[PATCH] D90688: [CaptureTracking] Avoid overly restrictive dominates check

[Nikita Popov via Phabricator via llvm-commits]

nikic added a comment.

I've applied a couple of fixes to CaptureTracking, the main ones are: https://github.com/llvm/llvm-project/commit/d35366bccae0016418660337ce94e3d7d0ff391e is a potential correctness fix, https://github.com/llvm/llvm-project/commit/f63ab188c63be12871da75bfc5801a7fc752769b is a compile-time improvement.

I also gave caching the reachability query a try: https://llvm-compile-time-tracker.com/compare.php?from=5225c102649b5469d61385e598b744ac8f3dd1da&to=6d1d73dec948a0cbbf0dd6261d5664c4bfce92b1&stat=instructions The result is better, but we still have a 6% regression on tramp3d-v4 with ThinLTO (down from 25%).

One remaining problem in the current CaptureTracking implementation is that the use limit is not fully enforced: It's currently a limit on the the maximum number of direct uses, not transitive uses. If the value has 20 GEP uses, each of which has 20 uses itself, we'll happily explore all 400 of them.


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https://reviews.llvm.org/D90688