ext: Add support for comma-separated inputs of testlib argparser

Currently, the --isa, --variant and --length options of testlib
do not support comma-separated inputs. This commit adds the
support for such an input for those options.

The argument parser now supports specifying the parameters multiple
times as well as specifying multiple options at a time.

JIRA: https://gem5.atlassian.net/jira/software/c/projects/GEM5/issues/GEM5-770

Change-Id: I3c276a9b9d9c6b0b802ecf8e7f1f9a3dfafe45d1
Signed-off-by: Hoa Nguyen <hoanguyen@ucdavis.edu>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/34198
Maintainer: Bobby R. Bruce <bbruce@ucdavis.edu>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>

ext/testlib/configuration.py

@@ -486,6 +486,8 @@ def define_common_args(config):
     '''
     global common_args
 
+    parse_comma_separated_string = lambda st: st.split(',')
+
     # A list of common arguments/flags used across cli parsers.
     common_args = [
         Argument(
@@ -503,20 +505,23 @@ def define_common_args(config):
             help='A tag comparison used to select tests.'),
         Argument(
             '--isa',
-            action='append',
+            action='extend',
             default=[],
+            type=parse_comma_separated_string,
             help="Only tests that are valid with one of these ISAs. "
                  "Comma separated."),
         Argument(
             '--variant',
-            action='append',
+            action='extend',
             default=[],
+            type=parse_comma_separated_string,
             help="Only tests that are valid with one of these binary variants"
                  "(e.g., opt, debug). Comma separated."),
         Argument(
             '--length',
-            action='append',
+            action='extend',
             default=[],
+            type=parse_comma_separated_string,
             help="Only tests that are one of these lengths. Comma separated."),
         Argument(
             '--host',
@@ -596,6 +601,11 @@ def define_common_args(config):
 
 @add_metaclass(abc.ABCMeta)
 class ArgParser(object):
+    class ExtendAction(argparse.Action):
+        def __call__(self, parser, namespace, values, option_string=None):
+            items = getattr(namespace, self.dest, [])
+            items.extend(values)
+            setattr(namespace, self.dest, items)
 
     def __init__(self, parser):
         # Copy public methods of the parser.
@@ -603,6 +613,7 @@ class ArgParser(object):
             if not attr.startswith('_'):
                 setattr(self, attr, getattr(parser, attr))
         self.parser = parser
+        self.parser.register('action', 'extend', ArgParser.ExtendAction)
         self.add_argument = self.parser.add_argument
 
         # Argument will be added to all parsers and subparsers.