Imported Upstream version 5.18.0.225

Former-commit-id: 10196d987d5fc5564b9d3b33b1fdf13190f4d0b5

external/llvm/lib/Bitcode/Reader/BitstreamReader.cpp

@@ -0,0 +1,390 @@
+//===- 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"
+#include "llvm/ADT/StringRef.h"
+#include <cassert>
+#include <string>
+
+using namespace llvm;
+
+//===----------------------------------------------------------------------===//
+//  BitstreamCursor implementation
+//===----------------------------------------------------------------------===//
+
+/// 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 (BlockInfo) {
+    if (const BitstreamBlockInfo::BlockInfo *Info =
+            BlockInfo->getBlockInfo(BlockID)) {
+      CurAbbrevs.insert(CurAbbrevs.end(), Info->Abbrevs.begin(),
+                        Info->Abbrevs.end());
+    }
+  }
+
+  // Get the codesize of this block.
+  CurCodeSize = ReadVBR(bitc::CodeLenWidth);
+  // We can't read more than MaxChunkSize at a time
+  if (CurCodeSize > MaxChunkSize)
+    return true;
+
+  SkipToFourByteBoundary();
+  unsigned NumWords = Read(bitc::BlockSizeWidth);
+  if (NumWordsP) *NumWordsP = NumWords;
+
+  // Validate that this block is sane.
+  return CurCodeSize == 0 || AtEndOfStream();
+}
+
+static uint64_t readAbbreviatedField(BitstreamCursor &Cursor,
+                                     const BitCodeAbbrevOp &Op) {
+  assert(!Op.isLiteral() && "Not to be used with literals!");
+
+  // Decode the value as we are commanded.
+  switch (Op.getEncoding()) {
+  case BitCodeAbbrevOp::Array:
+  case BitCodeAbbrevOp::Blob:
+    llvm_unreachable("Should not reach here");
+  case BitCodeAbbrevOp::Fixed:
+    assert((unsigned)Op.getEncodingData() <= Cursor.MaxChunkSize);
+    return Cursor.Read((unsigned)Op.getEncodingData());
+  case BitCodeAbbrevOp::VBR:
+    assert((unsigned)Op.getEncodingData() <= Cursor.MaxChunkSize);
+    return Cursor.ReadVBR64((unsigned)Op.getEncodingData());
+  case BitCodeAbbrevOp::Char6:
+    return BitCodeAbbrevOp::DecodeChar6(Cursor.Read(6));
+  }
+  llvm_unreachable("invalid abbreviation encoding");
+}
+
+static void skipAbbreviatedField(BitstreamCursor &Cursor,
+                                 const BitCodeAbbrevOp &Op) {
+  assert(!Op.isLiteral() && "Not to be used with literals!");
+
+  // Decode the value as we are commanded.
+  switch (Op.getEncoding()) {
+  case BitCodeAbbrevOp::Array:
+  case BitCodeAbbrevOp::Blob:
+    llvm_unreachable("Should not reach here");
+  case BitCodeAbbrevOp::Fixed:
+    assert((unsigned)Op.getEncodingData() <= Cursor.MaxChunkSize);
+    Cursor.Read((unsigned)Op.getEncodingData());
+    break;
+  case BitCodeAbbrevOp::VBR:
+    assert((unsigned)Op.getEncodingData() <= Cursor.MaxChunkSize);
+    Cursor.ReadVBR64((unsigned)Op.getEncodingData());
+    break;
+  case BitCodeAbbrevOp::Char6:
+    Cursor.Read(6);
+    break;
+  }
+}
+
+/// skipRecord - Read the current record and discard it.
+unsigned BitstreamCursor::skipRecord(unsigned AbbrevID) {
+  // Skip unabbreviated records by reading past their entries.
+  if (AbbrevID == bitc::UNABBREV_RECORD) {
+    unsigned Code = ReadVBR(6);
+    unsigned NumElts = ReadVBR(6);
+    for (unsigned i = 0; i != NumElts; ++i)
+      (void)ReadVBR64(6);
+    return Code;
+  }
+
+  const BitCodeAbbrev *Abbv = getAbbrev(AbbrevID);
+  const BitCodeAbbrevOp &CodeOp = Abbv->getOperandInfo(0);
+  unsigned Code;
+  if (CodeOp.isLiteral())
+    Code = CodeOp.getLiteralValue();
+  else {
+    if (CodeOp.getEncoding() == BitCodeAbbrevOp::Array ||
+        CodeOp.getEncoding() == BitCodeAbbrevOp::Blob)
+      report_fatal_error("Abbreviation starts with an Array or a Blob");
+    Code = readAbbreviatedField(*this, CodeOp);
+  }
+
+  for (unsigned i = 1, 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(*this, 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.
+      // Decode the value as we are commanded.
+      switch (EltEnc.getEncoding()) {
+      default:
+        report_fatal_error("Array element type can't be an Array or a Blob");
+      case BitCodeAbbrevOp::Fixed:
+        assert((unsigned)EltEnc.getEncodingData() <= MaxChunkSize);
+        JumpToBit(GetCurrentBitNo() + NumElts * EltEnc.getEncodingData());
+        break;
+      case BitCodeAbbrevOp::VBR:
+        assert((unsigned)EltEnc.getEncodingData() <= MaxChunkSize);
+        for (; NumElts; --NumElts)
+          ReadVBR64((unsigned)EltEnc.getEncodingData());
+        break;
+      case BitCodeAbbrevOp::Char6:
+        JumpToBit(GetCurrentBitNo() + NumElts * 6);
+        break;
+      }
+      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)) {
+      skipToEnd();
+      break;
+    }
+
+    // Skip over the blob.
+    JumpToBit(NewEnd);
+  }
+  return Code;
+}
+
+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);
+
+  // Read the record code first.
+  assert(Abbv->getNumOperandInfos() != 0 && "no record code in abbreviation?");
+  const BitCodeAbbrevOp &CodeOp = Abbv->getOperandInfo(0);
+  unsigned Code;
+  if (CodeOp.isLiteral())
+    Code = CodeOp.getLiteralValue();
+  else {
+    if (CodeOp.getEncoding() == BitCodeAbbrevOp::Array ||
+        CodeOp.getEncoding() == BitCodeAbbrevOp::Blob)
+      report_fatal_error("Abbreviation starts with an Array or a Blob");
+    Code = readAbbreviatedField(*this, CodeOp);
+  }
+
+  for (unsigned i = 1, e = Abbv->getNumOperandInfos(); i != e; ++i) {
+    const BitCodeAbbrevOp &Op = Abbv->getOperandInfo(i);
+    if (Op.isLiteral()) {
+      Vals.push_back(Op.getLiteralValue());
+      continue;
+    }
+
+    if (Op.getEncoding() != BitCodeAbbrevOp::Array &&
+        Op.getEncoding() != BitCodeAbbrevOp::Blob) {
+      Vals.push_back(readAbbreviatedField(*this, 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.
+      if (i + 2 != e)
+        report_fatal_error("Array op not second to last");
+      const BitCodeAbbrevOp &EltEnc = Abbv->getOperandInfo(++i);
+      if (!EltEnc.isEncoding())
+        report_fatal_error(
+            "Array element type has to be an encoding of a type");
+
+      // Read all the elements.
+      switch (EltEnc.getEncoding()) {
+      default:
+        report_fatal_error("Array element type can't be an Array or a Blob");
+      case BitCodeAbbrevOp::Fixed:
+        for (; NumElts; --NumElts)
+          Vals.push_back(Read((unsigned)EltEnc.getEncodingData()));
+        break;
+      case BitCodeAbbrevOp::VBR:
+        for (; NumElts; --NumElts)
+          Vals.push_back(ReadVBR64((unsigned)EltEnc.getEncodingData()));
+        break;
+      case BitCodeAbbrevOp::Char6:
+        for (; NumElts; --NumElts)
+          Vals.push_back(BitCodeAbbrevOp::DecodeChar6(Read(6)));
+      }
+      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);
+      skipToEnd();
+      break;
+    }
+
+    // Otherwise, inform the streamer that we need these bytes in memory.  Skip
+    // over tail padding first, in case jumping to NewEnd invalidates the Blob
+    // pointer.
+    JumpToBit(NewEnd);
+    const char *Ptr = (const char *)getPointerToBit(CurBitPos, 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++);
+    }
+  }
+
+  return Code;
+}
+
+void BitstreamCursor::ReadAbbrevRecord() {
+  auto Abbv = std::make_shared<BitCodeAbbrev>();
+  unsigned NumOpInfo = ReadVBR(5);
+  for (unsigned i = 0; i != NumOpInfo; ++i) {
+    bool IsLiteral = Read(1);
+    if (IsLiteral) {
+      Abbv->Add(BitCodeAbbrevOp(ReadVBR64(8)));
+      continue;
+    }
+
+    BitCodeAbbrevOp::Encoding E = (BitCodeAbbrevOp::Encoding)Read(3);
+    if (BitCodeAbbrevOp::hasEncodingData(E)) {
+      uint64_t 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;
+      }
+
+      if ((E == BitCodeAbbrevOp::Fixed || E == BitCodeAbbrevOp::VBR) &&
+          Data > MaxChunkSize)
+        report_fatal_error(
+            "Fixed or VBR abbrev record with size > MaxChunkData");
+
+      Abbv->Add(BitCodeAbbrevOp(E, Data));
+    } else
+      Abbv->Add(BitCodeAbbrevOp(E));
+  }
+
+  if (Abbv->getNumOperandInfos() == 0)
+    report_fatal_error("Abbrev record with no operands");
+  CurAbbrevs.push_back(std::move(Abbv));
+}
+
+Optional<BitstreamBlockInfo>
+BitstreamCursor::ReadBlockInfoBlock(bool ReadBlockInfoNames) {
+  if (EnterSubBlock(bitc::BLOCKINFO_BLOCK_ID)) return None;
+
+  BitstreamBlockInfo NewBlockInfo;
+
+  SmallVector<uint64_t, 64> Record;
+  BitstreamBlockInfo::BlockInfo *CurBlockInfo = nullptr;
+
+  // Read all the records for this module.
+  while (true) {
+    BitstreamEntry Entry = advanceSkippingSubblocks(AF_DontAutoprocessAbbrevs);
+
+    switch (Entry.Kind) {
+    case llvm::BitstreamEntry::SubBlock: // Handled for us already.
+    case llvm::BitstreamEntry::Error:
+      return None;
+    case llvm::BitstreamEntry::EndBlock:
+      return std::move(NewBlockInfo);
+    case llvm::BitstreamEntry::Record:
+      // The interesting case.
+      break;
+    }
+
+    // Read abbrev records, associate them with CurBID.
+    if (Entry.ID == bitc::DEFINE_ABBREV) {
+      if (!CurBlockInfo) return None;
+      ReadAbbrevRecord();
+
+      // ReadAbbrevRecord installs the abbrev in CurAbbrevs.  Move it to the
+      // appropriate BlockInfo.
+      CurBlockInfo->Abbrevs.push_back(std::move(CurAbbrevs.back()));
+      CurAbbrevs.pop_back();
+      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 None;
+        CurBlockInfo = &NewBlockInfo.getOrCreateBlockInfo((unsigned)Record[0]);
+        break;
+      case bitc::BLOCKINFO_CODE_BLOCKNAME: {
+        if (!CurBlockInfo) return None;
+        if (!ReadBlockInfoNames)
+          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 None;
+        if (!ReadBlockInfoNames)
+          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;
+      }
+    }
+  }
+}