[PATCH] D68930: [InstCombine] Shift amount reassociation in shifty sign bit test (PR43595)

Dávid Bolvanský via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Fri Oct 18 10:48:54 PDT 2019


xbolva00 added a comment.

>> sadly i'm still seeing regressions (although smaller!) in target benchmark, and analysis of IR points to *this* missing pattern

But does this or base pattern shows up somewhere else (test suite/clang/chromium) than in your benchmark?

I think this is very rare pattern and it is not very good that we are going to add another rare pattern to InstCombine which is a slow pass already. I still think AggresiveInstCombine is better solution - or improve your code of interest manually.


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