C++ SmallVectorImpl::pop_back方法代码示例

/// Move the given iterators to the next leaf type in depth first traversal.
///
/// Performs a depth-first traversal of the type as specified by its arguments,
/// stopping at the next leaf node (which may be a legitimate scalar type or an
/// empty struct or array).
///
/// @param SubTypes List of the partial components making up the type from
/// outermost to innermost non-empty aggregate. The element currently
/// represented is SubTypes.back()->getTypeAtIndex(Path.back() - 1).
///
/// @param Path Set of extractvalue indices leading from the outermost type
/// (SubTypes[0]) to the leaf node currently represented.
///
/// @returns true if a new type was found, false otherwise. Calling this
/// function again on a finished iterator will repeatedly return
/// false. SubTypes.back()->getTypeAtIndex(Path.back()) is either an empty
/// aggregate or a non-aggregate
static bool advanceToNextLeafType(SmallVectorImpl<CompositeType *> &SubTypes,
                                  SmallVectorImpl<unsigned> &Path) {
  // First march back up the tree until we can successfully increment one of the
  // coordinates in Path.
  while (!Path.empty() && !indexReallyValid(SubTypes.back(), Path.back() + 1)) {
    Path.pop_back();
    SubTypes.pop_back();
  }

  // If we reached the top, then the iterator is done.
  if (Path.empty())
    return false;

  // We know there's *some* valid leaf now, so march back down the tree picking
  // out the left-most element at each node.
  ++Path.back();
  Type *DeeperType = SubTypes.back()->getTypeAtIndex(Path.back());
  while (DeeperType->isAggregateType()) {
    CompositeType *CT = cast<CompositeType>(DeeperType);
    if (!indexReallyValid(CT, 0))
      return true;

    SubTypes.push_back(CT);
    Path.push_back(0);

    DeeperType = CT->getTypeAtIndex(0U);
  }

  return true;
}

bool TokenLexer::MaybeRemoveCommaBeforeVaArgs(
    SmallVectorImpl<Token> &ResultToks, bool HasPasteOperator, MacroInfo *Macro,
    unsigned MacroArgNo, Preprocessor &PP) {
  // Is the macro argument __VA_ARGS__?
  if (!Macro->isVariadic() || MacroArgNo != Macro->getNumArgs()-1)
    return false;

  // In Microsoft-compatibility mode, a comma is removed in the expansion
  // of " ... , __VA_ARGS__ " if __VA_ARGS__ is empty.  This extension is
  // not supported by gcc.
  if (!HasPasteOperator && !PP.getLangOpts().MSVCCompat)
    return false;

  // GCC removes the comma in the expansion of " ... , ## __VA_ARGS__ " if
  // __VA_ARGS__ is empty, but not in strict C99 mode where there are no
  // named arguments, where it remains.  In all other modes, including C99
  // with GNU extensions, it is removed regardless of named arguments.
  // Microsoft also appears to support this extension, unofficially.
  if (PP.getLangOpts().C99 && !PP.getLangOpts().GNUMode
        && Macro->getNumArgs() < 2)
    return false;

  // Is a comma available to be removed?
  if (ResultToks.empty() || !ResultToks.back().is(tok::comma))
    return false;

  // Issue an extension diagnostic for the paste operator.
  if (HasPasteOperator)
    PP.Diag(ResultToks.back().getLocation(), diag::ext_paste_comma);

  // Remove the comma.
  ResultToks.pop_back();

  if (!ResultToks.empty()) {
    // If the comma was right after another paste (e.g. "X##,##__VA_ARGS__"),
    // then removal of the comma should produce a placemarker token (in C99
    // terms) which we model by popping off the previous ##, giving us a plain
    // "X" when __VA_ARGS__ is empty.
    if (ResultToks.back().is(tok::hashhash))
      ResultToks.pop_back();

    // Remember that this comma was elided.
    ResultToks.back().setFlag(Token::CommaAfterElided);
  }

  // Never add a space, even if the comma, ##, or arg had a space.
  NextTokGetsSpace = false;
  return true;
}

bool convertUTF8ToUTF16String(StringRef SrcUTF8,
                              SmallVectorImpl<UTF16> &DstUTF16) {
    assert(DstUTF16.empty());

    // Avoid OOB by returning early on empty input.
    if (SrcUTF8.empty())
        return true;

    const UTF8 *Src = reinterpret_cast<const UTF8 *>(SrcUTF8.begin());
    const UTF8 *SrcEnd = reinterpret_cast<const UTF8 *>(SrcUTF8.end());

    // Allocate the same number of UTF-16 code units as UTF-8 code units. Encoding
    // as UTF-16 should always require the same amount or less code units than the
    // UTF-8 encoding.  Allocate one extra byte for the null terminator though,
    // so that someone calling DstUTF16.data() gets a null terminated string.
    // We resize down later so we don't have to worry that this over allocates.
    DstUTF16.resize(SrcUTF8.size()+1);
    UTF16 *Dst = &DstUTF16[0];
    UTF16 *DstEnd = Dst + DstUTF16.size();

    ConversionResult CR =
        ConvertUTF8toUTF16(&Src, SrcEnd, &Dst, DstEnd, strictConversion);
    assert(CR != targetExhausted);

    if (CR != conversionOK) {
        DstUTF16.clear();
        return false;
    }

    DstUTF16.resize(Dst - &DstUTF16[0]);
    DstUTF16.push_back(0);
    DstUTF16.pop_back();
    return true;
}

void LiveVariables::UpdatePhysRegDefs(MachineInstr *MI,
                                      SmallVectorImpl<unsigned> &Defs) {
  while (!Defs.empty()) {
    unsigned Reg = Defs.back();
    Defs.pop_back();
    for (MCSubRegIterator SubRegs(Reg, TRI, /*IncludeSelf=*/true);
         SubRegs.isValid(); ++SubRegs) {
      unsigned SubReg = *SubRegs;
      PhysRegDef[SubReg]  = MI;
      PhysRegUse[SubReg]  = nullptr;
    }
  }
}

void Scop::buildScop(TempScop &tempScop,
                      const Region &CurRegion,
                      SmallVectorImpl<Loop*> &NestLoops,
                      SmallVectorImpl<unsigned> &Scatter,
                      LoopInfo &LI) {
  Loop *L = castToLoop(CurRegion, LI);

  if (L)
    NestLoops.push_back(L);

  unsigned loopDepth = NestLoops.size();
  assert(Scatter.size() > loopDepth && "Scatter not big enough!");

  for (Region::const_element_iterator I = CurRegion.element_begin(),
       E = CurRegion.element_end(); I != E; ++I)
    if (I->isSubRegion())
      buildScop(tempScop, *(I->getNodeAs<Region>()), NestLoops, Scatter, LI);
    else {
      BasicBlock *BB = I->getNodeAs<BasicBlock>();

      if (isTrivialBB(BB, tempScop))
        continue;

      Stmts.push_back(new ScopStmt(*this, tempScop, CurRegion, *BB, NestLoops,
                                   Scatter));

      // Increasing the Scattering function is OK for the moment, because
      // we are using a depth first iterator and the program is well structured.
      ++Scatter[loopDepth];
    }

  if (!L)
    return;

  // Exiting a loop region.
  Scatter[loopDepth] = 0;
  NestLoops.pop_back();
  ++Scatter[loopDepth-1];
}

MipsInstrInfo::BranchType MipsInstrInfo::AnalyzeBranch(
    MachineBasicBlock &MBB, MachineBasicBlock *&TBB, MachineBasicBlock *&FBB,
    SmallVectorImpl<MachineOperand> &Cond, bool AllowModify,
    SmallVectorImpl<MachineInstr *> &BranchInstrs) const {

  MachineBasicBlock::reverse_iterator I = MBB.rbegin(), REnd = MBB.rend();

  // Skip all the debug instructions.
  while (I != REnd && I->isDebugValue())
    ++I;

  if (I == REnd || !isUnpredicatedTerminator(*I)) {
    // This block ends with no branches (it just falls through to its succ).
    // Leave TBB/FBB null.
    TBB = FBB = nullptr;
    return BT_NoBranch;
  }

  MachineInstr *LastInst = &*I;
  unsigned LastOpc = LastInst->getOpcode();
  BranchInstrs.push_back(LastInst);

  // Not an analyzable branch (e.g., indirect jump).
  if (!getAnalyzableBrOpc(LastOpc))
    return LastInst->isIndirectBranch() ? BT_Indirect : BT_None;

  // Get the second to last instruction in the block.
  unsigned SecondLastOpc = 0;
  MachineInstr *SecondLastInst = nullptr;

  if (++I != REnd) {
    SecondLastInst = &*I;
    SecondLastOpc = getAnalyzableBrOpc(SecondLastInst->getOpcode());

    // Not an analyzable branch (must be an indirect jump).
    if (isUnpredicatedTerminator(*SecondLastInst) && !SecondLastOpc)
      return BT_None;
  }

  // If there is only one terminator instruction, process it.
  if (!SecondLastOpc) {
    // Unconditional branch.
    if (LastInst->isUnconditionalBranch()) {
      TBB = LastInst->getOperand(0).getMBB();
      return BT_Uncond;
    }

    // Conditional branch
    AnalyzeCondBr(LastInst, LastOpc, TBB, Cond);
    return BT_Cond;
  }

  // If we reached here, there are two branches.
  // If there are three terminators, we don't know what sort of block this is.
  if (++I != REnd && isUnpredicatedTerminator(*I))
    return BT_None;

  BranchInstrs.insert(BranchInstrs.begin(), SecondLastInst);

  // If second to last instruction is an unconditional branch,
  // analyze it and remove the last instruction.
  if (SecondLastInst->isUnconditionalBranch()) {
    // Return if the last instruction cannot be removed.
    if (!AllowModify)
      return BT_None;

    TBB = SecondLastInst->getOperand(0).getMBB();
    LastInst->eraseFromParent();
    BranchInstrs.pop_back();
    return BT_Uncond;
  }

  // Conditional branch followed by an unconditional branch.
  // The last one must be unconditional.
  if (!LastInst->isUnconditionalBranch())
    return BT_None;

  AnalyzeCondBr(SecondLastInst, SecondLastOpc, TBB, Cond);
  FBB = LastInst->getOperand(0).getMBB();

  return BT_CondUncond;
}

static std::error_code createUniqueEntity(const Twine &Model, int &ResultFD,
                                          SmallVectorImpl<char> &ResultPath,
                                          bool MakeAbsolute, unsigned Mode,
                                          FSEntity Type) {
  SmallString<128> ModelStorage;
  Model.toVector(ModelStorage);

  if (MakeAbsolute) {
    // Make model absolute by prepending a temp directory if it's not already.
    if (!sys::path::is_absolute(Twine(ModelStorage))) {
      SmallString<128> TDir;
      sys::path::system_temp_directory(true, TDir);
      sys::path::append(TDir, Twine(ModelStorage));
      ModelStorage.swap(TDir);
    }
  }

  // From here on, DO NOT modify model. It may be needed if the randomly chosen
  // path already exists.
  ResultPath = ModelStorage;
  // Null terminate.
  ResultPath.push_back(0);
  ResultPath.pop_back();

retry_random_path:
  // Replace '%' with random chars.
  for (unsigned i = 0, e = ModelStorage.size(); i != e; ++i) {
    if (ModelStorage[i] == '%')
      ResultPath[i] = "0123456789abcdef"[sys::Process::GetRandomNumber() & 15];
  }

  // Try to open + create the file.
  switch (Type) {
  case FS_File: {
    if (std::error_code EC =
            sys::fs::openFileForWrite(Twine(ResultPath.begin()), ResultFD,
                                      sys::fs::F_RW | sys::fs::F_Excl, Mode)) {
      if (EC == errc::file_exists)
        goto retry_random_path;
      return EC;
    }

    return std::error_code();
  }

  case FS_Name: {
    std::error_code EC =
        sys::fs::access(ResultPath.begin(), sys::fs::AccessMode::Exist);
    if (EC == errc::no_such_file_or_directory)
      return std::error_code();
    if (EC)
      return EC;
    goto retry_random_path;
  }

  case FS_Dir: {
    if (std::error_code EC =
            sys::fs::create_directory(ResultPath.begin(), false)) {
      if (EC == errc::file_exists)
        goto retry_random_path;
      return EC;
    }
    return std::error_code();
  }
  }
  llvm_unreachable("Invalid Type");
}

//.........这里部分代码省略.........
	// This is another base case for the recursion.  In this case, we know
	// that we have looped back to a type that we have previously visited.
	// Generate the appropriate upreference to handle this.
	if (Slot < CurSize) {
		OS << '\\' << unsigned(CurSize-Slot);     // Here's the upreference
		return;
	}

	TypeStack.push_back(Ty);    // Recursive case: Add us to the stack..

	switch (Ty->getTypeID()) {
		case Type::VoidTyID:      OS << "void"; break;
		case Type::FloatTyID:					break;
		case Type::DoubleTyID:					break;
		case Type::X86_FP80TyID:				break;
		case Type::FP128TyID:					break;
		case Type::PPC_FP128TyID:				break;
		case Type::LabelTyID:     OS << "label"; break;
		case Type::MetadataTyID:  OS << "metadata"; break;
		case Type::X86_MMXTyID:					break;
		case Type::IntegerTyID: {
			unsigned bitWidth=cast<IntegerType>(Ty)->getBitWidth();
			switch (bitWidth){
				case 1:			  OS << "bit";  break;
				case 8:			  OS << "int";  break;
				case 16:		  OS << "int";  break;
				case 32:		  OS << "int";  break;
				default:						break;
			}
			break;
		}
		case Type::FunctionTyID: {
	const FunctionType *FTy = cast<FunctionType>(Ty);
    CalcTypeName(FTy->getReturnType(), TypeStack, OS);
    OS << " (";
    for (FunctionType::param_iterator I = FTy->param_begin(),
         E = FTy->param_end(); I != E; ++I) {
      if (I != FTy->param_begin())
        OS << ", ";
      CalcTypeName(*I, TypeStack, OS);
    }
    if (FTy->isVarArg()) {
      if (FTy->getNumParams()) OS << ", ";
      OS << "...";
    }
    OS << ')';
    break;
  }
		case Type::StructTyID: {
			const StructType *STy = cast<StructType>(Ty);
			OS << "TYPEDEF ";
			CalcTypeName(Ty,TypeStack,OS);
			OS << " {";
			int i=0;
			for (StructType::element_iterator I = STy->element_begin(),
					E = STy->element_end(); I != E; ++I) {
				OS << ' ';
				CalcTypeName(*I, TypeStack, OS);
				OS << " u"<<i;
				i++;
				if (llvm::next(I) == STy->element_end())
				OS << ' ';
				else
				OS << ';';
			}
			OS << '}';
			break;
		}
  case Type::PointerTyID: {
    const PointerType *PTy = cast<PointerType>(Ty);
    CalcTypeName(PTy->getElementType(), TypeStack, OS);
  //  if (unsigned AddressSpace = PTy->getAddressSpace())
  //    OS << " addrspace(" << AddressSpace << ')';
  //  OS << '*';
    break;
  }
		case Type::ArrayTyID: {
			const ArrayType *ATy = cast<ArrayType>(Ty);
			CalcTypeName(ATy->getElementType(),TypeStack,OS);
			OS << '[' << ATy->getNumElements() << ']';
			break;
		}

  case Type::VectorTyID: {
    const VectorType *PTy = cast<VectorType>(Ty);
    OS << "<" << PTy->getNumElements() << " x ";
    CalcTypeName(PTy->getElementType(), TypeStack, OS);
    OS << '>';
    break;
  }
  case Type::OpaqueTyID:
    OS << "opaque";
    break;
  default:
    OS << "<unrecognized-type>";
    break;
  }

  TypeStack.pop_back();       // Remove self from stack.
}

static std::error_code
createUniqueEntity(const Twine &Model, int &ResultFD,
                   SmallVectorImpl<char> &ResultPath, bool MakeAbsolute,
                   unsigned Mode, FSEntity Type,
                   sys::fs::OpenFlags Flags = sys::fs::OF_None) {
  SmallString<128> ModelStorage;
  Model.toVector(ModelStorage);

  if (MakeAbsolute) {
    // Make model absolute by prepending a temp directory if it's not already.
    if (!sys::path::is_absolute(Twine(ModelStorage))) {
      SmallString<128> TDir;
      sys::path::system_temp_directory(true, TDir);
      sys::path::append(TDir, Twine(ModelStorage));
      ModelStorage.swap(TDir);
    }
  }

  // From here on, DO NOT modify model. It may be needed if the randomly chosen
  // path already exists.
  ResultPath = ModelStorage;
  // Null terminate.
  ResultPath.push_back(0);
  ResultPath.pop_back();

  // Limit the number of attempts we make, so that we don't infinite loop. E.g.
  // "permission denied" could be for a specific file (so we retry with a
  // different name) or for the whole directory (retry would always fail).
  // Checking which is racy, so we try a number of times, then give up.
  std::error_code EC;
  for (int Retries = 128; Retries > 0; --Retries) {
    // Replace '%' with random chars.
    for (unsigned i = 0, e = ModelStorage.size(); i != e; ++i) {
      if (ModelStorage[i] == '%')
        ResultPath[i] =
            "0123456789abcdef"[sys::Process::GetRandomNumber() & 15];
    }

    // Try to open + create the file.
    switch (Type) {
    case FS_File: {
      EC = sys::fs::openFileForReadWrite(Twine(ResultPath.begin()), ResultFD,
                                         sys::fs::CD_CreateNew, Flags, Mode);
      if (EC) {
        // errc::permission_denied happens on Windows when we try to open a file
        // that has been marked for deletion.
        if (EC == errc::file_exists || EC == errc::permission_denied)
          continue;
        return EC;
      }

      return std::error_code();
    }

    case FS_Name: {
      EC = sys::fs::access(ResultPath.begin(), sys::fs::AccessMode::Exist);
      if (EC == errc::no_such_file_or_directory)
        return std::error_code();
      if (EC)
        return EC;
      continue;
    }

    case FS_Dir: {
      EC = sys::fs::create_directory(ResultPath.begin(), false);
      if (EC) {
        if (EC == errc::file_exists)
          continue;
        return EC;
      }
      return std::error_code();
    }
    }
    llvm_unreachable("Invalid Type");
  }
  return EC;
}