aboutsummaryrefslogtreecommitdiff
path: root/lib/Bitcode/Reader/BitstreamReader.cpp
diff options
context:
space:
mode:
Diffstat (limited to 'lib/Bitcode/Reader/BitstreamReader.cpp')
-rw-r--r--lib/Bitcode/Reader/BitstreamReader.cpp371
1 files changed, 371 insertions, 0 deletions
diff --git a/lib/Bitcode/Reader/BitstreamReader.cpp b/lib/Bitcode/Reader/BitstreamReader.cpp
new file mode 100644
index 0000000000..942346b44e
--- /dev/null
+++ b/lib/Bitcode/Reader/BitstreamReader.cpp
@@ -0,0 +1,371 @@
+//===- BitstreamReader.cpp - BitstreamReader implementation ---------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Bitcode/BitstreamReader.h"
+
+using namespace llvm;
+
+//===----------------------------------------------------------------------===//
+// BitstreamCursor implementation
+//===----------------------------------------------------------------------===//
+
+void BitstreamCursor::operator=(const BitstreamCursor &RHS) {
+ freeState();
+
+ BitStream = RHS.BitStream;
+ NextChar = RHS.NextChar;
+ CurWord = RHS.CurWord;
+ BitsInCurWord = RHS.BitsInCurWord;
+ CurCodeSize = RHS.CurCodeSize;
+
+ // Copy abbreviations, and bump ref counts.
+ CurAbbrevs = RHS.CurAbbrevs;
+ for (size_t i = 0, e = CurAbbrevs.size(); i != e; ++i)
+ CurAbbrevs[i]->addRef();
+
+ // Copy block scope and bump ref counts.
+ BlockScope = RHS.BlockScope;
+ for (size_t S = 0, e = BlockScope.size(); S != e; ++S) {
+ std::vector<BitCodeAbbrev*> &Abbrevs = BlockScope[S].PrevAbbrevs;
+ for (size_t i = 0, e = Abbrevs.size(); i != e; ++i)
+ Abbrevs[i]->addRef();
+ }
+}
+
+void BitstreamCursor::freeState() {
+ // Free all the Abbrevs.
+ for (size_t i = 0, e = CurAbbrevs.size(); i != e; ++i)
+ CurAbbrevs[i]->dropRef();
+ CurAbbrevs.clear();
+
+ // Free all the Abbrevs in the block scope.
+ for (size_t S = 0, e = BlockScope.size(); S != e; ++S) {
+ std::vector<BitCodeAbbrev*> &Abbrevs = BlockScope[S].PrevAbbrevs;
+ for (size_t i = 0, e = Abbrevs.size(); i != e; ++i)
+ Abbrevs[i]->dropRef();
+ }
+ BlockScope.clear();
+}
+
+/// EnterSubBlock - Having read the ENTER_SUBBLOCK abbrevid, enter
+/// the block, and return true if the block has an error.
+bool 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 (const BitstreamReader::BlockInfo *Info =
+ BitStream->getBlockInfo(BlockID)) {
+ for (size_t i = 0, e = Info->Abbrevs.size(); i != e; ++i) {
+ CurAbbrevs.push_back(Info->Abbrevs[i]);
+ CurAbbrevs.back()->addRef();
+ }
+ }
+
+ // Get the codesize of this block.
+ CurCodeSize = ReadVBR(bitc::CodeLenWidth);
+ SkipToFourByteBoundary();
+ unsigned NumWords = Read(bitc::BlockSizeWidth);
+ if (NumWordsP) *NumWordsP = NumWords;
+
+ // Validate that this block is sane.
+ if (CurCodeSize == 0 || AtEndOfStream())
+ return true;
+
+ return false;
+}
+
+void BitstreamCursor::readAbbreviatedLiteral(const BitCodeAbbrevOp &Op,
+ SmallVectorImpl<uint64_t> &Vals) {
+ assert(Op.isLiteral() && "Not a literal");
+ // If the abbrev specifies the literal value to use, use it.
+ Vals.push_back(Op.getLiteralValue());
+}
+
+void BitstreamCursor::readAbbreviatedField(const BitCodeAbbrevOp &Op,
+ SmallVectorImpl<uint64_t> &Vals) {
+ assert(!Op.isLiteral() && "Use ReadAbbreviatedLiteral for literals!");
+
+ // Decode the value as we are commanded.
+ switch (Op.getEncoding()) {
+ case BitCodeAbbrevOp::Array:
+ case BitCodeAbbrevOp::Blob:
+ assert(0 && "Should not reach here");
+ case BitCodeAbbrevOp::Fixed:
+ Vals.push_back(Read((unsigned)Op.getEncodingData()));
+ break;
+ case BitCodeAbbrevOp::VBR:
+ Vals.push_back(ReadVBR64((unsigned)Op.getEncodingData()));
+ break;
+ case BitCodeAbbrevOp::Char6:
+ Vals.push_back(BitCodeAbbrevOp::DecodeChar6(Read(6)));
+ break;
+ }
+}
+
+void BitstreamCursor::skipAbbreviatedField(const BitCodeAbbrevOp &Op) {
+ assert(!Op.isLiteral() && "Use ReadAbbreviatedLiteral for literals!");
+
+ // Decode the value as we are commanded.
+ switch (Op.getEncoding()) {
+ case BitCodeAbbrevOp::Array:
+ case BitCodeAbbrevOp::Blob:
+ assert(0 && "Should not reach here");
+ case BitCodeAbbrevOp::Fixed:
+ (void)Read((unsigned)Op.getEncodingData());
+ break;
+ case BitCodeAbbrevOp::VBR:
+ (void)ReadVBR64((unsigned)Op.getEncodingData());
+ break;
+ case BitCodeAbbrevOp::Char6:
+ (void)Read(6);
+ break;
+ }
+}
+
+
+
+/// skipRecord - Read the current record and discard it.
+void BitstreamCursor::skipRecord(unsigned AbbrevID) {
+ // Skip unabbreviated records by reading past their entries.
+ if (AbbrevID == bitc::UNABBREV_RECORD) {
+ unsigned Code = ReadVBR(6);
+ (void)Code;
+ unsigned NumElts = ReadVBR(6);
+ for (unsigned i = 0; i != NumElts; ++i)
+ (void)ReadVBR64(6);
+ return;
+ }
+
+ const BitCodeAbbrev *Abbv = getAbbrev(AbbrevID);
+
+ for (unsigned i = 0, 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) {
+ skipAbbreviatedField(Op);
+ continue;
+ }
+
+ if (Op.getEncoding() == BitCodeAbbrevOp::Array) {
+ // Array case. Read the number of elements as a vbr6.
+ unsigned NumElts = ReadVBR(6);
+
+ // Get the element encoding.
+ assert(i+2 == e && "array op not second to last?");
+ const BitCodeAbbrevOp &EltEnc = Abbv->getOperandInfo(++i);
+
+ // Read all the elements.
+ for (; NumElts; --NumElts)
+ skipAbbreviatedField(EltEnc);
+ continue;
+ }
+
+ assert(Op.getEncoding() == BitCodeAbbrevOp::Blob);
+ // Blob case. Read the number of bytes as a vbr6.
+ unsigned NumElts = ReadVBR(6);
+ SkipToFourByteBoundary(); // 32-bit alignment
+
+ // Figure out where the end of this blob will be including tail padding.
+ size_t NewEnd = GetCurrentBitNo()+((NumElts+3)&~3)*8;
+
+ // If this would read off the end of the bitcode file, just set the
+ // record to empty and return.
+ if (!canSkipToPos(NewEnd/8)) {
+ NextChar = BitStream->getBitcodeBytes().getExtent();
+ break;
+ }
+
+ // Skip over the blob.
+ JumpToBit(NewEnd);
+ }
+}
+
+unsigned BitstreamCursor::readRecord(unsigned AbbrevID,
+ SmallVectorImpl<uint64_t> &Vals,
+ StringRef *Blob) {
+ if (AbbrevID == bitc::UNABBREV_RECORD) {
+ unsigned Code = ReadVBR(6);
+ unsigned NumElts = ReadVBR(6);
+ for (unsigned i = 0; i != NumElts; ++i)
+ Vals.push_back(ReadVBR64(6));
+ return Code;
+ }
+
+ const BitCodeAbbrev *Abbv = getAbbrev(AbbrevID);
+
+ for (unsigned i = 0, e = Abbv->getNumOperandInfos(); i != e; ++i) {
+ const BitCodeAbbrevOp &Op = Abbv->getOperandInfo(i);
+ if (Op.isLiteral()) {
+ readAbbreviatedLiteral(Op, Vals);
+ continue;
+ }
+
+ if (Op.getEncoding() != BitCodeAbbrevOp::Array &&
+ Op.getEncoding() != BitCodeAbbrevOp::Blob) {
+ readAbbreviatedField(Op, Vals);
+ continue;
+ }
+
+ if (Op.getEncoding() == BitCodeAbbrevOp::Array) {
+ // Array case. Read the number of elements as a vbr6.
+ unsigned NumElts = ReadVBR(6);
+
+ // Get the element encoding.
+ assert(i+2 == e && "array op not second to last?");
+ const BitCodeAbbrevOp &EltEnc = Abbv->getOperandInfo(++i);
+
+ // Read all the elements.
+ for (; NumElts; --NumElts)
+ readAbbreviatedField(EltEnc, Vals);
+ continue;
+ }
+
+ assert(Op.getEncoding() == BitCodeAbbrevOp::Blob);
+ // Blob case. Read the number of bytes as a vbr6.
+ unsigned NumElts = ReadVBR(6);
+ SkipToFourByteBoundary(); // 32-bit alignment
+
+ // Figure out where the end of this blob will be including tail padding.
+ size_t CurBitPos = GetCurrentBitNo();
+ size_t NewEnd = CurBitPos+((NumElts+3)&~3)*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);
+ NextChar = BitStream->getBitcodeBytes().getExtent();
+ break;
+ }
+
+ // Otherwise, inform the streamer that we need these bytes in memory.
+ const char *Ptr = (const char*)
+ BitStream->getBitcodeBytes().getPointer(CurBitPos/8, 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.
+ for (; NumElts; --NumElts)
+ Vals.push_back((unsigned char)*Ptr++);
+ }
+ // Skip over tail padding.
+ JumpToBit(NewEnd);
+ }
+
+ unsigned Code = (unsigned)Vals[0];
+ Vals.erase(Vals.begin());
+ return Code;
+}
+
+
+void BitstreamCursor::ReadAbbrevRecord() {
+ BitCodeAbbrev *Abbv = new BitCodeAbbrev();
+ unsigned NumOpInfo = ReadVBR(5);
+ for (unsigned i = 0; i != NumOpInfo; ++i) {
+ bool IsLiteral = Read(1) ? true : false;
+ if (IsLiteral) {
+ Abbv->Add(BitCodeAbbrevOp(ReadVBR64(8)));
+ continue;
+ }
+
+ BitCodeAbbrevOp::Encoding E = (BitCodeAbbrevOp::Encoding)Read(3);
+ if (BitCodeAbbrevOp::hasEncodingData(E)) {
+ unsigned Data = ReadVBR64(5);
+
+ // 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;
+ }
+
+ Abbv->Add(BitCodeAbbrevOp(E, Data));
+ } else
+ Abbv->Add(BitCodeAbbrevOp(E));
+ }
+ CurAbbrevs.push_back(Abbv);
+}
+
+bool BitstreamCursor::ReadBlockInfoBlock() {
+ // If this is the second stream to get to the block info block, skip it.
+ if (BitStream->hasBlockInfoRecords())
+ return SkipBlock();
+
+ if (EnterSubBlock(bitc::BLOCKINFO_BLOCK_ID)) return true;
+
+ SmallVector<uint64_t, 64> Record;
+ BitstreamReader::BlockInfo *CurBlockInfo = 0;
+
+ // Read all the records for this module.
+ while (1) {
+ BitstreamEntry Entry = advanceSkippingSubblocks(AF_DontAutoprocessAbbrevs);
+
+ switch (Entry.Kind) {
+ case llvm::BitstreamEntry::SubBlock: // Handled for us already.
+ case llvm::BitstreamEntry::Error:
+ return true;
+ case llvm::BitstreamEntry::EndBlock:
+ return false;
+ case llvm::BitstreamEntry::Record:
+ // The interesting case.
+ break;
+ }
+
+ // Read abbrev records, associate them with CurBID.
+ if (Entry.ID == bitc::DEFINE_ABBREV) {
+ if (!CurBlockInfo) return true;
+ ReadAbbrevRecord();
+
+ // ReadAbbrevRecord installs the abbrev in CurAbbrevs. Move it to the
+ // appropriate BlockInfo.
+ BitCodeAbbrev *Abbv = CurAbbrevs.back();
+ CurAbbrevs.pop_back();
+ CurBlockInfo->Abbrevs.push_back(Abbv);
+ continue;
+ }
+
+ // Read a record.
+ Record.clear();
+ switch (readRecord(Entry.ID, Record)) {
+ default: break; // Default behavior, ignore unknown content.
+ case bitc::BLOCKINFO_CODE_SETBID:
+ if (Record.size() < 1) return true;
+ CurBlockInfo = &BitStream->getOrCreateBlockInfo((unsigned)Record[0]);
+ break;
+ case bitc::BLOCKINFO_CODE_BLOCKNAME: {
+ if (!CurBlockInfo) return true;
+ if (BitStream->isIgnoringBlockInfoNames()) break; // Ignore name.
+ std::string Name;
+ for (unsigned i = 0, e = Record.size(); i != e; ++i)
+ Name += (char)Record[i];
+ CurBlockInfo->Name = Name;
+ break;
+ }
+ case bitc::BLOCKINFO_CODE_SETRECORDNAME: {
+ if (!CurBlockInfo) return true;
+ if (BitStream->isIgnoringBlockInfoNames()) break; // Ignore name.
+ std::string Name;
+ for (unsigned i = 1, e = Record.size(); i != e; ++i)
+ Name += (char)Record[i];
+ CurBlockInfo->RecordNames.push_back(std::make_pair((unsigned)Record[0],
+ Name));
+ break;
+ }
+ }
+ }
+}
+
generated by cgit v1.2.3-18-g5258 (git 2.32.0) at 2024-11-24 00:22:10 +0000