[klee-dev] using klee with Siemens Benchmarks

Thu Mar 7 12:44:21 GMT 2013

On Mar 7, 2013 5:53 AM, "Paul Marinescu"
<paul.marinescu at imperial.ac.uk<javascript:_e({}, 'cvml',
'paul.marinescu at imperial.ac.uk');>>
wrote:
>
> 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.
>

Urmas,

To expand a bit on Paul's first question to try to improve my own
understanding...

As I understand things, the point of the MC/DC coverage criterion as
typically applied to the certification of life-critical airborne systems is
that, given a good spec, one can check the adequacy of a set of test cases
for a given implementation by checking that the test cases achieve 100%
coverage of both the requirements and the implementation logic and state
vector.

In this world, MC/DC is helpful because it finds many bugs with a number of
test cases that grows linearly, rather than exponentially, in the number
of, e.g., conditional branches and bits of program state.

The work that you are examining seems, from casual inspection, to be about
assessing the claim that MC/DC (and related adequacy criteria) really are
adequate. (Urmas: did I get this right?)

As a result, as Paul somewhat tersely replied: what's the executable spec
-- i.e., the "true set of requirements" from which MC/DC or other test
cases might be generated?

Regards,

Michael

P.S. - also, have you played with using Klee to check equivalence or
bisimulation of two programs?

(Here's an old post that I wrote up to quickly illustrate one approach:

http://mstone.info/posts/klee_quickcheck/

)

> Paul
>
>
> On 7 Mar 2013, at 05:06, Urmas Repinski <urrimus at hotmail.com<javascript:_e({}, 'cvml', '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 <javascript:_e({}, 'cvml',
'paul.marinescu at imperial.ac.uk');>
>> Date: Wed, 6 Mar 2013 21:19:54 +0000
>> CC: klee-dev at imperial.ac.uk <javascript:_e({}, 'cvml',
'klee-dev at imperial.ac.uk');>
>> To: urrimus at hotmail.com <javascript:_e({}, 'cvml',
'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<javascript:_e({}, 'cvml', '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>_______________________________________________
>>> klee-dev mailing list
>>> klee-dev at imperial.ac.uk <javascript:_e({}, 'cvml',
'klee-dev at imperial.ac.uk');>
>>> https://mailman.ic.ac.uk/mailman/listinfo/klee-dev
>>
>>
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