[llvm] [AMDGPU] Preserve instruction flags in ILP scheduler (PR #211190)

[Matt Arsenault via llvm-commits]

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@@ -367,6 +367,26 @@ void GCNIterativeScheduler::scheduleBest(Region &R) {
   R.BestSchedule.reset();
 }
 
+void GCNIterativeScheduler::restoreFlags(MachineInstr &MI) {
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arsenm wrote:

```suggestion
void GCNIterativeScheduler::restoreDeadFlags(MachineInstr &MI) {
```

This doesn't do anything with general flags 

https://github.com/llvm/llvm-project/pull/211190