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CONTROL FLOW GRAPH.

  • INTRODUCTION

    • Graphs.

      • A Graph is a collection of vertices and connections between them.
      • The vertices are nodes and the connections are known as edges.
      • Each edge connects a pair of vertices. If the edges are directional, the graph is known as a directed graph.
      • Each edge can be assigned a number that represents values such as cost, distance, length or weight. Such a graph is then called a weighted directed graph.

    • Control Flow Graphs.

      • Developed by Frances E. Allen in the 1970s, Control Flow Graphs (CFG)are a static analysis of software code used in software testing.
      • Blocks of code in the source code represent nodes in the graph. Sequential flows between blocks of code represent edges between nodes. CFG have designated entry points and exit points.
      • A CFG is known as a Single Entry Single Exit (SESE) graph if it only has a single entry node and a single exit node. A problem that arose during researchon static analysis is how to deal with loops in the CFG.
      • In an attempt to solve these issues, Simple and Prime paths were introduced.

    • Simple Paths

      • From theory, it should be clear that loops are problematic. It is not always possible to know at compile time or even before then how many times the loop would be executed.
      • This problem is similar to that of the Halting Problem (which is algorithmically unsolvable).
      • In an attempt to approach this problem, CFGs make use of something called a
      • Simple Path. A Simple Path is a path of any length that satisfies the following properties
        • Only the first and last node in the path may be repeated.
        • All edges used in the path needs to exist in the graph.

    • Prime Paths

      • To reduce the possible paths created by Simple Paths, Prime Paths were introduced.
      • A Prime Path is a Simple Path that is not a sub-path of another Simple Path. In other words, a Prime Path is the longest Simple Path that does not form part of another Simple Path.

REQUIREMENTS BEFORE RUNNING CODES:

  • Install an IDE that compiles and runs Java codes. Recommendation VS Code
  • link: How to setup WSL Ubuntu terminal shell and run it from Visual Studio Code
  • link: How to Install Java JDK 17 on Windows 11

  • Installing Oracle JDK on Windows subsystem for Linux.

    • Run WSL as Administrator
    • set -ex
    • NB: Update links for other JDK Versions
    • export JDK_URL=http://download.oracle.com/otn-pub/java/jdk/8u131-b11/d54c1d3a095b4ff2b6607d096fa80163/jdk-8u131-linux-x64.tar.gz
    • export UNLIMITED_STRENGTH_URL=http://download.oracle.com/otn-pub/java/jce/8/jce_policy-8.zip
    • wget --no-cookies --header "Cookie: oraclelicense=accept-securebackup-cookie" ${JDK_URL}
    • Extract the archive: tar -xzvf jdk-*.tar.gz
    • Clean up the tar: rm -fr jdk-*.tar.gz
    • Make the jvm dir: sudo mkdir -p /usr/lib/jvm
    • Move the server jre: sudo mv jdk1.8* /usr/lib/jvm/oracle_jdk8
    • Install unlimited strength policy: wget --no-cookies --header "Cookie: oraclelicense=accept-securebackup-cookie" ${UNLIMITED_STRENGTH_URL}
    • unzip jce_policy-8.zip
    • mv UnlimitedJCEPolicyJDK8/local_policy.jar /usr/lib/jvm/oracle_jdk8/jre/lib/security/
    • mv UnlimitedJCEPolicyJDK8/US_export_policy.jar /usr/lib/jvm/oracle_jdk8/jre/lib/security/
    • sudo update-alternatives --install /usr/bin/java java /usr/lib/jvm/oracle_jdk8/jre/bin/java 2000
    • sudo update-alternatives --install /usr/bin/javac javac /usr/lib/jvm/oracle_jdk8/bin/javac 2000
    • sudo echo "export J2SDKDIR=/usr/lib/jvm/oracle_jdk8 export J2REDIR=/usr/lib/jvm/oracle_jdk8/jre export PATH=$PATH:/usr/lib/jvm/oracle_jdk8/bin:/usr/lib/jvm/oracle_jdk8/db/bin:/usr/lib/jvm/oracle_jdk8/jre/bin export JAVA_HOME=/usr/lib/jvm/oracle_jdk8 export DERBY_HOME=/usr/lib/jvm/oracle_jdk8/db" | sudo tee -a /etc/profile.d/oraclejdk.sh

MAKEFILE

NB: A makefile Is Included to compile and run the codes on the terminal with the following commands:=
  • make clean
  • make
  • make run
default:
	javac *.java

run:
	java App

clean:
	rm -f *.class
	reset
	clear

tar:
	tar -cvz CFG.java Node.java Edge.java Path.java -f CFG_In_Java.tar.gz

unzip:
	tar -zxvf *.tar