commit-reach: add trace2 instrumentation to paint_down_to_common()

Add a step counter and trace2_data_intmax() call so that the number
of commits visited during the paint walk is observable via
GIT_TRACE2_EVENT. This provides a way to measure the impact of
future optimizations without relying on wall-clock benchmarks alone.

Some step counts already vary across commit-graph modes (e.g.
in_merge_bases_many:self) because the pre-existing min_generation
optimization short-circuits the walk when generation data is
available.

Signed-off-by: Kristofer Karlsson <krka@spotify.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

0 files changed, 0 insertions, 0 deletions