[llvm] [AMDGPU] Teach iterative schedulers about IGLP (PR #134953)

[Austin Kerbow via llvm-commits]

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@@ -18,6 +18,7 @@ namespace llvm {
 namespace AMDGPU {
 // The current phase of instruction scheduling
 enum class SchedulingPhase { Initial, PreRAReentry, PostRA };
+
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kerbowa wrote:

```suggestion

```

https://github.com/llvm/llvm-project/pull/134953