[all-commits] [llvm/llvm-project] 073b25: [SimplifyCFG] Redirect switch cases that lead to U...

[Max Kazantsev via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 073b254cffeffdef36ffbee0c9afdc0da9cd6ac3
      https://github.com/llvm/llvm-project/commit/073b254cffeffdef36ffbee0c9afdc0da9cd6ac3
  Author: Max Kazantsev <mkazantsev at azul.com>
  Date:   2021-09-21 (Tue, 21 Sep 2021)

  Changed paths:
    M llvm/lib/Transforms/Utils/SimplifyCFG.cpp
    M llvm/test/CodeGen/AArch64/arm64-ccmp.ll
    M llvm/test/Transforms/SimplifyCFG/switch_ub.ll

  Log Message:
  -----------
  [SimplifyCFG] Redirect switch cases that lead to UB into an unreachable block

When following a case of a switch instruction is guaranteed to lead to
UB, we can safely break these edges and redirect those cases into a newly
created unreachable block. As result, CFG will become simpler and we can
remove some of Phi inputs to make further analyzes easier.

Patch by Dmitry Bakunevich!

Differential Revision: https://reviews.llvm.org/D109428
Reviewed By: lebedev.ri