |
| AbbrevList Abbrevs; |
| }; |
| |
| class BlockInfoRecordsMap; |
| using SharedBlockInfoMap = std::shared_ptr<BlockInfoRecordsMap>; |
| |
| // Holds the global abbreviations in the BlockInfo block of the bitcode file. |
| // Sharing is used to allow parallel parses. Share by using std::share_ptr's |
| // and std::shared_from_this(). |
| // |
| // Note: The BlockInfo block must be parsed before sharing of the |
| // BlockInfoRecordsMap. Therefore, before changing to a parallel parse, the |
| // BlockInfoRecordsMap must be frozen. Failure to do so, can lead to |
| // unexpected behaviour. |
| // |
| // In practice, this means that only function blocks can be parsed in |
| // parallel. |
| class BlockInfoRecordsMap : |
| public std::enable_shared_from_this<BlockInfoRecordsMap> { |
| friend class NaClBitstreamReader; |
| BlockInfoRecordsMap(const BlockInfoRecordsMap&) = delete; |
| BlockInfoRecordsMap &operator=(const BlockInfoRecordsMap&) = delete; |
| public: |
| using InfosMap = std::unordered_map<unsigned, std::unique_ptr<BlockInfo>>; |
| |
| static SharedBlockInfoMap create() { |
| return SharedBlockInfoMap(new BlockInfoRecordsMap()); |
| } |
| ~BlockInfoRecordsMap() = default; |
| |
| bool isFrozen() const { |
| return IsFrozen.load(); |
| } |
| |
| // Returns true if already frozen. |
| bool freeze() { |
| return IsFrozen.exchange(true); |
| } |
| |
| BlockInfo *getBlockInfo(unsigned BlockID) { |
| auto Pos = KnownInfos.find(BlockID); |
| if (Pos != KnownInfos.end()) |
| return Pos->second.get(); |
| return getOrCreateUnknownBlockInfo(BlockID); |
| } |
| |
| // Locks the BlockInfoRecordsMap for the lifetime of the UpdateLock. Used |
| // to allow the parsing of a BlockInfo block, and install global |
| // abbreviations. |
| // |
| // Verifies that the BlockInfoRecordsMap didn't get frozen during the |
| // instance's lifetime as a safety precaution. That is, it checks that no |
| // bitstream reader was created to share the global abbreviations before the |
| // global abbreviations are defined. |
| class UpdateLock { |
| UpdateLock() = delete; |
| UpdateLock(const UpdateLock&) = delete; |
| UpdateLock &operator=(const UpdateLock&) = delete; |
| public: |
| explicit UpdateLock(BlockInfoRecordsMap &BlockInfoRecords); |
| ~UpdateLock(); |
| private: |
| // The BlockInfoRecordsMap to update. |
| BlockInfoRecordsMap &BlockInfoRecords; |
| // The locked mutex from BlockInfoRecordsMap; |
| std::unique_lock<std::mutex> Lock; |
| }; |
| |
| private: |
| // The set of known BlockInfo's. This map is prepopulated so that fast |
| // lookup can be performed thread safe (i.e. without using a lock). |
| InfosMap KnownInfos; |
| // The set of unknown BlockInfo's. This map is to handle unknown (and hence, |
| // invalid) PNaCl bitcode files. This map is updated incrementally, and uses |
| // UnknownBlockInfoLock to make it thread safe. |
| InfosMap UnknownInfos; |
| // True if the known BlockInfo blocks are frozen (i.e. the bitstream reader |
| // will ignore the BlockInfo block). |
| std::atomic_bool IsFrozen; |
| // Lock to use to update this data structure. |
| std::mutex UpdateRecordsLock; |
| // Lock to get/create an unknonw block info. |
| std::mutex UnknownBlockInfoLock; |
| |
| BlockInfoRecordsMap(); |
| |
| BlockInfo *getOrCreateUnknownBlockInfo(unsigned BlockID); |
| }; |
| |
| private: |
| friend class NaClBitstreamCursor; |
| |
| std::unique_ptr<MemoryObject> BitcodeBytes; |
| |
| SharedBlockInfoMap BlockInfoRecords; |
| |
| /// \brief Holds the offset of the first byte after the header. |
| size_t InitialAddress; |
| |
| // Holds the number of bytes to add to the bitcode position, when reporting |
| // errors. Useful when using parallel parses of function blocks. |
| size_t ErrorOffset = 0; |
| |
| // True if filler should be added to byte align records. |
| bool AlignBitcodeRecords = false; |
| NaClBitstreamReader(const NaClBitstreamReader&) = delete; |
| void operator=(const NaClBitstreamReader&) = delete; |
| |
| |
| void initFromHeader(NaClBitcodeHeader &Header) { |
| InitialAddress = Header.getHeaderSize(); |
| AlignBitcodeRecords = Header.getAlignBitcodeRecords(); |
| } |
| |
| public: |
| /// Read stream from sequence of bytes [Start .. End) after parsing |
| /// the given bitcode header. |
| NaClBitstreamReader(const unsigned char *Start, const unsigned char *End, |
| NaClBitcodeHeader &Header) |
| : BitcodeBytes(getNonStreamedMemoryObject(Start, End)), |
| BlockInfoRecords(BlockInfoRecordsMap::create()) { |
| initFromHeader(Header); |
| } |
| |
| /// Read stream from Bytes, after parsing the given bitcode header. |
| NaClBitstreamReader(MemoryObject *Bytes, NaClBitcodeHeader &Header) |
| : BitcodeBytes(Bytes), BlockInfoRecords(BlockInfoRecordsMap::create()) |
| { initFromHeader(Header); } |
| |
| /// Read stream from bytes, starting at the given initial address. |
| /// Provides simple API for unit testing. |
| NaClBitstreamReader(MemoryObject *Bytes, size_t InitialAddress) |
| : BitcodeBytes(Bytes), BlockInfoRecords(BlockInfoRecordsMap::create()), |
| InitialAddress(InitialAddress) {} |
| |
| /// Read stream from sequence of bytes [Start .. End), using the global |
| /// abbreviations of the given bitstream reader. Assumes that [Start .. End) |
| /// is copied from Reader's memory object. |
| NaClBitstreamReader(size_t StartAddress, const unsigned char *Start, |
| const unsigned char *End, NaClBitstreamReader *Reader) |
| : BitcodeBytes(getNonStreamedMemoryObject(Start, End)), |
| BlockInfoRecords(Reader->BlockInfoRecords), InitialAddress(0), |
| ErrorOffset(StartAddress) { BlockInfoRecords->freeze(); } |
| |
| // Returns the memory object that is being read. |
| MemoryObject &getBitcodeBytes() { return *BitcodeBytes; } |
| |
| ~NaClBitstreamReader() {} |
| |
| /// \brief Returns the initial address (after the header) of the input stream. |
| size_t getInitialAddress() const { |
| return InitialAddress; |
| } |
| |
| /// Returns the byte address of the first byte in the bitstream. Used |
| /// for error reporting. |
| size_t getErrorOffset() const { return ErrorOffset; } |
| |
| //===--------------------------------------------------------------------===// |
| // Block Manipulation |
| //===--------------------------------------------------------------------===// |
| |
| BlockInfo *getBlockInfo(unsigned BlockID) { |
| return BlockInfoRecords->getBlockInfo(BlockID); |
| } |
| }; |
| |
| /// When advancing through a bitstream cursor, each advance can discover a few |
| /// different kinds of entries: |
| struct NaClBitstreamEntry { |
| 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 NaClBitstreamEntry getError() { |
| NaClBitstreamEntry E; E.Kind = Error; return E; |
| } |
| static NaClBitstreamEntry getEndBlock() { |
| NaClBitstreamEntry E; E.Kind = EndBlock; return E; |
| } |
| static NaClBitstreamEntry getSubBlock(unsigned ID) { |
| NaClBitstreamEntry E; E.Kind = SubBlock; E.ID = ID; return E; |
| } |
| static NaClBitstreamEntry getRecord(unsigned AbbrevID) { |
| NaClBitstreamEntry E; E.Kind = Record; E.ID = AbbrevID; return E; |
| } |
| }; |
| |
| /// Models default view of a bitcode record. |
| typedef SmallVector<uint64_t, 8> NaClBitcodeRecordVector; |
| |
| /// Class NaClAbbrevListener is used to allow instances of class |
| /// NaClBitcodeParser to listen to record details when processing |
| /// abbreviations. The major reason for using a listener is that the |
| /// NaCl bitcode reader would require a major rewrite (including the |
| /// introduction of more overhead) if we were to lift abbreviations up |
| /// to the bitcode reader. That is, not only would we have to lift the |
| /// block processing up into the readers (i.e. many blocks in |
| /// NaClBitcodeReader and NaClBitcodeParser), but add many new API's |
| /// to allow the readers to update internals of the bit stream reader |
| /// appropriately. |
| class NaClAbbrevListener { |
| NaClAbbrevListener(const NaClAbbrevListener&) = delete; |
| void operator=(const NaClAbbrevListener&) = delete; |
| public: |
| NaClAbbrevListener() {} |
| virtual ~NaClAbbrevListener() {} |
| |
| /// Called to process the read abbreviation. |
| virtual void ProcessAbbreviation(NaClBitCodeAbbrev *Abbrv, |
| bool IsLocal) = 0; |
| |
| /// Called after entering block. NumWords is the number of words |
| /// in the block. |
| virtual void BeginBlockInfoBlock(unsigned NumWords) = 0; |
| |
| /// Called if a naclbitc::BLOCKINFO_CODE_SETBID record is found in |
| /// NaClBitstreamCursor::ReadBlockInfoBlock. |
| virtual void SetBID() = 0; |
| |
| /// Called just before an EndBlock record is processed by |
| /// NaClBitstreamCursor::ReadBlockInfoBlock |
| virtual void EndBlockInfoBlock() = 0; |
| |
| /// The values of the bitcode record associated with the called |
| /// virtual function. |
| NaClBitcodeRecordVector Values; |
| |
| /// Start bit for current record being processed in |
| /// NaClBitstreamCursor::ReadBlockInfoBlock. |
| uint64_t StartBit; |
| }; |
| |
| /// 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, NaClBitstreamCursors are heavy-weight objects |
| /// that should not be passed by value. |
| class NaClBitstreamCursor { |
| public: |
| /// This class handles errors in the bitstream reader. Redirects |
| /// fatal error messages to virtual method Fatal. |
| class ErrorHandler { |
| ErrorHandler(const ErrorHandler &) = delete; |
| ErrorHandler &operator=(const ErrorHandler &) = delete; |
| public: |
| explicit ErrorHandler(NaClBitstreamCursor &Cursor) : Cursor(Cursor) {} |
| LLVM_ATTRIBUTE_NORETURN |
| virtual void Fatal(const std::string &ErrorMessage) const; |
| virtual ~ErrorHandler() {} |
| uint64_t getCurrentBitNo() const { |
| return Cursor.GetCurrentBitNo(); |
| } |
| private: |
| NaClBitstreamCursor &Cursor; |
| }; |
| |
| private: |
| friend class Deserializer; |
| NaClBitstreamReader *BitStream; |
| size_t NextChar; |
| // The current error handler for the bitstream reader. |
| std::unique_ptr<ErrorHandler> ErrHandler; |
| |
| // The size of the bitcode. 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(word_t)-1] inclusive. |
| unsigned BitsInCurWord; |
| |
| // Data specific to a block being scanned. |
| class Block { |
| public: |
| Block() = delete; |
| Block &operator=(const Block &Rhs) { |
| GlobalAbbrevs = Rhs.GlobalAbbrevs; |
| NumGlobalAbbrevs = Rhs.NumGlobalAbbrevs; |
| LocalAbbrevs = Rhs.LocalAbbrevs; |
| CodeAbbrev = Rhs.CodeAbbrev; |
| return *this; |
| } |
| Block(NaClBitstreamReader::BlockInfo *GlobalAbbrevs, |
| NaClBitcodeSelectorAbbrev& CodeAbbrev) |
| : GlobalAbbrevs(GlobalAbbrevs), |
| NumGlobalAbbrevs(GlobalAbbrevs->getAbbrevs().getVector().size()), |
| LocalAbbrevs(), CodeAbbrev(CodeAbbrev) {} |
| Block(NaClBitstreamReader::BlockInfo *GlobalAbbrevs) |
| : GlobalAbbrevs(GlobalAbbrevs), |
| NumGlobalAbbrevs(GlobalAbbrevs->getAbbrevs().getVector().size()), |
| LocalAbbrevs(), CodeAbbrev() {} |
| ~Block() = default; |
| const NaClBitstreamReader::AbbrevList &getGlobalAbbrevs() const { |
| return GlobalAbbrevs->getAbbrevs(); |
| } |
| unsigned getNumGlobalAbbrevs() const { return NumGlobalAbbrevs; } |
| const NaClBitstreamReader::AbbrevList &getLocalAbbrevs() const { |
| return LocalAbbrevs; |
| } |
| const NaClBitcodeSelectorAbbrev &getCodeAbbrev() const { |
| return CodeAbbrev; |
| } |
| void setCodeAbbrev(NaClBitcodeSelectorAbbrev &Abbrev) { |
| CodeAbbrev = Abbrev; |
| } |
| NaClBitCodeAbbrev *appendLocalCreate() { |
| return LocalAbbrevs.appendCreate(); |
| } |
| void moveLocalAbbrevToAbbrevList(NaClBitstreamReader::AbbrevList *List) { |
| if (List != &LocalAbbrevs) { |
| NaClBitCodeAbbrev *Abbv = LocalAbbrevs.last(); |
| List->append(Abbv); |
| LocalAbbrevs.popLast(); |
| } |
| } |
| private: |
| friend class NaClBitstreamCursor; |
| // The global abbreviations associated with this scope. |
| NaClBitstreamReader::BlockInfo *GlobalAbbrevs; |
| // Number of abbreviations when block was entered. Used to limit scope of |
| // CurBlockInfo, since any abbreviation added inside a BlockInfo block |
| // (within this block) must not effect global abbreviations. |
| unsigned NumGlobalAbbrevs; |
| NaClBitstreamReader::AbbrevList LocalAbbrevs; |
| // This is the declared size of code values used for the current block, in |
| // bits. |
| NaClBitcodeSelectorAbbrev CodeAbbrev; |
| }; |
| |
| /// This tracks the Block-specific information for each nested block. |
| SmallVector<Block, 8> BlockScope; |
| |
| NaClBitstreamCursor(const NaClBitstreamCursor &) = delete; |
| NaClBitstreamCursor &operator=(const NaClBitstreamCursor &) = delete; |
| |
| public: |
| NaClBitstreamCursor() : ErrHandler(new ErrorHandler(*this)) { |
| init(nullptr); |
| } |
| |
| explicit NaClBitstreamCursor(NaClBitstreamReader &R) |
| : ErrHandler(new ErrorHandler(*this)) { init(&R); } |
| |
| void init(NaClBitstreamReader *R) { |
| freeState(); |
| BitStream = R; |
| NextChar = (BitStream == nullptr) ? 0 : BitStream->getInitialAddress(); |
| Size = 0; |
| BitsInCurWord = 0; |
| if (BitStream) { |
| BlockScope.push_back( |
| Block(BitStream->getBlockInfo(naclbitc::TOP_LEVEL_BLOCKID))); |
| } |
| } |
| |
| ~NaClBitstreamCursor() { |
| freeState(); |
| } |
| |
| void freeState() { |
| while (!BlockScope.empty()) |
| BlockScope.pop_back(); |
| } |
| |
| // Replaces the current bitstream error handler with the new |
| // handler. Takes ownership of the new handler and deletes it when |
| // it is no longer needed. |
| void setErrorHandler(std::unique_ptr<ErrorHandler> &NewHandler) { |
| ErrHandler = std::move(NewHandler); |
| } |
| |
| 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 BlockScope.back().getCodeAbbrev().NumBits; |
| } |
| |
| /// Return the bit # of the bit we are reading. |
| uint64_t GetCurrentBitNo() const { |
| return NextChar*CHAR_BIT - BitsInCurWord; |
| } |
| |
| /// Converts the given position into the corresponding Error position. |
| uint64_t getErrorBitNo(uint64_t Position) const { |
| return BitStream->getErrorOffset() * CHAR_BIT + Position; |
| } |
| |
| /// Returns the current bit address for reporting errors. |
| uint64_t getErrorBitNo() const { |
| return getErrorBitNo(GetCurrentBitNo()); |
| } |
| |
| NaClBitstreamReader *getBitStreamReader() { |
| return BitStream; |
| } |
| const NaClBitstreamReader *getBitStreamReader() const { |
| return BitStream; |
| } |
| |
| /// Returns the current bit address (string) of the bit cursor. |
| std::string getCurrentBitAddress() const { |
| return naclbitc::getBitAddress(GetCurrentBitNo()); |
| } |
| |
| /// 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. |
| /// Use the given abbreviation listener (if provided). |
| NaClBitstreamEntry advance(unsigned Flags, NaClAbbrevListener *Listener) { |
| while (1) { |
| unsigned Code = ReadCode(); |
| if (Code == naclbitc::END_BLOCK) { |
| // Pop the end of the block unless Flags tells us not to. |
| if (!(Flags & AF_DontPopBlockAtEnd) && ReadBlockEnd()) |
| return NaClBitstreamEntry::getError(); |
| return NaClBitstreamEntry::getEndBlock(); |
| } |
| |
| if (Code == naclbitc::ENTER_SUBBLOCK) |
| return NaClBitstreamEntry::getSubBlock(ReadSubBlockID()); |
| |
| if (Code == naclbitc::DEFINE_ABBREV && |
| !(Flags & AF_DontAutoprocessAbbrevs)) { |
| // We read and accumulate abbrev's, the client can't do anything with |
| // them anyway. |
| ReadAbbrevRecord(true, Listener); |
| continue; |
| } |
| |
| return NaClBitstreamEntry::getRecord(Code); |
| } |
| } |
| |
| /// This is a convenience function for clients that don't expect any |
| /// subblocks. This just skips over them automatically. |
| NaClBitstreamEntry advanceSkippingSubblocks(unsigned Flags = 0) { |
| while (1) { |
| // If we found a normal entry, return it. |
| NaClBitstreamEntry Entry = advance(Flags, 0); |
| if (Entry.Kind != NaClBitstreamEntry::SubBlock) |
| return Entry; |
| |
| // If we found a sub-block, just skip over it and check the next entry. |
| if (SkipBlock()) |
| return NaClBitstreamEntry::getError(); |
| } |
| } |
| |
| /// Returns the starting byte of the word containing BitNo. |
| uintptr_t getStartWordByteForBit(uint64_t BitNo) const { |
| return uintptr_t(BitNo/CHAR_BIT) & ~(sizeof(word_t)-1); |
| } |
| |
| /// Returns the index of BitNo within the word it appears in. |
| unsigned getWordBitNo(uint64_t BitNo) const { |
| return unsigned(BitNo & (sizeof(word_t)*CHAR_BIT-1)); |
| } |
| |
| /// Returns the ending byte of the word containing BitNo. |
| uintptr_t getEndWordByteForBit(uint64_t BitNo) const { |
| return getStartWordByteForBit(BitNo) + |
| (getWordBitNo(BitNo) |
| ? sizeof(word_t) |
| : 0); |
| } |
| |
| /// Fills Buffer[Size] using bytes at Address (in the memory object being |
| /// read). Returns number of bytes filled (less than Size if at end of memory |
| /// object). |
| uint64_t fillBuffer(uint8_t *Buffer, size_t Size, size_t Address) const { |
| return BitStream->getBitcodeBytes().readBytes(Buffer, Size, Address); |
| } |
| |
| /// Reset the stream to the specified bit number. |
| void JumpToBit(uint64_t BitNo) { |
| const uintptr_t ByteNo = getStartWordByteForBit(BitNo); |
| const unsigned WordBitNo = getWordBitNo(BitNo); |
| if (!canSkipToPos(ByteNo)) |
| reportInvalidJumpToBit(BitNo); |
| |
| // 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() { |
| assert(Size == 0 || NextChar < (unsigned)Size); |
| |
| // Read the next word from the stream. |
| uint8_t Array[sizeof(word_t)] = {0}; |
| |
| uint64_t BytesRead = fillBuffer(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 * CHAR_BIT; |
| } |
| |
| word_t Read(unsigned NumBits) { |
| static const unsigned BitsInWord = sizeof(word_t) * CHAR_BIT; |
| |
| 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 SkipToByteBoundary() { |
| unsigned BitsToSkip = BitsInCurWord % CHAR_BIT; |
| if (BitsToSkip) { |
| CurWord >>= BitsToSkip; |
| BitsInCurWord -= BitsToSkip; |
| } |
| } |
| |
| void SkipToByteBoundaryIfAligned() { |
| if (BitStream->AlignBitcodeRecords) |
| SkipToByteBoundary(); |
| } |
| |
| 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() { |
| const NaClBitcodeSelectorAbbrev &CodeAbbrev = |
| BlockScope.back().getCodeAbbrev(); |
| return CodeAbbrev.IsFixed |
| ? Read(CodeAbbrev.NumBits) |
| : ReadVBR(CodeAbbrev.NumBits); |
| } |
| |
| // Block header: |
| // [ENTER_SUBBLOCK, blockid, newcodelen, <align4bytes>, blocklen] |
| |
| /// Having read the ENTER_SUBBLOCK code, read the BlockID for the block. |
| unsigned ReadSubBlockID() { |
| return ReadVBR(naclbitc::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(naclbitc::CodeLenWidth); |
| SkipToFourByteBoundary(); |
| unsigned NumFourBytes = Read(naclbitc::BlockSizeWidth); |
| |
| // Check that the block wasn't partially defined, and that the offset isn't |
| // bogus. |
| size_t SkipTo = GetCurrentBitNo() + NumFourBytes*4*CHAR_BIT; |
| if (AtEndOfStream() || !canSkipToPos(SkipTo/CHAR_BIT)) |
| 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(); |
| |
| BlockScope.pop_back(); |
| return false; |
| } |
| |
| private: |
| |
| //===--------------------------------------------------------------------===// |
| // Record Processing |
| //===--------------------------------------------------------------------===// |
| |
| private: |
| // Returns abbreviation encoding associated with Value. |
| NaClBitCodeAbbrevOp::Encoding getEncoding(uint64_t Value); |
| |
| void skipAbbreviatedField(const NaClBitCodeAbbrevOp &Op); |
| |
| // Reads the next Value using the abbreviation Op. Returns true only |
| // if Op is an array (and sets Value to the number of elements in the |
| // array). |
| inline bool readRecordAbbrevField(const NaClBitCodeAbbrevOp &Op, |
| uint64_t &Value); |
| |
| // Reads and returns the next value using the abbreviation Op, |
| // assuming Op appears after an array abbreviation. |
| inline uint64_t readArrayAbbreviatedField(const NaClBitCodeAbbrevOp &Op); |
| |
| // Reads the array abbreviation Op, NumArrayElements times, putting |
| // the read values in Vals. |
| inline void readArrayAbbrev(const NaClBitCodeAbbrevOp &Op, |
| unsigned NumArrayElements, |
| SmallVectorImpl<uint64_t> &Vals); |
| |
| // Reports that that abbreviation Index is not valid. |
| void reportInvalidAbbrevNumber(unsigned Index) const; |
| |
| // Reports that jumping to Bit is not valid. |
| void reportInvalidJumpToBit(uint64_t Bit) const; |
| |
| public: |
| |
| /// Return the abbreviation for the specified AbbrevId. |
| const NaClBitCodeAbbrev *getAbbrev(unsigned AbbrevID) const { |
| unsigned AbbrevNo = AbbrevID-naclbitc::FIRST_APPLICATION_ABBREV; |
| const Block &CurBlock = BlockScope.back(); |
| const unsigned NumGlobalAbbrevs = CurBlock.getNumGlobalAbbrevs(); |
| if (AbbrevNo < NumGlobalAbbrevs) |
| return CurBlock.getGlobalAbbrevs().getVector()[AbbrevNo]; |
| unsigned LocalAbbrevNo = AbbrevNo - NumGlobalAbbrevs; |
| NaClBitstreamReader::AbbrevListVector |
| LocalAbbrevs = CurBlock.getLocalAbbrevs().getVector(); |
| if (LocalAbbrevNo >= LocalAbbrevs.size()) |
| reportInvalidAbbrevNumber(AbbrevID); |
| return LocalAbbrevs[LocalAbbrevNo]; |
| } |
| |
| /// Read the current record and discard it. |
| void skipRecord(unsigned AbbrevID); |
| |
| unsigned readRecord(unsigned AbbrevID, SmallVectorImpl<uint64_t> &Vals); |
| |
| //===--------------------------------------------------------------------===// |
| // Abbrev Processing |
| //===--------------------------------------------------------------------===// |
| // IsLocal indicates where the abbreviation occurs. If it is in the |
| // BlockInfo block, IsLocal is false. In all other cases, IsLocal is |
| // true. |
| void ReadAbbrevRecord(bool IsLocal, |
| NaClAbbrevListener *Listener); |
| |
| // Skips over an abbreviation record. Duplicates code of ReadAbbrevRecord, |
| // except that no abbreviation is built. |
| void SkipAbbrevRecord(); |
| |
| bool ReadBlockInfoBlock(NaClAbbrevListener *Listener); |
| }; |
| |
| } // End llvm namespace |
| |
| #endif |