[PATCH] D105026: [2/2][LiveDebugVariables] Avoid reduntant DBG_VALUEs after virtregrewrite

[Orlando Cazalet-Hyams via Phabricator via llvm-commits]

Orlando added a comment.

I just wanted to add, this change makes the quadratic case mentioned by @jmorse in D105025 <https://reviews.llvm.org/D105025> more likely since the function is able to scan back further in some cases. If your performance testing shows that these patches noticeably impact compile time - as an alternative to the "already inserted DBG_VALIE cache map" solution with this patch in mind - it might be worth trying the approach of `RemoveRedundantDbgInstrs` (added in D71478 <https://reviews.llvm.org/D71478>)? i.e. Let LiveDebugVariables insert all the DBG_VALUES it usually does and then run a cleanup afterwards that only needs to traverse the instructions twice.


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https://reviews.llvm.org/D105026