[PATCH] D155940: [SimplifyCFG] Transform for merging the combination of phis in switch

[Hongyu Chen via Phabricator via llvm-commits]

XChy updated this revision to Diff 545346.
XChy added a comment.

- Add complete positive tests
- Fix bugs about preserving domtree

**Enhance further possible**: If BB and Succ share more than one predecessor and combine some phis meanwhile, we can also simplify CFG.
However, we are not able to erase the phi in BB completely here. Does it make sense still?
example <https://alive2.llvm.org/ce/z/AdGadM>


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D155940/new/

https://reviews.llvm.org/D155940

Files:
  llvm/lib/Transforms/Utils/Local.cpp
  llvm/test/CodeGen/ARM/jump-table-islands.ll
  llvm/test/Transforms/SimplifyCFG/branch-fold.ll
  llvm/test/Transforms/SimplifyCFG/merge-phis-in-switch.ll
  llvm/test/Transforms/SimplifyCFG/multiple-phis.ll
  llvm/test/Transforms/SimplifyCFG/switch-simplify-crash2.ll

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