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Cyclomatic Complexity Program control flow graphs are not strongly connected, but they become strongly connected when a "virtual edge" is added connecting the exit node to the entry node. It is possible to calculate the amount of (virtual) control flow through the virtual edge by using the conservation of flow equations at the entry and exit nodes, showing it to be the number of times that the module has been executed. Figure 2-5 shows the control flow graph for module "euclid" with the fifteen edges numbered 0 to 14 along with the fourteen nodes numbered 0 to 13. hissa.nist.gov /HHRFdata/Artifacts/ITLdoc/235/chapter2.htm   (2739 words)

NationMaster - Encyclopedia: Control flow graph The control flow graph is shown in Figure 2-2, in which each node is numbered 0 through 13 and edges are shown by lines connecting the nodes. It is possible to calculate the amount of (virtual) control flow through the virtual edge by using the conservation of flow equations at the entry and exit nodes, showing it to be the number of times that the module has been executed. A control flow graph G is said to be reducible if the removal of its back edges leads to an acyclic graph where each node can be reached from the initial node of G. Figure 4 sketches a simple algorithm for determining whether a control flow graph is non-reducible. www.nationmaster.com /encyclopedia/Control-flow-graph   (1446 words)

NationMaster - Encyclopedia: Flowchart The flowchart is one of the seven basic tools of quality control, which include the histogram, Pareto chart, check sheet, control chart, cause-and-effect diagram, flowchart, and scatter diagram. The control chart, also known as the Shewhart chart or process-behaviour chart is a statistical tool intended to assess the nature of variation in a process and to facilitate forecasting and management. A scatterplot or scatter graph is a graph used in statistics to visually display and compare two or more sets of related quantitative, or numerical, data by displaying only finitely many points, each having a coordinate on a horizontal and a vertical axis. www.nationmaster.com /encyclopedia/Flowchart   (2025 words)

Control flow graph Directed edge (graph theory)edges are used to represent jumps in the control flow. A CFG is a static representation of the program, and represents all alternatives of control flow. A cycle in a CFG may imply that there is a loop in the code (specifically, a cycle caused by a back edge to a ''dominator''). www.territoriopc.com /eng/control_flow_graph.php   (717 words)

Simplified Complexity Calculation In addition to counting predicates from the flow graph, it is possible to count them directly from the source code. It is possible, under special circumstances, to generate control flow graphs that do not model the execution semantics of boolean operators in a language. When the flow graph is planar (no edges cross) and divides the plane into R regions (including the infinite region "outside" the graph), the simplified formula for cyclomatic complexity is just R. This follows from Euler's formula, which states that for planar graphs n - e + R = 2. hissa.ncsl.nist.gov /HHRFdata/Artifacts/ITLdoc/235/chapter4.htm   (1375 words)

CIS841 Project - Tutorial The control flow graph is shown in Figure 1-2, in which each node is numbered 0 through 13 and edges are shown by lines connecting the nodes. The decision of the "while" loop is represented by node 7, and the upward flow of control to the next iteration is shown by the dashed line from node 10 to node 7. Although implicit control flow has significant implications for testing, there are strong reasons to ignore it at the level of module testing. www.cis.ksu.edu /~hankley/d841/Fa99/cycotut.html   (1119 words)

Our Approach The purpose of this method is to generate a control flow graph for the given input program. The CFG for a procedure p has size and can be constructed in time, linear in the number of simple and conditional statements in p. Purpose -> is to handle the flow graph of control statements, whose status is 1. www.iit.edu /~bhupvam/Projects/Quality/QualityCFG~1.htm   (366 words)

Data-flow analysis: identifying loops A control flow graph G is said to be reducible if the removal of its back edges leads to an acyclic graph where each node can be reached from the initial node of G. Figure 3 shows a control flow graph which is not reducible. Figure 4 sketches a simple algorithm for determining whether a control flow graph is non-reducible. www.csd.uwo.ca /~moreno/CS447/Lectures/CodeOptimization.html/node6.html   (550 words)

Project-Team-tropics:Static Analyses and Transformation of programs Representation of a procedure body as a directed graph, whose nodes, known as basic blocks, contain each a list of instructions to be executed in sequence, and whose arcs represent all possible control jumps that can occur at run-time. Directed graph that relates accesses to program variables, from the write access that defines a new value to the read accesses that use this value, and conversely from the read accesses to the write access that overwrites this value. Flow control instructions are represented uniformly inside the control flow graph. www.inria.fr /rapportsactivite/RA2005/tropics/uid21.html   (1115 words)

Semantic Designs: Control and Data Flow Analysis Commonly, a control flow graph ("flowchart") is produced, and flow analyses augment that graph with additional arcs or annotations on the nodes of the control flow graph ("facts"). As examples, DMS-derived C control flow graphs contain fork-join nodes used to model the C standard's notion of "sequence points", where subexpression with unspecified order must be complete before further computation occurs (e.g., the arguments to a function are evaluated in an arbitrary order, but the function call cannot occur until all are evaluated). Control flow graphs for a specific language (e.g, C or a dialect) is often implemented in DMS by using an attribute grammar evaluator that propagates control points around the abstract syntax tree and assembles those control points into a completed graph. www.semdesigns.com /Products/DMS/FlowAnalysis.html   (705 words)

The Machine-SUIF Control Flow Graph Library New CFG nodes are created with respect to a particular CFG and are immediately included in the graph's roster of nodes, even though they may have no connection to other nodes. To reflect such exceptional control paths, we provide a special kind of successor relation, used to describe flow of control from a call site directly to the exit node, or from the entry node to the point immediately after a call. When the CFG is constructed, impossible edges are included to be sure that every node is reachable from the entry, and every node has a path to the exit. www.eecs.harvard.edu /hube/software/nci/cfg.html   (5105 words)

Avrora - Control Flow Graph Tool A control flow graph is a representation of a program where contiguous regions of code without branches, known as basic blocks, are represented as nodes in a graph and edges between nodes indicate the possible flow of the program. By default, the control flow graph utility attempts to use the call instructions to determine the entrypoints into procedures and then tries to group basic blocks into procedures and then color them. There is, however, a way to specify the targets of these indirect control flow instructions so that those edges appear in the control flow graph that is generated. compilers.cs.ucla.edu /avrora/cfg.html   (627 words)

Control flow graph A control flow graph (CFG) is an abstract data structure used in compilers. The CFG is essential to several compiler optimizationss based on global dataflow analysis (def-use chaining, use-def chaining). If a block/subgraph is not connected from the subgraph containing the entry block, that block is unreachable during any execution, and so is dead code; it can be safely removed. www.xasa.com /wiki/en/wikipedia/c/co/control_flow_graph.html   (627 words)

224 Data flow exercise solution : ICS 224  Software Analysis and Testing : Thomas Alspaugh : UCI The flow graph is the control flow graph of the program with only the definitions included (Figure 1). A mapping from the control flow graph nodes to the transfer function for that kind of node. A mapping from the control flow graph to the appropriate way to combine inputs for that kind of node. www.ics.uci.edu /~alspaugh/2005-06/ics224/ics224-dataFlow.soln.htm   (946 words)

SA-C Compiler Overview In particular, the nodes of a data flow graph are simple operations, such as addition, bit shift, or a memory read/write. The data flow graph is therefore a convenient half-way point between source code and a circuit description. VHDL is generated by instantiating a component for every node in the data flow graph, and connecting the signals according to the edges. www.cs.colostate.edu /cameron/compiler.html   (669 words)

Culvert Design. Inlet and Outlet Control   (Site not responding. Last check: 2007-10-29) Inlet control means that flow through the culvert is limited by culvert entrance characteristics. Outlet control means that flow through the culvert is limited by friction between the flowing water and the culvert barrel. The term "outlet control" is a bit of a misnomer because friction along the entire length of the culvert is as important as the actual outlet condition (the tailwater depth). www.lmnoeng.com /Pipes/hds.htm   (1835 words)

Method and system of control flow graph construction invention Each node in a control flow graph represents a basic block which is a straight-line piece of code with no jumps or jump targets. A leader instruction may change the flow of control, for example, by starting a catch block; there are, however, instructions that change the control flow and are not leader instructions. In such an approach, CFG construction may be realized in at least two passes, one to identify leader instructions that start a block in the CFG, and then one or more to create the CFG. www.freshpatents.com /Method-and-system-of-control-flow-graph-construction-dt20060202ptan20060026571.php   (1405 words)

ControlFlowGraph (joeq 1.0 API) The control flow graph is a fundamental part of the quad intermediate representation. A control flow graph includes references to the entry and exit nodes, and the set of exception handlers for the method. The reversed graph is the graph where all edges are reversed. joeq.sourceforge.net /apidocs/joeq/Compiler/Quad/ControlFlowGraph.html   (899 words)

Control Flow Graph A control flow graph is a data structure built on top of the intermediate code representation (RTL instruction chain or trees) abstracting the control flow behavior of compiled function. It is an oriented graph where nodes are basic blocks and edges represent possible control flows from one basic block to another. The probability that control flow arrives via given edge to the destination basic block is called reverse probability and is not directly represented, but it may be easily computed from frequencies of basic blocks. www.ucw.cz /~hubicka/papers/proj/node18.html   (2664 words)

Static Disassembly of Obfuscated Binaries Creating an initial CFG that includes nodes that are not part of the real control flow graph can been seen as the opposite to the operation of a recursive disassembler. All edges in the control flow graph that point to the original basic block are changed to point to the first block, while all outgoing edges of the original block are assigned to the second. Table 2 shows the fraction (in percent) of correctly identified, valid instructions that were obtained using the control flow graph and the fraction obtained in the gap completion phase. www.usenix.org /events/sec04/tech/full_papers/kruegel/kruegel_html/disassemble.html   (9577 words)

Project-tropics:Static Analyses and Transformation of programs Representation of a procedure body as a directed graph, whose nodes, known as basic blocks, contain each a list of instructions to be executed in sequence, and whose arcs represent all possible control jumps that can occur at run-time. Directed graph that relates accesses to program variables, from the write access that defines a new value to the read accesses that use this value, and conversely from the read accesses to the write access that overwrites this value. Flow control instructions are represented uniformly inside the control flow graph. ralyx.inria.fr /2006/Raweb/tropics/uid21.html   (1125 words)

Control Flow Decompilation via Program Graph Decomposition All control in a hammock must be passed to the entry note called head and all control from the quants should pass via the exit note called focus. Control quant is non-decomposable subgraph of the graph of the program with just one entry and one exit node. Graphs are structured into semantically equivalent graphs, without the need of code replication or introduction of new variables. www.softpanorama.org /Algorithms/Decompilation/decompilation_of_control_structures.shtml   (3978 words)

White Box Testing - White Box Testing Techniques Flow graphs can be used to represent control flow in a program and can help in the derivation of the basis set. A graph matrix is a square matrix whose size is equivalent to the number of nodes in the flow graph. Graph theory algorithms can be applied to these graph matrices to help in the analysis necessary to produce the basis set. www.onestoptesting.com /types/Whitebox.asp   (879 words)

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