[Mlir-commits] [llvm] [mlir] [ADT] Make DenseMap/DenseSet more resilient agains OOM situations (PR #107251)

[Nikita Popov]

nikic wrote:

This direction looks quite concerning to me. LLVM is explicitly not designed to be exception safe, and this change is not at all free. It introduces significant implementation complexity, compile-time impact and memory usage impact.

The minimum requirement here is going to be that this does not have any compile-time/memory usage impact on people who do not need this functionality -- but I'm not convinced that we should accept this downstream at all, as a matter of policy.

Major compile-time regressions: https://llvm-compile-time-tracker.com/compare.php?from=f4dd1bc8fc625d3938f95b9d06aaaeebd2e90dca&to=1cb62cb5fb8eeca9641992f98f1b24b328410034&stat=instructions:u

Major memory usage regressions: https://llvm-compile-time-tracker.com/compare.php?from=f4dd1bc8fc625d3938f95b9d06aaaeebd2e90dca&to=1cb62cb5fb8eeca9641992f98f1b24b328410034&stat=max-rss

https://github.com/llvm/llvm-project/pull/107251