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

[Austin Kerbow via llvm-commits]

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@@ -118,21 +119,41 @@ void GCNIterativeScheduler::printSchedRP(raw_ostream &OS,
 }
 #endif
 
+void GCNIterativeScheduler::swapIGLPMutations(const Region &R, bool IsReentry) {
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kerbowa wrote:

I guess with less stages it's not worth caching this result like in the default scheduler?

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