C++ SmallVectorImpl::reserve方法代码示例

void DecodeVPERMILPMask(const Constant *C, unsigned ElSize,
                        SmallVectorImpl<int> &ShuffleMask) {
  Type *MaskTy = C->getType();
  // It is not an error for the PSHUFB mask to not be a vector of i8 because the
  // constant pool uniques constants by their bit representation.
  // e.g. the following take up the same space in the constant pool:
  //   i128 -170141183420855150465331762880109871104
  //
  //   <2 x i64> <i64 -9223372034707292160, i64 -9223372034707292160>
  //
  //   <4 x i32> <i32 -2147483648, i32 -2147483648,
  //              i32 -2147483648, i32 -2147483648>

  unsigned MaskTySize = MaskTy->getPrimitiveSizeInBits();

  if (MaskTySize != 128 && MaskTySize != 256) // FIXME: Add support for AVX-512.
    return;

  // Only support vector types.
  if (!MaskTy->isVectorTy())
    return;

  // Make sure its an integer type.
  Type *VecEltTy = MaskTy->getVectorElementType();
  if (!VecEltTy->isIntegerTy())
    return;

  // Support any element type from byte up to element size.
  // This is necessary primarily because 64-bit elements get split to 32-bit
  // in the constant pool on 32-bit target.
  unsigned EltTySize = VecEltTy->getIntegerBitWidth();
  if (EltTySize < 8 || EltTySize > ElSize)
    return;

  unsigned NumElements = MaskTySize / ElSize;
  assert((NumElements == 2 || NumElements == 4 || NumElements == 8) &&
         "Unexpected number of vector elements.");
  ShuffleMask.reserve(NumElements);
  unsigned NumElementsPerLane = 128 / ElSize;
  unsigned Factor = ElSize / EltTySize;

  for (unsigned i = 0; i < NumElements; ++i) {
    Constant *COp = C->getAggregateElement(i * Factor);
    if (!COp) {
      ShuffleMask.clear();
      return;
    } else if (isa<UndefValue>(COp)) {
      ShuffleMask.push_back(SM_SentinelUndef);
      continue;
    }
    int Index = i & ~(NumElementsPerLane - 1);
    uint64_t Element = cast<ConstantInt>(COp)->getZExtValue();
    if (ElSize == 64)
      Index += (Element >> 1) & 0x1;
    else
      Index += Element & 0x3;
    ShuffleMask.push_back(Index);
  }

Error zlib::compress(StringRef InputBuffer,
                     SmallVectorImpl<char> &CompressedBuffer, int Level) {
  unsigned long CompressedSize = ::compressBound(InputBuffer.size());
  CompressedBuffer.reserve(CompressedSize);
  int Res =
      ::compress2((Bytef *)CompressedBuffer.data(), &CompressedSize,
                  (const Bytef *)InputBuffer.data(), InputBuffer.size(), Level);
  // Tell MemorySanitizer that zlib output buffer is fully initialized.
  // This avoids a false report when running LLVM with uninstrumented ZLib.
  __msan_unpoison(CompressedBuffer.data(), CompressedSize);
  CompressedBuffer.set_size(CompressedSize);
  return Res ? createError(convertZlibCodeToString(Res)) : Error::success();
}

void CaptureInfo::
getLocalCaptures(SmallVectorImpl<CapturedValue> &Result) const {
  if (!hasLocalCaptures()) return;

  Result.reserve(Count);

  // Filter out global variables.
  for (auto capture : getCaptures()) {
    if (!capture.getDecl()->getDeclContext()->isLocalContext())
      continue;

    Result.push_back(capture);
  }
}

/// fixupSubprogramName - Replace contains special characters used
/// in a typical Objective-C names with '.' in a given string.
static void fixupSubprogramName(DISubprogram Fn, SmallVectorImpl<char> &Out) {
  StringRef FName =
      Fn.getFunction() ? Fn.getFunction()->getName() : Fn.getName();
  FName = Function::getRealLinkageName(FName);

  StringRef Prefix("llvm.dbg.lv.");
  Out.reserve(FName.size() + Prefix.size());
  Out.append(Prefix.begin(), Prefix.end());

  bool isObjCLike = false;
  for (size_t i = 0, e = FName.size(); i < e; ++i) {
    char C = FName[i];
    if (C == '[')
      isObjCLike = true;

    if (isObjCLike && (C == '[' || C == ']' || C == ' ' || C == ':' ||
                       C == '+' || C == '(' || C == ')'))
      Out.push_back('.');
    else
      Out.push_back(C);
  }
}

/// ComputeActionsTable - Compute the actions table and gather the first action
/// index for each landing pad site.
unsigned DwarfException::
ComputeActionsTable(const SmallVectorImpl<const LandingPadInfo*> &LandingPads,
                    SmallVectorImpl<ActionEntry> &Actions,
                    SmallVectorImpl<unsigned> &FirstActions) {

  // The action table follows the call-site table in the LSDA. The individual
  // records are of two types:
  //
  //   * Catch clause
  //   * Exception specification
  //
  // The two record kinds have the same format, with only small differences.
  // They are distinguished by the "switch value" field: Catch clauses
  // (TypeInfos) have strictly positive switch values, and exception
  // specifications (FilterIds) have strictly negative switch values. Value 0
  // indicates a catch-all clause.
  //
  // Negative type IDs index into FilterIds. Positive type IDs index into
  // TypeInfos.  The value written for a positive type ID is just the type ID
  // itself.  For a negative type ID, however, the value written is the
  // (negative) byte offset of the corresponding FilterIds entry.  The byte
  // offset is usually equal to the type ID (because the FilterIds entries are
  // written using a variable width encoding, which outputs one byte per entry
  // as long as the value written is not too large) but can differ.  This kind
  // of complication does not occur for positive type IDs because type infos are
  // output using a fixed width encoding.  FilterOffsets[i] holds the byte
  // offset corresponding to FilterIds[i].

  const std::vector<unsigned> &FilterIds = MMI->getFilterIds();
  SmallVector<int, 16> FilterOffsets;
  FilterOffsets.reserve(FilterIds.size());
  int Offset = -1;

  for (std::vector<unsigned>::const_iterator
         I = FilterIds.begin(), E = FilterIds.end(); I != E; ++I) {
    FilterOffsets.push_back(Offset);
    Offset -= MCAsmInfo::getULEB128Size(*I);
  }

  FirstActions.reserve(LandingPads.size());

  int FirstAction = 0;
  unsigned SizeActions = 0;
  const LandingPadInfo *PrevLPI = 0;

  for (SmallVectorImpl<const LandingPadInfo *>::const_iterator
         I = LandingPads.begin(), E = LandingPads.end(); I != E; ++I) {
    const LandingPadInfo *LPI = *I;
    const std::vector<int> &TypeIds = LPI->TypeIds;
    unsigned NumShared = PrevLPI ? SharedTypeIds(LPI, PrevLPI) : 0;
    unsigned SizeSiteActions = 0;

    if (NumShared < TypeIds.size()) {
      unsigned SizeAction = 0;
      unsigned PrevAction = (unsigned)-1;

      if (NumShared) {
        unsigned SizePrevIds = PrevLPI->TypeIds.size();
        assert(Actions.size());
        PrevAction = Actions.size() - 1;
        SizeAction =
          MCAsmInfo::getSLEB128Size(Actions[PrevAction].NextAction) +
          MCAsmInfo::getSLEB128Size(Actions[PrevAction].ValueForTypeID);

        for (unsigned j = NumShared; j != SizePrevIds; ++j) {
          assert(PrevAction != (unsigned)-1 && "PrevAction is invalid!");
          SizeAction -=
            MCAsmInfo::getSLEB128Size(Actions[PrevAction].ValueForTypeID);
          SizeAction += -Actions[PrevAction].NextAction;
          PrevAction = Actions[PrevAction].Previous;
        }
      }

      // Compute the actions.
      for (unsigned J = NumShared, M = TypeIds.size(); J != M; ++J) {
        int TypeID = TypeIds[J];
        assert(-1 - TypeID < (int)FilterOffsets.size() && "Unknown filter id!");
        int ValueForTypeID = TypeID < 0 ? FilterOffsets[-1 - TypeID] : TypeID;
        unsigned SizeTypeID = MCAsmInfo::getSLEB128Size(ValueForTypeID);

        int NextAction = SizeAction ? -(SizeAction + SizeTypeID) : 0;
        SizeAction = SizeTypeID + MCAsmInfo::getSLEB128Size(NextAction);
        SizeSiteActions += SizeAction;

        ActionEntry Action = { ValueForTypeID, NextAction, PrevAction };
        Actions.push_back(Action);
        PrevAction = Actions.size() - 1;
      }

      // Record the first action of the landing pad site.
      FirstAction = SizeActions + SizeSiteActions - SizeAction + 1;
    } // else identical - re-use previous FirstAction

    // Information used when created the call-site table. The action record
    // field of the call site record is the offset of the first associated
    // action record, relative to the start of the actions table. This value is
    // biased by 1 (1 indicating the start of the actions table), and 0
    // indicates that there are no actions.
//.........这里部分代码省略.........