Move test to MIR/AMDGPU/mfi-no-ir

Author: optimisan

llvm/test/CodeGen/AMDGPU/virtual-registers.mir

@@ -578,3 +578,18 @@ body:             |
     SI_RETURN
 
 ...
+---
+name: vregs
+# FULL: registers:
+# FULL-NEXT:   - { id: 0, class: vgpr_32, preferred-register: '$vgpr1', flags: [ WWM_REG ] }
+# FULL-NEXT:   - { id: 1, class: sgpr_64, preferred-register: '$sgpr0_sgpr1', flags: [  ] }
+# FULL-NEXT:   - { id: 2, class: sgpr_64, preferred-register: '', flags: [  ] }
+registers:
+  - { id: 0, class: vgpr_32, preferred-register: $vgpr1, flags: [ WWM_REG ]}
+  - { id: 1, class: sgpr_64, preferred-register: $sgpr0_sgpr1 }
+  - { id: 2, class: sgpr_64, flags: [ ] }
+body: |
+  bb.0:
+    %2:sgpr_64 = COPY %1
+    %1:sgpr_64 = COPY %0
+...