[llvm] [RISCV] Adopt SpacemitX60's scheduling model for `-mtune=generic` (PR #167008)

[Pengcheng Wang via llvm-commits]

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@@ -92,21 +92,25 @@ class RISCVTuneProcessorModel<string n, SchedMachineModel m,
 defvar GenericTuneFeatures = [TuneOptimizedNF2SegmentLoadStore,
                               TuneEnableSelectOptimize];
 
+// `generic-rv32`, and `generic-rv64` are expected to target
+// in-order application processors designed for general-purpose computing.
 def GENERIC_RV32 : RISCVProcessorModel<"generic-rv32",
-                                       NoSchedModel,
+                                       SpacemitX60Model,
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wangpc-pp wrote:

Do we need to duplicate the `SpacemitX60Model` to another file in case we need to support more extensions that `spacemit-x60` doesn't support.

https://github.com/llvm/llvm-project/pull/167008