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

[Matt Arsenault via llvm-commits]

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@@ -730,7 +730,12 @@ void LiveIntervals::addKillFlags(const VirtRegMap *VRM) {
     // Find the regunit intervals for the assigned register. They may overlap
     // the virtual register live range, cancelling any kills.
     RU.clear();
-    for (MCRegUnit Unit : TRI->regunits(PhysReg)) {
+    LaneBitmask ArtificialLanes = LaneBitmask::getNone();
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arsenm wrote:

```suggestion
    LaneBitmask ArtificialLanes;
```

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