1 //===- BitstreamWriter.h - Low-level bitstream writer interface -*- C++ -*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // This header defines the BitstreamWriter class. This class can be used to 10 // write an arbitrary bitstream, regardless of its contents. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #ifndef LLVM_BITSTREAM_BITSTREAMWRITER_H 15 #define LLVM_BITSTREAM_BITSTREAMWRITER_H 16 17 #include "llvm/ADT/ArrayRef.h" 18 #include "llvm/ADT/Optional.h" 19 #include "llvm/ADT/SmallVector.h" 20 #include "llvm/ADT/StringRef.h" 21 #include "llvm/Bitstream/BitCodes.h" 22 #include "llvm/Support/Endian.h" 23 #include "llvm/Support/raw_ostream.h" 24 #include <algorithm> 25 #include <vector> 26 27 namespace llvm { 28 29 class BitstreamWriter { 30 /// Out - The buffer that keeps unflushed bytes. 31 SmallVectorImpl<char> &Out; 32 33 /// FS - The file stream that Out flushes to. If FS is nullptr, it does not 34 /// support read or seek, Out cannot be flushed until all data are written. 35 raw_fd_stream *FS; 36 37 /// FlushThreshold - If FS is valid, this is the threshold (unit B) to flush 38 /// FS. 39 const uint64_t FlushThreshold; 40 41 /// CurBit - Always between 0 and 31 inclusive, specifies the next bit to use. 42 unsigned CurBit; 43 44 /// CurValue - The current value. Only bits < CurBit are valid. 45 uint32_t CurValue; 46 47 /// CurCodeSize - This is the declared size of code values used for the 48 /// current block, in bits. 49 unsigned CurCodeSize; 50 51 /// BlockInfoCurBID - When emitting a BLOCKINFO_BLOCK, this is the currently 52 /// selected BLOCK ID. 53 unsigned BlockInfoCurBID; 54 55 /// CurAbbrevs - Abbrevs installed at in this block. 56 std::vector<std::shared_ptr<BitCodeAbbrev>> CurAbbrevs; 57 58 struct Block { 59 unsigned PrevCodeSize; 60 size_t StartSizeWord; 61 std::vector<std::shared_ptr<BitCodeAbbrev>> PrevAbbrevs; 62 Block(unsigned PCS, size_t SSW) : PrevCodeSize(PCS), StartSizeWord(SSW) {} 63 }; 64 65 /// BlockScope - This tracks the current blocks that we have entered. 66 std::vector<Block> BlockScope; 67 68 /// BlockInfo - This contains information emitted to BLOCKINFO_BLOCK blocks. 69 /// These describe abbreviations that all blocks of the specified ID inherit. 70 struct BlockInfo { 71 unsigned BlockID; 72 std::vector<std::shared_ptr<BitCodeAbbrev>> Abbrevs; 73 }; 74 std::vector<BlockInfo> BlockInfoRecords; 75 76 void WriteByte(unsigned char Value) { 77 Out.push_back(Value); 78 FlushToFile(); 79 } 80 81 void WriteWord(unsigned Value) { 82 Value = support::endian::byte_swap<uint32_t, support::little>(Value); 83 Out.append(reinterpret_cast<const char *>(&Value), 84 reinterpret_cast<const char *>(&Value + 1)); 85 FlushToFile(); 86 } 87 88 uint64_t GetNumOfFlushedBytes() const { return FS ? FS->tell() : 0; } 89 90 size_t GetBufferOffset() const { return Out.size() + GetNumOfFlushedBytes(); } 91 92 size_t GetWordIndex() const { 93 size_t Offset = GetBufferOffset(); 94 assert((Offset & 3) == 0 && "Not 32-bit aligned"); 95 return Offset / 4; 96 } 97 98 /// If the related file stream supports reading, seeking and writing, flush 99 /// the buffer if its size is above a threshold. 100 void FlushToFile() { 101 if (!FS) 102 return; 103 if (Out.size() < FlushThreshold) 104 return; 105 FS->write((char *)&Out.front(), Out.size()); 106 Out.clear(); 107 } 108 109 public: 110 /// Create a BitstreamWriter that writes to Buffer \p O. 111 /// 112 /// \p FS is the file stream that \p O flushes to incrementally. If \p FS is 113 /// null, \p O does not flush incrementially, but writes to disk at the end. 114 /// 115 /// \p FlushThreshold is the threshold (unit M) to flush \p O if \p FS is 116 /// valid. 117 BitstreamWriter(SmallVectorImpl<char> &O, raw_fd_stream *FS = nullptr, 118 uint32_t FlushThreshold = 512) 119 : Out(O), FS(FS), FlushThreshold(FlushThreshold << 20), CurBit(0), 120 CurValue(0), CurCodeSize(2) {} 121 122 ~BitstreamWriter() { 123 assert(CurBit == 0 && "Unflushed data remaining"); 124 assert(BlockScope.empty() && CurAbbrevs.empty() && "Block imbalance"); 125 } 126 127 /// Retrieve the current position in the stream, in bits. 128 uint64_t GetCurrentBitNo() const { return GetBufferOffset() * 8 + CurBit; } 129 130 /// Retrieve the number of bits currently used to encode an abbrev ID. 131 unsigned GetAbbrevIDWidth() const { return CurCodeSize; } 132 133 //===--------------------------------------------------------------------===// 134 // Basic Primitives for emitting bits to the stream. 135 //===--------------------------------------------------------------------===// 136 137 /// Backpatch a 32-bit word in the output at the given bit offset 138 /// with the specified value. 139 void BackpatchWord(uint64_t BitNo, unsigned NewWord) { 140 using namespace llvm::support; 141 uint64_t ByteNo = BitNo / 8; 142 uint64_t StartBit = BitNo & 7; 143 uint64_t NumOfFlushedBytes = GetNumOfFlushedBytes(); 144 145 if (ByteNo >= NumOfFlushedBytes) { 146 assert((!endian::readAtBitAlignment<uint32_t, little, unaligned>( 147 &Out[ByteNo - NumOfFlushedBytes], StartBit)) && 148 "Expected to be patching over 0-value placeholders"); 149 endian::writeAtBitAlignment<uint32_t, little, unaligned>( 150 &Out[ByteNo - NumOfFlushedBytes], NewWord, StartBit); 151 return; 152 } 153 154 // If the byte offset to backpatch is flushed, use seek to backfill data. 155 // First, save the file position to restore later. 156 uint64_t CurPos = FS->tell(); 157 158 // Copy data to update into Bytes from the file FS and the buffer Out. 159 char Bytes[9]; // Use one more byte to silence a warning from Visual C++. 160 size_t BytesNum = StartBit ? 8 : 4; 161 size_t BytesFromDisk = std::min(static_cast<uint64_t>(BytesNum), NumOfFlushedBytes - ByteNo); 162 size_t BytesFromBuffer = BytesNum - BytesFromDisk; 163 164 // When unaligned, copy existing data into Bytes from the file FS and the 165 // buffer Out so that it can be updated before writing. For debug builds 166 // read bytes unconditionally in order to check that the existing value is 0 167 // as expected. 168 #ifdef NDEBUG 169 if (StartBit) 170 #endif 171 { 172 FS->seek(ByteNo); 173 ssize_t BytesRead = FS->read(Bytes, BytesFromDisk); 174 (void)BytesRead; // silence warning 175 assert(BytesRead >= 0 && static_cast<size_t>(BytesRead) == BytesFromDisk); 176 for (size_t i = 0; i < BytesFromBuffer; ++i) 177 Bytes[BytesFromDisk + i] = Out[i]; 178 assert((!endian::readAtBitAlignment<uint32_t, little, unaligned>( 179 Bytes, StartBit)) && 180 "Expected to be patching over 0-value placeholders"); 181 } 182 183 // Update Bytes in terms of bit offset and value. 184 endian::writeAtBitAlignment<uint32_t, little, unaligned>(Bytes, NewWord, 185 StartBit); 186 187 // Copy updated data back to the file FS and the buffer Out. 188 FS->seek(ByteNo); 189 FS->write(Bytes, BytesFromDisk); 190 for (size_t i = 0; i < BytesFromBuffer; ++i) 191 Out[i] = Bytes[BytesFromDisk + i]; 192 193 // Restore the file position. 194 FS->seek(CurPos); 195 } 196 197 void BackpatchWord64(uint64_t BitNo, uint64_t Val) { 198 BackpatchWord(BitNo, (uint32_t)Val); 199 BackpatchWord(BitNo + 32, (uint32_t)(Val >> 32)); 200 } 201 202 void Emit(uint32_t Val, unsigned NumBits) { 203 assert(NumBits && NumBits <= 32 && "Invalid value size!"); 204 assert((Val & ~(~0U >> (32-NumBits))) == 0 && "High bits set!"); 205 CurValue |= Val << CurBit; 206 if (CurBit + NumBits < 32) { 207 CurBit += NumBits; 208 return; 209 } 210 211 // Add the current word. 212 WriteWord(CurValue); 213 214 if (CurBit) 215 CurValue = Val >> (32-CurBit); 216 else 217 CurValue = 0; 218 CurBit = (CurBit+NumBits) & 31; 219 } 220 221 void FlushToWord() { 222 if (CurBit) { 223 WriteWord(CurValue); 224 CurBit = 0; 225 CurValue = 0; 226 } 227 } 228 229 void EmitVBR(uint32_t Val, unsigned NumBits) { 230 assert(NumBits <= 32 && "Too many bits to emit!"); 231 uint32_t Threshold = 1U << (NumBits-1); 232 233 // Emit the bits with VBR encoding, NumBits-1 bits at a time. 234 while (Val >= Threshold) { 235 Emit((Val & ((1 << (NumBits-1))-1)) | (1 << (NumBits-1)), NumBits); 236 Val >>= NumBits-1; 237 } 238 239 Emit(Val, NumBits); 240 } 241 242 void EmitVBR64(uint64_t Val, unsigned NumBits) { 243 assert(NumBits <= 32 && "Too many bits to emit!"); 244 if ((uint32_t)Val == Val) 245 return EmitVBR((uint32_t)Val, NumBits); 246 247 uint32_t Threshold = 1U << (NumBits-1); 248 249 // Emit the bits with VBR encoding, NumBits-1 bits at a time. 250 while (Val >= Threshold) { 251 Emit(((uint32_t)Val & ((1 << (NumBits-1))-1)) | 252 (1 << (NumBits-1)), NumBits); 253 Val >>= NumBits-1; 254 } 255 256 Emit((uint32_t)Val, NumBits); 257 } 258 259 /// EmitCode - Emit the specified code. 260 void EmitCode(unsigned Val) { 261 Emit(Val, CurCodeSize); 262 } 263 264 //===--------------------------------------------------------------------===// 265 // Block Manipulation 266 //===--------------------------------------------------------------------===// 267 268 /// getBlockInfo - If there is block info for the specified ID, return it, 269 /// otherwise return null. 270 BlockInfo *getBlockInfo(unsigned BlockID) { 271 // Common case, the most recent entry matches BlockID. 272 if (!BlockInfoRecords.empty() && BlockInfoRecords.back().BlockID == BlockID) 273 return &BlockInfoRecords.back(); 274 275 for (unsigned i = 0, e = static_cast<unsigned>(BlockInfoRecords.size()); 276 i != e; ++i) 277 if (BlockInfoRecords[i].BlockID == BlockID) 278 return &BlockInfoRecords[i]; 279 return nullptr; 280 } 281 282 void EnterSubblock(unsigned BlockID, unsigned CodeLen) { 283 // Block header: 284 // [ENTER_SUBBLOCK, blockid, newcodelen, <align4bytes>, blocklen] 285 EmitCode(bitc::ENTER_SUBBLOCK); 286 EmitVBR(BlockID, bitc::BlockIDWidth); 287 EmitVBR(CodeLen, bitc::CodeLenWidth); 288 FlushToWord(); 289 290 size_t BlockSizeWordIndex = GetWordIndex(); 291 unsigned OldCodeSize = CurCodeSize; 292 293 // Emit a placeholder, which will be replaced when the block is popped. 294 Emit(0, bitc::BlockSizeWidth); 295 296 CurCodeSize = CodeLen; 297 298 // Push the outer block's abbrev set onto the stack, start out with an 299 // empty abbrev set. 300 BlockScope.emplace_back(OldCodeSize, BlockSizeWordIndex); 301 BlockScope.back().PrevAbbrevs.swap(CurAbbrevs); 302 303 // If there is a blockinfo for this BlockID, add all the predefined abbrevs 304 // to the abbrev list. 305 if (BlockInfo *Info = getBlockInfo(BlockID)) { 306 CurAbbrevs.insert(CurAbbrevs.end(), Info->Abbrevs.begin(), 307 Info->Abbrevs.end()); 308 } 309 } 310 311 void ExitBlock() { 312 assert(!BlockScope.empty() && "Block scope imbalance!"); 313 const Block &B = BlockScope.back(); 314 315 // Block tail: 316 // [END_BLOCK, <align4bytes>] 317 EmitCode(bitc::END_BLOCK); 318 FlushToWord(); 319 320 // Compute the size of the block, in words, not counting the size field. 321 size_t SizeInWords = GetWordIndex() - B.StartSizeWord - 1; 322 uint64_t BitNo = uint64_t(B.StartSizeWord) * 32; 323 324 // Update the block size field in the header of this sub-block. 325 BackpatchWord(BitNo, SizeInWords); 326 327 // Restore the inner block's code size and abbrev table. 328 CurCodeSize = B.PrevCodeSize; 329 CurAbbrevs = std::move(B.PrevAbbrevs); 330 BlockScope.pop_back(); 331 } 332 333 //===--------------------------------------------------------------------===// 334 // Record Emission 335 //===--------------------------------------------------------------------===// 336 337 private: 338 /// EmitAbbreviatedLiteral - Emit a literal value according to its abbrev 339 /// record. This is a no-op, since the abbrev specifies the literal to use. 340 template<typename uintty> 341 void EmitAbbreviatedLiteral(const BitCodeAbbrevOp &Op, uintty V) { 342 assert(Op.isLiteral() && "Not a literal"); 343 // If the abbrev specifies the literal value to use, don't emit 344 // anything. 345 assert(V == Op.getLiteralValue() && 346 "Invalid abbrev for record!"); 347 } 348 349 /// EmitAbbreviatedField - Emit a single scalar field value with the specified 350 /// encoding. 351 template<typename uintty> 352 void EmitAbbreviatedField(const BitCodeAbbrevOp &Op, uintty V) { 353 assert(!Op.isLiteral() && "Literals should use EmitAbbreviatedLiteral!"); 354 355 // Encode the value as we are commanded. 356 switch (Op.getEncoding()) { 357 default: llvm_unreachable("Unknown encoding!"); 358 case BitCodeAbbrevOp::Fixed: 359 if (Op.getEncodingData()) 360 Emit((unsigned)V, (unsigned)Op.getEncodingData()); 361 break; 362 case BitCodeAbbrevOp::VBR: 363 if (Op.getEncodingData()) 364 EmitVBR64(V, (unsigned)Op.getEncodingData()); 365 break; 366 case BitCodeAbbrevOp::Char6: 367 Emit(BitCodeAbbrevOp::EncodeChar6((char)V), 6); 368 break; 369 } 370 } 371 372 /// EmitRecordWithAbbrevImpl - This is the core implementation of the record 373 /// emission code. If BlobData is non-null, then it specifies an array of 374 /// data that should be emitted as part of the Blob or Array operand that is 375 /// known to exist at the end of the record. If Code is specified, then 376 /// it is the record code to emit before the Vals, which must not contain 377 /// the code. 378 template <typename uintty> 379 void EmitRecordWithAbbrevImpl(unsigned Abbrev, ArrayRef<uintty> Vals, 380 StringRef Blob, Optional<unsigned> Code) { 381 const char *BlobData = Blob.data(); 382 unsigned BlobLen = (unsigned) Blob.size(); 383 unsigned AbbrevNo = Abbrev-bitc::FIRST_APPLICATION_ABBREV; 384 assert(AbbrevNo < CurAbbrevs.size() && "Invalid abbrev #!"); 385 const BitCodeAbbrev *Abbv = CurAbbrevs[AbbrevNo].get(); 386 387 EmitCode(Abbrev); 388 389 unsigned i = 0, e = static_cast<unsigned>(Abbv->getNumOperandInfos()); 390 if (Code) { 391 assert(e && "Expected non-empty abbreviation"); 392 const BitCodeAbbrevOp &Op = Abbv->getOperandInfo(i++); 393 394 if (Op.isLiteral()) 395 EmitAbbreviatedLiteral(Op, Code.getValue()); 396 else { 397 assert(Op.getEncoding() != BitCodeAbbrevOp::Array && 398 Op.getEncoding() != BitCodeAbbrevOp::Blob && 399 "Expected literal or scalar"); 400 EmitAbbreviatedField(Op, Code.getValue()); 401 } 402 } 403 404 unsigned RecordIdx = 0; 405 for (; i != e; ++i) { 406 const BitCodeAbbrevOp &Op = Abbv->getOperandInfo(i); 407 if (Op.isLiteral()) { 408 assert(RecordIdx < Vals.size() && "Invalid abbrev/record"); 409 EmitAbbreviatedLiteral(Op, Vals[RecordIdx]); 410 ++RecordIdx; 411 } else if (Op.getEncoding() == BitCodeAbbrevOp::Array) { 412 // Array case. 413 assert(i + 2 == e && "array op not second to last?"); 414 const BitCodeAbbrevOp &EltEnc = Abbv->getOperandInfo(++i); 415 416 // If this record has blob data, emit it, otherwise we must have record 417 // entries to encode this way. 418 if (BlobData) { 419 assert(RecordIdx == Vals.size() && 420 "Blob data and record entries specified for array!"); 421 // Emit a vbr6 to indicate the number of elements present. 422 EmitVBR(static_cast<uint32_t>(BlobLen), 6); 423 424 // Emit each field. 425 for (unsigned i = 0; i != BlobLen; ++i) 426 EmitAbbreviatedField(EltEnc, (unsigned char)BlobData[i]); 427 428 // Know that blob data is consumed for assertion below. 429 BlobData = nullptr; 430 } else { 431 // Emit a vbr6 to indicate the number of elements present. 432 EmitVBR(static_cast<uint32_t>(Vals.size()-RecordIdx), 6); 433 434 // Emit each field. 435 for (unsigned e = Vals.size(); RecordIdx != e; ++RecordIdx) 436 EmitAbbreviatedField(EltEnc, Vals[RecordIdx]); 437 } 438 } else if (Op.getEncoding() == BitCodeAbbrevOp::Blob) { 439 // If this record has blob data, emit it, otherwise we must have record 440 // entries to encode this way. 441 442 if (BlobData) { 443 assert(RecordIdx == Vals.size() && 444 "Blob data and record entries specified for blob operand!"); 445 446 assert(Blob.data() == BlobData && "BlobData got moved"); 447 assert(Blob.size() == BlobLen && "BlobLen got changed"); 448 emitBlob(Blob); 449 BlobData = nullptr; 450 } else { 451 emitBlob(Vals.slice(RecordIdx)); 452 } 453 } else { // Single scalar field. 454 assert(RecordIdx < Vals.size() && "Invalid abbrev/record"); 455 EmitAbbreviatedField(Op, Vals[RecordIdx]); 456 ++RecordIdx; 457 } 458 } 459 assert(RecordIdx == Vals.size() && "Not all record operands emitted!"); 460 assert(BlobData == nullptr && 461 "Blob data specified for record that doesn't use it!"); 462 } 463 464 public: 465 /// Emit a blob, including flushing before and tail-padding. 466 template <class UIntTy> 467 void emitBlob(ArrayRef<UIntTy> Bytes, bool ShouldEmitSize = true) { 468 // Emit a vbr6 to indicate the number of elements present. 469 if (ShouldEmitSize) 470 EmitVBR(static_cast<uint32_t>(Bytes.size()), 6); 471 472 // Flush to a 32-bit alignment boundary. 473 FlushToWord(); 474 475 // Emit literal bytes. 476 for (const auto &B : Bytes) { 477 assert(isUInt<8>(B) && "Value too large to emit as byte"); 478 WriteByte((unsigned char)B); 479 } 480 481 // Align end to 32-bits. 482 while (GetBufferOffset() & 3) 483 WriteByte(0); 484 } 485 void emitBlob(StringRef Bytes, bool ShouldEmitSize = true) { 486 emitBlob(makeArrayRef((const uint8_t *)Bytes.data(), Bytes.size()), 487 ShouldEmitSize); 488 } 489 490 /// EmitRecord - Emit the specified record to the stream, using an abbrev if 491 /// we have one to compress the output. 492 template <typename Container> 493 void EmitRecord(unsigned Code, const Container &Vals, unsigned Abbrev = 0) { 494 if (!Abbrev) { 495 // If we don't have an abbrev to use, emit this in its fully unabbreviated 496 // form. 497 auto Count = static_cast<uint32_t>(makeArrayRef(Vals).size()); 498 EmitCode(bitc::UNABBREV_RECORD); 499 EmitVBR(Code, 6); 500 EmitVBR(Count, 6); 501 for (unsigned i = 0, e = Count; i != e; ++i) 502 EmitVBR64(Vals[i], 6); 503 return; 504 } 505 506 EmitRecordWithAbbrevImpl(Abbrev, makeArrayRef(Vals), StringRef(), Code); 507 } 508 509 /// EmitRecordWithAbbrev - Emit a record with the specified abbreviation. 510 /// Unlike EmitRecord, the code for the record should be included in Vals as 511 /// the first entry. 512 template <typename Container> 513 void EmitRecordWithAbbrev(unsigned Abbrev, const Container &Vals) { 514 EmitRecordWithAbbrevImpl(Abbrev, makeArrayRef(Vals), StringRef(), None); 515 } 516 517 /// EmitRecordWithBlob - Emit the specified record to the stream, using an 518 /// abbrev that includes a blob at the end. The blob data to emit is 519 /// specified by the pointer and length specified at the end. In contrast to 520 /// EmitRecord, this routine expects that the first entry in Vals is the code 521 /// of the record. 522 template <typename Container> 523 void EmitRecordWithBlob(unsigned Abbrev, const Container &Vals, 524 StringRef Blob) { 525 EmitRecordWithAbbrevImpl(Abbrev, makeArrayRef(Vals), Blob, None); 526 } 527 template <typename Container> 528 void EmitRecordWithBlob(unsigned Abbrev, const Container &Vals, 529 const char *BlobData, unsigned BlobLen) { 530 return EmitRecordWithAbbrevImpl(Abbrev, makeArrayRef(Vals), 531 StringRef(BlobData, BlobLen), None); 532 } 533 534 /// EmitRecordWithArray - Just like EmitRecordWithBlob, works with records 535 /// that end with an array. 536 template <typename Container> 537 void EmitRecordWithArray(unsigned Abbrev, const Container &Vals, 538 StringRef Array) { 539 EmitRecordWithAbbrevImpl(Abbrev, makeArrayRef(Vals), Array, None); 540 } 541 template <typename Container> 542 void EmitRecordWithArray(unsigned Abbrev, const Container &Vals, 543 const char *ArrayData, unsigned ArrayLen) { 544 return EmitRecordWithAbbrevImpl(Abbrev, makeArrayRef(Vals), 545 StringRef(ArrayData, ArrayLen), None); 546 } 547 548 //===--------------------------------------------------------------------===// 549 // Abbrev Emission 550 //===--------------------------------------------------------------------===// 551 552 private: 553 // Emit the abbreviation as a DEFINE_ABBREV record. 554 void EncodeAbbrev(const BitCodeAbbrev &Abbv) { 555 EmitCode(bitc::DEFINE_ABBREV); 556 EmitVBR(Abbv.getNumOperandInfos(), 5); 557 for (unsigned i = 0, e = static_cast<unsigned>(Abbv.getNumOperandInfos()); 558 i != e; ++i) { 559 const BitCodeAbbrevOp &Op = Abbv.getOperandInfo(i); 560 Emit(Op.isLiteral(), 1); 561 if (Op.isLiteral()) { 562 EmitVBR64(Op.getLiteralValue(), 8); 563 } else { 564 Emit(Op.getEncoding(), 3); 565 if (Op.hasEncodingData()) 566 EmitVBR64(Op.getEncodingData(), 5); 567 } 568 } 569 } 570 public: 571 572 /// Emits the abbreviation \p Abbv to the stream. 573 unsigned EmitAbbrev(std::shared_ptr<BitCodeAbbrev> Abbv) { 574 EncodeAbbrev(*Abbv); 575 CurAbbrevs.push_back(std::move(Abbv)); 576 return static_cast<unsigned>(CurAbbrevs.size())-1 + 577 bitc::FIRST_APPLICATION_ABBREV; 578 } 579 580 //===--------------------------------------------------------------------===// 581 // BlockInfo Block Emission 582 //===--------------------------------------------------------------------===// 583 584 /// EnterBlockInfoBlock - Start emitting the BLOCKINFO_BLOCK. 585 void EnterBlockInfoBlock() { 586 EnterSubblock(bitc::BLOCKINFO_BLOCK_ID, 2); 587 BlockInfoCurBID = ~0U; 588 BlockInfoRecords.clear(); 589 } 590 private: 591 /// SwitchToBlockID - If we aren't already talking about the specified block 592 /// ID, emit a BLOCKINFO_CODE_SETBID record. 593 void SwitchToBlockID(unsigned BlockID) { 594 if (BlockInfoCurBID == BlockID) return; 595 SmallVector<unsigned, 2> V; 596 V.push_back(BlockID); 597 EmitRecord(bitc::BLOCKINFO_CODE_SETBID, V); 598 BlockInfoCurBID = BlockID; 599 } 600 601 BlockInfo &getOrCreateBlockInfo(unsigned BlockID) { 602 if (BlockInfo *BI = getBlockInfo(BlockID)) 603 return *BI; 604 605 // Otherwise, add a new record. 606 BlockInfoRecords.emplace_back(); 607 BlockInfoRecords.back().BlockID = BlockID; 608 return BlockInfoRecords.back(); 609 } 610 611 public: 612 613 /// EmitBlockInfoAbbrev - Emit a DEFINE_ABBREV record for the specified 614 /// BlockID. 615 unsigned EmitBlockInfoAbbrev(unsigned BlockID, std::shared_ptr<BitCodeAbbrev> Abbv) { 616 SwitchToBlockID(BlockID); 617 EncodeAbbrev(*Abbv); 618 619 // Add the abbrev to the specified block record. 620 BlockInfo &Info = getOrCreateBlockInfo(BlockID); 621 Info.Abbrevs.push_back(std::move(Abbv)); 622 623 return Info.Abbrevs.size()-1+bitc::FIRST_APPLICATION_ABBREV; 624 } 625 }; 626 627 628 } // End llvm namespace 629 630 #endif 631