[PATCH] D64630: [DebugInfo] Address performance regression with r364515

[Vedant Kumar via Phabricator via llvm-commits]

vsk added a comment.

I guess there are a few alternatives to consider that call for changing data structures. Perhaps it makes more sense to start with the approach taken here to address the performance issue and to keep an eye out for any more problems. BTW @jmorse is this patch still rebased on top of r364515? I don't see `mergingChangesDbgValue` anymore.



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Comment at: llvm/lib/CodeGen/RegisterCoalescer.cpp:3338
   // If the Reg is live all the way through this block, no non-live DBG_VALUEs
-  // can be merged with the live range of Other. Exit early.
+  // can be merged with the live range of the other. Exit early.
   if (RegLivenessIt != RegLiveness.end() &&
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IIUC there's no need to check for the case where Reg is live & OtherLiveness is not, because makeDeadDbgValsUndef is called once for each vreg in a coalesce pair. (Assuming that's correct) maybe that's worth a comment here, or in the function doc.


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https://reviews.llvm.org/D64630