On 3/31/22 16:55, Sebastian Huber wrote:
Hello,
gcov supports currently branch coverage. Some projects require modified
condition/decision coverage (MC/DC):
https://en.wikipedia.org/wiki/Modified_condition/decision_coverage
In general, 100% branch coverage does not imply 100% MC/DC coverage:
https://www.adacore.com/uploads_gems/Couverture_ERTS-2012.pdf
The paper contains a criterion under which 100% branch coverage implies 100%
MC/DC coverage:
"Theorem 1 If the BDD of a decision D is a tree (with
only one path from the root to any condition node),
then BDD edge coverage implies MCDC"
The BDD is the Binary Decision Diagram. I have no idea how the compiler and the
coverage supports works in GCC. Is this BDD available for the coverage support
and could the coverage support check for this property and then for example add
it to the gcov information? If the BDD of a decision is not a tree, then we
would have to record which paths through the BDD are covered to get the MC/DC
coverage. This would require extra storage and instrumentation. According to
the paper, the BDD is usually a tree in real world applications. Does this
sound like feasible feature for GCC? Could it be even a GSoC project?
Kind regards,
Sebastian
Hi.
There's a patch review for the feature:
https://gcc.gnu.org/pipermail/gcc-patches/2022-March/592065.html
Martin
