1 //===- BitstreamReader.cpp - BitstreamReader implementation ---------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 #include "llvm/Bitcode/BitstreamReader.h"
14 //===----------------------------------------------------------------------===//
15 // BitstreamCursor implementation
16 //===----------------------------------------------------------------------===//
18 void BitstreamCursor::operator=(const BitstreamCursor &RHS) {
21 BitStream = RHS.BitStream;
22 NextChar = RHS.NextChar;
23 CurWord = RHS.CurWord;
24 BitsInCurWord = RHS.BitsInCurWord;
25 CurCodeSize = RHS.CurCodeSize;
27 // Copy abbreviations, and bump ref counts.
28 CurAbbrevs = RHS.CurAbbrevs;
29 for (unsigned i = 0, e = static_cast<unsigned>(CurAbbrevs.size());
31 CurAbbrevs[i]->addRef();
33 // Copy block scope and bump ref counts.
34 BlockScope = RHS.BlockScope;
35 for (unsigned S = 0, e = static_cast<unsigned>(BlockScope.size());
37 std::vector<BitCodeAbbrev*> &Abbrevs = BlockScope[S].PrevAbbrevs;
38 for (unsigned i = 0, e = static_cast<unsigned>(Abbrevs.size());
44 void BitstreamCursor::freeState() {
45 // Free all the Abbrevs.
46 for (unsigned i = 0, e = static_cast<unsigned>(CurAbbrevs.size());
48 CurAbbrevs[i]->dropRef();
51 // Free all the Abbrevs in the block scope.
52 for (unsigned S = 0, e = static_cast<unsigned>(BlockScope.size());
54 std::vector<BitCodeAbbrev*> &Abbrevs = BlockScope[S].PrevAbbrevs;
55 for (unsigned i = 0, e = static_cast<unsigned>(Abbrevs.size());
57 Abbrevs[i]->dropRef();
62 /// EnterSubBlock - Having read the ENTER_SUBBLOCK abbrevid, enter
63 /// the block, and return true if the block has an error.
64 bool BitstreamCursor::EnterSubBlock(unsigned BlockID, unsigned *NumWordsP) {
65 // Save the current block's state on BlockScope.
66 BlockScope.push_back(Block(CurCodeSize));
67 BlockScope.back().PrevAbbrevs.swap(CurAbbrevs);
69 // Add the abbrevs specific to this block to the CurAbbrevs list.
70 if (const BitstreamReader::BlockInfo *Info =
71 BitStream->getBlockInfo(BlockID)) {
72 for (unsigned i = 0, e = static_cast<unsigned>(Info->Abbrevs.size());
74 CurAbbrevs.push_back(Info->Abbrevs[i]);
75 CurAbbrevs.back()->addRef();
79 // Get the codesize of this block.
80 CurCodeSize = ReadVBR(bitc::CodeLenWidth);
81 SkipToFourByteBoundary();
82 unsigned NumWords = Read(bitc::BlockSizeWidth);
83 if (NumWordsP) *NumWordsP = NumWords;
85 // Validate that this block is sane.
86 if (CurCodeSize == 0 || AtEndOfStream())
92 void BitstreamCursor::readAbbreviatedLiteral(const BitCodeAbbrevOp &Op,
93 SmallVectorImpl<uint64_t> &Vals) {
94 assert(Op.isLiteral() && "Not a literal");
95 // If the abbrev specifies the literal value to use, use it.
96 Vals.push_back(Op.getLiteralValue());
99 void BitstreamCursor::readAbbreviatedField(const BitCodeAbbrevOp &Op,
100 SmallVectorImpl<uint64_t> &Vals) {
101 assert(!Op.isLiteral() && "Use ReadAbbreviatedLiteral for literals!");
103 // Decode the value as we are commanded.
104 switch (Op.getEncoding()) {
105 case BitCodeAbbrevOp::Array:
106 case BitCodeAbbrevOp::Blob:
107 assert(0 && "Should not reach here");
108 case BitCodeAbbrevOp::Fixed:
109 Vals.push_back(Read((unsigned)Op.getEncodingData()));
111 case BitCodeAbbrevOp::VBR:
112 Vals.push_back(ReadVBR64((unsigned)Op.getEncodingData()));
114 case BitCodeAbbrevOp::Char6:
115 Vals.push_back(BitCodeAbbrevOp::DecodeChar6(Read(6)));
120 void BitstreamCursor::skipAbbreviatedField(const BitCodeAbbrevOp &Op) {
121 assert(!Op.isLiteral() && "Use ReadAbbreviatedLiteral for literals!");
123 // Decode the value as we are commanded.
124 switch (Op.getEncoding()) {
125 case BitCodeAbbrevOp::Array:
126 case BitCodeAbbrevOp::Blob:
127 assert(0 && "Should not reach here");
128 case BitCodeAbbrevOp::Fixed:
129 (void)Read((unsigned)Op.getEncodingData());
131 case BitCodeAbbrevOp::VBR:
132 (void)ReadVBR64((unsigned)Op.getEncodingData());
134 case BitCodeAbbrevOp::Char6:
142 /// skipRecord - Read the current record and discard it.
143 void BitstreamCursor::skipRecord(unsigned AbbrevID) {
144 // Skip unabbreviated records by reading past their entries.
145 if (AbbrevID == bitc::UNABBREV_RECORD) {
146 unsigned Code = ReadVBR(6);
148 unsigned NumElts = ReadVBR(6);
149 for (unsigned i = 0; i != NumElts; ++i)
154 const BitCodeAbbrev *Abbv = getAbbrev(AbbrevID);
156 for (unsigned i = 0, e = Abbv->getNumOperandInfos(); i != e; ++i) {
157 const BitCodeAbbrevOp &Op = Abbv->getOperandInfo(i);
161 if (Op.getEncoding() != BitCodeAbbrevOp::Array &&
162 Op.getEncoding() != BitCodeAbbrevOp::Blob) {
163 skipAbbreviatedField(Op);
167 if (Op.getEncoding() == BitCodeAbbrevOp::Array) {
168 // Array case. Read the number of elements as a vbr6.
169 unsigned NumElts = ReadVBR(6);
171 // Get the element encoding.
172 assert(i+2 == e && "array op not second to last?");
173 const BitCodeAbbrevOp &EltEnc = Abbv->getOperandInfo(++i);
175 // Read all the elements.
176 for (; NumElts; --NumElts)
177 skipAbbreviatedField(EltEnc);
181 assert(Op.getEncoding() == BitCodeAbbrevOp::Blob);
182 // Blob case. Read the number of bytes as a vbr6.
183 unsigned NumElts = ReadVBR(6);
184 SkipToFourByteBoundary(); // 32-bit alignment
186 // Figure out where the end of this blob will be including tail padding.
187 size_t NewEnd = GetCurrentBitNo()+((NumElts+3)&~3)*8;
189 // If this would read off the end of the bitcode file, just set the
190 // record to empty and return.
191 if (!canSkipToPos(NewEnd/8)) {
192 NextChar = BitStream->getBitcodeBytes().getExtent();
196 // Skip over the blob.
201 unsigned BitstreamCursor::readRecord(unsigned AbbrevID,
202 SmallVectorImpl<uint64_t> &Vals,
204 if (AbbrevID == bitc::UNABBREV_RECORD) {
205 unsigned Code = ReadVBR(6);
206 unsigned NumElts = ReadVBR(6);
207 for (unsigned i = 0; i != NumElts; ++i)
208 Vals.push_back(ReadVBR64(6));
212 const BitCodeAbbrev *Abbv = getAbbrev(AbbrevID);
214 for (unsigned i = 0, e = Abbv->getNumOperandInfos(); i != e; ++i) {
215 const BitCodeAbbrevOp &Op = Abbv->getOperandInfo(i);
216 if (Op.isLiteral()) {
217 readAbbreviatedLiteral(Op, Vals);
221 if (Op.getEncoding() != BitCodeAbbrevOp::Array &&
222 Op.getEncoding() != BitCodeAbbrevOp::Blob) {
223 readAbbreviatedField(Op, Vals);
227 if (Op.getEncoding() == BitCodeAbbrevOp::Array) {
228 // Array case. Read the number of elements as a vbr6.
229 unsigned NumElts = ReadVBR(6);
231 // Get the element encoding.
232 assert(i+2 == e && "array op not second to last?");
233 const BitCodeAbbrevOp &EltEnc = Abbv->getOperandInfo(++i);
235 // Read all the elements.
236 for (; NumElts; --NumElts)
237 readAbbreviatedField(EltEnc, Vals);
241 assert(Op.getEncoding() == BitCodeAbbrevOp::Blob);
242 // Blob case. Read the number of bytes as a vbr6.
243 unsigned NumElts = ReadVBR(6);
244 SkipToFourByteBoundary(); // 32-bit alignment
246 // Figure out where the end of this blob will be including tail padding.
247 size_t CurBitPos = GetCurrentBitNo();
248 size_t NewEnd = CurBitPos+((NumElts+3)&~3)*8;
250 // If this would read off the end of the bitcode file, just set the
251 // record to empty and return.
252 if (!canSkipToPos(NewEnd/8)) {
253 Vals.append(NumElts, 0);
254 NextChar = BitStream->getBitcodeBytes().getExtent();
258 // Otherwise, inform the streamer that we need these bytes in memory.
259 const char *Ptr = (const char*)
260 BitStream->getBitcodeBytes().getPointer(CurBitPos/8, NumElts);
262 // If we can return a reference to the data, do so to avoid copying it.
264 *Blob = StringRef(Ptr, NumElts);
266 // Otherwise, unpack into Vals with zero extension.
267 for (; NumElts; --NumElts)
268 Vals.push_back((unsigned char)*Ptr++);
270 // Skip over tail padding.
274 unsigned Code = (unsigned)Vals[0];
275 Vals.erase(Vals.begin());
280 void BitstreamCursor::ReadAbbrevRecord() {
281 BitCodeAbbrev *Abbv = new BitCodeAbbrev();
282 unsigned NumOpInfo = ReadVBR(5);
283 for (unsigned i = 0; i != NumOpInfo; ++i) {
284 bool IsLiteral = Read(1) ? true : false;
286 Abbv->Add(BitCodeAbbrevOp(ReadVBR64(8)));
290 BitCodeAbbrevOp::Encoding E = (BitCodeAbbrevOp::Encoding)Read(3);
291 if (BitCodeAbbrevOp::hasEncodingData(E)) {
292 unsigned Data = ReadVBR64(5);
294 // As a special case, handle fixed(0) (i.e., a fixed field with zero bits)
295 // and vbr(0) as a literal zero. This is decoded the same way, and avoids
296 // a slow path in Read() to have to handle reading zero bits.
297 if ((E == BitCodeAbbrevOp::Fixed || E == BitCodeAbbrevOp::VBR) &&
299 Abbv->Add(BitCodeAbbrevOp(0));
303 Abbv->Add(BitCodeAbbrevOp(E, Data));
305 Abbv->Add(BitCodeAbbrevOp(E));
307 CurAbbrevs.push_back(Abbv);
310 bool BitstreamCursor::ReadBlockInfoBlock() {
311 // If this is the second stream to get to the block info block, skip it.
312 if (BitStream->hasBlockInfoRecords())
315 if (EnterSubBlock(bitc::BLOCKINFO_BLOCK_ID)) return true;
317 SmallVector<uint64_t, 64> Record;
318 BitstreamReader::BlockInfo *CurBlockInfo = 0;
320 // Read all the records for this module.
322 BitstreamEntry Entry = advanceSkippingSubblocks(AF_DontAutoprocessAbbrevs);
324 switch (Entry.Kind) {
325 case llvm::BitstreamEntry::SubBlock: // Handled for us already.
326 case llvm::BitstreamEntry::Error:
328 case llvm::BitstreamEntry::EndBlock:
330 case llvm::BitstreamEntry::Record:
331 // The interesting case.
335 // Read abbrev records, associate them with CurBID.
336 if (Entry.ID == bitc::DEFINE_ABBREV) {
337 if (!CurBlockInfo) return true;
340 // ReadAbbrevRecord installs the abbrev in CurAbbrevs. Move it to the
341 // appropriate BlockInfo.
342 BitCodeAbbrev *Abbv = CurAbbrevs.back();
343 CurAbbrevs.pop_back();
344 CurBlockInfo->Abbrevs.push_back(Abbv);
350 switch (readRecord(Entry.ID, Record)) {
351 default: break; // Default behavior, ignore unknown content.
352 case bitc::BLOCKINFO_CODE_SETBID:
353 if (Record.size() < 1) return true;
354 CurBlockInfo = &BitStream->getOrCreateBlockInfo((unsigned)Record[0]);
356 case bitc::BLOCKINFO_CODE_BLOCKNAME: {
357 if (!CurBlockInfo) return true;
358 if (BitStream->isIgnoringBlockInfoNames()) break; // Ignore name.
360 for (unsigned i = 0, e = Record.size(); i != e; ++i)
361 Name += (char)Record[i];
362 CurBlockInfo->Name = Name;
365 case bitc::BLOCKINFO_CODE_SETRECORDNAME: {
366 if (!CurBlockInfo) return true;
367 if (BitStream->isIgnoringBlockInfoNames()) break; // Ignore name.
369 for (unsigned i = 1, e = Record.size(); i != e; ++i)
370 Name += (char)Record[i];
371 CurBlockInfo->RecordNames.push_back(std::make_pair((unsigned)Record[0],