Add MachineVerifier test case

Author: michaelmaitland

llvm/test/MachineVerifier/copy-scalable.mir

@@ -0,0 +1,23 @@
+# NOTE: Assertions have been autogenerated by utils/update_mir_test_checks.py UTC_ARGS: --version 3
+# RUN: llc -mtriple=riscv64 -o - -global-isel -run-pass=none -verify-machineinstrs %s | FileCheck %s
+# REQUIRES: riscv64-registered-target
+
+---
+name:            test_copy_fixed_to_scalable
+legalized:       true
+regBankSelected: false
+selected:        false
+tracksRegLiveness: true
+registers:
+  - { id: 0, class: _, preferred-register: '' }
+liveins:
+body:             |
+  bb.0:
+    liveins: $v8
+
+    ; CHECK-LABEL: name: test_copy_fixed_to_scalable
+    ; CHECK: liveins: $v8
+    ; CHECK-NEXT: {{  $}}
+    ; CHECK-NEXT: [[COPY:%[0-9]+]]:_(<vscale x 1 x s8>) = COPY $v8
+    %0:_(<vscale x 1 x s8>) = COPY $v8
+...