[PATCH] D121381: [MemorySSA] Support lazy use optimization

[Alina Sbirlea via Phabricator via llvm-commits]

asbirlea added a comment.

Thank you for sending this out!

Broadly the changes look good. The patch as is can also give some compile-time improvements for cases where MSSA is built and preserved in loop pipelines and need only be optimized before LICM, not before the first loop pass in the pipeline. This also means results may change based on the delayed optimization.
This should hold true for both Legacy and NPM, but I see in practice there's a difference only for LPM (http://llvm-compile-time-tracker.com/compare.php?from=067c035012fc061ad6378458774ac2df117283c6&to=59191057243e34d85b644716ef2811bfea8efd1e&stat=instructions)

Let me test this out as is first. Then separately with the EarlyCSE ensureOptimized() removed to check if the gains in compile-time are not coupled with run time regressions.


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  https://reviews.llvm.org/D121381/new/

https://reviews.llvm.org/D121381