[Utils] Hide the default behavior change of D68819 under a flag

With D69701, the options used when running the script on a file will be
recorded and reused on a rerun. This allows us to hide new features
behind flags, starting with the "define" that was introduced in D68819.

Author: jdoerfert

llvm/utils/UpdateTestChecks/common.py

@@ -305,9 +305,9 @@ def add_checks(output_lines, comment_marker, prefix_list, func_dict, func_name,
       break
 
 def add_ir_checks(output_lines, comment_marker, prefix_list, func_dict,
-                  func_name, preserve_names):
+                  func_name, preserve_names, function_sig):
   # Label format is based on IR string.
-  function_def_regex = 'define {{[^@]+}}'
+  function_def_regex = 'define {{[^@]+}}' if function_sig else ''
   check_label_format = '{} %s-LABEL: {}@%s%s'.format(comment_marker, function_def_regex)
   add_checks(output_lines, comment_marker, prefix_list, func_dict, func_name,
              check_label_format, False, preserve_names)

llvm/utils/update_cc_test_checks.py

@@ -187,7 +187,7 @@ def main():
   for filename in args.tests:
     with open(filename) as f:
       input_lines = [l.rstrip() for l in f]
-    
+
     first_line = input_lines[0] if input_lines else ""
     if 'autogenerated' in first_line and script_name not in first_line:
       common.warn("Skipping test which wasn't autogenerated by " + script_name, filename)
@@ -298,7 +298,7 @@ def main():
             if added:
               output_lines.append('//')
             added.add(mangled)
-            common.add_ir_checks(output_lines, '//', run_list, func_dict, mangled, False)
+            common.add_ir_checks(output_lines, '//', run_list, func_dict, mangled, False, False)
       output_lines.append(line.rstrip('\n'))
 
     # Update the test file.

llvm/utils/update_test_checks.py

@@ -180,7 +180,7 @@ def main():
 
         # Print out the various check lines here.
         common.add_ir_checks(output_lines, ';', prefix_list, func_dict,
-                             func_name, args.preserve_names)
+                             func_name, args.preserve_names, args.function_signature)
         is_in_function_start = False
 
       if is_in_function: