Creates a non-null object that represent a ArithmeticException and that has the given origin. If the ArithmeticException was created by the VM while evaluating an instruction with the program counter pc you use the method ValueOriginForImmediateVMException to translate that pc to the appropriate ValueOrigin.

Creates a non-null object that represent a ArrayIndexOutOfBoundsException and that has the given origin. If the ArrayIndexOutOfBoundsException was created by the VM while evaluating an instruction with the program counter pc you use the method ValueOriginForImmediateVMException to translate that pc to the appropriate ValueOrigin.

Creates a non-null object that represent a ArrayStoreException and that has the given origin. If the ArrayStoreException was created by the VM while evaluating an instruction with the program counter pc you use the method ValueOriginForImmediateVMException to translate that pc to the appropriate ValueOrigin.

Factory method to create a representation of a boolean value with the given initial value and origin.

The domain may ignore the information about the value and the origin (origin).

Factory method to create a representation of a boolean value if we know the origin of the value.

The domain may ignore the information about the origin (origin).

Factory method to create a DomainValue that represents the given byte value and that was created (explicitly or implicitly) by the instruction with the specified program counter.

The domain may ignore the information about the value and the origin (origin).

Factory method to create a DomainValue that was created (explicitly or implicitly) by the instruction with the specified program counter.

The domain may ignore the information about the origin (origin).

Factory method to create a DomainValue that represents the given char value and that was created (explicitly or implicitly) by the instruction with the specified program counter.

Factory method to create a DomainValue that was created (explicitly or implicitly) by the instruction with the specified program counter.

The domain may ignore the information about the origin (origin).

Creates a non-null object that represent a ClassCastException and that has the given origin. If the ClassCastException was created by the VM while evaluating an instruction with the program counter pc you use the method ValueOriginForImmediateVMException to translate that pc to the appropriate ValueOrigin.

Factory method to create a DomainValue that represents a runtime value of type "Class<T>" and that was created by the instruction with the specified program counter.

This function is called by OPAL when a class constant (LDC(_W) instruction) is put on the stack.

The domain may ignore the information about the value and the origin (vo).

Summary

The properties of the domain value are:

• Initialized: Yes and the type represented by the class is the given type.
• Type: java.lang.Class<t:Type>
• Null: No

The class tag can be used to create type safe arrays or to extract the concrete type of the domain value.

val DomainReferenceValue(v) = value // of type "DomainValue"
// v is now of the type DomainReferenceValue

The class tag for the type DomainValue.

Required to generate instances of arrays in which values of type DomainValue can be stored in a type-safe manner.

Initialization

In the sub-trait or class that fixes the type of DomainValue it is necessary to implement this abstract val using:

val DomainValueTag : ClassTag[DomainValue] = implicitly

(As of Scala 2.10 it is necessary that you do not use implicit in the subclass - it will compile, but fail at runtime.)

Factory method to create a DomainValue that represents the given double value and that was created (explicitly or implicitly) by the instruction with the specified program counter.

The domain may ignore the information about the value and the origin (vo).

Factory method to create a DomainValue that was created (explicitly or implicitly) by the instruction with the specified program counter, but where we have no knowledge about the precise value.

The domain may ignore the information about the origin (vo).

Factory method to create a DomainValue with the specified origin. The origin is typically the program counter of the instruction that created this value/where the value was observed for the first time.

The domain may ignore the information about the origin (origin).

Factory method to create a DomainValue with the specified origin. The origin is typically the program counter of the instruction that created this value/where the value was observed for the first time.

The domain may ignore the information about the origin (origin).

Creates a non-null object that represent an IllegalMonitorStateException and that has the given origin. If the IllegalMonitorStateException was created by the VM while evaluating an instruction with the program counter pc you should use the method ValueOriginForImmediateVMException to translate that pc to the appropriate ValueOrigin.

Factory method to create a DomainValue that represents an initialized reference value of the given type and that was created (explicitly or implicitly) by the instruction with the specified program counter.

General Remarks

The given type usually identifies a class type (not an interface type) that is not abstract, but in some cases (e.g. consider java.awt.Toolkit()) it may be useful/meaningful to relax this requirement and to state that the class precisely represents the runtime type – even so the class is abstract. However, such decisions need to be made by the domain.

This method is used by the OPAL framework to create reference values that are normally internally created by the JVM (in particular exceptions such as NullPointerException and ClassCastException). However, it can generally be used to create initialized objects/arrays.

Summary

The properties of the domain value are:

• Initialized: Yes
• Type: precise (i.e., this type is not an upper bound, the type correctly models the runtime type.)
• Null: No (This value is not null.)

Factory method to create a DomainValue that represents the given integer value and that was created (explicitly or implicitly) by the instruction with the specified program counter.

The domain may ignore the information about the value and the origin (origin).

Factory method to create a DomainValue that was created (explicitly or implicitly) by the instruction with the specified program counter.

The domain may ignore the information about the origin (origin).

Factory method to create a DomainValue that represents the given long value and that was created (explicitly or implicitly) by the instruction with the specified program counter.

The domain may ignore the information about the value and the origin (vo).

Factory method to create a DomainValue that was created (explicitly or implicitly) by the instruction with the specified program counter.

The domain may ignore the information about the origin (vo).

The result of the merge of two incompatible values has to be reported as a MetaInformationUpdate[DomainIllegalValue].

Creates a non-null object that represent a NegativeArraySizeException and that has the given origin. If the NegativeArraySizeException was created by the VM while evaluating an instruction with the program counter pc you use the method ValueOriginForImmediateVMException to translate that pc to the appropriate ValueOrigin.

Creates a new DomainValue that represents a new, uninitialized instance of an object of the given type. The object was created by the (NEW) instruction with the specified program counter.

OPAL calls this method when it evaluates newobject instructions. If the bytecode is valid a call of one of the (super) object's constructors will subsequently initialize the object.

Summary

The properties of the domain value are:

• Initialized: no (only the memory is allocated for the object)
• Type: precise (i.e., this type is not an upper bound, the type correctly models the runtime type.)
• Null: no (This value is not null.)

Represents a non-null reference value with the given type as an upper type bound.

The domain may ignore the information about the value and the origin (vo).

Summary

The properties of the domain value are:

• Initialized: Yes (the constructor was called)
• Type: Upper Bound
• Null: No (This value is not null.)

Creates a non-null object that represent a NullPointerException and that has the given origin. If the NullPointerException was created by the VM while evaluating an instruction with the program counter pc you should use the method ValueOriginForImmediateVMException to translate that pc to the appropriate ValueOrigin.

Factory method to create a DomainValue that represents value null and and that was created (explicitly or implicitly) by the instruction with the specified program counter.

The domain may ignore the information about the value and the origin (pc).

Summary

The properties of the domain value are:

• Initialized: N/A
• Type: Null
• Null: Yes

Factory method to create a DomainValue that represents either a reference value that has the given type and is initialized or the value null. However, the information whether the value is null or not is not available. Furthermore, the type may also just be an upper bound.

The domain may ignore the information about the value and the origin, but it has to remain possible for the domain to identify the component type of an array.

Summary

The properties of the domain value are:

• Initialized: Yes (if non-null the constructor was called/the array was initialized)
• Type: Upper Bound
• Null: Unknown
• Content: Unknown

Factory method to create an instance of a ReturnAddressValue.

Factory method to create a DomainValue that represents the given short value and that was created (explicitly or implicitly) by the instruction with the specified program counter.

Factory method to create a DomainValue that was created (explicitly or implicitly) by the instruction with the specified program counter.

The domain may ignore the information about the origin (origin).

Factory method to create a DomainValue that represents the given string value and that was created by the instruction with the specified program counter.

This function is called by OPAL-AI when a string constant (LDC(_W) instruction) is put on the stack.

The domain may ignore the information about the value and the origin (vo).

Summary

The properties of the domain value are:

• Initialized: Yes and the String's value is the given value. The string may be empty (""), but it is never null.
• Type: java.lang.String
• Null: No

The singleton instance of the IllegalValue.

The singleton instance of ReturnAddressValues

Creates a non-null object that represent a Throwable object and that has the given origin. If the Throwable was created by the VM while evaluating an instruction with the program counter pc you should use the method ValueOriginForImmediateVMException to translate that pc to the appropriate ValueOrigin.

Creates a new DomainValue that represents the this value of a constructor before the super constructor is called. Hence, the value origin is necessarily always -1.

OPAL calls this method when it creates the initial locals for constructors.

Summary

The properties of the domain value are:

• Initialized: no (only the memory is allocated for the object)
• Type: upper bound
• Null: no (This value is not null.)

If true the processing of the exception handlers related to an invoke statement will be aborted if the relation between the type of the thrown exception and the caught type is unknown.

If true the processing of the exception handlers related to an athrow statement will be aborted if the relation between the type of the thrown exception and the caught type is unknown.

Called by the abstract interpreter when an exception is thrown that is not (guaranteed to be) handled within the same method.

The given value, which is a value with computational type reference, is returned by the return instruction with the given pc.

Returns the array's length or throws a NullPointerException.

This project's class hierarchy.

Usually, just a redirect to the Project's class hierarchy or the default class hierarchy.

The given value, which is a value with computational type double, is returned by the return instruction with the given pc.

The given value, which is a value with computational type float, is returned by the return instruction with the given pc.

Returns the field's value and/or a new NullPointerException if the given objectref represents the value null.

Returns the field's value.

Tests if the two given integer values are equal.

Tests if the first integer value is smaller than the second value.

Tests if the first integer value is less than or equal to the second value.

Returns Yes iff at least one possible extension of the given value is in the specified range; that is, if the intersection of the range of values captured by the given value and the specified range is non-empty.

For example, if the given value captures all positive integer values and the specified range is [-1,1] then the answer has to be Yes. If we know nothing about the potential extension of the given value the answer will be Unknown. The answer is No iff both ranges are non-overlapping.

Returns Yes iff at least one (possible) extension of a given value is not in the specified range; that is, if the set difference of the range of values captured by the given value and the specified range is non-empty. For example, if the given value has the integer value 10 and the specified range is [0,Integer.MAX_VALUE] then the answer has to be No. But, if the given value represents the range [-5,Integer.MAX_VALUE] and the specified range is again [0,Integer.MAX_VALUE] then the answer has to be Yes.

The answer is Yes iff the analysis determined that at runtime value will have a value that is not in the specified range. If the analysis(domain) is not able to determine whether the value is or is not in the given range then the answer has to be Unknown.

The given value, which is a value with computational type integer, is returned by the return instruction with the given pc.

Tries to determine – under the assumption that the given value is not null – if the runtime type of the given reference value could be a subtype of the specified reference type supertype. I.e., if the type of the value is not precisely known, then all subtypes of the value's type are also taken into consideration when analyzing the subtype relation and only if we can guarantee that none is a subtype of the given supertype the answer will be No.

Conversion of the given long value to a double value.

Conversion of the given long value to a float value.

Conversion of the given long value to an integer value.

Add of two long values.

Boolean and of two long values.

Comparison (==) of two long values.

Division of two long values.

Multiplication of two long values.

Negation of a long value.

Returns the dynamic constant's value.

Boolean or of two long values.

Remainder of two long values.

The given value, which is a value with computational type long, is returned by the return instruction with the given pc.

Shift left of a long value.

Shift right of a long value.

Subtraction of two long values.

Unsigned shift right of a long value.

xor of two long values.

Handles a monitorenter instruction.

Handles a monitorexit instruction.

Creates a representation of a new multidimensional array. The return value is either a new array or a NegativeArraySizeException if count is negative.

The return value is either a new array or a NegativeArraySizeException if count is negative.

Sets the field's value if the given objectref is not null(in the Domain). In the latter case a NullPointerException is thrown.

Sets the field's value.

Compares the given values for reference equality. Returns Yes if both values point to the same instance and returns No if both objects are known not to point to the same instance. The latter is, e.g., trivially the case when both values have a different concrete type. Otherwise Unknown is returned.

If both values are representing the null value the org.opalj.Answer is Yes.

Determines whether the given value is null (Yes), maybe null (Unknown) or is not null (No).

Called by the abstract interpreter when the type bound of the top most stack value needs to be refined. This method is only called by the abstract interpreter iff an immediately preceding subtype query (typeOf(value) <: bound) returned Unknown. This method must not be ignored – w.r.t. refining the top-most stack value; it is e.g., used by org.opalj.br.instructions.CHECKCAST instructions.

A domain that is able to identify aliases can use this information to propagate the information to the other aliases.

Sets the is null property of the top-most stack value to Yes. This method is called by the framework when the top-most operand stack value has to be null, but a previous isNull check returned Unknown. E.g., after a org.opalj.br.instructions.CHECKCAST that fails or if a InstanceOf check has succeeded.

This method can be ignored; i.e., the return value can be (operands,locals). However, a domain that tracks alias information can use this information to propagate the information to the other aliases.

Called when a return instruction with the given pc is reached. In other words, when the method returns normally.

If true, all instructions that may raise an arithmetic exception (e.g., idiv, ldiv) should do so if it is impossible to statically determine that no exception will occur. But, if we can statically determine that the operation will raise an exception then the exception will be thrown – independently of this setting. Furthermore, if we can statically determine that no exception will be raised, no exception will be thrown. Hence, this setting only affects computations with values with incomplete information.

If true an ArrayIndexOutOfBoundsException is thrown if the index cannot be verified to be valid.

If true an ArrayStoreException is thrown if it cannot be verified that the value can be stored in the array.

If true a ClassCastException is thrown by CHECKCAST instructions if it cannot be verified that no ClassCastException will be thrown.

Throw a ClassNotFoundException if the a specific reference type is not known in the current context. The context is typically a specific Project.

Determines the behavior how method calls are handled when the exceptions that the called method may throw are unknown.

If true then monitorexit and the (XXX)return instructions will throw IllegalMonitorStateExceptions unless the analysis is able to determine that the exception is guaranteed not to be raised.

If true a NegativeArraySizeException is thrown if the index cannot be verified to be positive.

Returns true if potential NullPointerExceptions should be thrown and false if such NullPointerExceptions should be ignored. However, if the interpreter identifies a situation in which a NullPointerException is guaranteed to be thrown, it will be thrown.

Returns true if potential NullPointerExceptions should be thrown and false if such NullPointerExceptions should be ignored. However, if the interpreter identifies a situation in which a NullPointerException is guaranteed to be thrown, it will be thrown.

Returns true if potential NullPointerExceptions should be thrown and false if such NullPointerExceptions should be ignored. However, if the interpreter identifies a situation in which a NullPointerException is guaranteed to be thrown, it will be thrown. Example:

def demo(o : Object) {
     o.toString  // - If "true", a NullPointerException will ALSO be thrown;
                 //   the operation also succeeds.
                 // - If "false" the operation will "just" succeed
}

Returns true if potential NullPointerExceptions should be thrown and false if such NullPointerExceptions should be ignored. However, if the interpreter identifies a situation in which a NullPointerException is guaranteed to be thrown, it will be thrown.

If true a VM level NullPointerExceptions is thrown if the exception that is to be thrown may be null.

Creates a DomainValue that represents a value with the given type and which is initialized using the JVM's default value for that type. E.g., for IntegerValues the value is set to 0. In case of a ReferenceType the value is the ReferenceValuesFactory#NullValue.

Creates a domain value from the given value information that represents a properly domain value. A representation of a proper value is created even if the value information is provided for an uninitialized value.

Factory method to create a representation of the integer constant value 0.

OPAL in particular uses this special value for performing subsequent computations against the fixed value 0 (e.g., for if_XX instructions).

(The origin (ValueOrigin) that is used is the ConstantValueOrigin to signify that this value was not created by the program.)

The domain may ignore the information about the value.

Called by the AI framework for each load constant method handle (org.opalj.br.instructions.LoadMethodHandle) instruction to get a representation of/a DomainValue that represents the handle.

Called by the framework for each load constant method type (org.opalj.br.instructions.LoadMethodType) instruction to get a domain-specific representation of the method descriptor as a MethodType.

The result of merging two values should never be reported as a StructuralUpdate if the computed value is an IllegalValue. The JVM semantics guarantee that the value will not be used and, hence, continuing the interpretation is meaningless.

Factory method to create domain values with a specific type. I.e., values for which we have some type information but no precise value or source information. However, the value is guaranteed to be null or properly initialized.

For example, if valueType is a reference type it may be possible that the actual value is null, but such knowledge is not available.

The framework uses this method when a method is to be analyzed, but no parameter values are given and initial values need to be generated. This method is not used elsewhere by the framework.

Called by the abstract interpreter when the abstract interpretation of a method has ended. The abstract interpretation of a method ends if either the fixpoint is reached or the interpretation was aborted.

By default this method does nothing.

Domains that override this method are expected to also call super.abstractInterpretationEnded(aiResult).

This method is called after all values which differ have been joined, but before joinPostProcessing will be called.

This methods is called after the evaluation of the instruction with the given pc with respect to targetPC, but before the values are propagated (joined) and before it is checked whether the interpretation needs to be continued. I.e., if the operands (newOperands) or locals (newLocals) are further refined then the refined operands and locals are joined (if necessary).

This method is called immediately before a join operation with regard to the specified pc is performed.

Called by the framework after evaluating the instruction with the given pc. I.e., the state of all potential successor instructions was updated and the flow method was called – potentially multiple times – accordingly.

By default this method does nothing.

Called by the framework after performing a computation to inform the domain about the result. That is, after evaluating the effect of the instruction with currentPC on the current stack and register and (if necessary) joining the updated stack and registers with the stack and registers associated with the instruction successorPC. (Hence, this method is ONLY called for return instructions if the return instruction throws an IllegalMonitorStateException.) This function basically informs the domain about the instruction that may be evaluated next. The flow function is called for every possible successor of the instruction with currentPC. This includes all branch targets as well as those instructions that handle exceptions.

In some cases it will even be the case that flow is called multiple times with the same pair of program counters: (currentPC, successorPC). This may happen, e.g., in case of a switch instruction where multiple values have the same body/target instruction and we do not have precise information about the switch value. E.g., as in the following snippet:

switch (i) {  // pc: X => Y (for "1"), Y (for "2"), Y (for "3")
case 1:
case 2:
case 3: System.out.println("Great.");            // pc: Y
default: System.out.println("Not So Great.");    // pc: Z
}

The flow function is also called after instructions that are domain independent such as dup and load instructions which just manipulate the registers and stack in a generic way. This enables the domain to precisely follow the evaluation progress and in particular to perform control-flow dependent analyses.

Tests if the two given integer values are not equal.

Sets the given domain value to theValue.

This function is called by OPAL before it starts to explore the branch where this condition has to hold. (This function is, e.g., called whenever we explore the branches of a switch-case statement.) I.e., the constraint is established before a potential join operation.

Tests if the given integer value is 0 or maybe 0.

Tests if the first integer value is larger than the second value.

Tests if the given integer value is > 0 or maybe > 0.

Tests if the first integer value is larger than or equal to the second value.

Tests if the given value is greater than or equal to 0 or maybe greater than or equal to 0.

Tests if the given integer value is < 0 or maybe < 0.

Tests if the given integer value is less than or equal to 0 or maybe less than or equal to 0.

Tests if the given integer value is not 0 or maybe not 0.

Tests if subtype is known to be subtype of supertype. See org.opalj.br.ClassHierarchy's isSubtypeOf method for details.

Tests if subtype is known to be subtype of supertype. See org.opalj.br.ClassHierarchy's isSubtypeOf method for details.

Joins the given operand stacks and local variables.

In general there should be no need to refine this method. Overriding this method should only be done for analysis purposes.

Performance

This method heavily relies on reference comparisons to speed up the overall process of performing an abstract interpretation of a method. Hence, a computation should – whenever possible – return (one of) the original object(s) if that value has the same abstract state as the result. Furthermore, if all original values capture the same abstract state as the result of the computation, the "left" value/the value that was already used in the past should be returned.

Enables the customization of the behavior of the base join method.

This method in particular enables, in case of a MetaInformationUpdate, to raise the update type to force the continuation of the abstract interpretation process.

Methods should always override this method and should call the super method.