[PATCH] Remove dead code from LoopUnswitch

[Hal Finkel]

Chris, et al.,

LoopUnswitch's code simplification routine has code to convert conditional to unconditional branches, after unswitching makes the condition constant, and then remove any blocks that renders dead. Unfortunately, this code is dead, currently broken, and furthermore, has never been alive (at least as far back at 2006). I propose that, at least for now, we nuke it.

Regarding the general functionality, I see (at least) two possible options:

 1. Fix/rewrite this functionality within LoopUnswitch

 2. Run SimplifyCFG after running LoopUnswitch: we currently run InstCombine after running LoopUnswitch, and so the loop pass manager is already done after running LoopUnswitch, and SE is already being invalidated by InstCombine, so it does not look like, if we added SimplifyCFG after InstCombine, we'd really lose much.

Thoughts?

Thanks again,
Hal

-- 
Hal Finkel
Assistant Computational Scientist
Leadership Computing Facility
Argonne National Laboratory
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