[klee-dev] using klee with Siemens Benchmarks

Thu Mar 7 12:34:23 GMT 2013

Yes, Thank You.

1. How do you define 'design structure'?

      This depends on tool what i am using for test generation. KLEE uses symbolic states and branches, i have also design's model - parsed design representation using hammock graph structure, any tool what generates inputs will have own design representation, and generated tests will depend on the design's representation's structure, more detailed model will generate more complete inputs.

2. You might be criticising
 an apple for not being a good orange. KLEE is designed to tests the 
program it's being executed on, and if one also wants to test 41 
variants, he/she will run KLEE again on the variants. I'm not sure what 
you would expect, even in a simple scenario like ....

    Regression testing requires 2 versions of the design - correct one and faulty one, and generates inputs, based on detecting behavioral differences between two versions of the design, if i am not mistaken.

    I am, from the other hand, want to use only one version of the design, and to generate as complete inputs as possible.

    KLEE is pretty fast and reliable in terms of coverage, but i need to make inputs detect various states on the program, various errors.

    According to http://pleuma.cc.gatech.edu/aristotle/Tools/subjects/ in Siemens Benchmarks Regression testing were used, all faulty versions of the design were processed and complete set of inputs, that detect already known errors were generated.

    This works well if i have set of faulty versions, but what if not, if i have only one version of the design and want to generate complete inputs for it?

Any help will be appreciated,
Urmas Repinski

Subject: Re: [klee-dev] using klee with Siemens Benchmarks
From: paul.marinescu at imperial.ac.uk
Date: Thu, 7 Mar 2013 10:52:56 +0000
CC: klee-dev at imperial.ac.uk
To: urrimus at hotmail.com

1. How do you define 'design structure'?2. You might be criticising an apple for not being a good orange. KLEE is designed to tests the program it's being executed on, and if one also wants to test 41 variants, he/she will run KLEE again on the variants. I'm not sure what you would expect, even in a simple scenario like
if (input = 100) { //something}
You would need to generate 2^sizeof(input) inputs to take into account all possible mutations to the literal 100 using regression testing.
Paul

On 7 Mar 2013, at 05:06, Urmas Repinski <urrimus at hotmail.com> wrote:Hello.

Yes.

So KLEE takes into account only the coverage, if all paths are covered, but does not take into account entire design structure.

The errors provided by siemens benchmarks are in the operators (+ -> -, > -> <, etc) and in numbers (2 -> 3, 70 -> 80), and with klee inputs even if corresponding nodes in the design's model representation are activated, error is not propagated to the output.

Its a pity, if it is possible to test the entire structure with klee inputs (activate different bits in variables with inputs, confirm that operators values take influence on the output) then klee generated inputs will be more useful for practical imlementation.

It is possible to investigate error types, found in siemens benchmarks, and improve test generation with klee.

I am writing one article about the errors in the designs at the moment, it will be published in the september, and then i will send it to the list too.

Maybe this will make possible to improve input generation and make klee more usable in actual industry.

Urmas Repinski

Subject: Re: [klee-dev] using klee with Siemens Benchmarks
From: paul.marinescu at imperial.ac.uk
Date: Wed, 6 Mar 2013 21:19:54 +0000
CC: klee-dev at imperial.ac.uk
To: urrimus at hotmail.com

Hello Urmas,It's not that clear what you're trying to do but I assume you want to use the inputs generated by KLEE on one program version to test 41 variants. I'm afraid this might not be that easy.
KLEE actually gets nearly 100% statement and branch coverage on the original program ('nearly' because there's some unreachable code). You should run it without the POSIX runtime and uclibc because you're not using them anyway. What you get is:
--------------------------------------------------------------------------| Path       | Instrs | Time(s) | ICov(%) | BCov(%) | ICount | Solver(%) |--------------------------------------------------------------------------| klee-out-0 |   5951 |    0.26 |   99.36 |   94.44 |    311 |     91.92 |--------------------------------------------------------------------------
>From what I can tell, the path coverage is also 100%, counting just feasible paths, so there are no other inputs to generate as far as KLEE is concerned.
Paul
On 6 Mar 2013, at 12:31, Urmas Repinski <urrimus at hotmail.com> wrote:Hello.

My name is Urmas Repinski, PhD student in Tallinn University of Technology, Estonia.

I am trying to generate inputs for Siemens Benchmarks with KLEE.

Siemens Benchmarks - C designs with various erroneous versions for testing error localization and error correction in C designs.
They can be located and downloaded from http://pleuma.cc.gatech.edu/aristotle/Tools/subjects/

I am testing KLEE with tcas design, it is smallest and simplest.

Siemens benchmarks provide their inputs, tcas/script/runall.sh script has 1607 lines of execution of the design, and it is easy extract 1607 various inputs for the design.
But i have no idea how the inputs were generated, attaching siemens benchmarks inputs to the letter (file INPUTS_tcas_Siemens_arg).

I want to compare Siemens inputs with inputs, generated by klee.

I had installed klee as it is written in documentation - http://klee.llvm.org/GetStarted.html - with uclibc support.

Installed llvm-gcc-4.2, llvm-gcc-4.5, originally provided by Linux Mint 12 uses too new version of gcc, and this generated error then used llvm-gcc, but ok, this error solved.

When i take tcas/v1/tcas.c design, adding corresponding modification to generate inputs with klee (tcas_original.c and tcas_modified.c are attached to the letter), i get 45 inputs generated, and after modifying klee output to suitable format i get klee outputs (file KLEE_OUTPUT_arg).

urmas-PBL21 src # llvm-gcc --emit-llvm -c -g tcas.c
urmas-PBL21 src # klee --libc=uclibc  --posix-runtime   tcas.o 
KLEE: NOTE: Using model: /home/urmas/forensic/thirdparty-install/klee/Release+Asserts/lib/libkleeRuntimePOSIX.bca
KLEE: output directory = "klee-out-143"
KLEE: WARNING: undefined reference to function: fwrite
KLEE: WARNING ONCE: calling external: syscall(16, 0, 21505, 54549392)
KLEE: WARNING ONCE: calling __user_main with extra arguments.

KLEE: done: total instructions = 14790
KLEE: done: completed paths = 45
KLEE: done: generated tests = 45

This outputs have same coverage than Siemens Inputs, but most of errors in erroneous designs are simply not detected, while Simenes inputs detect all errors.

Inputs KLEE: Coverage - 92.5532%.  Total Inputs - 45 Detected Errors - 8/41
Inputs Siemens Benchmarks: Coverage - 93.0851%. Total Inputs - 1607, Detected Erroneous designs - 41/41

Maybe i have something wrong with KLEE arguments when i execute klee, can somebody help me with right klee execution?
I had tested klee with various options, but i still have 45 generated inputs. Is it possible to increase somehow number of generated inputs with klee?
Maybe WARNING KLEE: WARNING: undefined reference to function: fwrite aborts executions somewhere, but there is no fwrite function in tcas design.

Urmas Repinski
<INPUTS_tcas_Siemens_arg><tcas_original.c><tcas_modified.c><KLEE_OUTPUT_arg>_______________________________________________
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