scons: Identify runs that fail and runs with stats differences

This patch changes the regression script such that it is possible to
identify the runs that fail with an exit code, and those that finish
with stats differences. The ones that truly fail are reported as
FAILED, and those that finish with changed stats as CHANGED.

The yellow colour has been reclaimed from the skipped regressions and
is now used for the changed ones. With no obvious good option left the
skipped ones are now in cyan.

While I was editing the script I also bumped any occurence of M5 to
gem5.

tests/SConscript

@@ -82,7 +82,7 @@ def run_test(target, source, env):
     target[0] : status
 
     Sources are:
-    source[0] : M5 binary
+    source[0] : gem5 binary
     source[1] : tests/run.py script
     source[2] : reference stats file
 
@@ -105,10 +105,14 @@ def run_test(target, source, env):
     if env['BATCH']:
         cmd = '%s -t %d %s' % (env['BATCH_CMD'], timeout, cmd)
 
+    # Create a default value for the status string, changed as needed
+    # based on the status.
+    status_str = "passed."
+
     pre_exec_time = time.time()
     status = env.Execute(env.subst(cmd, target=target, source=source))
     if status == 0:
-        # M5 terminated normally.
+        # gem5 terminated normally.
         # Run diff on output & ref directories to find differences.
         # Exclude the stats file since we will use diff-out on that.
 
@@ -137,35 +141,34 @@ def run_test(target, source, env):
         diffcmd = '$DIFFOUT ${SOURCES[2]} %s > %s' \
                   % (os.path.join(tgt_dir, 'stats.txt'), statsdiff)
         diffcmd = env.subst(diffcmd, target=target, source=source)
-        status = env.Execute(diffcmd, strfunction=None)
+        diff_status = env.Execute(diffcmd, strfunction=None)
+        # If there is a difference, change the status string to say so
+        if diff_status != 0:
+            status_str = "CHANGED!"
         print "===== Statistics differences ====="
         print contents(statsdiff)
 
-    else: # m5 exit status != 0
+    else: # gem5 exit status != 0
-        # M5 did not terminate properly, so no need to check the output
+        # Consider it a failed test unless the exit status is 2
+        status_str = "FAILED!"
+        # gem5 did not terminate properly, so no need to check the output
         if signaled(status):
-            print 'M5 terminated with signal', signum(status)
+            print 'gem5 terminated with signal', signum(status)
             if signum(status) in retry_signals:
                 # Consider the test incomplete; don't create a 'status' output.
                 # Hand the return status to scons and let scons decide what
                 # to do about it (typically terminate unless run with -k).
                 return status
         elif status == 2:
-            # The test was skipped
+            # The test was skipped, change the status string to say so
-            pass
+            status_str = "skipped."
         else:
-            print 'M5 exited with non-zero status', status
+            print 'gem5 exited with non-zero status', status
         # complete but failed execution (call to exit() with non-zero
         # status, SIGABORT due to assertion failure, etc.)... fall through
         # and generate FAILED status as if output comparison had failed
 
-    # Generate status file contents based on exit status of m5 or diff-out
+    # Generate status file contents based on exit status of gem5 and diff-out
-    if status == 0:
-        status_str = "passed."
-    elif status == 2:
-        status_str = "skipped."
-    else:
-        status_str = "FAILED!"
     f = file(str(target[0]), 'w')
     print >>f, tgt_dir, status_str
     f.close()
@@ -191,10 +194,12 @@ def print_test(target, source, env):
     # skip the punctuation
     if status == "FAILED!":
         status = termcap.Red + status[:-1] + termcap.Normal + status[-1]
+    elif status == "CHANGED!":
+        status = termcap.Yellow + status[:-1] + termcap.Normal + status[-1]
     elif status == "passed.":
         status = termcap.Green + status[:-1] + termcap.Normal + status[-1]
     elif status == "skipped.":
-        status = termcap.Yellow + status[:-1] + termcap.Normal + status[-1]
+        status = termcap.Cyan + status[:-1] + termcap.Normal + status[-1]
 
     # put it back in the list and join with space
     words[-1] = status