This repository contains the implementation of ARDiff: an equivalence checking framework that allows scaling symbolic-execution-based equivalence checking for cases that consider two subsequent versions of a program.

It includes:

• The implementation of ARDiff abstraction-refinement approach ("ARDiff: Scaling Program Equivalence Checking via Iterative Abstraction and Refinement of Common Code", ESEC/FSE, 2020)
• An implementation of DSE -- a baseline equivalence checking technique ("Differential Symbolic Execution", FSE, 2008)
• An implementation of IMP-S -- a baseline equivalence checking technique ("Regression Verification using Impact Summaries", SPIN, 2013)

Installing

Java Development Kit (JDK) version 8 is required.

Clone the repository:

git clone https://github.com/resess/ARDiff.git

ARDiff has dependencies on JPF-core, JPF-Symbc Z3-solver. We included all dependencies in the tool.

JPF

Pre-built versions of JPF-Symbc. and JPF-core are included in the project under the folder jpf-git.

You need to create in your home directory a .jpf directory.

On Linux/OSX:

mkdir ~/.jpf

On Windows:

mkdir %UserProfile%/.jpf

Next, inside the .jpf directory, you need to include a file name "site.properties" with the following content:

jpf-core = /.../path-to-ARDiff_Equiv_Checking-folder/Implementation/jpf-git/jpf-core
jpf-symbc = /.../path-to-ARDiff_Equiv_Checking-folder/Implementation/jpf-git/jpf-symbc
extensions = ${jpf-core},${jpf-symbc}

Z3

For checking the equivalence of symbolic summaries, the Z3 constraint solver is used.

The Z3 library files needed by JPF-symbc for Unix and Windows are provided in our Implementation directory (under jpf-git/jpf-symbc/lib) and must be included in the PATH (Windows) or LD_LIBRARY_PATH (Linux) or DYLD_LIBRARY_PATH (OSX) environnment variable. For example:

export LD_LIBRARY_PATH="/.../path-to-ARDiff_Equiv_Checking-folder/Implementation/jpf-git/jpf-symbc/lib"

You can refer to Z3 for more information or to build Z3 yourself.

Setup

The .jar file to run the framework is provided in:

/.../path-to-ARDiff_Equiv_Checking-folder/Implementation/target/artifacts/Implementation_jar/Implementation.jar

The project can also be opened as a Maven project in an IDE in order to change/update the source code. The main class is Runner.Runner

Usage

You should run the tool from the ARDiff_Equiv_Checking/Implementation folder:

cd /.../path-to-ARDiff_Equiv_Checking-folder/Implementation/

java -jar target/artifacts/Implementation_jar/Implementation.jar --path1 path/to/the/first/method --path2 path/to/the/second/method --tool ToolName --t timeout --bound LoopBoundLimit --minint Integer --maxint Integer --mindouble Double --maxdouble Double

For OSX/Linux users, if you are running into some issues indicating "no libz3java in java.library.path", try adding Z3 directory ("jpf-git/jpf-symbc/lib") to "java.library.path":

java -Djava.library.path=jpf-git/jpf-symbc/lib -jar target/artifacts/Implementation_jar/Implementation.jar --path1 path/to/the/first/method --path2 path/to/the/second/method --tool ToolName --t timeout --bound LoopBoundLimit --minint Integer --maxint Integer --mindouble Double --maxdouble Double

There are 9 arguments for configuring the framework: --path1 and --path2 are mandatory and the other eight are optional.

You need to give the paths to two (compilable) Java classes (with different names), each containing one of the target methods.

• Note that the signature (i.e the name and the input parameters) and the return type must be the same for the two methods.

• If the classes contain more than one method, the first method is considered as the target method for equivalence checking.

• The final result and time are shown in the terminal. Extra information from running the tools will be stored in the directory of --path1. In particular, the final result is stored under path1/outputs

You can also choose the tool, the bound limit to unroll loops in JPF-symbc and min and max values for integers and doubles.

You can choose the timeout in milliseconds. This timeout is for constraint solving in both JPF-symbc and Z3, it is not an overall timeout for the tool.

If you want to stop the tool after t seconds, for example 5, you can use any timeout mechanism. On Linux or OSX for instance, the Linux timeout command:

timeout 5 java -jar target/artifacts/Implementation_jar/Implementation.jar --path1 path/to/the/first/method --path2 path/to/the/second/method --tool ToolName  --t timeout --bound LoopBoundLimit --minint Integer --maxint Integer --mindouble Double --maxdouble Double

You might need to install first "coreutils".

For OSX users :

brew install coreutils

For Linux users :

apt-get install coreutils

On Windows, you can use the START-TIMEOUT builtins combination or other timeout tools, for example this one.

To obtain the overall time taken by the tool, in addition to the detailed times (in milisecond) we provide, you can also use timing mechanisms such as the Linux time command which gives you the CPU runtime of the process:

time java -jar target/artifacts/Implementation_jar/Implementation.jar --path1 path/to/the/first/method --path2 path/to/the/second/method --tool ToolName  --t timeout --bound LoopBoundLimit --minint Integer --maxint Integer --mindouble Double --maxdouble Double

Example

Executing the following command (on OSX) runs ARDiff on the example "Airy/MAX/Eq".

time timeout 300 java -jar target/artifacts/Implementation_jar/Implementation.jar --path1 ../benchmarks/Airy/MAX/Eq/oldV.java --path2 ../benchmarks/Airy/MAX/Eq/newV.java --tool A 

Benchmark

You can find our dataset here:

/.../path-to-ARDiff_Equiv_Checking-folder/benchmarks/

Running ARDiff on Our Benchmark

You can run each pair of methods in the benchmark individually (as described above) or run all of them in sequence by running the script we provided.

There are three scripts for running the tool on the benchmark, one for each operating system.

Note, in terms of system requirements, running benchmarks need at least 16 GB memory and the expected runtime is 10-14 hrs.

• 16GB is a safe bound to ensure symbolic execution and the SMT solver can handle complex examples. This requirement can be easily modified by changing the -Xms parameter in the scripts, however we can not guarantee that you will obtain the same results (as some cases might become UNKNOWN)

For example, the following script is for Linux users:

cd /.../path-to-ARDiff_Equiv_Checking-folder/Implementation/
sh RunningBenchmarksOnLinux.sh

OSX users should use RunningBenchmarksOnMac.sh.

The script runs DSE, IMP-S, and ARDiff on each Equivalent and Non-Equivalent pairs of methods for each benchmark.