[LLVMdev] Meaning of llvm-cov 'taken at least once'

[Justin Bogner]

George King <gwk.lists at gmail.com> writes:
> Today I played around with the llvm-cov from the 3.5rc3 release; here
> is an example of output:
>
> Function 'main'
> Lines executed:91.67% of 24
> Branches executed:100.00% of 11
> Taken at least once:81.82% of 11
> No calls
>
> What is the meaning of 'branches executed' versus 'taken at least
> once'? I would imagine that the first implied the second, so I'm
> clearly missing something.

Branches executed means the branch condition was evaluated, whereas
taken at least once means that the branch was followed. A condition
that's always false will be executed but not taken.

> Also, what is the alternative to 'no calls'? I see that in every
> function in my single-file example; does it mean calls across
> compilation units?

This looks like an unimplemented feature. My understanding is that clang
doesn't provide the necessary instrumentation for this to tell you
anything interesting.