| //===- BitstreamReader.cpp - BitstreamReader implementation ---------------===// |
| // |
| // 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 |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "llvm/Bitstream/BitstreamReader.h" |
| #include "llvm/ADT/StringRef.h" |
| #include <cassert> |
| #include <string> |
| |
| using namespace llvm; |
| |
| //===----------------------------------------------------------------------===// |
| // BitstreamCursor implementation |
| //===----------------------------------------------------------------------===// |
| |
| /// Having read the ENTER_SUBBLOCK abbrevid, enter the block. |
| Error 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 (BlockInfo) { |
| if (const BitstreamBlockInfo::BlockInfo *Info = |
| BlockInfo->getBlockInfo(BlockID)) { |
| llvm::append_range(CurAbbrevs, Info->Abbrevs); |
| } |
| } |
| |
| // Get the codesize of this block. |
| Expected<uint32_t> MaybeVBR = ReadVBR(bitc::CodeLenWidth); |
| if (!MaybeVBR) |
| return MaybeVBR.takeError(); |
| CurCodeSize = MaybeVBR.get(); |
| |
| if (CurCodeSize > MaxChunkSize) |
| return llvm::createStringError( |
| std::errc::illegal_byte_sequence, |
| "can't read more than %zu at a time, trying to read %u", +MaxChunkSize, |
| CurCodeSize); |
| |
| SkipToFourByteBoundary(); |
| Expected<word_t> MaybeNum = Read(bitc::BlockSizeWidth); |
| if (!MaybeNum) |
| return MaybeNum.takeError(); |
| word_t NumWords = MaybeNum.get(); |
| if (NumWordsP) |
| *NumWordsP = NumWords; |
| |
| if (CurCodeSize == 0) |
| return llvm::createStringError( |
| std::errc::illegal_byte_sequence, |
| "can't enter sub-block: current code size is 0"); |
| if (AtEndOfStream()) |
| return llvm::createStringError( |
| std::errc::illegal_byte_sequence, |
| "can't enter sub block: already at end of stream"); |
| |
| return Error::success(); |
| } |
| |
| static Expected<uint64_t> readAbbreviatedField(BitstreamCursor &Cursor, |
| const BitCodeAbbrevOp &Op) { |
| assert(!Op.isLiteral() && "Not to be used with literals!"); |
| |
| // Decode the value as we are commanded. |
| switch (Op.getEncoding()) { |
| case BitCodeAbbrevOp::Array: |
| case BitCodeAbbrevOp::Blob: |
| llvm_unreachable("Should not reach here"); |
| case BitCodeAbbrevOp::Fixed: |
| assert((unsigned)Op.getEncodingData() <= Cursor.MaxChunkSize); |
| return Cursor.Read((unsigned)Op.getEncodingData()); |
| case BitCodeAbbrevOp::VBR: |
| assert((unsigned)Op.getEncodingData() <= Cursor.MaxChunkSize); |
| return Cursor.ReadVBR64((unsigned)Op.getEncodingData()); |
| case BitCodeAbbrevOp::Char6: |
| if (Expected<unsigned> Res = Cursor.Read(6)) |
| return BitCodeAbbrevOp::DecodeChar6(Res.get()); |
| else |
| return Res.takeError(); |
| } |
| llvm_unreachable("invalid abbreviation encoding"); |
| } |
| |
| /// skipRecord - Read the current record and discard it. |
| Expected<unsigned> BitstreamCursor::skipRecord(unsigned AbbrevID) { |
| // Skip unabbreviated records by reading past their entries. |
| if (AbbrevID == bitc::UNABBREV_RECORD) { |
| Expected<uint32_t> MaybeCode = ReadVBR(6); |
| if (!MaybeCode) |
| return MaybeCode.takeError(); |
| unsigned Code = MaybeCode.get(); |
| Expected<uint32_t> MaybeVBR = ReadVBR(6); |
| if (!MaybeVBR) |
| return MaybeVBR.get(); |
| unsigned NumElts = MaybeVBR.get(); |
| for (unsigned i = 0; i != NumElts; ++i) |
| if (Expected<uint64_t> Res = ReadVBR64(6)) |
| ; // Skip! |
| else |
| return Res.takeError(); |
| return Code; |
| } |
| |
| const BitCodeAbbrev *Abbv = getAbbrev(AbbrevID); |
| const BitCodeAbbrevOp &CodeOp = Abbv->getOperandInfo(0); |
| unsigned Code; |
| if (CodeOp.isLiteral()) |
| Code = CodeOp.getLiteralValue(); |
| else { |
| if (CodeOp.getEncoding() == BitCodeAbbrevOp::Array || |
| CodeOp.getEncoding() == BitCodeAbbrevOp::Blob) |
| return llvm::createStringError( |
| std::errc::illegal_byte_sequence, |
| "Abbreviation starts with an Array or a Blob"); |
| Expected<uint64_t> MaybeCode = readAbbreviatedField(*this, CodeOp); |
| if (!MaybeCode) |
| return MaybeCode.takeError(); |
| Code = MaybeCode.get(); |
| } |
| |
| for (unsigned i = 1, 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) { |
| if (Expected<uint64_t> MaybeField = readAbbreviatedField(*this, Op)) |
| continue; |
| else |
| return MaybeField.takeError(); |
| } |
| |
| if (Op.getEncoding() == BitCodeAbbrevOp::Array) { |
| // Array case. Read the number of elements as a vbr6. |
| Expected<uint32_t> MaybeNum = ReadVBR(6); |
| if (!MaybeNum) |
| return MaybeNum.takeError(); |
| unsigned NumElts = MaybeNum.get(); |
| |
| // Get the element encoding. |
| assert(i+2 == e && "array op not second to last?"); |
| const BitCodeAbbrevOp &EltEnc = Abbv->getOperandInfo(++i); |
| |
| // Read all the elements. |
| // Decode the value as we are commanded. |
| switch (EltEnc.getEncoding()) { |
| default: |
| report_fatal_error("Array element type can't be an Array or a Blob"); |
| case BitCodeAbbrevOp::Fixed: |
| assert((unsigned)EltEnc.getEncodingData() <= MaxChunkSize); |
| if (Error Err = |
| JumpToBit(GetCurrentBitNo() + static_cast<uint64_t>(NumElts) * |
| EltEnc.getEncodingData())) |
| return std::move(Err); |
| break; |
| case BitCodeAbbrevOp::VBR: |
| assert((unsigned)EltEnc.getEncodingData() <= MaxChunkSize); |
| for (; NumElts; --NumElts) |
| if (Expected<uint64_t> Res = |
| ReadVBR64((unsigned)EltEnc.getEncodingData())) |
| ; // Skip! |
| else |
| return Res.takeError(); |
| break; |
| case BitCodeAbbrevOp::Char6: |
| if (Error Err = JumpToBit(GetCurrentBitNo() + NumElts * 6)) |
| return std::move(Err); |
| break; |
| } |
| continue; |
| } |
| |
| assert(Op.getEncoding() == BitCodeAbbrevOp::Blob); |
| // Blob case. Read the number of bytes as a vbr6. |
| Expected<uint32_t> MaybeNum = ReadVBR(6); |
| if (!MaybeNum) |
| return MaybeNum.takeError(); |
| unsigned NumElts = MaybeNum.get(); |
| SkipToFourByteBoundary(); // 32-bit alignment |
| |
| // Figure out where the end of this blob will be including tail padding. |
| const size_t NewEnd = GetCurrentBitNo() + alignTo(NumElts, 4) * 8; |
| |
| // If this would read off the end of the bitcode file, just set the |
| // record to empty and return. |
| if (!canSkipToPos(NewEnd/8)) { |
| skipToEnd(); |
| break; |
| } |
| |
| // Skip over the blob. |
| if (Error Err = JumpToBit(NewEnd)) |
| return std::move(Err); |
| } |
| return Code; |
| } |
| |
| Expected<unsigned> BitstreamCursor::readRecord(unsigned AbbrevID, |
| SmallVectorImpl<uint64_t> &Vals, |
| StringRef *Blob) { |
| if (AbbrevID == bitc::UNABBREV_RECORD) { |
| Expected<uint32_t> MaybeCode = ReadVBR(6); |
| if (!MaybeCode) |
| return MaybeCode.takeError(); |
| uint32_t Code = MaybeCode.get(); |
| Expected<uint32_t> MaybeNumElts = ReadVBR(6); |
| if (!MaybeNumElts) |
| return MaybeNumElts.takeError(); |
| uint32_t NumElts = MaybeNumElts.get(); |
| Vals.reserve(Vals.size() + NumElts); |
| |
| for (unsigned i = 0; i != NumElts; ++i) |
| if (Expected<uint64_t> MaybeVal = ReadVBR64(6)) |
| Vals.push_back(MaybeVal.get()); |
| else |
| return MaybeVal.takeError(); |
| return Code; |
| } |
| |
| const BitCodeAbbrev *Abbv = getAbbrev(AbbrevID); |
| |
| // Read the record code first. |
| assert(Abbv->getNumOperandInfos() != 0 && "no record code in abbreviation?"); |
| const BitCodeAbbrevOp &CodeOp = Abbv->getOperandInfo(0); |
| unsigned Code; |
| if (CodeOp.isLiteral()) |
| Code = CodeOp.getLiteralValue(); |
| else { |
| if (CodeOp.getEncoding() == BitCodeAbbrevOp::Array || |
| CodeOp.getEncoding() == BitCodeAbbrevOp::Blob) |
| report_fatal_error("Abbreviation starts with an Array or a Blob"); |
| if (Expected<uint64_t> MaybeCode = readAbbreviatedField(*this, CodeOp)) |
| Code = MaybeCode.get(); |
| else |
| return MaybeCode.takeError(); |
| } |
| |
| for (unsigned i = 1, e = Abbv->getNumOperandInfos(); i != e; ++i) { |
| const BitCodeAbbrevOp &Op = Abbv->getOperandInfo(i); |
| if (Op.isLiteral()) { |
| Vals.push_back(Op.getLiteralValue()); |
| continue; |
| } |
| |
| if (Op.getEncoding() != BitCodeAbbrevOp::Array && |
| Op.getEncoding() != BitCodeAbbrevOp::Blob) { |
| if (Expected<uint64_t> MaybeVal = readAbbreviatedField(*this, Op)) |
| Vals.push_back(MaybeVal.get()); |
| else |
| return MaybeVal.takeError(); |
| continue; |
| } |
| |
| if (Op.getEncoding() == BitCodeAbbrevOp::Array) { |
| // Array case. Read the number of elements as a vbr6. |
| Expected<uint32_t> MaybeNumElts = ReadVBR(6); |
| if (!MaybeNumElts) |
| return MaybeNumElts.takeError(); |
| uint32_t NumElts = MaybeNumElts.get(); |
| Vals.reserve(Vals.size() + NumElts); |
| |
| // Get the element encoding. |
| if (i + 2 != e) |
| report_fatal_error("Array op not second to last"); |
| const BitCodeAbbrevOp &EltEnc = Abbv->getOperandInfo(++i); |
| if (!EltEnc.isEncoding()) |
| report_fatal_error( |
| "Array element type has to be an encoding of a type"); |
| |
| // Read all the elements. |
| switch (EltEnc.getEncoding()) { |
| default: |
| report_fatal_error("Array element type can't be an Array or a Blob"); |
| case BitCodeAbbrevOp::Fixed: |
| for (; NumElts; --NumElts) |
| if (Expected<SimpleBitstreamCursor::word_t> MaybeVal = |
| Read((unsigned)EltEnc.getEncodingData())) |
| Vals.push_back(MaybeVal.get()); |
| else |
| return MaybeVal.takeError(); |
| break; |
| case BitCodeAbbrevOp::VBR: |
| for (; NumElts; --NumElts) |
| if (Expected<uint64_t> MaybeVal = |
| ReadVBR64((unsigned)EltEnc.getEncodingData())) |
| Vals.push_back(MaybeVal.get()); |
| else |
| return MaybeVal.takeError(); |
| break; |
| case BitCodeAbbrevOp::Char6: |
| for (; NumElts; --NumElts) |
| if (Expected<SimpleBitstreamCursor::word_t> MaybeVal = Read(6)) |
| Vals.push_back(BitCodeAbbrevOp::DecodeChar6(MaybeVal.get())); |
| else |
| return MaybeVal.takeError(); |
| } |
| continue; |
| } |
| |
| assert(Op.getEncoding() == BitCodeAbbrevOp::Blob); |
| // Blob case. Read the number of bytes as a vbr6. |
| Expected<uint32_t> MaybeNumElts = ReadVBR(6); |
| if (!MaybeNumElts) |
| return MaybeNumElts.takeError(); |
| uint32_t NumElts = MaybeNumElts.get(); |
| SkipToFourByteBoundary(); // 32-bit alignment |
| |
| // Figure out where the end of this blob will be including tail padding. |
| size_t CurBitPos = GetCurrentBitNo(); |
| const size_t NewEnd = CurBitPos + alignTo(NumElts, 4) * 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); |
| skipToEnd(); |
| break; |
| } |
| |
| // Otherwise, inform the streamer that we need these bytes in memory. Skip |
| // over tail padding first, in case jumping to NewEnd invalidates the Blob |
| // pointer. |
| if (Error Err = JumpToBit(NewEnd)) |
| return std::move(Err); |
| const char *Ptr = (const char *)getPointerToBit(CurBitPos, 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. |
| auto *UPtr = reinterpret_cast<const unsigned char *>(Ptr); |
| Vals.append(UPtr, UPtr + NumElts); |
| } |
| } |
| |
| return Code; |
| } |
| |
| Error BitstreamCursor::ReadAbbrevRecord() { |
| auto Abbv = std::make_shared<BitCodeAbbrev>(); |
| Expected<uint32_t> MaybeNumOpInfo = ReadVBR(5); |
| if (!MaybeNumOpInfo) |
| return MaybeNumOpInfo.takeError(); |
| unsigned NumOpInfo = MaybeNumOpInfo.get(); |
| for (unsigned i = 0; i != NumOpInfo; ++i) { |
| Expected<word_t> MaybeIsLiteral = Read(1); |
| if (!MaybeIsLiteral) |
| return MaybeIsLiteral.takeError(); |
| bool IsLiteral = MaybeIsLiteral.get(); |
| if (IsLiteral) { |
| Expected<uint64_t> MaybeOp = ReadVBR64(8); |
| if (!MaybeOp) |
| return MaybeOp.takeError(); |
| Abbv->Add(BitCodeAbbrevOp(MaybeOp.get())); |
| continue; |
| } |
| |
| Expected<word_t> MaybeEncoding = Read(3); |
| if (!MaybeEncoding) |
| return MaybeEncoding.takeError(); |
| BitCodeAbbrevOp::Encoding E = |
| (BitCodeAbbrevOp::Encoding)MaybeEncoding.get(); |
| if (BitCodeAbbrevOp::hasEncodingData(E)) { |
| Expected<uint64_t> MaybeData = ReadVBR64(5); |
| if (!MaybeData) |
| return MaybeData.takeError(); |
| uint64_t Data = MaybeData.get(); |
| |
| // 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; |
| } |
| |
| if ((E == BitCodeAbbrevOp::Fixed || E == BitCodeAbbrevOp::VBR) && |
| Data > MaxChunkSize) |
| report_fatal_error( |
| "Fixed or VBR abbrev record with size > MaxChunkData"); |
| |
| Abbv->Add(BitCodeAbbrevOp(E, Data)); |
| } else |
| Abbv->Add(BitCodeAbbrevOp(E)); |
| } |
| |
| if (Abbv->getNumOperandInfos() == 0) |
| report_fatal_error("Abbrev record with no operands"); |
| CurAbbrevs.push_back(std::move(Abbv)); |
| |
| return Error::success(); |
| } |
| |
| Expected<Optional<BitstreamBlockInfo>> |
| BitstreamCursor::ReadBlockInfoBlock(bool ReadBlockInfoNames) { |
| if (llvm::Error Err = EnterSubBlock(bitc::BLOCKINFO_BLOCK_ID)) |
| return std::move(Err); |
| |
| BitstreamBlockInfo NewBlockInfo; |
| |
| SmallVector<uint64_t, 64> Record; |
| BitstreamBlockInfo::BlockInfo *CurBlockInfo = nullptr; |
| |
| // Read all the records for this module. |
| while (true) { |
| Expected<BitstreamEntry> MaybeEntry = |
| advanceSkippingSubblocks(AF_DontAutoprocessAbbrevs); |
| if (!MaybeEntry) |
| return MaybeEntry.takeError(); |
| BitstreamEntry Entry = MaybeEntry.get(); |
| |
| switch (Entry.Kind) { |
| case llvm::BitstreamEntry::SubBlock: // Handled for us already. |
| case llvm::BitstreamEntry::Error: |
| return None; |
| case llvm::BitstreamEntry::EndBlock: |
| return std::move(NewBlockInfo); |
| case llvm::BitstreamEntry::Record: |
| // The interesting case. |
| break; |
| } |
| |
| // Read abbrev records, associate them with CurBID. |
| if (Entry.ID == bitc::DEFINE_ABBREV) { |
| if (!CurBlockInfo) return None; |
| if (Error Err = ReadAbbrevRecord()) |
| return std::move(Err); |
| |
| // ReadAbbrevRecord installs the abbrev in CurAbbrevs. Move it to the |
| // appropriate BlockInfo. |
| CurBlockInfo->Abbrevs.push_back(std::move(CurAbbrevs.back())); |
| CurAbbrevs.pop_back(); |
| continue; |
| } |
| |
| // Read a record. |
| Record.clear(); |
| Expected<unsigned> MaybeBlockInfo = readRecord(Entry.ID, Record); |
| if (!MaybeBlockInfo) |
| return MaybeBlockInfo.takeError(); |
| switch (MaybeBlockInfo.get()) { |
| default: |
| break; // Default behavior, ignore unknown content. |
| case bitc::BLOCKINFO_CODE_SETBID: |
| if (Record.size() < 1) |
| return None; |
| CurBlockInfo = &NewBlockInfo.getOrCreateBlockInfo((unsigned)Record[0]); |
| break; |
| case bitc::BLOCKINFO_CODE_BLOCKNAME: { |
| if (!CurBlockInfo) |
| return None; |
| if (!ReadBlockInfoNames) |
| break; // Ignore name. |
| CurBlockInfo->Name = std::string(Record.begin(), Record.end()); |
| break; |
| } |
| case bitc::BLOCKINFO_CODE_SETRECORDNAME: { |
| if (!CurBlockInfo) return None; |
| if (!ReadBlockInfoNames) |
| break; // Ignore name. |
| CurBlockInfo->RecordNames.emplace_back( |
| (unsigned)Record[0], std::string(Record.begin() + 1, Record.end())); |
| break; |
| } |
| } |
| } |
| } |
