[llvm] [CodeGen] Add MachineRegisterClassInfo analysis pass (PR #120690)

[Pengcheng Wang via llvm-commits]

================
@@ -345,9 +347,11 @@
 ; GCN-O1-NEXT:        Slot index numbering
 ; GCN-O1-NEXT:        Live Interval Analysis
 ; GCN-O1-NEXT:        Machine Natural Loop Construction
+; GCN-O1-NEXT:        Machine Register Class Info Analysis
 ; GCN-O1-NEXT:        Register Coalescer
 ; GCN-O1-NEXT:        Rename Disconnected Subregister Components
 ; GCN-O1-NEXT:        Rewrite Partial Register Uses
+; GCN-O1-NEXT:        Machine Register Class Info Analysis
----------------
wangpc-pp wrote:

So why would it be uncached?  I noticed that every time it prints something like:
```
 -*- 'Machine InstCombiner' is the last user of following pass instances. Free these instances
[2025-01-13 16:24:20.826283744] 0x555561c532c0      Freeing Pass 'Machine Trace Metrics' on Function 'test'...
```
Why would it be unused as there are several uses in the late pipeline? Is this a bug?

https://github.com/llvm/llvm-project/pull/120690