[PATCH] D73988: Add documentation on git bisecting across the MLIR merge.

[Mehdi AMINI via Phabricator via llvm-commits]

mehdi_amini accepted this revision.
mehdi_amini added a comment.
This revision is now accepted and ready to land.

Nice doc! Thanks.



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Comment at: llvm/docs/GitBisecting.rst:98
+merged, at every revision at ``C`` or earlier, *only* the ``mlir/`` directory
+exists, and nothing else does. This confused both ``git bisect`` and most
+run scripts.
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Why does it confuse `git bisect`? I would expect your run script to try ` ninja -C ../llvm-build-project clang || exit 125` and just skip the revisions?


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Comment at: llvm/docs/GitBisecting.rst:108
+``git bisect start -- clang llvm compiler-rt``. That way, the commits in
+``mlir`` are never evaluated.
+
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Using directory filtering to drive the bisection and skip unrelated revisions seems like a good general recommendation independently of MLIR or merges.
Someone bisecting in `lld` for example could skip most revisions.


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Comment at: llvm/docs/GitBisecting.rst:118
+``run.sh`` script does *not* work: git seems to get confused about the
+directories appearing and disappearing and soon errors out with XXX
+
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Seems like it answers my previous question (should this explanation be moved there?).

The part about git being confused about directories appearing and disappearing is a bit strange: surely there are many directories that will appear and disappear during the bisection?


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