[llvm] [RISCV][Peephole] Checking regclass compatibility in VMV (PR #138844)

[Luke Lau via llvm-commits]

================
@@ -607,6 +612,11 @@ bool RISCVVectorPeephole::foldVMV_V_V(MachineInstr &MI) {
   if (!MRI->hasOneUse(MI.getOperand(2).getReg()))
     return false;
 
+  const TargetRegisterClass *RC1 = MRI->getRegClass(MI.getOperand(0).getReg());
+  const TargetRegisterClass *RC2 = MRI->getRegClass(MI.getOperand(2).getReg());
+  if (!RC1->hasSubClassEq(RC2))
+    return false;
+
----------------
lukel97 wrote:

Is this being hit by the 

```
    %0:vr = PseudoVMV_V_I_MF2 $noreg, 0, -1, 5 /* e32 */, 0 /* tu, mu */
     %1:vrnov0 = PseudoVMV_V_V_MF2 $noreg, %0, 0, 5 /* e32 */, 0 /* tu, mu */
```

in the added test case? Can this be split out into two separate tests, one for foldVMV_V_V and one for foldUndefPassthruVMV_V_V?

https://github.com/llvm/llvm-project/pull/138844