Help on Gcov

[Ian Lance Taylor]

Harry Trinta <harrytpc@gmail.com> writes:

> - The instrumentator uses any technique to reduce the amount of
> instrumentation points, for example, dominance?

Yes.

> - I know that the instrumentation is done at compile time. However, it
> is done in C code or in compiled code ?

I'm not sure I understand this question.  The compiler generates the
instrumentation code.  It doesn't generate C code.  It just adds
additional function calls as it compiles.  So perhaps the answer is that
the instrumentation is done in compiled code.

> - What commands runs when the probes are executed? The probes calls
> some function in lib? What?

There are several different functions.  They all have names start with
"__gcov_".

> Now I'd  want to know more about the sources that I have identified as
> part of gcov:
>
> - coverage.c: I do not know.

Generates the .gcno file.  If you don't know what that means, see
http://gcc.gnu.org/onlinedocs/gcc/Gcov-Data-Files.html .

> - gcov: It is responsible for generating the file. gcov?

Part of the gcov program which turns the .gcda files into a readable
form.

> - profile:

Branch probability coverage support.

> - gcov-io: Responsible for reading and writing files. gcda and. gcno?

Yes.  Used by both gcov and the runtime library.

> - libgcov: library that supports the execution of the instrumented program?

Yes.

> - tree-profile.c: insert the probes in code?

Yes.

> Which of these files are used during compile? And which of these files
> are used during program execution?

All of the above are used at compile time except libgcov.  gcov-io is
used at both compile time and runtime.

Ian