[PATCH] D103009: [DSE] Transform memset + malloc --> calloc (PR25892)

[Alexander Kornienko via Phabricator via llvm-commits]

alexfh added a comment.

This commit seems to cause memory usage (rss) increase in MariaDB's mysqld by a factor of 4. Looking back into the history, I found that the previous commit here caused the same regression, but we quickly picked up the revert and moved on. Now I'm trying to isolate the problem, but it's taking time.
So far, my sole hypothesis is that malloc + memset of a smaller size can still be converted to calloc. But I have no evidence so far. Naive attempts to synthetically reproduce this didn't work. Maybe this only happens when some UB is in place, but again, I have nothing to back this up.

Given this is a quite serious regression, can we roll this back while I'm investigating?


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D103009/new/

https://reviews.llvm.org/D103009