[PATCH v2 0/2] Reuse --contains traversal results

The memoized traversal used by git tag avoids repeating graph walks for refs with shared history. Extend it to the other ref-filter users after making the existing traversal safe for cycles introduced by replacement refs.

Signed-off-by: Tamir Duberstein <tamird@gmail.com>

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Changes in v2:
- Split cycle handling into a preparatory patch.
- Exercise cycle handling through the existing git tag path.
- Move perf result verification out of setup.
- Link to v1: https://patch.msgid.link/20260607-ref-filter-memoized-contains-v1-1-a1972dde9c76@gmail.com

---
Tamir Duberstein (2):
      commit-reach: handle cycles in contains walk
      ref-filter: memoize --contains with generations

 commit-reach.c                 | 43 ++++++++++++++++++++++++++++++------
 commit-reach.h                 | 10 ++++++++-
 t/perf/p1500-graph-walks.sh    | 49 +++++++++++++++++++++++++++++++++++++++++-
 t/t6301-for-each-ref-errors.sh | 22 +++++++++++++++++++
 t/t7004-tag.sh                 | 21 ++++++++++++++++++
 5 files changed, 137 insertions(+), 8 deletions(-)
---
base-commit: 9ac3f193c05c2237e2b14ebaa1149e9fc8a1abe0
change-id: 20260607-ref-filter-memoized-contains-7cb6b3bccad1

Best regards, -- Tamir Duberstein <tamird@gmail.com>