update_mir_test_checks: Improve message when updating fails

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@316133 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/utils/update_mir_test_checks.py b/utils/update_mir_test_checks.py
index e2ae3e7..469f6c1 100755
--- a/utils/update_mir_test_checks.py
+++ b/utils/update_mir_test_checks.py
@@ -399,8 +399,12 @@
     args = parser.parse_args()
 
     for test in args.tests:
-        update_test_file(args.llc, test, args.remove_common_prefixes,
-                         verbose=args.verbose)
+        try:
+            update_test_file(args.llc, test, args.remove_common_prefixes,
+                             verbose=args.verbose)
+        except Exception:
+            warn('Error processing file', test_file=test)
+            raise
 
 
 if __name__ == '__main__':