[llvm] [CodeGen] Use RegisterClassInfo for remaining allocation-order users (PR #216510)

[Matt Arsenault via llvm-commits]

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@@ -2453,6 +2454,8 @@ void HexagonFrameLowering::optimizeSpillSlots(MachineFunction &MF,
   auto &HII = *HST.getInstrInfo();
   auto &HRI = *HST.getRegisterInfo();
   auto &MRI = MF.getRegInfo();
+  RegisterClassInfo RCI;
+  RCI.runOnMachineFunction(MF);
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arsenm wrote:

We don't want these throwaway instances, this should be threaded from the pass manager analysis query. I'd leave the hexagon case out of this PR 

https://github.com/llvm/llvm-project/pull/216510