[llvm] [CodeGen] Fix stale LiveIntervals regmask tables after MachineBasicBl… (PR #209610)

[Matt Arsenault via llvm-commits]

================
@@ -294,6 +294,27 @@ void LiveIntervals::computeRegMasks() {
   }
 }
 
+void LiveIntervals::reassignRegMaskSlots(MachineBasicBlock *Orig,
+                                         MachineBasicBlock *SplitBB) {
+  assert(Orig && SplitBB && Orig != SplitBB);
----------------
arsenm wrote:

Make the blocks references?

https://github.com/llvm/llvm-project/pull/209610