[PATCH] D106593: [WIP][SimplifyCFG] Replace FoldTwoEntryPHINode i1 hack with a different hack.

Thu Jul 22 13:55:27 PDT 2021

lebedev.ri added a comment.

I like this, it's far less fragile,
but as https://bugs.llvm.org/show_bug.cgi?id=51149 reports,
there are some bad performance concerns with `FoldTwoEntryPHINode`,
and in fact i just tuned/fixed heuristic in rG7ef6f019090f3979fa345105b9ac95ac589c6cf9 <https://reviews.llvm.org/rG7ef6f019090f3979fa345105b9ac95ac589c6cf9>
to workaround them.

Presumably `FoldTwoEntryPHINode` is missing some other profitability check.
Not sure about plain build, but we could at least try to use branch weights.

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D106593/new/

https://reviews.llvm.org/D106593