@NotNull
  private DfaValue getMethodResultValue(
      MethodCallInstruction instruction,
      @Nullable DfaValue qualifierValue,
      DfaValueFactory factory) {
    DfaValue precalculated = instruction.getPrecalculatedReturnValue();
    if (precalculated != null) {
      return precalculated;
    }

    final PsiType type = instruction.getResultType();
    final MethodCallInstruction.MethodType methodType = instruction.getMethodType();

    if (methodType == MethodCallInstruction.MethodType.UNBOXING) {
      return factory.getBoxedFactory().createUnboxed(qualifierValue);
    }

    if (methodType == MethodCallInstruction.MethodType.BOXING) {
      DfaValue boxed = factory.getBoxedFactory().createBoxed(qualifierValue);
      return boxed == null ? factory.createTypeValue(type, Nullness.NOT_NULL) : boxed;
    }

    if (methodType == MethodCallInstruction.MethodType.CAST) {
      assert qualifierValue != null;
      if (qualifierValue instanceof DfaConstValue) {
        Object casted =
            TypeConversionUtil.computeCastTo(((DfaConstValue) qualifierValue).getValue(), type);
        return factory
            .getConstFactory()
            .createFromValue(casted, type, ((DfaConstValue) qualifierValue).getConstant());
      }
      return qualifierValue;
    }

    if (type != null && (type instanceof PsiClassType || type.getArrayDimensions() > 0)) {
      Nullness nullability = myReturnTypeNullability.get(instruction);
      if (nullability == Nullness.UNKNOWN && factory.isUnknownMembersAreNullable()) {
        nullability = Nullness.NULLABLE;
      }
      return factory.createTypeValue(type, nullability);
    }
    return DfaUnknownValue.getInstance();
  }
 private DfaValue getDfaContractReturnValue(
     MethodContract contract, MethodCallInstruction instruction, DfaValueFactory factory) {
   switch (contract.returnValue) {
     case NULL_VALUE:
       return factory.getConstFactory().getNull();
     case NOT_NULL_VALUE:
       return factory.createTypeValue(instruction.getResultType(), Nullness.NOT_NULL);
     case TRUE_VALUE:
       return factory.getConstFactory().getTrue();
     case FALSE_VALUE:
       return factory.getConstFactory().getFalse();
     case THROW_EXCEPTION:
       return factory.getConstFactory().getContractFail();
     default:
       return getMethodResultValue(instruction, null, factory);
   }
 }
  @Override
  public DfaInstructionState[] visitTypeCast(
      TypeCastInstruction instruction, DataFlowRunner runner, DfaMemoryState memState) {
    final DfaValueFactory factory = runner.getFactory();
    DfaValue dfaExpr = factory.createValue(instruction.getCasted());
    if (dfaExpr != null) {
      DfaTypeValue dfaType =
          (DfaTypeValue) factory.createTypeValue(instruction.getCastTo(), Nullness.UNKNOWN);
      DfaRelationValue dfaInstanceof =
          factory.getRelationFactory().createRelation(dfaExpr, dfaType, INSTANCEOF_KEYWORD, false);
      if (dfaInstanceof != null && !memState.applyInstanceofOrNull(dfaInstanceof)) {
        onInstructionProducesCCE(instruction);
      }
    }

    if (instruction.getCastTo() instanceof PsiPrimitiveType) {
      memState.push(runner.getFactory().getBoxedFactory().createUnboxed(memState.pop()));
    }

    return nextInstruction(instruction, runner, memState);
  }
  @Override
  public DfaInstructionState[] visitAssign(
      AssignInstruction instruction, DataFlowRunner runner, DfaMemoryState memState) {
    DfaValue dfaSource = memState.pop();
    DfaValue dfaDest = memState.pop();

    if (dfaDest instanceof DfaVariableValue) {
      DfaVariableValue var = (DfaVariableValue) dfaDest;

      DfaValueFactory factory = runner.getFactory();
      if (dfaSource instanceof DfaVariableValue
          && factory.getVarFactory().getAllQualifiedBy(var).contains(dfaSource)) {
        Nullness nullability =
            memState.isNotNull(dfaSource)
                ? Nullness.NOT_NULL
                : ((DfaVariableValue) dfaSource).getInherentNullability();
        dfaSource =
            factory.createTypeValue(((DfaVariableValue) dfaSource).getVariableType(), nullability);
      }

      if (var.getInherentNullability() == Nullness.NOT_NULL) {
        checkNotNullable(
            memState,
            dfaSource,
            NullabilityProblem.assigningToNotNull,
            instruction.getRExpression());
      }
      final PsiModifierListOwner psi = var.getPsiVariable();
      if (!(psi instanceof PsiField) || !psi.hasModifierProperty(PsiModifier.VOLATILE)) {
        memState.setVarValue(var, dfaSource);
      }
    } else if (dfaDest instanceof DfaTypeValue && ((DfaTypeValue) dfaDest).isNotNull()) {
      checkNotNullable(
          memState, dfaSource, NullabilityProblem.assigningToNotNull, instruction.getRExpression());
    }

    memState.push(dfaDest);

    return nextInstruction(instruction, runner, memState);
  }