[NFC][PowerPC] Add a new MIR file to test mi-peephole pass

llvm/test/CodeGen/PowerPC/mi-peephole.mir

@@ -0,0 +1,37 @@
+# RUN: llc -mtriple=powerpc64le--linux-gnu -run-pass ppc-mi-peepholes %s -o - \
+# RUN:   -verify-machineinstrs | FileCheck %s
+
+---
+name:            testRLDIC
+alignment:       16
+tracksRegLiveness: true
+registers:
+  - { id: 0, class: g8rc }
+  - { id: 1, class: g8rc }
+  - { id: 2, class: g8rc }
+liveins:
+  - { reg: '$x3', virtual-reg: '%0' }
+  - { reg: '$x4', virtual-reg: '%1' }
+frameInfo:
+  maxAlignment:    1
+machineFunctionInfo: {}
+body:             |
+body:             |
+  bb.0.entry:
+    liveins: $x3, $x4
+
+    %1:g8rc = COPY $x4
+    %0:g8rc = COPY $x3
+    %2:g8rc = RLDICL killed %1, 0, 32
+    %3:g8rc = RLDICR %2, 2, 61
+    $x3 = COPY %3
+    BLR8 implicit $lr8, implicit $rm, implicit $x3
+
+  ; CHECK-LABEL: testRLDIC
+  ; CHECK: bb.0.entry:
+  ; CHECK:   %1:g8rc = COPY $x4
+  ; CHECK:   %0:g8rc = COPY $x3
+  ; CHECK:   %3:g8rc = RLDIC %1, 2, 30
+  ; CHECK:   $x3 = COPY %3
+  ; CHECK:   BLR8 implicit $lr8, implicit $rm, implicit $x3
+...