[llvm] CodeGen: Run LiveIntervals before PHIElimination and drop LiveVariables from it (PR #228618)

[Matt Arsenault via llvm-commits]

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@@ -100,12 +98,8 @@ class PHIEliminationImpl {
 
   /// Split critical edges where necessary for good coalescer performance.
   bool SplitPHIEdges(MachineFunction &MF, MachineBasicBlock &MBB,
-                     MachineLoopInfo *MLI,
-                     std::vector<SparseBitVector<>> *LiveInSets,
-                     MachineDomTreeUpdater &MDTU);
+                     MachineLoopInfo *MLI, MachineDomTreeUpdater &MDTU);
 
-  // These functions are temporary abstractions around LiveVariables and
-  // LiveIntervals, so they can go away when LiveVariables does.
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arsenm wrote:

Probably should but I wanted to keep this as mechanically straightforward as possible 

https://github.com/llvm/llvm-project/pull/228618