module: Control and parse gem5's statistics log file

Gem5's statistics log file contains plenty of interesting information
that are not exposed so far. This module enables control and parsing of
the statistics file by:
 - configuring periodic dumps of statistics;
 - marking Regions of Interest (ROIs);
 - and extracting values of specific fields during the ROIs.

devlib/utils/gem5.py

@@ -0,0 +1,43 @@
+#    Copyright 2017 ARM Limited
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import re
+
+
+GEM5STATS_FIELD_REGEX = re.compile("^(?P<key>[^- ]\S*) +(?P<value>[^#]+).+$")
+GEM5STATS_DUMP_HEAD = '---------- Begin Simulation Statistics ----------'
+GEM5STATS_DUMP_TAIL = '---------- End Simulation Statistics   ----------'
+GEM5STATS_ROI_NUMBER = 8
+
+
+def iter_statistics_dump(stats_file):
+    '''
+    Yields statistics dumps as dicts. The parameter is assumed to be a stream 
+    reading from the statistics log file.
+    '''
+    cur_dump = {}
+    while True:
+        line = stats_file.readline()
+        if not line:
+            break
+        if GEM5STATS_DUMP_TAIL in line:
+            yield cur_dump
+            cur_dump = {}
+        else:
+            res = GEM5STATS_FIELD_REGEX.match(line) 
+            if res:
+                k = res.group("key")
+                v = res.group("value").split()
+                cur_dump[k] = v[0] if len(v)==1 else set(v)
+