C++ CharUnits::isZero方法代码示例

void SwiftAggLowering::addLegalTypedData(llvm::Type *type,
                                         CharUnits begin, CharUnits end) {
  // Require the type to be naturally aligned.
  if (!begin.isZero() && !begin.isMultipleOf(getNaturalAlignment(CGM, type))) {

    // Try splitting vector types.
    if (auto vecTy = dyn_cast<llvm::VectorType>(type)) {
      auto split = splitLegalVectorType(CGM, end - begin, vecTy);
      auto eltTy = split.first;
      auto numElts = split.second;

      auto eltSize = (end - begin) / numElts;
      assert(eltSize == getTypeStoreSize(CGM, eltTy));
      for (size_t i = 0, e = numElts; i != e; ++i) {
        addLegalTypedData(eltTy, begin, begin + eltSize);
        begin += eltSize;
      }
      assert(begin == end);
      return;
    }

    return addOpaqueData(begin, end);
  }

  addEntry(type, begin, end);
}

llvm::Value *ItaniumCXXABI::InitializeArrayCookie(CodeGenFunction &CGF,
                                                  llvm::Value *NewPtr,
                                                  llvm::Value *NumElements,
                                                  const CXXNewExpr *expr,
                                                  QualType ElementType) {
  assert(NeedsArrayCookie(expr));

  unsigned AS = cast<llvm::PointerType>(NewPtr->getType())->getAddressSpace();

  ASTContext &Ctx = getContext();
  QualType SizeTy = Ctx.getSizeType();
  CharUnits SizeSize = Ctx.getTypeSizeInChars(SizeTy);

  // The size of the cookie.
  CharUnits CookieSize =
    std::max(SizeSize, Ctx.getTypeAlignInChars(ElementType));

  // Compute an offset to the cookie.
  llvm::Value *CookiePtr = NewPtr;
  CharUnits CookieOffset = CookieSize - SizeSize;
  if (!CookieOffset.isZero())
    CookiePtr = CGF.Builder.CreateConstInBoundsGEP1_64(CookiePtr,
                                                 CookieOffset.getQuantity());

  // Write the number of elements into the appropriate slot.
  llvm::Value *NumElementsPtr
    = CGF.Builder.CreateBitCast(CookiePtr,
                                CGF.ConvertType(SizeTy)->getPointerTo(AS));
  CGF.Builder.CreateStore(NumElements, NumElementsPtr);

  // Finally, compute a pointer to the actual data buffer by skipping
  // over the cookie completely.
  return CGF.Builder.CreateConstInBoundsGEP1_64(NewPtr,
                                                CookieSize.getQuantity());  
}

void CGRecordLayoutBuilder::AppendBytes(CharUnits numBytes) {
  if (numBytes.isZero())
    return;

  // Append the padding field
  AppendField(NextFieldOffset, getByteArrayType(numBytes));
}

void CastSizeChecker::checkPreStmt(const CastExpr *CE,CheckerContext &C) const {
  const Expr *E = CE->getSubExpr();
  ASTContext &Ctx = C.getASTContext();
  QualType ToTy = Ctx.getCanonicalType(CE->getType());
  const PointerType *ToPTy = dyn_cast<PointerType>(ToTy.getTypePtr());

  if (!ToPTy)
    return;

  QualType ToPointeeTy = ToPTy->getPointeeType();

  // Only perform the check if 'ToPointeeTy' is a complete type.
  if (ToPointeeTy->isIncompleteType())
    return;

  ProgramStateRef state = C.getState();
  const MemRegion *R = state->getSVal(E, C.getLocationContext()).getAsRegion();
  if (!R)
    return;

  const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(R);
  if (!SR)
    return;

  SValBuilder &svalBuilder = C.getSValBuilder();
  SVal extent = SR->getExtent(svalBuilder);
  const llvm::APSInt *extentInt = svalBuilder.getKnownValue(state, extent);
  if (!extentInt)
    return;

  CharUnits regionSize = CharUnits::fromQuantity(extentInt->getSExtValue());
  CharUnits typeSize = C.getASTContext().getTypeSizeInChars(ToPointeeTy);

  // Ignore void, and a few other un-sizeable types.
  if (typeSize.isZero())
    return;

  if (regionSize % typeSize == 0)
    return;

  if (evenFlexibleArraySize(Ctx, regionSize, typeSize, ToPointeeTy))
    return;

  if (ExplodedNode *errorNode = C.generateErrorNode()) {
    if (!BT)
      BT.reset(new BuiltinBug(this, "Cast region with wrong size.",
                                    "Cast a region whose size is not a multiple"
                                    " of the destination type size."));
    auto R = llvm::make_unique<BugReport>(*BT, BT->getDescription(), errorNode);
    R->addRange(CE->getSourceRange());
    C.emitReport(std::move(R));
  }
}

void CastSizeChecker::PreVisitCastExpr(CheckerContext &C, const CastExpr *CE) {
  const Expr *E = CE->getSubExpr();
  ASTContext &Ctx = C.getASTContext();
  QualType ToTy = Ctx.getCanonicalType(CE->getType());
  PointerType *ToPTy = dyn_cast<PointerType>(ToTy.getTypePtr());

  if (!ToPTy)
    return;

  QualType ToPointeeTy = ToPTy->getPointeeType();

  const GRState *state = C.getState();
  const MemRegion *R = state->getSVal(E).getAsRegion();
  if (R == 0)
    return;

  const SymbolicRegion *SR = dyn_cast<SymbolicRegion>(R);
  if (SR == 0)
    return;

  ValueManager &ValMgr = C.getValueManager();
  SVal Extent = SR->getExtent(ValMgr);

  SValuator &SVator = ValMgr.getSValuator();
  const llvm::APSInt *ExtentInt = SVator.getKnownValue(state, Extent);
  if (!ExtentInt)
    return;

  CharUnits RegionSize = CharUnits::fromQuantity(ExtentInt->getSExtValue());
  CharUnits TypeSize = C.getASTContext().getTypeSizeInChars(ToPointeeTy);
  
  // Ignore void, and a few other un-sizeable types.
  if (TypeSize.isZero())
    return;
  
  if (RegionSize % TypeSize != 0) {
    if (ExplodedNode *N = C.GenerateSink()) {
      if (!BT)
        BT = new BuiltinBug("Cast region with wrong size.",
                            "Cast a region whose size is not a multiple of the"
                            " destination type size.");
      RangedBugReport *R = new RangedBugReport(*BT, BT->getDescription(), N);
      R->addRange(CE->getSourceRange());
      C.EmitReport(R);
    }
  }
}

void ItaniumCXXABI::ReadArrayCookie(CodeGenFunction &CGF,
                                    llvm::Value *Ptr,
                                    const CXXDeleteExpr *expr,
                                    QualType ElementType,
                                    llvm::Value *&NumElements,
                                    llvm::Value *&AllocPtr,
                                    CharUnits &CookieSize) {
  // Derive a char* in the same address space as the pointer.
  unsigned AS = cast<llvm::PointerType>(Ptr->getType())->getAddressSpace();
  llvm::Type *CharPtrTy = CGF.Builder.getInt8Ty()->getPointerTo(AS);

  // If we don't need an array cookie, bail out early.
  if (!NeedsArrayCookie(expr, ElementType)) {
    AllocPtr = CGF.Builder.CreateBitCast(Ptr, CharPtrTy);
    NumElements = 0;
    CookieSize = CharUnits::Zero();
    return;
  }

  QualType SizeTy = getContext().getSizeType();
  CharUnits SizeSize = getContext().getTypeSizeInChars(SizeTy);
  llvm::Type *SizeLTy = CGF.ConvertType(SizeTy);
  
  CookieSize
    = std::max(SizeSize, getContext().getTypeAlignInChars(ElementType));

  CharUnits NumElementsOffset = CookieSize - SizeSize;

  // Compute the allocated pointer.
  AllocPtr = CGF.Builder.CreateBitCast(Ptr, CharPtrTy);
  AllocPtr = CGF.Builder.CreateConstInBoundsGEP1_64(AllocPtr,
                                                    -CookieSize.getQuantity());

  llvm::Value *NumElementsPtr = AllocPtr;
  if (!NumElementsOffset.isZero())
    NumElementsPtr =
      CGF.Builder.CreateConstInBoundsGEP1_64(NumElementsPtr,
                                             NumElementsOffset.getQuantity());
  NumElementsPtr = 
    CGF.Builder.CreateBitCast(NumElementsPtr, SizeLTy->getPointerTo(AS));
  NumElements = CGF.Builder.CreateLoad(NumElementsPtr);
}

/// Check if we are casting to a struct with a flexible array at the end.
/// \code
/// struct foo {
///   size_t len;
///   struct bar data[];
/// };
/// \endcode
/// or
/// \code
/// struct foo {
///   size_t len;
///   struct bar data[0];
/// }
/// \endcode
/// In these cases it is also valid to allocate size of struct foo + a multiple
/// of struct bar.
static bool evenFlexibleArraySize(ASTContext &Ctx, CharUnits RegionSize,
                                  CharUnits TypeSize, QualType ToPointeeTy) {
  const RecordType *RT = ToPointeeTy->getAs<RecordType>();
  if (!RT)
    return false;

  const RecordDecl *RD = RT->getDecl();
  RecordDecl::field_iterator Iter(RD->field_begin());
  RecordDecl::field_iterator End(RD->field_end());
  const FieldDecl *Last = 0;
  for (; Iter != End; ++Iter)
    Last = *Iter;
  assert(Last && "empty structs should already be handled");

  const Type *ElemType = Last->getType()->getArrayElementTypeNoTypeQual();
  CharUnits FlexSize;
  if (const ConstantArrayType *ArrayTy =
        Ctx.getAsConstantArrayType(Last->getType())) {
    FlexSize = Ctx.getTypeSizeInChars(ElemType);
    if (ArrayTy->getSize() == 1 && TypeSize > FlexSize)
      TypeSize -= FlexSize;
    else if (ArrayTy->getSize() != 0)
      return false;
  } else if (RD->hasFlexibleArrayMember()) {
    FlexSize = Ctx.getTypeSizeInChars(ElemType);
  } else {
    return false;
  }

  if (FlexSize.isZero())
    return false;

  CharUnits Left = RegionSize - TypeSize;
  if (Left.isNegative())
    return false;

  if (Left % FlexSize == 0)
    return true;

  return false;
}

const MemRegion *StoreManager::CastRegion(const MemRegion *R, QualType CastToTy) {

  ASTContext& Ctx = StateMgr.getContext();

  // Handle casts to Objective-C objects.
  if (CastToTy->isObjCObjectPointerType())
    return R->StripCasts();

  if (CastToTy->isBlockPointerType()) {
    // FIXME: We may need different solutions, depending on the symbol
    // involved.  Blocks can be casted to/from 'id', as they can be treated
    // as Objective-C objects.  This could possibly be handled by enhancing
    // our reasoning of downcasts of symbolic objects.
    if (isa<CodeTextRegion>(R) || isa<SymbolicRegion>(R))
      return R;

    // We don't know what to make of it.  Return a NULL region, which
    // will be interpretted as UnknownVal.
    return NULL;
  }

  // Now assume we are casting from pointer to pointer. Other cases should
  // already be handled.
  QualType PointeeTy = CastToTy->getAs<PointerType>()->getPointeeType();
  QualType CanonPointeeTy = Ctx.getCanonicalType(PointeeTy);

  // Handle casts to void*.  We just pass the region through.
  if (CanonPointeeTy.getLocalUnqualifiedType() == Ctx.VoidTy)
    return R;

  // Handle casts from compatible types.
  if (R->isBoundable())
    if (const TypedRegion *TR = dyn_cast<TypedRegion>(R)) {
      QualType ObjTy = Ctx.getCanonicalType(TR->getValueType());
      if (CanonPointeeTy == ObjTy)
        return R;
    }

  // Process region cast according to the kind of the region being cast.
  switch (R->getKind()) {
    case MemRegion::CXXThisRegionKind:
    case MemRegion::GenericMemSpaceRegionKind:
    case MemRegion::StackLocalsSpaceRegionKind:
    case MemRegion::StackArgumentsSpaceRegionKind:
    case MemRegion::HeapSpaceRegionKind:
    case MemRegion::UnknownSpaceRegionKind:
    case MemRegion::NonStaticGlobalSpaceRegionKind:
    case MemRegion::StaticGlobalSpaceRegionKind: {
      assert(0 && "Invalid region cast");
      break;
    }

    case MemRegion::FunctionTextRegionKind:
    case MemRegion::BlockTextRegionKind:
    case MemRegion::BlockDataRegionKind:
    case MemRegion::StringRegionKind:
      // FIXME: Need to handle arbitrary downcasts.
    case MemRegion::SymbolicRegionKind:
    case MemRegion::AllocaRegionKind:
    case MemRegion::CompoundLiteralRegionKind:
    case MemRegion::FieldRegionKind:
    case MemRegion::ObjCIvarRegionKind:
    case MemRegion::VarRegionKind:
    case MemRegion::CXXObjectRegionKind:
      return MakeElementRegion(R, PointeeTy);

    case MemRegion::ElementRegionKind: {
      // If we are casting from an ElementRegion to another type, the
      // algorithm is as follows:
      //
      // (1) Compute the "raw offset" of the ElementRegion from the
      //     base region.  This is done by calling 'getAsRawOffset()'.
      //
      // (2a) If we get a 'RegionRawOffset' after calling
      //      'getAsRawOffset()', determine if the absolute offset
      //      can be exactly divided into chunks of the size of the
      //      casted-pointee type.  If so, create a new ElementRegion with
      //      the pointee-cast type as the new ElementType and the index
      //      being the offset divded by the chunk size.  If not, create
      //      a new ElementRegion at offset 0 off the raw offset region.
      //
      // (2b) If we don't a get a 'RegionRawOffset' after calling
      //      'getAsRawOffset()', it means that we are at offset 0.
      //
      // FIXME: Handle symbolic raw offsets.

      const ElementRegion *elementR = cast<ElementRegion>(R);
      const RegionRawOffset &rawOff = elementR->getAsArrayOffset();
      const MemRegion *baseR = rawOff.getRegion();

      // If we cannot compute a raw offset, throw up our hands and return
      // a NULL MemRegion*.
      if (!baseR)
        return NULL;

      CharUnits off = CharUnits::fromQuantity(rawOff.getByteOffset());

      if (off.isZero()) {
        // Edge case: we are at 0 bytes off the beginning of baseR.  We
        // check to see if type we are casting to is the same as the base
//.........这里部分代码省略.........

void CGRecordLayoutBuilder::LayoutUnion(const RecordDecl *D) {
  assert(D->isUnion() && "Can't call LayoutUnion on a non-union record!");

  const ASTRecordLayout &layout = Types.getContext().getASTRecordLayout(D);

  llvm::Type *unionType = 0;
  CharUnits unionSize = CharUnits::Zero();
  CharUnits unionAlign = CharUnits::Zero();

  bool hasOnlyZeroSizedBitFields = true;
  bool checkedFirstFieldZeroInit = false;

  unsigned fieldNo = 0;
  for (RecordDecl::field_iterator field = D->field_begin(),
       fieldEnd = D->field_end(); field != fieldEnd; ++field, ++fieldNo) {
    assert(layout.getFieldOffset(fieldNo) == 0 &&
          "Union field offset did not start at the beginning of record!");
    llvm::Type *fieldType = LayoutUnionField(*field, layout);

    if (!fieldType)
      continue;

    if (field->getDeclName() && !checkedFirstFieldZeroInit) {
      CheckZeroInitializable(field->getType());
      checkedFirstFieldZeroInit = true;
    }

    hasOnlyZeroSizedBitFields = false;

    CharUnits fieldAlign = CharUnits::fromQuantity(
                          Types.getDataLayout().getABITypeAlignment(fieldType));
    CharUnits fieldSize = CharUnits::fromQuantity(
                             Types.getDataLayout().getTypeAllocSize(fieldType));

    if (fieldAlign < unionAlign)
      continue;

    if (fieldAlign > unionAlign || fieldSize > unionSize) {
      unionType = fieldType;
      unionAlign = fieldAlign;
      unionSize = fieldSize;
    }
  }

  // Now add our field.
  if (unionType) {
    AppendField(CharUnits::Zero(), unionType);

    if (getTypeAlignment(unionType) > layout.getAlignment()) {
      // We need a packed struct.
      Packed = true;
      unionAlign = CharUnits::One();
    }
  }
  if (unionAlign.isZero()) {
    (void)hasOnlyZeroSizedBitFields;
    assert(hasOnlyZeroSizedBitFields &&
           "0-align record did not have all zero-sized bit-fields!");
    unionAlign = CharUnits::One();
  }

  // Append tail padding.
  CharUnits recordSize = layout.getSize();
  if (recordSize > unionSize)
    AppendPadding(recordSize, unionAlign);
}

void
CodeGenFunction::EmitNullInitialization(llvm::Value *DestPtr, QualType Ty) {
  // Ignore empty classes in C++.
  if (getContext().getLangOptions().CPlusPlus) {
    if (const RecordType *RT = Ty->getAs<RecordType>()) {
      if (cast<CXXRecordDecl>(RT->getDecl())->isEmpty())
        return;
    }
  }

  // Cast the dest ptr to the appropriate i8 pointer type.
  unsigned DestAS =
    cast<llvm::PointerType>(DestPtr->getType())->getAddressSpace();
  llvm::Type *BP = Builder.getInt8PtrTy(DestAS);
  if (DestPtr->getType() != BP)
    DestPtr = Builder.CreateBitCast(DestPtr, BP);

  // Get size and alignment info for this aggregate.
  std::pair<CharUnits, CharUnits> TypeInfo = 
    getContext().getTypeInfoInChars(Ty);
  CharUnits Size = TypeInfo.first;
  CharUnits Align = TypeInfo.second;

  llvm::Value *SizeVal;
  const VariableArrayType *vla;

  // Don't bother emitting a zero-byte memset.
  if (Size.isZero()) {
    // But note that getTypeInfo returns 0 for a VLA.
    if (const VariableArrayType *vlaType =
          dyn_cast_or_null<VariableArrayType>(
                                          getContext().getAsArrayType(Ty))) {
      QualType eltType;
      llvm::Value *numElts;
      llvm::tie(numElts, eltType) = getVLASize(vlaType);

      SizeVal = numElts;
      CharUnits eltSize = getContext().getTypeSizeInChars(eltType);
      if (!eltSize.isOne())
        SizeVal = Builder.CreateNUWMul(SizeVal, CGM.getSize(eltSize));
      vla = vlaType;
    } else {
      return;
    }
  } else {
    SizeVal = CGM.getSize(Size);
    vla = 0;
  }

  // If the type contains a pointer to data member we can't memset it to zero.
  // Instead, create a null constant and copy it to the destination.
  // TODO: there are other patterns besides zero that we can usefully memset,
  // like -1, which happens to be the pattern used by member-pointers.
  if (!CGM.getTypes().isZeroInitializable(Ty)) {
    // For a VLA, emit a single element, then splat that over the VLA.
    if (vla) Ty = getContext().getBaseElementType(vla);

    llvm::Constant *NullConstant = CGM.EmitNullConstant(Ty);

    llvm::GlobalVariable *NullVariable = 
      new llvm::GlobalVariable(CGM.getModule(), NullConstant->getType(),
                               /*isConstant=*/true, 
                               llvm::GlobalVariable::PrivateLinkage,
                               NullConstant, Twine());
    llvm::Value *SrcPtr =
      Builder.CreateBitCast(NullVariable, Builder.getInt8PtrTy());

    if (vla) return emitNonZeroVLAInit(*this, Ty, DestPtr, SrcPtr, SizeVal);

    // Get and call the appropriate llvm.memcpy overload.
    Builder.CreateMemCpy(DestPtr, SrcPtr, SizeVal, Align.getQuantity(), false);
    return;
  } 
  
  // Otherwise, just memset the whole thing to zero.  This is legal
  // because in LLVM, all default initializers (other than the ones we just
  // handled above) are guaranteed to have a bit pattern of all zeros.
  Builder.CreateMemSet(DestPtr, Builder.getInt8(0), SizeVal, 
                       Align.getQuantity(), false);
}

void APValue::printPretty(raw_ostream &Out, ASTContext &Ctx, QualType Ty) const{
  switch (getKind()) {
  case APValue::Uninitialized:
    Out << "<uninitialized>";
    return;
  case APValue::Int:
    if (Ty->isBooleanType())
      Out << (getInt().getBoolValue() ? "true" : "false");
    else
      Out << getInt();
    return;
  case APValue::Float:
    Out << GetApproxValue(getFloat());
    return;
  case APValue::Vector: {
    Out << '{';
    QualType ElemTy = Ty->getAs<VectorType>()->getElementType();
    getVectorElt(0).printPretty(Out, Ctx, ElemTy);
    for (unsigned i = 1; i != getVectorLength(); ++i) {
      Out << ", ";
      getVectorElt(i).printPretty(Out, Ctx, ElemTy);
    }
    Out << '}';
    return;
  }
  case APValue::ComplexInt:
    Out << getComplexIntReal() << "+" << getComplexIntImag() << "i";
    return;
  case APValue::ComplexFloat:
    Out << GetApproxValue(getComplexFloatReal()) << "+"
        << GetApproxValue(getComplexFloatImag()) << "i";
    return;
  case APValue::LValue: {
    LValueBase Base = getLValueBase();
    if (!Base) {
      Out << "0";
      return;
    }

    bool IsReference = Ty->isReferenceType();
    QualType InnerTy
      = IsReference ? Ty.getNonReferenceType() : Ty->getPointeeType();
    if (InnerTy.isNull())
      InnerTy = Ty;

    if (!hasLValuePath()) {
      // No lvalue path: just print the offset.
      CharUnits O = getLValueOffset();
      CharUnits S = Ctx.getTypeSizeInChars(InnerTy);
      if (!O.isZero()) {
        if (IsReference)
          Out << "*(";
        if (O % S) {
          Out << "(char*)";
          S = CharUnits::One();
        }
        Out << '&';
      } else if (!IsReference)
        Out << '&';

      if (const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>())
        Out << *VD;
      else {
        assert(Base.get<const Expr *>() != nullptr &&
               "Expecting non-null Expr");
        Base.get<const Expr*>()->printPretty(Out, nullptr,
                                             Ctx.getPrintingPolicy());
      }

      if (!O.isZero()) {
        Out << " + " << (O / S);
        if (IsReference)
          Out << ')';
      }
      return;
    }

    // We have an lvalue path. Print it out nicely.
    if (!IsReference)
      Out << '&';
    else if (isLValueOnePastTheEnd())
      Out << "*(&";

    QualType ElemTy;
    if (const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>()) {
      Out << *VD;
      ElemTy = VD->getType();
    } else {
      const Expr *E = Base.get<const Expr*>();
      assert(E != nullptr && "Expecting non-null Expr");
      E->printPretty(Out, nullptr, Ctx.getPrintingPolicy());
      ElemTy = E->getType();
    }

    ArrayRef<LValuePathEntry> Path = getLValuePath();
    const CXXRecordDecl *CastToBase = nullptr;
    for (unsigned I = 0, N = Path.size(); I != N; ++I) {
      if (ElemTy->getAs<RecordType>()) {
        // The lvalue refers to a class type, so the next path entry is a base
        // or member.
//.........这里部分代码省略.........