Rebased PNaCl localmods in LLVM to 223109

lib/Bitcode/NaCl/Reader/NaClBitstreamReader.cpp

Index: lib/Bitcode/NaCl/Reader/NaClBitstreamReader.cpp
diff --git a/lib/Bitcode/NaCl/Reader/NaClBitstreamReader.cpp b/lib/Bitcode/NaCl/Reader/NaClBitstreamReader.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..2eba5bb0cfe6ba200ea7ae58291e479a3d88a08e
--- /dev/null
+++ b/lib/Bitcode/NaCl/Reader/NaClBitstreamReader.cpp
@@ -0,0 +1,361 @@
+//===- NaClBitstreamReader.cpp --------------------------------------------===//
+//     NaClBitstreamReader 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/NaCl/NaClBitstreamReader.h"
+#include "llvm/Support/raw_ostream.h"
+
+using namespace llvm;
+
+//===----------------------------------------------------------------------===//
+//  NaClBitstreamCursor implementation
+//===----------------------------------------------------------------------===//
+
+void NaClBitstreamCursor::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<NaClBitCodeAbbrev*> &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 NaClBitstreamCursor::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 NaClBitstreamReader::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.IsFixed = true;
+  CurCodeSize.NumBits = ReadVBR(naclbitc::CodeLenWidth);
+  SkipToFourByteBoundary();
+  unsigned NumWords = Read(naclbitc::BlockSizeWidth);
+  if (NumWordsP) *NumWordsP = NumWords;
+
+  // Validate that this block is sane.
+  if (CurCodeSize.NumBits == 0 || AtEndOfStream())
+    return true;
+
+  return false;
+}
+
+void NaClBitstreamCursor::skipAbbreviatedField(const NaClBitCodeAbbrevOp &Op) {
+  // Decode the value as we are commanded.
+  switch (Op.getEncoding()) {
+  case NaClBitCodeAbbrevOp::Literal:
+    report_fatal_error("Not to be used with literals!");
+  case NaClBitCodeAbbrevOp::Fixed:
+    (void)Read((unsigned)Op.getValue());
+    break;
+  case NaClBitCodeAbbrevOp::VBR:
+    (void)ReadVBR64((unsigned)Op.getValue());
+    break;
+  case NaClBitCodeAbbrevOp::Array:
+    report_fatal_error("Bad array abbreviation encoding!");
+  case NaClBitCodeAbbrevOp::Char6:
+    (void)Read(6);
+    break;
+  }
+}
+
+/// skipRecord - Read the current record and discard it.
+void NaClBitstreamCursor::skipRecord(unsigned AbbrevID) {
+  // Skip unabbreviated records by reading past their entries.
+  if (AbbrevID == naclbitc::UNABBREV_RECORD) {
+    unsigned Code = ReadVBR(6);
+    (void)Code;
+    unsigned NumElts = ReadVBR(6);
+    for (unsigned i = 0; i != NumElts; ++i)
+      (void)ReadVBR64(6);
+    return;
+  }
+
+  const NaClBitCodeAbbrev *Abbv = getAbbrev(AbbrevID);
+
+  for (unsigned i = 0, e = Abbv->getNumOperandInfos(); i != e; ++i) {
+    const NaClBitCodeAbbrevOp &Op = Abbv->getOperandInfo(i);
+    switch (Op.getEncoding()) {
+    default:
+      skipAbbreviatedField(Op);
+      break;
+    case NaClBitCodeAbbrevOp::Literal:
+      break;
+    case NaClBitCodeAbbrevOp::Array: {
+      // Array case.  Read the number of elements as a vbr6.
+      unsigned NumElts = ReadVBR(6);
+
+      // Get the element encoding.
+      const NaClBitCodeAbbrevOp &EltEnc = Abbv->getOperandInfo(++i);
+
+      // Read all the elements.
+      for (; NumElts; --NumElts)
+        skipAbbreviatedField(EltEnc);
+      break;
+    }
+    }
+  }
+}
+
+bool NaClBitstreamCursor::readRecordAbbrevField(
+    const NaClBitCodeAbbrevOp &Op, uint64_t &Value) {
+  switch (Op.getEncoding()) {
+  case NaClBitCodeAbbrevOp::Literal:
+    Value = Op.getValue();
+    break;
+  case NaClBitCodeAbbrevOp::Array:
+    // Returns number of elements in the array.
+    Value = ReadVBR(6);
+    return true;
+  case NaClBitCodeAbbrevOp::Fixed:
+    Value = Read((unsigned)Op.getValue());
+    break;
+  case NaClBitCodeAbbrevOp::VBR:
+    Value = ReadVBR64((unsigned)Op.getValue());
+    break;
+  case NaClBitCodeAbbrevOp::Char6:
+    Value = NaClBitCodeAbbrevOp::DecodeChar6(Read(6));
+    break;
+  }
+  return false;
+}
+
+uint64_t NaClBitstreamCursor::readArrayAbbreviatedField(
+    const NaClBitCodeAbbrevOp &Op) {
+  // Decode the value as we are commanded.
+  switch (Op.getEncoding()) {
+  case NaClBitCodeAbbrevOp::Literal:
+    report_fatal_error("Not to be used with literals!");
+  case NaClBitCodeAbbrevOp::Fixed:
+    return Read((unsigned)Op.getValue());
+  case NaClBitCodeAbbrevOp::VBR:
+    return ReadVBR64((unsigned)Op.getValue());
+  case NaClBitCodeAbbrevOp::Array:
+    report_fatal_error("Bad array abbreviation encoding!");
+  case NaClBitCodeAbbrevOp::Char6:
+    return NaClBitCodeAbbrevOp::DecodeChar6(Read(6));
+  }
+  llvm_unreachable("unhandled NaClBitCodeAbbrevOp encoding");
+}
+
+void NaClBitstreamCursor::readArrayAbbrev(
+    const NaClBitCodeAbbrevOp &Op, unsigned NumArrayElements,
+    SmallVectorImpl<uint64_t> &Vals) {
+  for (; NumArrayElements; --NumArrayElements) {
+    Vals.push_back(readArrayAbbreviatedField(Op));
+  }
+}
+
+unsigned NaClBitstreamCursor::readRecord(unsigned AbbrevID,
+                                         SmallVectorImpl<uint64_t> &Vals) {
+  if (AbbrevID == naclbitc::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 NaClBitCodeAbbrev *Abbv = getAbbrev(AbbrevID);
+  unsigned NumOperands = Abbv->getNumOperandInfos();
+  assert(NumOperands > 0 && "Too few operands for abbreviation!");
+
+  uint64_t Value;
+
+  // Read code.
+  unsigned Code;
+  if (readRecordAbbrevField(Abbv->getOperandInfo(0), Value)) {
+    // Array found, use to read all elements.
+    assert(Value > 0 && "No code found for record!");
+    const NaClBitCodeAbbrevOp &Op = Abbv->getOperandInfo(1);
+    Code = readArrayAbbreviatedField(Op);
+    readArrayAbbrev(Op, Value - 1, Vals);
+    return Code;
+  }
+  Code = Value;
+
+  // Read arguments.
+  for (unsigned i = 1; i != NumOperands; ++i) {
+    if (readRecordAbbrevField(Abbv->getOperandInfo(i), Value)) {
+      ++i;
+      readArrayAbbrev(Abbv->getOperandInfo(i), Value, Vals);
+      return Code;
+    }
+    Vals.push_back(Value);
+  }
+  return Code;
+}
+
+
+namespace {
+
+static NaClBitCodeAbbrevOp::Encoding getEncoding(uint64_t Encoding) {
+  if (!NaClBitCodeAbbrevOp::isValidEncoding(Encoding)) {
+    std::string Buffer;
+    raw_string_ostream StrBuf(Buffer);
+    StrBuf << "Invalid abbreviation encoding " << Encoding
+           << "specified in bitcode file";
+    report_fatal_error(StrBuf.str());
+  }
+  return NaClBitCodeAbbrevOp::Encoding(Encoding);
+}
+
+} // end of anonymous space.
+
+void NaClBitstreamCursor::ReadAbbrevRecord(bool IsLocal,
+                                           NaClAbbrevListener *Listener) {
+  NaClBitCodeAbbrev *Abbv = new NaClBitCodeAbbrev();
+  unsigned NumOpInfo = ReadVBR(5);
+  if (Listener) Listener->Values.push_back(NumOpInfo);
+  for (unsigned i = 0; i != NumOpInfo; ++i) {
+    bool IsLiteral = Read(1) ? true : false;
+    if (Listener) Listener->Values.push_back(IsLiteral);
+    if (IsLiteral) {
+      uint64_t Value = ReadVBR64(8);
+      if (Listener) Listener->Values.push_back(Value);
+      Abbv->Add(NaClBitCodeAbbrevOp(Value));
+      continue;
+    }
+    NaClBitCodeAbbrevOp::Encoding E = getEncoding(Read(3));
+    if (Listener) Listener->Values.push_back(E);
+    if (NaClBitCodeAbbrevOp::hasValue(E)) {
+      unsigned Data = ReadVBR64(5);
+      if (Listener) Listener->Values.push_back(Data);
+
+      // 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 == NaClBitCodeAbbrevOp::Fixed || E == NaClBitCodeAbbrevOp::VBR) &&
+          Data == 0) {
+        if (Listener) Listener->Values.push_back(0);
+        Abbv->Add(NaClBitCodeAbbrevOp(0));
+        continue;
+      }
+      if (!NaClBitCodeAbbrevOp::isValid(E, Data)) {
+        std::string Buffer;
+        raw_string_ostream StrBuf(Buffer);
+        StrBuf << "Invalid abbreviation encoding ("
+               << NaClBitCodeAbbrevOp::getEncodingName(E)
+               << ", " << Data << ")";
+        report_fatal_error(StrBuf.str());
+      }
+      Abbv->Add(NaClBitCodeAbbrevOp(E, Data));
+    } else {
+      if (!NaClBitCodeAbbrevOp::isValid(E)) {
+        std::string Buffer;
+        raw_string_ostream StrBuf(Buffer);
+        StrBuf << "Invalid abbreviation encoding ("
+               << NaClBitCodeAbbrevOp::getEncodingName(E) << ")";
+        report_fatal_error(StrBuf.str());
+      }
+      Abbv->Add(NaClBitCodeAbbrevOp(E));
+    }
+  }
+  if (!Abbv->isValid())
+    report_fatal_error("Invalid abbreviation specified in bitcode file");
+  CurAbbrevs.push_back(Abbv);
+  if (Listener) {
+    Listener->ProcessAbbreviation(Abbv, IsLocal);
+    // Reset record information of the listener.
+    Listener->Values.clear();
+    Listener->StartBit = GetCurrentBitNo();
+  }
+}
+
+void NaClBitstreamCursor::SkipAbbrevRecord() {
+  unsigned NumOpInfo = ReadVBR(5);
+  for (unsigned i = 0; i != NumOpInfo; ++i) {
+    bool IsLiteral = Read(1) ? true : false;
+    if (IsLiteral) {
+      ReadVBR64(8);
+      continue;
+    }
+    NaClBitCodeAbbrevOp::Encoding E = getEncoding(Read(3));
+    if (NaClBitCodeAbbrevOp::hasValue(E)) {
+      ReadVBR64(5);
+    }
+  }
+}
+
+bool NaClBitstreamCursor::ReadBlockInfoBlock(NaClAbbrevListener *Listener) {
+  // If this is the second stream to get to the block info block, skip it.
+  if (BitStream->hasBlockInfoRecords())
+    return SkipBlock();
+
+  unsigned NumWords;
+  if (EnterSubBlock(naclbitc::BLOCKINFO_BLOCK_ID, &NumWords)) return true;
+
+  if (Listener) Listener->BeginBlockInfoBlock(NumWords);
+
+  NaClBitcodeRecordVector Record;
+  NaClBitstreamReader::BlockInfo *CurBlockInfo = 0;
+
+  // Read records of the BlockInfo block.
+  while (1) {
+    if (Listener) Listener->StartBit = GetCurrentBitNo();
+    NaClBitstreamEntry Entry = advance(AF_DontAutoprocessAbbrevs, Listener);
+
+    switch (Entry.Kind) {
+    case llvm::NaClBitstreamEntry::SubBlock:  // PNaCl doesn't allow!
+    case llvm::NaClBitstreamEntry::Error:
+      return true;
+    case llvm::NaClBitstreamEntry::EndBlock:
+      if (Listener) Listener->EndBlockInfoBlock();
+      return false;
+    case llvm::NaClBitstreamEntry::Record:
+      // The interesting case.
+      break;
+    }
+
+    // Read abbrev records, associate them with CurBID.
+    if (Entry.ID == naclbitc::DEFINE_ABBREV) {
+      if (!CurBlockInfo) return true;
+      ReadAbbrevRecord(false, Listener);
+
+      // ReadAbbrevRecord installs the abbrev in CurAbbrevs.  Move it to the
+      // appropriate BlockInfo.
+      NaClBitCodeAbbrev *Abbv = CurAbbrevs.back();
+      CurAbbrevs.pop_back();
+      CurBlockInfo->Abbrevs.push_back(Abbv);
+      continue;
+    }
+
+    // Read a record.
+    Record.clear();
+    switch (readRecord(Entry.ID, Record)) {
+      default: 
+        // No other records should be found!
+        return true;
+      case naclbitc::BLOCKINFO_CODE_SETBID:
+        if (Record.size() < 1) return true;
+        CurBlockInfo = &BitStream->getOrCreateBlockInfo((unsigned)Record[0]);
+        if (Listener) {
+          Listener->Values = Record;
+          Listener->SetBID();
+        }
+        break;
+    }
+  }
+}