[klee-dev] Replacing external printf with an internal version for the Klee tests.

[Daniel Liew]

On 7 October 2014 23:47, Willem Pinckaers
<willem_list_klee at lekkertech.net> wrote:
> Hi List,
>
> Currently most tests for Klee depend on an externally provided printf function. Support for external functions has some side effects, among them:
>
> - Memory usage is doubled for all non symbolic allocations.
> - The bitcode being tested has to have the same data layout as the compiled version of Klee.

For the test suite I really don't think the memory usage matters. They
are mostly small programs and testing external function calls is
important because it is an important feature of KLEE because real
world code inevitably needs to call into a C library or make system
calls at some point.

> Without support for external functions Klee memory usage for non symbolic allocations can be reduced by about 50% and Klee could be made to analyze bit code that uses a different data layout.

Outside of the test suite I could see these being potentially useful
but if you really need this wouldn't it be simpler if your program had
no external function calls? If your program has external calls and you
disable external call support in KLEE your program probably isn't
going to run.


>   This currently hits a bug in llvm 3.4 and 3.5 where lli with force-interpreter=true does not properly execute va_start. But (after adopting the tests to link in the new printf) most test cases pass using force-interpreter=false.

Could you report that to the LLVM developers?

Thanks,
Dan.