[all-commits] [llvm/llvm-project] 4f051f: [InstCombine] avoid crash sinking to unreachable b...

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  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 4f051fe37438632d10480c346520a0de624dbebf
      https://github.com/llvm/llvm-project/commit/4f051fe37438632d10480c346520a0de624dbebf
  Author: Sanjay Patel <spatel at rotateright.com>
  Date:   2020-12-10 (Thu, 10 Dec 2020)

  Changed paths:
    M llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
    M llvm/test/Transforms/InstCombine/phi-select-constant.ll

  Log Message:
  -----------
  [InstCombine] avoid crash sinking to unreachable block

The test is reduced from the example in D82005.

Similar to 94f6d365e, the test here would assert in
the DomTree when we tried to convert a select to a
phi with an unreachable block operand.

We may want to add some kind of guard code in DomTree
itself to avoid this sort of problem.