[llvm] [LiveIntervals] Ignore artificial regs when adding kill flags (PR #116963)

[Matt Arsenault via llvm-commits]

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@@ -659,3 +659,11 @@ bool MachineRegisterInfo::isReservedRegUnit(unsigned Unit) const {
   }
   return false;
 }
+
+bool MachineRegisterInfo::isArtificialRegUnit(unsigned Unit) const {
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arsenm wrote:

This should go in MCRegisterInfo, it's a constant property of the register. isReservedRegUnit is a stateful property depending on the current MachineFunction, so it should remain here

https://github.com/llvm/llvm-project/pull/116963