[PATCH] D56772: [MIR] Add simple PRE pass to MachineCSE

[Anton Afanasyev via Phabricator via llvm-commits]

anton-afanasyev added a comment.

Also, I don't think the heavy functions here (like `findNearestCommonDominator()` and `isPotentiallyReachable()`) can significant impact compile time -- they are called rarely only for two BBs with common subexpressions, which is unusual. Taking the `machine-cse.NumCSE` statistics above as example, one can make an estimation of no more than 10-100 calls of these functions for the benchs from test suite. Also, these heavy calls are already cached in a sense, they are using prebuilt Machine Dominator Tree.


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  https://reviews.llvm.org/D56772/new/

https://reviews.llvm.org/D56772