[UpdateCCTestChecks] Implement --global-value-regex

`--check-globals` activates checks for all global values, and
`--global-value-regex` filters them.  For example, I'd like to use it
in OpenMP offload codegen tests to check only global variables like
`.offload_maptypes*`.

Reviewed By: jdoerfert

Differential Revision: https://reviews.llvm.org/D104742

utils/UpdateTestChecks/common.py

@@ -36,9 +36,12 @@ def parse_commandline_args(parser):
                       help='List of regular expressions to replace matching value names')
   parser.add_argument('--prefix-filecheck-ir-name', default='',
                       help='Add a prefix to FileCheck IR value names to avoid conflicts with scripted names')
+  parser.add_argument('--global-value-regex', nargs='+', default=[],
+                      help='List of regular expressions that a global value declaration must match to generate a check (has no effect if checking globals is not enabled)')
   args = parser.parse_args()
-  global _verbose
+  global _verbose, _global_value_regex
   _verbose = args.verbose
+  _global_value_regex = args.global_value_regex
   return args
 
 
@@ -796,13 +799,27 @@ def add_global_checks(glob_val_dict, comment_marker, prefix_list, output_lines,
         if not glob_val_dict[checkprefix][nameless_value.check_prefix]:
           continue
 
-        output_lines.append(comment_marker + SEPARATOR)
-
+        check_lines = []
         global_vars_seen_before = [key for key in global_vars_seen.keys()]
         for line in glob_val_dict[checkprefix][nameless_value.check_prefix]:
+          if _global_value_regex:
+            matched = False
+            for regex in _global_value_regex:
+              if re.match('^@' + regex + ' = ', line):
+                matched = True
+                break
+            if not matched:
+              continue
           tmp = generalize_check_lines([line], is_analyze, set(), global_vars_seen)
           check_line = '%s %s: %s' % (comment_marker, checkprefix, tmp[0])
+          check_lines.append(check_line)
+        if not check_lines:
+          continue
+
+        output_lines.append(comment_marker + SEPARATOR)
+        for check_line in check_lines:
           output_lines.append(check_line)
+
         printed_prefixes.add((checkprefix, nameless_value.check_prefix))
 
         # Remembe new global variables we have not seen before