Re: [PATCH] Add condition coverage profiling

["Jørgen Kvalsvik" <jorgen.kvalsvik@woven-planet.global>]

On 22/04/2022 07:37, Sebastian Huber wrote:
> 
> 
> On 17/04/2022 13:27, Jørgen Kvalsvik wrote:
>>> In theory, would it be possible to print the state of the truth table with the
>>> information available in the gcda and gcno files? For example:
>>>
>>> Truth table for: a && (b || c)) && d
>>>
>>> 0 | 1 | 2 | 3 || covered
>>> --+---+---+---++--------
>>> 0 | X | X | X || Y
>>> 0 | X | X | X || Y
>>> 0 | X | X | X || Y
>>> 0 | X | X | X || Y
>>> 0 | X | X | X || Y
>>> 0 | X | X | X || Y
>>> 0 | X | X | X || Y
>>> 0 | X | X | X || Y
>>> 1 | 0 | 0 | X || N
>>> 1 | 0 | 0 | X || N
>>> 1 | 0 | 1 | 0 || N
>>> 1 | 0 | 1 | 1 || N
>>> 1 | 1 | X | 0 || Y
>>> 1 | 1 | X | 0 || Y
>>> 1 | 1 | X | 1 || Y
>>> 1 | 1 | X | 1 || Y
>> Maybe? We would at least need to store the masking tables too, which right now
>> are implicitly stored as in the instrumentation. It's not too bad, but it
>> probably means the two functions should return some richer structure, which in
>> turn means a little bit of redesign. Computing the truth table itself shouldn't
>> be difficult.
> 
> Using the tool in the context of safety-critical application would normally
> require also a tool qualification. For GCC, this is a bit unrealistic. It would
> help if the tool output can be verified. Being able to inspect the masking
> tables could help a reviewer to check what the tool did for a sample set of inputs.
> 

It would be useful for the developer too. Recording the masking vectors isn't
hard (they have to be computed after all), maybe it as opt-in behind a flag?