[all-commits] [llvm/llvm-project] 40569d: [DSE, MSSA] Move reachability check to main loop.

[Florian Hahn via All-commits]

  Branch: refs/heads/master
  Home:   https://github.com/llvm/llvm-project
  Commit: 40569db7b3d71b5f4f71108015165c6224b0b242
      https://github.com/llvm/llvm-project/commit/40569db7b3d71b5f4f71108015165c6224b0b242
  Author: Florian Hahn <flo at fhahn.com>
  Date:   2020-06-21 (Sun, 21 Jun 2020)

  Changed paths:
    M llvm/lib/Transforms/Scalar/DeadStoreElimination.cpp
    A llvm/test/Transforms/DeadStoreElimination/MSSA/multiblock-unreachable.ll

  Log Message:
  -----------
  [DSE,MSSA] Move reachability check to main loop.

As we traverse the CFG backwards, we could end up reaching unreachable
blocks. For unreachable blocks, we won't have computed post order
numbers and because DomAccess is reachable, unreachable blocks cannot be
on any path from it.

This fixes a crash with unreachable blocks.