[llvm] [CodeGen] Remove `applySplitCriticalEdges` in `MachineDominatorTree` (PR #97055)

[via llvm-commits]

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@@ -391,9 +390,8 @@ bool MachineLICMBase::runOnMachineFunction(MachineFunction &MF) {
     else {
       // CSEMap is initialized for loop header when the first instruction is
       // being hoisted.
-      MachineDomTreeNode *N = DT->getNode(CurLoop->getHeader());
       FirstInLoop = true;
-      HoistOutOfLoop(N, CurLoop, CurPreheader);
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paperchalice wrote:

`N` is no longer a node in `DT` when we split critical edges eagerly in failed tests before.

https://github.com/llvm/llvm-project/pull/97055