[PATCH] D87555: [DivRemPairs] Add an initial case for hoisting to a common predecessor.

[Sanjay Patel via Phabricator via llvm-commits]

spatel added a comment.

I'm not seeing why we need the guaranteed-to-execute checks with the proposed instruction movement. In general, div/rem are special because of their UB problems, but in this case we have:

  /// We can largely ignore the normal safety and cost constraints on speculation
  /// of these ops when we find a matching pair. This is because we are already
  /// guaranteed that any exceptions and most cost are already incurred by the
  /// first member of the pair.

In other words, this is similar to hoisting a normal math binop once we find the other member of the pair.


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  https://reviews.llvm.org/D87555/new/

https://reviews.llvm.org/D87555