[PATCH] D84264: [SCCP] Directly remove non-feasible edges

Nikita Popov via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Sat Jul 25 02:21:39 PDT 2020


nikic added a comment.

- How do I get the pre-ipsccp IR under NewPM -- without getting a full print-after-all dump? There is no opt-bisect and I didn't find anything else. Is inserting manual `M.dump()` calls really the state of the art here?
- How do I reduce test cases under NewPM? After wrangling with it for a while, I finally understood that bugpoint just doesn't understand NewPM at all. So I tried llvm-reduce. After learning how to make that work -- which seems way more complicated than bugpoint -- it just managed to break the module after a couple iterations :(

Per a recent mailing list thread, people have been using NewPM in production for years -- how do you debug issues under it?

For the record, this is the IR dump I managed to get: https://gist.github.com/nikic/138cbd24f0c87b847d52fa9d941a4ae4 And the reason why this only affects NewPM is that we don't preserve DT/PDT under the LegacyPM in this pass at all.


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