stats: track if the stats have been enabled and prevent requesting master id

Track the point in the initialization where statistics have been registered.
After this point registering new masterIds can no longer work as some
SimObjects may have sized stats vectors based on the previous value. If someone
tries to register a masterId after this point the simulator executes fatal().

5 files changed, 27 insertions, 3 deletions

diff --git a/src/base/statistics.cc b/src/base/statistics.cc
index e3f3ad78b..545d08cab 100644
--- a/src/base/statistics.cc
+++ b/src/base/statistics.cc
@@ -441,6 +441,23 @@ registerResetCallback(Callback *cb)
     resetQueue.add(cb);
 }
 
+bool _enabled = false;
+
+bool
+enabled()
+{
+    return _enabled;
+}
+
+void
+enable()
+{
+    if (_enabled)
+        fatal("Stats are already enabled");
+
+    _enabled = true;
+}
+
 } // namespace Stats
 
 void
diff --git a/src/base/statistics.hh b/src/base/statistics.hh
index 1f8a59326..cb63af708 100644
--- a/src/base/statistics.hh
+++ b/src/base/statistics.hh
@@ -3126,6 +3126,8 @@ sum(Temp val)
 /** Dump all statistics data to the registered outputs */
 void dump();
 void reset();
+void enable();
+bool enabled();
 
 /**
  * Register a callback that should be called whenever statistics are
diff --git a/src/python/m5/stats/__init__.py b/src/python/m5/stats/__init__.py
index 9b5af84fb..1d7e3bc5d 100644
--- a/src/python/m5/stats/__init__.py
+++ b/src/python/m5/stats/__init__.py
@@ -82,6 +82,8 @@ def enable():
         stats_dict[stat.name] = stat
         stat.enable()
 
+    internal.stats.enable();
+
 def prepare():
     '''Prepare all stats for data access.  This must be done before
     dumping and serialization.'''
diff --git a/src/python/swig/stats.i b/src/python/swig/stats.i
index 87810d305..14a6966b1 100644
--- a/src/python/swig/stats.i
+++ b/src/python/swig/stats.i
@@ -146,6 +146,8 @@ void schedStatEvent(bool dump, bool reset,
                     Tick when = curTick(), Tick repeat = 0);
 
 void processResetQueue();
+void enable();
+bool enabled();
 
 std::list<Info *> &statsList();
 
diff --git a/src/sim/system.cc b/src/sim/system.cc
index 40f5ea0ce..815a4cf1c 100644
--- a/src/sim/system.cc
+++ b/src/sim/system.cc
@@ -410,10 +410,11 @@ System::getMasterId(std::string master_name)
         }
     }
 
-    // todo: Check if stats are enabled yet
-    // I just don't know a good way to do it
+    // Verify that the statistics haven't been enabled yet
+    // Otherwise objects will have sized their stat buckets and
+    // they will be too small
 
-    if (false)
+    if (Stats::enabled())
         fatal("Can't request a masterId after regStats(). \
                 You must do so in init().\n");