klee option: -only-output-states-covering-new changes coverage?

[Double Dave]

Hello all,

I'm currently analyzing on a piece of source code with klee-fp and then check the coverage using gcov.

If i run klee with the following options:
klee -optimize $filename


I will get:
KLEE: done: total instructions = 79373864
KLEE: done: completed paths = 56583
KLEE: done: generated tests = 28334

and a coverage of: Lines executed:74.21% of 919


Running it with:
klee -optimize -only-output-states-covering-new $filename


and I will get:

KLEE: done: total instructions = 79373864
KLEE: done: completed paths = 56583
KLEE: done: generated tests = 7

and a only a coverage of: Lines executed:58.87% of 919

Is this the normal behavior of klee?
I thought the coverage should be the same since there shouldn't be any repetitive states.
It would be nice to use -only-output-states-covering-new since it will drastically reduce the time klee runs: 10h without and 10min with this option.


Regards,
David