config: Add a --without-python option to build process

Add the ability to build libgem5 without embedded Python or the
ability to configure with Python.

This is a prelude to a patch to allow config.ini files to be loaded
into libgem5 using only C++ which would make embedding gem5 within
other simulation systems easier.

This adds a few registration interfaces to things which cross
between Python and C++.  Namely: stats dumping and SimObject resolving

src/python/SConscript

@@ -31,8 +31,8 @@
 
 Import('*')
 
-Source('swig/pyevent.cc')
-Source('swig/pyobject.cc')
+Source('swig/pyevent.cc', skip_no_python=True)
+Source('swig/pyobject.cc', skip_no_python=True)
 
 PySource('', 'importer.py')
 PySource('m5', 'm5/__init__.py')

src/python/m5/stats/__init__.py

@@ -41,6 +41,7 @@ def initText(filename, desc=True):
 
 def initSimStats():
     internal.stats.initSimStats()
+    internal.stats.registerPythonStatsHandlers()
 
 names = []
 stats_dict = {}

src/python/swig/pyobject.cc

@@ -157,9 +157,12 @@ extern "C" SimObject *convertSwigSimObjectPtr(PyObject *);
 // these in sim/main.cc as well that are handled without this define.
 #define PCC(s)  const_cast<char *>(s)
 
+/** Single instance of PythonSimObjectResolver as its action is effectively
+ *  static but SimObjectResolver can use a non-persistent object */
+PythonSimObjectResolver pythonSimObjectResolver;
 
 SimObject *
-resolveSimObject(const string &name)
+PythonSimObjectResolver::resolveSimObject(const string &name)
 {
     PyObject *module = PyImport_ImportModule(PCC("m5.SimObject"));
     if (module == NULL)
@@ -188,3 +191,9 @@ resolveSimObject(const string &name)
 
     return obj;
 }
+
+Checkpoint *
+getCheckpoint(const std::string &cpt_dir)
+{
+    return new Checkpoint(cpt_dir, pythonSimObjectResolver);
+}

src/python/swig/pyobject.hh

@@ -36,7 +36,12 @@
 #include "sim/sim_object.hh"
 
 extern "C" SimObject *convertSwigSimObjectPtr(PyObject *);
-SimObject *resolveSimObject(const std::string &name);
+
+/** Resolve a SimObject name using the Python configuration */
+class PythonSimObjectResolver : public SimObjectResolver
+{
+    SimObject *resolveSimObject(const std::string &name);
+};
 
 EtherInt * lookupEthPort(SimObject *so, const std::string &name, int i);
 
@@ -53,11 +58,8 @@ serializeAll(const std::string &cpt_dir)
     Serializable::serializeAll(cpt_dir);
 }
 
-inline Checkpoint *
-getCheckpoint(const std::string &cpt_dir)
-{
-    return new Checkpoint(cpt_dir);
-}
+Checkpoint *
+getCheckpoint(const std::string &cpt_dir);
 
 inline void
 unserializeGlobals(Checkpoint *cp)

src/python/swig/stats.i

@@ -43,6 +43,7 @@
 #include "base/statistics.hh"
 #include "sim/core.hh"
 #include "sim/stat_control.hh"
+#include "sim/stat_register.hh"
 
 namespace Stats {
 template <class T>
@@ -64,20 +65,6 @@ Stats_Info_flags_set(Info *info, FlagsType flags)
     info->flags = flags;
 }
 
-inline void
-processResetQueue()
-{
-    extern CallbackQueue resetQueue;
-    resetQueue.process();
-}
-
-inline void
-processDumpQueue()
-{
-    extern CallbackQueue dumpQueue;
-    dumpQueue.process();
-}
-
 inline char *
 PCC(const char *string)
 {
@@ -102,13 +89,13 @@ call_module_function(const char *module_name, const char *func_name)
 }
 
 void
-dump()
+pythonDump()
 {
     call_module_function("m5.stats", "dump");
 }
 
 void
-reset()
+pythonReset()
 {
     call_module_function("m5.stats", "reset");
 }
@@ -150,6 +137,8 @@ template <class T> T cast_info(Info *info);
 void initSimStats();
 Output *initText(const std::string &filename, bool desc);
 
+void registerPythonStatsHandlers();
+
 void schedStatEvent(bool dump, bool reset,
                     Tick when = curTick(), Tick repeat = 0);