Program Dependence Graph (PDG) Construction Quiz

<p>Graphs do not produce complete slices for all types of programs</p> Signup and view all the answers

<p>The object variables selected by the programmer</p> Signup and view all the answers

<p>Handling linear dependence within sub-statements of programs</p> Signup and view all the answers

<p>It leads to a loss of completeness in many cases.</p> Signup and view all the answers

<p>To improve the completeness of program slices when an object variable is selected as the slicing criterion.</p> Signup and view all the answers

<p>It is used for extracting statements that affect the value of a variable at a given program point.</p> Signup and view all the answers

<p>To support polymorphism, dynamic binding, and inheritance.</p> Signup and view all the answers

<p>They are not always complete, missing some code that can affect the slicing criterion.</p> Signup and view all the answers

<p>The bug will remain undetected and may cause further issues.</p> Signup and view all the answers

<p>To ensure that the slice computed from a variable produces specialized code equivalent to the original program.</p> Signup and view all the answers

<p>The exclusion of some required data members from object variables.</p> Signup and view all the answers

<p>The set of program variables whose value is accessed at statement n</p> Signup and view all the answers

<p>When m post-dominates one but not all of n’s CFG successors</p> Signup and view all the answers

<p>v is defined in node n and used in node m without being redefined in between</p> Signup and view all the answers

<p>Parameter passing between method calls and definitions</p> Signup and view all the answers

<p>By augmenting its representation to consider object-oriented programs</p> Signup and view all the answers

<p>As separate trees for each possible dynamic type connected to the corresponding method definition</p> Signup and view all the answers

<p>Infinite representation of object parameters</p> Signup and view all the answers

<p>Augments its representation to consider OO programs.</p> Signup and view all the answers

<p>Separate trees for each possible dynamic type connected to the corresponding method definition.</p> Signup and view all the answers

<p>Infinite representation of object parameters.</p> Signup and view all the answers

<p>When a statement modifies the object the variable points to, but not its data members</p> Signup and view all the answers

<p>The DEF set contains the data member followed by the object variable itself</p> Signup and view all the answers

<p>Data members of an object can only be accessed through a method call</p> Signup and view all the answers

<p>To simplify the computation of flow dependence</p> Signup and view all the answers

<p>It poses new difficulties in the computation of flow dependence</p> Signup and view all the answers

<p>The DEF set is transformed into an ordered sequence with the data members defined first, followed by the caller object itself</p> Signup and view all the answers

<p>An alias assignment occurs when two object variables point to different objects</p> Signup and view all the answers

<p>When an object variable is defined through the return of a method call</p> Signup and view all the answers

<p>Modifies at least one data member but not its reference</p> Signup and view all the answers

<p>It poses new difficulties in flow dependence computation.</p> Signup and view all the answers

<p>Data members can only be accessed through a method call.</p> Signup and view all the answers

<p>Partial definitions occur when no variable is used after its definition, while total definitions include assignments through method returns.</p> Signup and view all the answers

<p>It cannot produce complete slices for Java OO programs</p> Signup and view all the answers

<p>Primitive variables</p> Signup and view all the answers

<p>Multiple data members</p> Signup and view all the answers

<p>When all its data members are defined by a constructor call</p> Signup and view all the answers

<p>Only used and defined data members have a representation in the unfolding tree</p> Signup and view all the answers

<p>Control dependence subtree of the selected object variable</p> Signup and view all the answers

<p>Flow dependences of object variables</p> Signup and view all the answers

<p>The order in which all data members are defined</p> Signup and view all the answers

<p>All data members followed by the object variable</p> Signup and view all the answers

<p>The DEF set includes both old and new memory locations</p> Signup and view all the answers

<p>Define all data members of an object variable</p> Signup and view all the answers

<p>Method call does not depend on any data member of object variable a1 to define data member x</p> Signup and view all the answers

<p>Standard notion of flow dependence for objects</p> Signup and view all the answers

<p>Replacing the current definition of flow dependence with three more accurate definitions</p> Signup and view all the answers

<p>More concrete slicing criteria</p> Signup and view all the answers

<p>DEF and USE sets</p> Signup and view all the answers

<p>Program variables that are defined and used at this CFG node</p> Signup and view all the answers

<p>The DEF and USE sets for every statement</p> Signup and view all the answers

<p>To represent all possible execution paths of a method</p> Signup and view all the answers

<p>5</p> Signup and view all the answers

<p>All program variables defined at that node</p> Signup and view all the answers

<p>All variables used in the program at that node</p> Signup and view all the answers

<p>To extract the part of the program that can affect the values computed at a given program point (slicing criterion).</p> Signup and view all the answers

<p>The assumptions provide an incomplete slice in all cases, specifically when some object variables are selected as the slicing criterion.</p> Signup and view all the answers

<p>The sets DEF, USE, and KILL need to be redefined to distinguish when object variables are totally or partially used or defined in method calls.</p> Signup and view all the answers

<p>The standard definition is insufficient to capture the dependences between partial definitions of objects.</p> Signup and view all the answers

<p>To deal with Java object-oriented programs and represent the System Dependence Graph (SDG).</p> Signup and view all the answers

<p>The <code>DEF</code> set of a node in a CFG contains the set of program variables that are defined at the node.</p> Signup and view all the answers

<p>The purpose is to extract from a program the set of statements that affect the value of a variable at a given program point, which is known as the slicing criterion.</p> Signup and view all the answers

<p>The fundamental problem is incompleteness, where the slices contain less code than needed, leading to the exclusion of some code that can affect the slicing criterion.</p> Signup and view all the answers

<p>The impact is that the slicing criterion includes the definition of the method and tracks down where the values of the data members come from.</p> Signup and view all the answers

<p>The flow dependence is characterized by the fact that a node m is control dependent on a node n in the CFG.</p> Signup and view all the answers

<p>The DEF set denotes the variables being defined at the node, while the USE set denotes the variables being used at the node.</p> Signup and view all the answers

<p>The paper presents the extension of program representations with the addition of object-flow dependence as a solution to the problem.</p> Signup and view all the answers

<p>The selection of an object variable as the slicing criterion is crucial for the definition of flow dependence.</p> Signup and view all the answers

<p>Object variables in Java consist of data members and methods.</p> Signup and view all the answers

<p>The SSLDG extends the model to accept object variables as the slicing criterion.</p> Signup and view all the answers

<p>The purpose is to extend the representation to accept object variables as the slicing criterion.</p> Signup and view all the answers

<p>The purpose is to obtain complete slices when an object variable is selected as the slicing criterion.</p> Signup and view all the answers

<p>Program slicing is used to identify and extract relevant parts of a program for tasks such as debugging, software maintenance, and program specialization.</p> Signup and view all the answers

<p>Control dependence and flow dependence</p> Signup and view all the answers

<p>To connect the PDGs of all the methods of a program and simulate parameter passing between calls and definitions.</p> Signup and view all the answers

<p>It defines a class entry node for each class, connected to the method Enter nodes of all its methods by class membership arcs.</p> Signup and view all the answers

<p>It represents the caller and its defined and used data members as a tree.</p> Signup and view all the answers

<p>To address the issue of potentially infinite tree representation when an object is represented recursively.</p> Signup and view all the answers

<p>The static representation of the program needs to define both possibilities.</p> Signup and view all the answers

<p>The object parameter is represented in the graph as a tree structure, with a subtree for each possible dynamic class.</p> Signup and view all the answers

<p>The JSysDG represents the relationship with a tree representation, linking only data members inside each type tree.</p> Signup and view all the answers

<p>It occurs when a variable v is in DEF(n), v is in USE(m), and there exists a control-flow path from n to m where v is not redefined.</p> Signup and view all the answers

<p>To accurately represent the dependence between objects and their data members in the program.</p> Signup and view all the answers

<p>When an object variable is redefined with only some of its data members, leaving others unchanged.</p> Signup and view all the answers

<p>The potential for infinite tree representation when an object is represented recursively.</p> Signup and view all the answers

<p>primitive variables</p> Signup and view all the answers

<p>An object variable v that points to a memory location m1 is totally defined in a program statement s if the execution of s makes v to point to m2, and m1 is not equal to m2.</p> Signup and view all the answers

<p>The ordered sequence DEF os includes all the data members being defined first, and the object variable is defined at the end.</p> Signup and view all the answers

<p>The main problem is that a statement may modify only some of the data members of an object variable, leading to partial definitions being split into different statements.</p> Signup and view all the answers

<p>The JSysDG can produce incomplete slices, leading to limitations in accurately representing Java OO programs.</p> Signup and view all the answers

<p>The JSysDG assumes that when an object variable is the caller of a method call, only the used and defined data members of the object have a representation in the unfolding tree as argument-in and argument-out nodes respectively.</p> Signup and view all the answers

<p>The standard notion of flow dependence needs to be extended for the case of objects in order to solve the identified problem.</p> Signup and view all the answers

<p>The paper presents the need to extend the standard notion of flow dependence for the case of objects in order to solve the identified problem.</p> Signup and view all the answers

<p>The purpose of the JSysDG is to accurately represent the dependencies and flow of object-oriented programs, allowing for the computation of program slices.</p> Signup and view all the answers

<p>The object variable is considered to be totally defined in that program statement, according to the definition provided in the text.</p> Signup and view all the answers

<p>Program slicing is significant in helping with software maintenance, debugging, and program specialization by allowing developers to focus on specific parts of the code that are relevant to the task at hand.</p> Signup and view all the answers

<p>The slicing criterion is a set of program statements and predicates that might affect the value of a program variable v that is defined or used at a program point p; (p, v) is known as the slicing criterion.</p> Signup and view all the answers

<p>DEF os (#13) = [a1.x, a1. y , a1]</p> Signup and view all the answers

<p>∅</p> Signup and view all the answers

<p>When a statement modifies at least one data member of an object variable, but not the object it points to.</p> Signup and view all the answers

<p>A method call that defines a data member of the caller, and an assignment of an object variable’s data member.</p> Signup and view all the answers

<p>An ordered sequence that contains the data member followed by the object variable itself.</p> Signup and view all the answers

<p>It allows differentiation of the specific moment in which a data member and an object is defined or used, and allows slicing a program with respect to a specific instant in the computation.</p> Signup and view all the answers

<p>It allows differentiation of the specific moment in which a data member and an object is defined or used, and thus allows slicing a program with respect to a specific instant in the computation.</p> Signup and view all the answers

<p>It provides an enhanced graph representation for object variables at the scope of a method call.</p> Signup and view all the answers

<p>The standard definition is insufficient to account for the partial definition of an object variable.</p> Signup and view all the answers

<p>The computation of the usual flow dependence encounters difficulties due to the partial definition of an object variable.</p> Signup and view all the answers

<p>They represent the value of the object variable before and after the call, including the data members used or defined inside the function call.</p> Signup and view all the answers

<p>The differentiation of the specific moment in which a data member and an object is defined or used.</p> Signup and view all the answers

<p>The JSysDG addresses the problem of representing objects recursively and dealing with object variables that can be partially defined or used in a statement.</p> Signup and view all the answers

<p>The incremental evolution from CFG to JSysDG aims to properly represent the program in order to automatically obtain the desired slice.</p> Signup and view all the answers

<p>For an assignment of an object variable’s data member, the DEF set turns into the set of variables that are defined at that statement.</p> Signup and view all the answers

<p>The new method is significant for distinguishing when object variables are being totally or partially used or defined in method calls.</p> Signup and view all the answers

<p>The main limitation of JSysDG is its incompleteness when slicing an object that is the caller of a method call.</p> Signup and view all the answers

<p>The JSysDG aims to solve the problem of representing object variables and their dependencies accurately in method calls.</p> Signup and view all the answers

<p>When an assignment statement makes an object variable point to a different memory location, the dependencies and definitions of the object variable may change.</p> Signup and view all the answers

<p>The purpose of extending the representations with the addition of object-flow dependence is to accurately capture the flow of object variables and their dependencies.</p> Signup and view all the answers

<p>Program slicing is significant for understanding and analyzing the impact and dependencies of specific parts of a program, which is crucial for software maintenance, debugging, and program specialization.</p> Signup and view all the answers

<p>A method call that defines some or all of the data members of the caller can impact the dependencies and definitions of the caller object variable.</p> Signup and view all the answers

<p>The paper presents an approach that solves the problem by replacing the current definition of flow dependence with more accurate definitions for object variables.</p> Signup and view all the answers

<p>The ordered sequence of definitions for an object variable includes the standard definition for primitive variables and a pair of new definitions for object variables called object-flow dependence and object-reference dependence.</p> Signup and view all the answers

<p>To extract the part of the program that can affect the values computed at a given program point.</p> Signup and view all the answers

<p>It leads to a scenario where the slice obtained by JSysDG is not complete when selecting some object variables as the slicing criterion.</p> Signup and view all the answers

<p>The slices obtained from JSysDG do not produce complete slices in all cases, specifically when some object variables are selected as the slicing criterion.</p> Signup and view all the answers

<p>The main limitation is that JSysDG does not produce complete slices in all cases, particularly when certain object variables are chosen as the slicing criterion.</p> Signup and view all the answers

<p>The incompleteness result proves that the graphs used in program slicing do not produce complete slices in all cases, especially when some object variables are selected as the slicing criterion.</p> Signup and view all the answers

<p>ClDG enhances the SDG representation by dealing with class-level dependencies, such as static method calls and static data members.</p> Signup and view all the answers

<p>To extract from a program the set of statements that affect the value of a variable at a given program point.</p> Signup and view all the answers

<p>The representation of dependences between partial definitions of objects is ill-defined, leading to a loss of completeness.</p> Signup and view all the answers

<p>The set of statements in the program that affect the value of the selected object variable at a given program point.</p> Signup and view all the answers

<p>JSysDG is not prepared to select an object variable as the slicing criterion, and it can produce a slice where only some of its required data members are included.</p> Signup and view all the answers

<p>To introduce a program slicing technique for object-oriented programs based on the new program representation.</p> Signup and view all the answers

<p>It allows for a more accurate flow representation between object variables and their data members.</p> Signup and view all the answers

<p>The JSysDG is not prepared to select an object variable as the slicing criterion, leading to incompleteness in the computed slices.</p> Signup and view all the answers

<p>The minimal slice of the code in Fig. 1a has been computed with the JSysDG.</p> Signup and view all the answers

<p>A specific flow dependence for object type variables called object-flow dependence is added to the representations.</p> Signup and view all the answers

<p>It leads to a loss of completeness in many cases.</p> Signup and view all the answers

<p>Completeness is a fundamental property required by most applications of program slicing.</p> Signup and view all the answers

<p>The purpose is to extract the set of statements that affect the value of a variable at a given program point.</p> Signup and view all the answers

<p>The purpose of JSysDG is to represent polymorphic calls and dynamic binding.</p> Signup and view all the answers

<p>Node m is control dependent on node n if m post-dominates one but not all of n’s CFG successors.</p> Signup and view all the answers

<p>ClDG represents class entry nodes for each class, connected to method Enter nodes and data membership arcs.</p> Signup and view all the answers

<p>JSysDG aims to represent polymorphic calls and dynamic binding, addressing the challenges of polymorphic objects and method calls with polymorphic parameters.</p> Signup and view all the answers

<p>Program slicing is significant in identifying and isolating relevant parts of a program, aiding in software maintenance, debugging, and program specialization.</p> Signup and view all the answers

<p>The ordered sequence DEF os for an object variable includes the variables that define its data members.</p> Signup and view all the answers

<p>Flow dependence occurs when a variable v is defined in node n, used in node m, and there exists a control-flow path from n to m where v is not redefined.</p> Signup and view all the answers

<p>When an assignment statement changes the reference of an object variable, it affects the control and flow dependences associated with the object variable.</p> Signup and view all the answers

<p>Partial definitions of object variables occur when only some of the data members of an object variable are defined, leading to incomplete information about the object.</p> Signup and view all the answers

<p>Liang and Harrold's assumptions lead to the DEF set including a tree structure representing each possible dynamic class and its data members.</p> Signup and view all the answers

<p>The main limitation of JSysDG is the potential for infinite tree representation when objects are represented recursively.</p> Signup and view all the answers

<p>The purpose of program slicing is to identify and extract relevant parts of a program based on a slicing criterion, aiding in program analysis and understanding.</p> Signup and view all the answers

<p>When an object variable is the caller of a method call, only the used and defined data members of the object have a representation in the unfolding tree as argument-in and argument-out nodes respectively.</p> Signup and view all the answers

<p>The DEF set for this statement includes the object variable itself and all its data members, and the order in which all these definitions occur is crucial for the definition of flow dependence.</p> Signup and view all the answers

<p>The flow dependences of object variables need to be redefined so that slices are correctly computed when a whole object variable is selected as the slicing criterion.</p> Signup and view all the answers

<p>The flow dependence between nodes n and m in a CFG is based on the set of program statements and predicates that might affect the value of a program variable v that is defined or used at a program point p.</p> Signup and view all the answers

<p>Object variables in Java consist of a collection of data members, where each data member can be a primitive variable or another object variable.</p> Signup and view all the answers

<p>The standard notion of flow dependence for the case of objects needs to be extended.</p> Signup and view all the answers

<p>The DEF set includes the object variable itself and all its data members, while the USE set denotes the program statements and predicates that might affect the value of a program variable v that is defined or used at a program point p.</p> Signup and view all the answers

<p>When a variable cannot be used without being previously defined in Java, it leads to a flow dependence between the definition and use of that variable.</p> Signup and view all the answers

<p>The purpose of SSLDG is to annotate definitions and uses of object variables in program statements, particularly for the case of objects.</p> Signup and view all the answers

<p>Primitive variables are always defined and used atomically in Java.</p> Signup and view all the answers

<p>The new method is significant for extending the standard notion of flow dependence for the case of objects, as it allows for a more accurate description of the DEF and USE sets when object variables are contained inside them.</p> Signup and view all the answers

<p>The purpose of program slicing is to obtain a set of program statements and predicates that might affect the value of a program variable, based on a slicing criterion.</p> Signup and view all the answers

<p>The three more accurate definitions are: the standard definition of flow dependence for primitive variables, object-flow dependence, and object-reference dependence.</p> Signup and view all the answers

<p>The 'defined variables (DEF)' and 'used variables (USE)' sets of each statement are specialized.</p> Signup and view all the answers

<p>The purpose is to properly represent the program and automatically obtain the desired slice.</p> Signup and view all the answers

<p>A node m is control dependent on a node n in a CFG if the execution of n influences the possible execution of m.</p> Signup and view all the answers

<p>The impact is that the JSysDG slice may become incomplete, leading to missing data members and even method calls like the constructor.</p> Signup and view all the answers

<p>The DEF and USE sets for every statement need to be redefined to properly represent definitions and uses of object variables and their data members.</p> Signup and view all the answers

<p>The main problem is that the usual flow dependence was designed for variables that are atomically defined or used in a single statement, and it has not been reconsidered to deal with object variables that can be partially defined or used.</p> Signup and view all the answers

<p>The 'defined variables (DEF)' set contains the program variables that are defined at the statement, while the 'used variables (USE)' set contains the program variables that are used at the statement.</p> Signup and view all the answers

<p>The JSysDG assumes that the data members of an object are atomically defined or used in a single statement.</p> Signup and view all the answers

<p>The purpose of SSLDG is to extend the theoretical model proposed by JSysDG to accept more concrete slicing criteria.</p> Signup and view all the answers

<p>The main limitation is the incompleteness problem when slicing an object that is the caller of a method call, resulting in incomplete slices.</p> Signup and view all the answers

<p>A partial definition involves defining or using only one of its data members in a statement.</p> Signup and view all the answers

<p>Polymorphic calls and dynamic binding are represented as nodes in the JSysDG.</p> Signup and view all the answers

<p>The extension JSysDG deals with representing objects recursively.</p> Signup and view all the answers

<p>The JSysDG addresses the issue of incompleteness when representing objects recursively.</p> Signup and view all the answers

<p>The paper presents the incompleteness result of representing objects recursively.</p> Signup and view all the answers

<p>In Java, a variable cannot be used without being previously defined.</p> Signup and view all the answers

<p>The DEF set denotes the definitions while the USE set denotes the uses at each CFG node.</p> Signup and view all the answers

<p>The ClDG represents the dependencies between classes in an Object-Oriented program.</p> Signup and view all the answers

<p>The representations need to be extended to solve the problem identified in the previous section.</p> Signup and view all the answers

<p>The ordered sequence of definitions for an object variable in the mentioned statement is DEF os (#13) = [a1.x, a1. y , a1].</p> Signup and view all the answers

<p>The impact is that the DEF set is transformed into an ordered sequence, including all the data members defined inside the method followed by the object variable itself.</p> Signup and view all the answers

<p>In the scenario where no variable is used, the USE set equals to ∅ (empty set).</p> Signup and view all the answers

<p>Program slicing is significant in various disciplines such as software maintenance, debugging, and program specialization as it allows for the extraction of relevant portions of a program.</p> Signup and view all the answers