C++ CharUnits类代码示例

LValue CGObjCRuntime::EmitValueForIvarAtOffset(CodeGen::CodeGenFunction &CGF,
                                               const ObjCInterfaceDecl *OID,
                                               llvm::Value *BaseValue,
                                               const ObjCIvarDecl *Ivar,
                                               unsigned CVRQualifiers,
                                               llvm::Value *Offset) {
  // Compute (type*) ( (char *) BaseValue + Offset)
  QualType IvarTy = Ivar->getType();
  llvm::Type *LTy = CGF.CGM.getTypes().ConvertTypeForMem(IvarTy);
  llvm::Value *V = CGF.Builder.CreateBitCast(BaseValue, CGF.Int8PtrTy);
  V = CGF.Builder.CreateInBoundsGEP(V, Offset, "add.ptr");

  if (!Ivar->isBitField()) {
    V = CGF.Builder.CreateBitCast(V, llvm::PointerType::getUnqual(LTy));
    LValue LV = CGF.MakeNaturalAlignAddrLValue(V, IvarTy);
    LV.getQuals().addCVRQualifiers(CVRQualifiers);
    return LV;
  }

  // We need to compute an access strategy for this bit-field. We are given the
  // offset to the first byte in the bit-field, the sub-byte offset is taken
  // from the original layout. We reuse the normal bit-field access strategy by
  // treating this as an access to a struct where the bit-field is in byte 0,
  // and adjust the containing type size as appropriate.
  //
  // FIXME: Note that currently we make a very conservative estimate of the
  // alignment of the bit-field, because (a) it is not clear what guarantees the
  // runtime makes us, and (b) we don't have a way to specify that the struct is
  // at an alignment plus offset.
  //
  // Note, there is a subtle invariant here: we can only call this routine on
  // non-synthesized ivars but we may be called for synthesized ivars.  However,
  // a synthesized ivar can never be a bit-field, so this is safe.
  uint64_t FieldBitOffset = LookupFieldBitOffset(CGF.CGM, OID, 0, Ivar);
  uint64_t BitOffset = FieldBitOffset % CGF.CGM.getContext().getCharWidth();
  uint64_t AlignmentBits = CGF.CGM.getContext().getTargetInfo().getCharAlign();
  uint64_t BitFieldSize = Ivar->getBitWidthValue(CGF.getContext());
  CharUnits StorageSize =
    CGF.CGM.getContext().toCharUnitsFromBits(
      llvm::RoundUpToAlignment(BitOffset + BitFieldSize, AlignmentBits));
  CharUnits Alignment = CGF.CGM.getContext().toCharUnitsFromBits(AlignmentBits);

  // Allocate a new CGBitFieldInfo object to describe this access.
  //
  // FIXME: This is incredibly wasteful, these should be uniqued or part of some
  // layout object. However, this is blocked on other cleanups to the
  // Objective-C code, so for now we just live with allocating a bunch of these
  // objects.
  CGBitFieldInfo *Info = new (CGF.CGM.getContext()) CGBitFieldInfo(
    CGBitFieldInfo::MakeInfo(CGF.CGM.getTypes(), Ivar, BitOffset, BitFieldSize,
                             CGF.CGM.getContext().toBits(StorageSize),
                             Alignment.getQuantity()));

  V = CGF.Builder.CreateBitCast(V,
                                llvm::Type::getIntNPtrTy(CGF.getLLVMContext(),
                                                         Info->StorageSize));
  return LValue::MakeBitfield(V, *Info,
                              IvarTy.withCVRQualifiers(CVRQualifiers),
                              Alignment);
}

void SlicingCheck::check(const MatchFinder::MatchResult &Result) {
  const auto *BaseDecl = Result.Nodes.getNodeAs<CXXRecordDecl>("BaseDecl");
  const auto *DerivedDecl =
      Result.Nodes.getNodeAs<CXXRecordDecl>("DerivedDecl");
  const auto *Call = Result.Nodes.getNodeAs<Expr>("Call");
  assert(BaseDecl != nullptr);
  assert(DerivedDecl != nullptr);
  assert(Call != nullptr);

  // Warn when slicing the vtable.
  // We're looking through all the methods in the derived class and see if they
  // override some methods in the base class.
  // It's not enough to just test whether the class is polymorphic because we
  // would be fine slicing B to A if no method in B (or its bases) overrides
  // anything in A:
  //   class A { virtual void f(); };
  //   class B : public A {};
  // because in that case calling A::f is the same as calling B::f.
  DiagnoseSlicedOverriddenMethods(*Call, *DerivedDecl, *BaseDecl);

  // Warn when slicing member variables.
  const auto &BaseLayout =
      BaseDecl->getASTContext().getASTRecordLayout(BaseDecl);
  const auto &DerivedLayout =
      DerivedDecl->getASTContext().getASTRecordLayout(DerivedDecl);
  const CharUnits StateSize =
      DerivedLayout.getDataSize() - BaseLayout.getDataSize();
  if (StateSize.isPositive()) {
    diag(Call->getExprLoc(), "slicing object from type %0 to %1 discards "
                             "%2 bytes of state")
        << DerivedDecl << BaseDecl << static_cast<int>(StateSize.getQuantity());
  }
}

void ExprEngine::
VisitUnaryExprOrTypeTraitExpr(const UnaryExprOrTypeTraitExpr *Ex,
                              ExplodedNode *Pred,
                              ExplodedNodeSet &Dst) {
  StmtNodeBuilder Bldr(Pred, Dst, *currBldrCtx);

  QualType T = Ex->getTypeOfArgument();
  
  if (Ex->getKind() == UETT_SizeOf) {
    if (!T->isIncompleteType() && !T->isConstantSizeType()) {
      assert(T->isVariableArrayType() && "Unknown non-constant-sized type.");
      
      // FIXME: Add support for VLA type arguments and VLA expressions.
      // When that happens, we should probably refactor VLASizeChecker's code.
      return;
    }
    else if (T->getAs<ObjCObjectType>()) {
      // Some code tries to take the sizeof an ObjCObjectType, relying that
      // the compiler has laid out its representation.  Just report Unknown
      // for these.
      return;
    }
  }
  
  APSInt Value = Ex->EvaluateKnownConstInt(getContext());
  CharUnits amt = CharUnits::fromQuantity(Value.getZExtValue());
  
  ProgramStateRef state = Pred->getState();
  state = state->BindExpr(Ex, Pred->getLocationContext(),
                          svalBuilder.makeIntVal(amt.getQuantity(),
                                                     Ex->getType()));
  Bldr.generateNode(Ex, Pred, state);
}

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::Type *
CGRecordLayoutBuilder::LayoutUnionField(const FieldDecl *Field,
                                        const ASTRecordLayout &Layout) {
  Fields[Field] = 0;
  if (Field->isBitField()) {
    uint64_t FieldSize = Field->getBitWidthValue(Types.getContext());

    // Ignore zero sized bit fields.
    if (FieldSize == 0)
      return 0;

    unsigned StorageBits = llvm::RoundUpToAlignment(
      FieldSize, Types.getTarget().getCharAlign());
    CharUnits NumBytesToAppend
      = Types.getContext().toCharUnitsFromBits(StorageBits);

    llvm::Type *FieldTy = llvm::Type::getInt8Ty(Types.getLLVMContext());
    if (NumBytesToAppend > CharUnits::One())
      FieldTy = llvm::ArrayType::get(FieldTy, NumBytesToAppend.getQuantity());

    // Add the bit field info.
    BitFields[Field] = CGBitFieldInfo::MakeInfo(Types, Field, 0, FieldSize,
                                                StorageBits,
                                                Alignment.getQuantity());
    return FieldTy;
  }

  // This is a regular union field.
  return Types.ConvertTypeForMem(Field->getType());
}

void CGRecordLowering::insertPadding() {
  std::vector<std::pair<CharUnits, CharUnits> > Padding;
  CharUnits Size = CharUnits::Zero();
  for (std::vector<MemberInfo>::const_iterator Member = Members.begin(),
                                               MemberEnd = Members.end();
       Member != MemberEnd; ++Member) {
    if (!Member->Data)
      continue;
    CharUnits Offset = Member->Offset;
    assert(Offset >= Size);
    // Insert padding if we need to.
    if (Offset !=
        Size.alignTo(Packed ? CharUnits::One() : getAlignment(Member->Data)))
      Padding.push_back(std::make_pair(Size, Offset - Size));
    Size = Offset + getSize(Member->Data);
  }
  if (Padding.empty())
    return;
  // Add the padding to the Members list and sort it.
  for (std::vector<std::pair<CharUnits, CharUnits> >::const_iterator
        Pad = Padding.begin(), PadEnd = Padding.end();
        Pad != PadEnd; ++Pad)
    Members.push_back(StorageInfo(Pad->first, getByteArrayType(Pad->second)));
  std::stable_sort(Members.begin(), Members.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());  
}

RegionOffset MemRegion::getAsOffset() const {
    const MemRegion *R = this;
    int64_t Offset = 0;

    while (1) {
        switch (R->getKind()) {
        default:
            return RegionOffset(0);
        case SymbolicRegionKind:
        case AllocaRegionKind:
        case CompoundLiteralRegionKind:
        case CXXThisRegionKind:
        case StringRegionKind:
        case VarRegionKind:
        case CXXTempObjectRegionKind:
            goto Finish;
        case ElementRegionKind: {
            const ElementRegion *ER = cast<ElementRegion>(R);
            QualType EleTy = ER->getValueType();

            if (!IsCompleteType(getContext(), EleTy))
                return RegionOffset(0);

            SVal Index = ER->getIndex();
            if (const nonloc::ConcreteInt *CI=dyn_cast<nonloc::ConcreteInt>(&Index)) {
                int64_t i = CI->getValue().getSExtValue();
                CharUnits Size = getContext().getTypeSizeInChars(EleTy);
                Offset += i * Size.getQuantity() * 8;
            } else {
                // We cannot compute offset for non-concrete index.
                return RegionOffset(0);
            }
            R = ER->getSuperRegion();
            break;
        }
        case FieldRegionKind: {
            const FieldRegion *FR = cast<FieldRegion>(R);
            const RecordDecl *RD = FR->getDecl()->getParent();
            if (!RD->isCompleteDefinition())
                // We cannot compute offset for incomplete type.
                return RegionOffset(0);
            // Get the field number.
            unsigned idx = 0;
            for (RecordDecl::field_iterator FI = RD->field_begin(),
                    FE = RD->field_end(); FI != FE; ++FI, ++idx)
                if (FR->getDecl() == *FI)
                    break;

            const ASTRecordLayout &Layout = getContext().getASTRecordLayout(RD);
            // This is offset in bits.
            Offset += Layout.getFieldOffset(idx);
            R = FR->getSuperRegion();
            break;
        }
        }
    }

Finish:
    return RegionOffset(R, Offset);
}

void CGNVCUDARuntime::emitDeviceStubBodyLegacy(CodeGenFunction &CGF,
                                               FunctionArgList &Args) {
  // Emit a call to cudaSetupArgument for each arg in Args.
  llvm::FunctionCallee cudaSetupArgFn = getSetupArgumentFn();
  llvm::BasicBlock *EndBlock = CGF.createBasicBlock("setup.end");
  CharUnits Offset = CharUnits::Zero();
  for (const VarDecl *A : Args) {
    CharUnits TyWidth, TyAlign;
    std::tie(TyWidth, TyAlign) =
        CGM.getContext().getTypeInfoInChars(A->getType());
    Offset = Offset.alignTo(TyAlign);
    llvm::Value *Args[] = {
        CGF.Builder.CreatePointerCast(CGF.GetAddrOfLocalVar(A).getPointer(),
                                      VoidPtrTy),
        llvm::ConstantInt::get(SizeTy, TyWidth.getQuantity()),
        llvm::ConstantInt::get(SizeTy, Offset.getQuantity()),
    };
    llvm::CallBase *CB = CGF.EmitRuntimeCallOrInvoke(cudaSetupArgFn, Args);
    llvm::Constant *Zero = llvm::ConstantInt::get(IntTy, 0);
    llvm::Value *CBZero = CGF.Builder.CreateICmpEQ(CB, Zero);
    llvm::BasicBlock *NextBlock = CGF.createBasicBlock("setup.next");
    CGF.Builder.CreateCondBr(CBZero, NextBlock, EndBlock);
    CGF.EmitBlock(NextBlock);
    Offset += TyWidth;
  }

  // Emit the call to cudaLaunch
  llvm::FunctionCallee cudaLaunchFn = getLaunchFn();
  llvm::Value *Arg = CGF.Builder.CreatePointerCast(CGF.CurFn, CharPtrTy);
  CGF.EmitRuntimeCallOrInvoke(cudaLaunchFn, Arg);
  CGF.EmitBranch(EndBlock);

  CGF.EmitBlock(EndBlock);
}

// Returns an adjusted base cast to i8*, since we do more address arithmetic on
// it.
llvm::Value *
MicrosoftCXXABI::AdjustVirtualBase(CodeGenFunction &CGF,
                                   const CXXRecordDecl *RD, llvm::Value *Base,
                                   llvm::Value *VirtualBaseAdjustmentOffset,
                                   llvm::Value *VBPtrOffset) {
  CGBuilderTy &Builder = CGF.Builder;
  Base = Builder.CreateBitCast(Base, CGM.Int8PtrTy);
  llvm::BasicBlock *OriginalBB = 0;
  llvm::BasicBlock *SkipAdjustBB = 0;
  llvm::BasicBlock *VBaseAdjustBB = 0;

  // In the unspecified inheritance model, there might not be a vbtable at all,
  // in which case we need to skip the virtual base lookup.  If there is a
  // vbtable, the first entry is a no-op entry that gives back the original
  // base, so look for a virtual base adjustment offset of zero.
  if (VBPtrOffset) {
    OriginalBB = Builder.GetInsertBlock();
    VBaseAdjustBB = CGF.createBasicBlock("memptr.vadjust");
    SkipAdjustBB = CGF.createBasicBlock("memptr.skip_vadjust");
    llvm::Value *IsVirtual =
      Builder.CreateICmpNE(VirtualBaseAdjustmentOffset, getZeroInt(),
                           "memptr.is_vbase");
    Builder.CreateCondBr(IsVirtual, VBaseAdjustBB, SkipAdjustBB);
    CGF.EmitBlock(VBaseAdjustBB);
  }

  // If we weren't given a dynamic vbptr offset, RD should be complete and we'll
  // know the vbptr offset.
  if (!VBPtrOffset) {
    CharUnits offs = getContext().getASTRecordLayout(RD).getVBPtrOffset();
    VBPtrOffset = llvm::ConstantInt::get(CGM.IntTy, offs.getQuantity());
  }
  // Load the vbtable pointer from the vbtable offset in the instance.
  llvm::Value *VBPtr =
    Builder.CreateInBoundsGEP(Base, VBPtrOffset, "memptr.vbptr");
  llvm::Value *VBTable =
    Builder.CreateBitCast(VBPtr, CGM.Int8PtrTy->getPointerTo(0));
  VBTable = Builder.CreateLoad(VBTable, "memptr.vbtable");
  // Load an i32 offset from the vb-table.
  llvm::Value *VBaseOffs =
    Builder.CreateInBoundsGEP(VBTable, VirtualBaseAdjustmentOffset);
  VBaseOffs = Builder.CreateBitCast(VBaseOffs, CGM.Int32Ty->getPointerTo(0));
  VBaseOffs = Builder.CreateLoad(VBaseOffs, "memptr.vbase_offs");
  // Add it to VBPtr.  GEP will sign extend the i32 value for us.
  llvm::Value *AdjustedBase = Builder.CreateInBoundsGEP(VBPtr, VBaseOffs);

  // Merge control flow with the case where we didn't have to adjust.
  if (VBaseAdjustBB) {
    Builder.CreateBr(SkipAdjustBB);
    CGF.EmitBlock(SkipAdjustBB);
    llvm::PHINode *Phi = Builder.CreatePHI(CGM.Int8PtrTy, 2, "memptr.base");
    Phi->addIncoming(Base, OriginalBB);
    Phi->addIncoming(AdjustedBase, VBaseAdjustBB);
    return Phi;
  }
  return AdjustedBase;
}

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));
  }
}

DefinedOrUnknownSVal TypedValueRegion::getExtent(SValBuilder &svalBuilder) const {
  ASTContext &Ctx = svalBuilder.getContext();
  QualType T = getDesugaredValueType(Ctx);

  if (isa<VariableArrayType>(T))
    return nonloc::SymbolVal(svalBuilder.getSymbolManager().getExtentSymbol(this));
  if (isa<IncompleteArrayType>(T))
    return UnknownVal();

  CharUnits size = Ctx.getTypeSizeInChars(T);
  QualType sizeTy = svalBuilder.getArrayIndexType();
  return svalBuilder.makeIntVal(size.getQuantity(), sizeTy);
}

// Scale a base value by a scaling factor, and return the scaled
// value as an SVal.  Used by 'computeOffset'.
static inline SVal scaleValue(ProgramStateRef state,
                              NonLoc baseVal, CharUnits scaling,
                              SValBuilder &sb) {
  return sb.evalBinOpNN(state, BO_Mul, baseVal,
                        sb.makeArrayIndex(scaling.getQuantity()),
                        sb.getArrayIndexType());
}

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

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

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);
    }
  }
}