blob: 28adfe6268f9ab526afa510c9dbe972304c77180 [file] [log] [blame]
//===- 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;
}
}
}
}