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//===- BitstreamWriter.h - Low-level bitstream writer interface -*- C++ -*-===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// This header defines the BitstreamWriter class. This class can be used to
// write an arbitrary bitstream, regardless of its contents.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_BITSTREAM_BITSTREAMWRITER_H
#define LLVM_BITSTREAM_BITSTREAMWRITER_H
#include "llvm/ADT/ArrayRef.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Bitstream/BitCodes.h"
#include "llvm/Support/Casting.h"
#include "llvm/Support/Endian.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/raw_ostream.h"
#include <algorithm>
#include <optional>
#include <vector>
namespace llvm {
class BitstreamWriter {
/// Owned buffer, used to init Buffer if the provided stream doesn't happen to
/// be a buffer itself.
SmallVector<char, 0> OwnBuffer;
/// Internal buffer for unflushed bytes (unless there is no stream to flush
/// to, case in which these are "the bytes"). The writer backpatches, so it is
/// efficient to buffer.
SmallVectorImpl<char> &Buffer;
/// FS - The file stream that Buffer flushes to. If FS is a raw_fd_stream, the
/// writer will incrementally flush at subblock boundaries. Otherwise flushing
/// will happen at the end of BitstreamWriter's lifetime.
raw_ostream *const FS;
/// FlushThreshold - this is the threshold (unit B) to flush to FS, if FS is a
/// raw_fd_stream.
const uint64_t FlushThreshold;
/// CurBit - Always between 0 and 31 inclusive, specifies the next bit to use.
unsigned CurBit = 0;
/// CurValue - The current value. Only bits < CurBit are valid.
uint32_t CurValue = 0;
/// CurCodeSize - This is the declared size of code values used for the
/// current block, in bits.
unsigned CurCodeSize = 2;
/// BlockInfoCurBID - When emitting a BLOCKINFO_BLOCK, this is the currently
/// selected BLOCK ID.
unsigned BlockInfoCurBID = 0;
/// CurAbbrevs - Abbrevs installed at in this block.
std::vector<std::shared_ptr<BitCodeAbbrev>> CurAbbrevs;
// Support for retrieving a section of the output, for purposes such as
// checksumming.
std::optional<size_t> BlockFlushingStartPos;
struct Block {
unsigned PrevCodeSize;
size_t StartSizeWord;
std::vector<std::shared_ptr<BitCodeAbbrev>> PrevAbbrevs;
Block(unsigned PCS, size_t SSW) : PrevCodeSize(PCS), StartSizeWord(SSW) {}
};
/// BlockScope - This tracks the current blocks that we have entered.
std::vector<Block> BlockScope;
/// 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<std::shared_ptr<BitCodeAbbrev>> Abbrevs;
};
std::vector<BlockInfo> BlockInfoRecords;
void WriteWord(unsigned Value) {
Value =
support::endian::byte_swap<uint32_t, llvm::endianness::little>(Value);
Buffer.append(reinterpret_cast<const char *>(&Value),
reinterpret_cast<const char *>(&Value + 1));
}
uint64_t GetNumOfFlushedBytes() const {
return fdStream() ? fdStream()->tell() : 0;
}
size_t GetBufferOffset() const {
return Buffer.size() + GetNumOfFlushedBytes();
}
size_t GetWordIndex() const {
size_t Offset = GetBufferOffset();
assert((Offset & 3) == 0 && "Not 32-bit aligned");
return Offset / 4;
}
void flushAndClear() {
assert(FS);
assert(!Buffer.empty());
assert(!BlockFlushingStartPos &&
"a call to markAndBlockFlushing should have been paired with a "
"call to getMarkedBufferAndResumeFlushing");
FS->write(Buffer.data(), Buffer.size());
Buffer.clear();
}
/// If the related file stream is a raw_fd_stream, flush the buffer if its
/// size is above a threshold. If \p OnClosing is true, flushing happens
/// regardless of thresholds.
void FlushToFile(bool OnClosing = false) {
if (!FS || Buffer.empty())
return;
if (OnClosing)
return flushAndClear();
if (BlockFlushingStartPos)
return;
if (fdStream() && Buffer.size() > FlushThreshold)
flushAndClear();
}
raw_fd_stream *fdStream() { return dyn_cast_or_null<raw_fd_stream>(FS); }
const raw_fd_stream *fdStream() const {
return dyn_cast_or_null<raw_fd_stream>(FS);
}
SmallVectorImpl<char> &getInternalBufferFromStream(raw_ostream &OutStream) {
if (auto *SV = dyn_cast<raw_svector_ostream>(&OutStream))
return SV->buffer();
return OwnBuffer;
}
public:
/// Create a BitstreamWriter over a raw_ostream \p OutStream.
/// If \p OutStream is a raw_svector_ostream, the BitstreamWriter will write
/// directly to the latter's buffer. In all other cases, the BitstreamWriter
/// will use an internal buffer and flush at the end of its lifetime.
///
/// In addition, if \p is a raw_fd_stream supporting seek, tell, and read
/// (besides write), the BitstreamWriter will also flush incrementally, when a
/// subblock is finished, and if the FlushThreshold is passed.
///
/// NOTE: \p FlushThreshold's unit is MB.
BitstreamWriter(raw_ostream &OutStream, uint32_t FlushThreshold = 512)
: Buffer(getInternalBufferFromStream(OutStream)),
FS(!isa<raw_svector_ostream>(OutStream) ? &OutStream : nullptr),
FlushThreshold(uint64_t(FlushThreshold) << 20) {}
/// Convenience constructor for users that start with a vector - avoids
/// needing to wrap it in a raw_svector_ostream.
BitstreamWriter(SmallVectorImpl<char> &Buff)
: Buffer(Buff), FS(nullptr), FlushThreshold(0) {}
~BitstreamWriter() {
FlushToWord();
assert(BlockScope.empty() && CurAbbrevs.empty() && "Block imbalance");
FlushToFile(/*OnClosing=*/true);
}
/// For scenarios where the user wants to access a section of the stream to
/// (for example) compute some checksum, disable flushing and remember the
/// position in the internal buffer where that happened. Must be paired with a
/// call to getMarkedBufferAndResumeFlushing.
void markAndBlockFlushing() {
assert(!BlockFlushingStartPos);
BlockFlushingStartPos = Buffer.size();
}
/// resumes flushing, but does not flush, and returns the section in the
/// internal buffer starting from the position marked with
/// markAndBlockFlushing. The return should be processed before any additional
/// calls to this object, because those may cause a flush and invalidate the
/// return.
StringRef getMarkedBufferAndResumeFlushing() {
assert(BlockFlushingStartPos);
size_t Start = *BlockFlushingStartPos;
BlockFlushingStartPos.reset();
return {&Buffer[Start], Buffer.size() - Start};
}
/// Retrieve the current position in the stream, in bits.
uint64_t GetCurrentBitNo() const { return GetBufferOffset() * 8 + CurBit; }
/// Retrieve the number of bits currently used to encode an abbrev ID.
unsigned GetAbbrevIDWidth() const { return CurCodeSize; }
//===--------------------------------------------------------------------===//
// Basic Primitives for emitting bits to the stream.
//===--------------------------------------------------------------------===//
/// Backpatch a byte in the output at the given bit offset with the specified
/// value.
void BackpatchByte(uint64_t BitNo, uint8_t NewByte) {
using namespace llvm::support;
uint64_t ByteNo = BitNo / 8;
uint64_t StartBit = BitNo & 7;
uint64_t NumOfFlushedBytes = GetNumOfFlushedBytes();
if (ByteNo >= NumOfFlushedBytes) {
assert((!endian::readAtBitAlignment<uint8_t, llvm::endianness::little,
unaligned>(
&Buffer[ByteNo - NumOfFlushedBytes], StartBit)) &&
"Expected to be patching over 0-value placeholders");
endian::writeAtBitAlignment<uint8_t, llvm::endianness::little, unaligned>(
&Buffer[ByteNo - NumOfFlushedBytes], NewByte, StartBit);
return;
}
// If we don't have a raw_fd_stream, GetNumOfFlushedBytes() should have
// returned 0, and we shouldn't be here.
assert(fdStream() != nullptr);
// If the byte offset to backpatch is flushed, use seek to backfill data.
// First, save the file position to restore later.
uint64_t CurPos = fdStream()->tell();
// Copy data to update into Bytes from the file FS and the buffer Out.
char Bytes[3]; // Use one more byte to silence a warning from Visual C++.
size_t BytesNum = StartBit ? 2 : 1;
size_t BytesFromDisk = std::min(static_cast<uint64_t>(BytesNum), NumOfFlushedBytes - ByteNo);
size_t BytesFromBuffer = BytesNum - BytesFromDisk;
// When unaligned, copy existing data into Bytes from the file FS and the
// buffer Buffer so that it can be updated before writing. For debug builds
// read bytes unconditionally in order to check that the existing value is 0
// as expected.
#ifdef NDEBUG
if (StartBit)
#endif
{
fdStream()->seek(ByteNo);
ssize_t BytesRead = fdStream()->read(Bytes, BytesFromDisk);
(void)BytesRead; // silence warning
assert(BytesRead >= 0 && static_cast<size_t>(BytesRead) == BytesFromDisk);
for (size_t i = 0; i < BytesFromBuffer; ++i)
Bytes[BytesFromDisk + i] = Buffer[i];
assert((!endian::readAtBitAlignment<uint8_t, llvm::endianness::little,
unaligned>(Bytes, StartBit)) &&
"Expected to be patching over 0-value placeholders");
}
// Update Bytes in terms of bit offset and value.
endian::writeAtBitAlignment<uint8_t, llvm::endianness::little, unaligned>(
Bytes, NewByte, StartBit);
// Copy updated data back to the file FS and the buffer Out.
fdStream()->seek(ByteNo);
fdStream()->write(Bytes, BytesFromDisk);
for (size_t i = 0; i < BytesFromBuffer; ++i)
Buffer[i] = Bytes[BytesFromDisk + i];
// Restore the file position.
fdStream()->seek(CurPos);
}
void BackpatchHalfWord(uint64_t BitNo, uint16_t Val) {
BackpatchByte(BitNo, (uint8_t)Val);
BackpatchByte(BitNo + 8, (uint8_t)(Val >> 8));
}
void BackpatchWord(uint64_t BitNo, unsigned Val) {
BackpatchHalfWord(BitNo, (uint16_t)Val);
BackpatchHalfWord(BitNo + 16, (uint16_t)(Val >> 16));
}
void BackpatchWord64(uint64_t BitNo, uint64_t Val) {
BackpatchWord(BitNo, (uint32_t)Val);
BackpatchWord(BitNo + 32, (uint32_t)(Val >> 32));
}
void Emit(uint32_t Val, unsigned NumBits) {
assert(NumBits && NumBits <= 32 && "Invalid value size!");
assert((Val & ~(~0U >> (32-NumBits))) == 0 && "High bits set!");
CurValue |= Val << CurBit;
if (CurBit + NumBits < 32) {
CurBit += NumBits;
return;
}
// Add the current word.
WriteWord(CurValue);
if (CurBit)
CurValue = Val >> (32-CurBit);
else
CurValue = 0;
CurBit = (CurBit+NumBits) & 31;
}
void FlushToWord() {
if (CurBit) {
WriteWord(CurValue);
CurBit = 0;
CurValue = 0;
}
}
void EmitVBR(uint32_t Val, unsigned NumBits) {
assert(NumBits <= 32 && "Too many bits to emit!");
uint32_t Threshold = 1U << (NumBits-1);
// Emit the bits with VBR encoding, NumBits-1 bits at a time.
while (Val >= Threshold) {
Emit((Val & ((1U << (NumBits - 1)) - 1)) | (1U << (NumBits - 1)),
NumBits);
Val >>= NumBits-1;
}
Emit(Val, NumBits);
}
void EmitVBR64(uint64_t Val, unsigned NumBits) {
assert(NumBits <= 32 && "Too many bits to emit!");
if ((uint32_t)Val == Val)
return EmitVBR((uint32_t)Val, NumBits);
uint32_t Threshold = 1U << (NumBits-1);
// Emit the bits with VBR encoding, NumBits-1 bits at a time.
while (Val >= Threshold) {
Emit(((uint32_t)Val & ((1U << (NumBits - 1)) - 1)) |
(1U << (NumBits - 1)),
NumBits);
Val >>= NumBits-1;
}
Emit((uint32_t)Val, NumBits);
}
/// EmitCode - Emit the specified code.
void EmitCode(unsigned Val) {
Emit(Val, CurCodeSize);
}
//===--------------------------------------------------------------------===//
// Block Manipulation
//===--------------------------------------------------------------------===//
/// getBlockInfo - If there is block info for the specified ID, return it,
/// otherwise return null.
BlockInfo *getBlockInfo(unsigned BlockID) {
// Common case, the most recent entry matches BlockID.
if (!BlockInfoRecords.empty() && BlockInfoRecords.back().BlockID == BlockID)
return &BlockInfoRecords.back();
for (BlockInfo &BI : BlockInfoRecords)
if (BI.BlockID == BlockID)
return &BI;
return nullptr;
}
void EnterSubblock(unsigned BlockID, unsigned CodeLen) {
// Block header:
// [ENTER_SUBBLOCK, blockid, newcodelen, <align4bytes>, blocklen]
EmitCode(bitc::ENTER_SUBBLOCK);
EmitVBR(BlockID, bitc::BlockIDWidth);
EmitVBR(CodeLen, bitc::CodeLenWidth);
FlushToWord();
size_t BlockSizeWordIndex = GetWordIndex();
unsigned OldCodeSize = CurCodeSize;
// Emit a placeholder, which will be replaced when the block is popped.
Emit(0, bitc::BlockSizeWidth);
CurCodeSize = CodeLen;
// Push the outer block's abbrev set onto the stack, start out with an
// empty abbrev set.
BlockScope.emplace_back(OldCodeSize, BlockSizeWordIndex);
BlockScope.back().PrevAbbrevs.swap(CurAbbrevs);
// If there is a blockinfo for this BlockID, add all the predefined abbrevs
// to the abbrev list.
if (BlockInfo *Info = getBlockInfo(BlockID))
append_range(CurAbbrevs, Info->Abbrevs);
}
void ExitBlock() {
assert(!BlockScope.empty() && "Block scope imbalance!");
const Block &B = BlockScope.back();
// Block tail:
// [END_BLOCK, <align4bytes>]
EmitCode(bitc::END_BLOCK);
FlushToWord();
// Compute the size of the block, in words, not counting the size field.
size_t SizeInWords = GetWordIndex() - B.StartSizeWord - 1;
uint64_t BitNo = uint64_t(B.StartSizeWord) * 32;
// Update the block size field in the header of this sub-block.
BackpatchWord(BitNo, SizeInWords);
// Restore the inner block's code size and abbrev table.
CurCodeSize = B.PrevCodeSize;
CurAbbrevs = std::move(B.PrevAbbrevs);
BlockScope.pop_back();
FlushToFile();
}
//===--------------------------------------------------------------------===//
// Record Emission
//===--------------------------------------------------------------------===//
private:
/// EmitAbbreviatedLiteral - Emit a literal value according to its abbrev
/// record. This is a no-op, since the abbrev specifies the literal to use.
template<typename uintty>
void EmitAbbreviatedLiteral(const BitCodeAbbrevOp &Op, uintty V) {
assert(Op.isLiteral() && "Not a literal");
// If the abbrev specifies the literal value to use, don't emit
// anything.
assert(V == Op.getLiteralValue() &&
"Invalid abbrev for record!");
}
/// EmitAbbreviatedField - Emit a single scalar field value with the specified
/// encoding.
template<typename uintty>
void EmitAbbreviatedField(const BitCodeAbbrevOp &Op, uintty V) {
assert(!Op.isLiteral() && "Literals should use EmitAbbreviatedLiteral!");
// Encode the value as we are commanded.
switch (Op.getEncoding()) {
default: llvm_unreachable("Unknown encoding!");
case BitCodeAbbrevOp::Fixed:
if (Op.getEncodingData())
Emit((unsigned)V, (unsigned)Op.getEncodingData());
break;
case BitCodeAbbrevOp::VBR:
if (Op.getEncodingData())
EmitVBR64(V, (unsigned)Op.getEncodingData());
break;
case BitCodeAbbrevOp::Char6:
Emit(BitCodeAbbrevOp::EncodeChar6((char)V), 6);
break;
}
}
/// EmitRecordWithAbbrevImpl - This is the core implementation of the record
/// emission code. If BlobData is non-null, then it specifies an array of
/// data that should be emitted as part of the Blob or Array operand that is
/// known to exist at the end of the record. If Code is specified, then
/// it is the record code to emit before the Vals, which must not contain
/// the code.
template <typename uintty>
void EmitRecordWithAbbrevImpl(unsigned Abbrev, ArrayRef<uintty> Vals,
StringRef Blob, std::optional<unsigned> Code) {
const char *BlobData = Blob.data();
unsigned BlobLen = (unsigned) Blob.size();
unsigned AbbrevNo = Abbrev-bitc::FIRST_APPLICATION_ABBREV;
assert(AbbrevNo < CurAbbrevs.size() && "Invalid abbrev #!");
const BitCodeAbbrev *Abbv = CurAbbrevs[AbbrevNo].get();
EmitCode(Abbrev);
unsigned i = 0, e = static_cast<unsigned>(Abbv->getNumOperandInfos());
if (Code) {
assert(e && "Expected non-empty abbreviation");
const BitCodeAbbrevOp &Op = Abbv->getOperandInfo(i++);
if (Op.isLiteral())
EmitAbbreviatedLiteral(Op, *Code);
else {
assert(Op.getEncoding() != BitCodeAbbrevOp::Array &&
Op.getEncoding() != BitCodeAbbrevOp::Blob &&
"Expected literal or scalar");
EmitAbbreviatedField(Op, *Code);
}
}
unsigned RecordIdx = 0;
for (; i != e; ++i) {
const BitCodeAbbrevOp &Op = Abbv->getOperandInfo(i);
if (Op.isLiteral()) {
assert(RecordIdx < Vals.size() && "Invalid abbrev/record");
EmitAbbreviatedLiteral(Op, Vals[RecordIdx]);
++RecordIdx;
} else if (Op.getEncoding() == BitCodeAbbrevOp::Array) {
// Array case.
assert(i + 2 == e && "array op not second to last?");
const BitCodeAbbrevOp &EltEnc = Abbv->getOperandInfo(++i);
// If this record has blob data, emit it, otherwise we must have record
// entries to encode this way.
if (BlobData) {
assert(RecordIdx == Vals.size() &&
"Blob data and record entries specified for array!");
// Emit a vbr6 to indicate the number of elements present.
EmitVBR(static_cast<uint32_t>(BlobLen), 6);
// Emit each field.
for (unsigned i = 0; i != BlobLen; ++i)
EmitAbbreviatedField(EltEnc, (unsigned char)BlobData[i]);
// Know that blob data is consumed for assertion below.
BlobData = nullptr;
} else {
// Emit a vbr6 to indicate the number of elements present.
EmitVBR(static_cast<uint32_t>(Vals.size()-RecordIdx), 6);
// Emit each field.
for (unsigned e = Vals.size(); RecordIdx != e; ++RecordIdx)
EmitAbbreviatedField(EltEnc, Vals[RecordIdx]);
}
} else if (Op.getEncoding() == BitCodeAbbrevOp::Blob) {
// If this record has blob data, emit it, otherwise we must have record
// entries to encode this way.
if (BlobData) {
assert(RecordIdx == Vals.size() &&
"Blob data and record entries specified for blob operand!");
assert(Blob.data() == BlobData && "BlobData got moved");
assert(Blob.size() == BlobLen && "BlobLen got changed");
emitBlob(Blob);
BlobData = nullptr;
} else {
emitBlob(Vals.slice(RecordIdx));
}
} else { // Single scalar field.
assert(RecordIdx < Vals.size() && "Invalid abbrev/record");
EmitAbbreviatedField(Op, Vals[RecordIdx]);
++RecordIdx;
}
}
assert(RecordIdx == Vals.size() && "Not all record operands emitted!");
assert(BlobData == nullptr &&
"Blob data specified for record that doesn't use it!");
}
public:
/// Emit a blob, including flushing before and tail-padding.
template <class UIntTy>
void emitBlob(ArrayRef<UIntTy> Bytes, bool ShouldEmitSize = true) {
// Emit a vbr6 to indicate the number of elements present.
if (ShouldEmitSize)
EmitVBR(static_cast<uint32_t>(Bytes.size()), 6);
// Flush to a 32-bit alignment boundary.
FlushToWord();
// Emit literal bytes.
assert(llvm::all_of(Bytes, [](UIntTy B) { return isUInt<8>(B); }));
Buffer.append(Bytes.begin(), Bytes.end());
// Align end to 32-bits.
while (GetBufferOffset() & 3)
Buffer.push_back(0);
}
void emitBlob(StringRef Bytes, bool ShouldEmitSize = true) {
emitBlob(ArrayRef((const uint8_t *)Bytes.data(), Bytes.size()),
ShouldEmitSize);
}
/// EmitRecord - Emit the specified record to the stream, using an abbrev if
/// we have one to compress the output.
template <typename Container>
void EmitRecord(unsigned Code, const Container &Vals, unsigned Abbrev = 0) {
if (!Abbrev) {
// If we don't have an abbrev to use, emit this in its fully unabbreviated
// form.
auto Count = static_cast<uint32_t>(std::size(Vals));
EmitCode(bitc::UNABBREV_RECORD);
EmitVBR(Code, 6);
EmitVBR(Count, 6);
for (unsigned i = 0, e = Count; i != e; ++i)
EmitVBR64(Vals[i], 6);
return;
}
EmitRecordWithAbbrevImpl(Abbrev, ArrayRef(Vals), StringRef(), Code);
}
/// EmitRecordWithAbbrev - Emit a record with the specified abbreviation.
/// Unlike EmitRecord, the code for the record should be included in Vals as
/// the first entry.
template <typename Container>
void EmitRecordWithAbbrev(unsigned Abbrev, const Container &Vals) {
EmitRecordWithAbbrevImpl(Abbrev, ArrayRef(Vals), StringRef(), std::nullopt);
}
/// EmitRecordWithBlob - Emit the specified record to the stream, using an
/// abbrev that includes a blob at the end. The blob data to emit is
/// specified by the pointer and length specified at the end. In contrast to
/// EmitRecord, this routine expects that the first entry in Vals is the code
/// of the record.
template <typename Container>
void EmitRecordWithBlob(unsigned Abbrev, const Container &Vals,
StringRef Blob) {
EmitRecordWithAbbrevImpl(Abbrev, ArrayRef(Vals), Blob, std::nullopt);
}
template <typename Container>
void EmitRecordWithBlob(unsigned Abbrev, const Container &Vals,
const char *BlobData, unsigned BlobLen) {
return EmitRecordWithAbbrevImpl(Abbrev, ArrayRef(Vals),
StringRef(BlobData, BlobLen), std::nullopt);
}
/// EmitRecordWithArray - Just like EmitRecordWithBlob, works with records
/// that end with an array.
template <typename Container>
void EmitRecordWithArray(unsigned Abbrev, const Container &Vals,
StringRef Array) {
EmitRecordWithAbbrevImpl(Abbrev, ArrayRef(Vals), Array, std::nullopt);
}
template <typename Container>
void EmitRecordWithArray(unsigned Abbrev, const Container &Vals,
const char *ArrayData, unsigned ArrayLen) {
return EmitRecordWithAbbrevImpl(
Abbrev, ArrayRef(Vals), StringRef(ArrayData, ArrayLen), std::nullopt);
}
//===--------------------------------------------------------------------===//
// Abbrev Emission
//===--------------------------------------------------------------------===//
private:
// Emit the abbreviation as a DEFINE_ABBREV record.
void EncodeAbbrev(const BitCodeAbbrev &Abbv) {
EmitCode(bitc::DEFINE_ABBREV);
EmitVBR(Abbv.getNumOperandInfos(), 5);
for (unsigned i = 0, e = static_cast<unsigned>(Abbv.getNumOperandInfos());
i != e; ++i) {
const BitCodeAbbrevOp &Op = Abbv.getOperandInfo(i);
Emit(Op.isLiteral(), 1);
if (Op.isLiteral()) {
EmitVBR64(Op.getLiteralValue(), 8);
} else {
Emit(Op.getEncoding(), 3);
if (Op.hasEncodingData())
EmitVBR64(Op.getEncodingData(), 5);
}
}
}
public:
/// Emits the abbreviation \p Abbv to the stream.
unsigned EmitAbbrev(std::shared_ptr<BitCodeAbbrev> Abbv) {
EncodeAbbrev(*Abbv);
CurAbbrevs.push_back(std::move(Abbv));
return static_cast<unsigned>(CurAbbrevs.size())-1 +
bitc::FIRST_APPLICATION_ABBREV;
}
//===--------------------------------------------------------------------===//
// BlockInfo Block Emission
//===--------------------------------------------------------------------===//
/// EnterBlockInfoBlock - Start emitting the BLOCKINFO_BLOCK.
void EnterBlockInfoBlock() {
EnterSubblock(bitc::BLOCKINFO_BLOCK_ID, 2);
BlockInfoCurBID = ~0U;
BlockInfoRecords.clear();
}
private:
/// SwitchToBlockID - If we aren't already talking about the specified block
/// ID, emit a BLOCKINFO_CODE_SETBID record.
void SwitchToBlockID(unsigned BlockID) {
if (BlockInfoCurBID == BlockID) return;
SmallVector<unsigned, 2> V;
V.push_back(BlockID);
EmitRecord(bitc::BLOCKINFO_CODE_SETBID, V);
BlockInfoCurBID = BlockID;
}
BlockInfo &getOrCreateBlockInfo(unsigned BlockID) {
if (BlockInfo *BI = getBlockInfo(BlockID))
return *BI;
// Otherwise, add a new record.
BlockInfoRecords.emplace_back();
BlockInfoRecords.back().BlockID = BlockID;
return BlockInfoRecords.back();
}
public:
/// EmitBlockInfoAbbrev - Emit a DEFINE_ABBREV record for the specified
/// BlockID.
unsigned EmitBlockInfoAbbrev(unsigned BlockID, std::shared_ptr<BitCodeAbbrev> Abbv) {
SwitchToBlockID(BlockID);
EncodeAbbrev(*Abbv);
// Add the abbrev to the specified block record.
BlockInfo &Info = getOrCreateBlockInfo(BlockID);
Info.Abbrevs.push_back(std::move(Abbv));
return Info.Abbrevs.size()-1+bitc::FIRST_APPLICATION_ABBREV;
}
};
} // End llvm namespace
#endif
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