[llvm] [AMDGPU] Implemented a patch to optimize SGPR spills (PR #93668)

[Matt Arsenault via llvm-commits]

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@@ -67,6 +67,9 @@ namespace {
     const MachineBlockFrequencyInfo *MBFI = nullptr;
     SlotIndexes *Indexes = nullptr;
 
+    // - preserves Analysis passes in case RA may be called afterwards.
+    bool preserveRegAllocNeededAnalysis = false;
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arsenm wrote:

There shouldn't be a reason to have a configuration flag for this. The pass can just unconditionally preserve the analyses.

This should also be a separate PR, not just a separate commit in this PR 

https://github.com/llvm/llvm-project/pull/93668