1 files changed, 26 insertions, 0 deletions
diff --git a/llvm/test/CodeGen/MIR/X86/unknown-subregister-index-op.mir b/llvm/test/CodeGen/MIR/X86/unknown-subregister-index-op.mir
new file mode 100644
index 00000000000..fa7e1ada932
--- /dev/null
+++ b/llvm/test/CodeGen/MIR/X86/unknown-subregister-index-op.mir
@@ -0,0 +1,26 @@
+# RUN: not llc -march=x86-64 -start-after machine-sink -stop-after machine-sink -o /dev/null %s 2>&1 | FileCheck %s
+# This test ensures that an error is reported when an unknown subregister index
+# is encountered.
+
+--- |
+
+  define zeroext i1 @t(i1 %c) {
+  entry:
+    ret i1 %c
+  }
+
+...
+---
+name:            t
+isSSA:           true
+tracksRegLiveness: true
+registers:
+  - { id: 0, class: gr32 }
+  - { id: 1, class: gr8 }
+  - { id: 2, class: gr8 }
+body: |
+  bb.0.entry:
+    ; CHECK: [[@LINE+1]]:35: unknown subregister index 'bit8'
+    %0 = INSERT_SUBREG %edi, %al, %subreg.bit8
+    RETQ %0
+...