[PATCH] D116692: [SimplifyCFG] Tail-merging all blocks with `unreachable` terminator, final take

[Roman Lebedev via Phabricator via llvm-commits]

lebedev.ri created this revision.
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This implements the approach disscussed in D104870 <https://reviews.llvm.org/D104870>:
instead of simply alaways tail-merging all `unreachable` blocks,
do so, then immediately try to sink from predecessors,
and if that fails, backtrack to before this tail-merging,
and do so losslessly, so that we can claim
that we haven't actually done any changes.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D116692

Files:
  llvm/include/llvm/Transforms/Utils/Local.h
  llvm/lib/Transforms/Scalar/SimplifyCFGPass.cpp
  llvm/lib/Transforms/Utils/SimplifyCFG.cpp
  llvm/test/CodeGen/Thumb2/setjmp_longjmp.ll
  llvm/test/Transforms/PhaseOrdering/AArch64/peel-multiple-unreachable-exits-for-vectorization.ll
  llvm/test/Transforms/SimplifyCFG/tail-merge-noreturn.ll

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