systemc: Seperate out the sc_main fiber and its bookkeeping.

By pulling out the sc_main fiber (scMainFiber), we can make it
available to different entities in the simulator and avoid having to
have parallel bookkeeping.

Also this will make it possible to hook into sc_main without putting
the code in sc_main.cc.

Change-Id: I7689441424238e9b2e4d2b48e945dea35fd8cc5d
Reviewed-on: https://gem5-review.googlesource.com/c/13977
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Gabe Black <gabeblack@google.com>

8 files changed, 186 insertions, 98 deletions

diff --git a/src/systemc/core/SConscript b/src/systemc/core/SConscript
index 1f5498b93..41abba417 100644
--- a/src/systemc/core/SConscript
+++ b/src/systemc/core/SConscript
@@ -50,6 +50,7 @@ if env['USE_SYSTEMC']:
     Source('sc_interface.cc')
     Source('sc_join.cc')
     Source('sc_main.cc')
+    Source('sc_main_fiber.cc')
     Source('sc_module.cc')
     Source('sc_module_name.cc')
     Source('sc_object.cc')
diff --git a/src/systemc/core/kernel.cc b/src/systemc/core/kernel.cc
index 11292c4a5..2fd3027da 100644
--- a/src/systemc/core/kernel.cc
+++ b/src/systemc/core/kernel.cc
@@ -33,6 +33,7 @@
 #include "systemc/core/channel.hh"
 #include "systemc/core/module.hh"
 #include "systemc/core/port.hh"
+#include "systemc/core/sc_main_fiber.hh"
 #include "systemc/core/scheduler.hh"
 
 namespace sc_gem5
@@ -41,7 +42,6 @@ namespace sc_gem5
 namespace
 {
 
-bool scMainDone = false;
 bool stopAfterCallbacks = false;
 bool startComplete = false;
 bool endComplete = false;
@@ -53,9 +53,6 @@ sc_core::sc_status _status = sc_core::SC_ELABORATION;
 bool Kernel::startOfSimulationComplete() { return startComplete; }
 bool Kernel::endOfSimulationComplete() { return endComplete; }
 
-bool Kernel::scMainFinished() { return scMainDone; }
-void Kernel::scMainFinished(bool finished) { scMainDone = finished; }
-
 sc_core::sc_status Kernel::status() { return _status; }
 void Kernel::status(sc_core::sc_status s) { _status = s; }
 
@@ -69,7 +66,7 @@ Kernel::Kernel(Params *params) :
 void
 Kernel::init()
 {
-    if (scMainDone)
+    if (scMainFiber.finished())
         return;
 
     if (stopAfterCallbacks)
@@ -89,7 +86,7 @@ Kernel::init()
 void
 Kernel::regStats()
 {
-    if (scMainDone || stopAfterCallbacks)
+    if (scMainFiber.finished() || stopAfterCallbacks)
         return;
 
     try {
@@ -113,7 +110,7 @@ Kernel::regStats()
 void
 Kernel::startup()
 {
-    if (scMainDone)
+    if (scMainFiber.finished())
         return;
 
     schedule(t0Event, curTick());
diff --git a/src/systemc/core/kernel.hh b/src/systemc/core/kernel.hh
index e0808fe47..b9a37d00a 100644
--- a/src/systemc/core/kernel.hh
+++ b/src/systemc/core/kernel.hh
@@ -64,9 +64,6 @@ class Kernel : public SimObject
     static bool startOfSimulationComplete();
     static bool endOfSimulationComplete();
 
-    static bool scMainFinished();
-    static void scMainFinished(bool);
-
   private:
     static void stopWork();
 
diff --git a/src/systemc/core/sc_main.cc b/src/systemc/core/sc_main.cc
index a5e0366b9..e2f69bb58 100644
--- a/src/systemc/core/sc_main.cc
+++ b/src/systemc/core/sc_main.cc
@@ -38,119 +38,67 @@
 #include "sim/init.hh"
 #include "systemc/core/kernel.hh"
 #include "systemc/core/python.hh"
+#include "systemc/core/sc_main_fiber.hh"
 #include "systemc/core/scheduler.hh"
 #include "systemc/ext/core/messages.hh"
 #include "systemc/ext/core/sc_main.hh"
 #include "systemc/ext/utils/sc_report_handler.hh"
 #include "systemc/utils/report.hh"
 
-// A weak symbol to detect if sc_main has been defined, and if so where it is.
-[[gnu::weak]] int sc_main(int argc, char *argv[]);
-
 namespace sc_core
 {
 
 namespace
 {
 
-bool scMainCalled = false;
-
-int _argc = 0;
-char **_argv = NULL;
-
-class ScMainFiber : public Fiber
-{
-  public:
-    std::string resultStr;
-    int resultInt;
-
-    ScMainFiber() : resultInt(1) {}
-
-    void
-    main()
-    {
-        if (::sc_main) {
-            try {
-                resultInt = ::sc_main(_argc, _argv);
-                if (resultInt)
-                    resultStr = "sc_main returned non-zero";
-                else
-                    resultStr = "sc_main finished";
-                // Make sure no systemc events/notifications are scheduled
-                // after sc_main returns.
-            } catch (const sc_report &r) {
-                // There was an exception nobody caught.
-                resultStr = "uncaught sc_report";
-                sc_gem5::reportHandlerProc(
-                        r, sc_report_handler::get_catch_actions());
-            } catch (...) {
-                // There was some other type of exception we need to wrap.
-                resultStr = "uncaught exception";
-                sc_gem5::reportHandlerProc(
-                        ::sc_gem5::reportifyException(),
-                        sc_report_handler::get_catch_actions());
-            }
-            ::sc_gem5::Kernel::scMainFinished(true);
-            ::sc_gem5::scheduler.clear();
-        } else {
-            // If python tries to call sc_main but no sc_main was defined...
-            fatal("sc_main called but not defined.\n");
-        }
-    }
-};
-
-ScMainFiber scMainFiber;
-
 // This wrapper adapts the python version of sc_main to the c++ version.
 void
 sc_main(pybind11::args args)
 {
-    panic_if(scMainCalled, "sc_main called more than once.");
+    panic_if(::sc_gem5::scMainFiber.called(),
+            "sc_main called more than once.");
 
-    _argc = args.size();
-    _argv = new char *[_argc];
+    int argc = args.size();
+    char **argv = new char *[argc];
 
-    // Initialize all the _argvs to NULL so we can delete [] them
+    // Initialize all the argvs to NULL so we can delete [] them
     // unconditionally.
-    for (int idx = 0; idx < _argc; idx++)
-        _argv[idx] = NULL;
+    for (int idx = 0; idx < argc; idx++)
+        argv[idx] = NULL;
 
     // Attempt to convert all the arguments to strings. If that fails, clean
     // up after ourselves. Also don't count this as a call to sc_main since
     // we never got to the c++ version of that function.
     try {
-        for (int idx = 0; idx < _argc; idx++) {
+        for (int idx = 0; idx < argc; idx++) {
             std::string arg = args[idx].cast<std::string>();
-            _argv[idx] = new char[arg.length() + 1];
-            strcpy(_argv[idx], arg.c_str());
+            argv[idx] = new char[arg.length() + 1];
+            strcpy(argv[idx], arg.c_str());
         }
     } catch (...) {
         // If that didn't work for some reason (probably a conversion error)
-        // blow away _argv and _argc and pass on the exception.
-        for (int idx = 0; idx < _argc; idx++)
-            delete [] _argv[idx];
-        delete [] _argv;
-        _argc = 0;
+        // blow away argv and argc and pass on the exception.
+        for (int idx = 0; idx < argc; idx++)
+            delete [] argv[idx];
+        delete [] argv;
+        argc = 0;
         throw;
     }
 
-    // At this point we're going to call the c++ sc_main, so we can't try
-    // again later.
-    scMainCalled = true;
-
-    scMainFiber.run();
+    ::sc_gem5::scMainFiber.setArgs(argc, argv);
+    ::sc_gem5::scMainFiber.run();
 }
 
 int
 sc_main_result_code()
 {
-    return scMainFiber.resultInt;
+    return ::sc_gem5::scMainFiber.resultInt();
 }
 
 std::string
 sc_main_result_str()
 {
-    return scMainFiber.resultStr;
+    return ::sc_gem5::scMainFiber.resultStr();
 }
 
 // Make our sc_main wrapper available in the internal _m5 python module under
@@ -174,13 +122,13 @@ sc_stop_mode _stop_mode = SC_STOP_FINISH_DELTA;
 int
 sc_argc()
 {
-    return _argc;
+    return ::sc_gem5::scMainFiber.argc();
 }
 
 const char *const *
 sc_argv()
 {
-    return _argv;
+    return ::sc_gem5::scMainFiber.argv();
 }
 
 void
diff --git a/src/systemc/core/sc_main_fiber.cc b/src/systemc/core/sc_main_fiber.cc
new file mode 100644
index 000000000..aa10c19c4
--- /dev/null
+++ b/src/systemc/core/sc_main_fiber.cc
@@ -0,0 +1,82 @@
+/*
+ * Copyright 2018 Google, Inc.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met: redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer;
+ * redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution;
+ * neither the name of the copyright holders nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * Authors: Gabe Black
+ */
+
+#include "systemc/core/sc_main_fiber.hh"
+
+#include <cstring>
+#include <string>
+
+#include "systemc/core/kernel.hh"
+#include "systemc/core/scheduler.hh"
+#include "systemc/ext/core/messages.hh"
+#include "systemc/ext/core/sc_main.hh"
+#include "systemc/ext/utils/sc_report_handler.hh"
+#include "systemc/utils/report.hh"
+
+// A weak symbol to detect if sc_main has been defined, and if so where it is.
+[[gnu::weak]] int sc_main(int argc, char *argv[]);
+
+namespace sc_gem5
+{
+
+void
+ScMainFiber::main()
+{
+    _called = true;
+
+    if (::sc_main) {
+        try {
+            _resultInt = ::sc_main(_argc, _argv);
+            if (_resultInt)
+                _resultStr = "sc_main returned non-zero";
+            else
+                _resultStr = "sc_main finished";
+            // Make sure no systemc events/notifications are scheduled
+            // after sc_main returns.
+        } catch (const ::sc_core::sc_report &r) {
+            // There was an exception nobody caught.
+            _resultStr = "uncaught sc_report";
+            reportHandlerProc(
+                    r, ::sc_core::sc_report_handler::get_catch_actions());
+        } catch (...) {
+            // There was some other type of exception we need to wrap.
+            _resultStr = "uncaught exception";
+            reportHandlerProc(reportifyException(),
+                    ::sc_core::sc_report_handler::get_catch_actions());
+        }
+        scheduler.clear();
+    } else {
+        // If python tries to call sc_main but no sc_main was defined...
+        fatal("sc_main called but not defined.\n");
+    }
+}
+
+ScMainFiber scMainFiber;
+
+} // namespace sc_gem5
diff --git a/src/systemc/core/sc_main_fiber.hh b/src/systemc/core/sc_main_fiber.hh
new file mode 100644
index 000000000..2e89f11df
--- /dev/null
+++ b/src/systemc/core/sc_main_fiber.hh
@@ -0,0 +1,70 @@
+/*
+ * Copyright 2018 Google, Inc.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met: redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer;
+ * redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution;
+ * neither the name of the copyright holders nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * Authors: Gabe Black
+ */
+
+#ifndef __SYSTEMC_CORE_SC_MAIN_FIBER_HH__
+#define __SYSTEMC_CORE_SC_MAIN_FIBER_HH__
+
+#include "base/fiber.hh"
+#include "base/logging.hh"
+
+namespace sc_gem5
+{
+
+class ScMainFiber : public Fiber
+{
+  private:
+    int _argc = 0;
+    char **_argv = NULL;
+    std::string _resultStr;
+    int _resultInt = 1;
+
+    bool _called = false;
+
+  public:
+    int argc() { return _argc; }
+    const char *const *argv() { return _argv; }
+    std::string resultStr() { return _resultStr; }
+    int resultInt() { return _resultInt; }
+    bool called() { return _called; }
+
+    void
+    setArgs(int new_argc, char **new_argv)
+    {
+        _argc = new_argc;
+        _argv = new_argv;
+    }
+
+    void main() override;
+};
+
+extern ScMainFiber scMainFiber;
+
+} // namespace sc_gem5
+
+#endif // __SYSTEMC_CORE_SC_MAIN_FIBER_HH__
diff --git a/src/systemc/core/scheduler.cc b/src/systemc/core/scheduler.cc
index 5e96a47d5..a2e52f0ca 100644
--- a/src/systemc/core/scheduler.cc
+++ b/src/systemc/core/scheduler.cc
@@ -33,6 +33,7 @@
 #include "base/logging.hh"
 #include "sim/eventq.hh"
 #include "systemc/core/kernel.hh"
+#include "systemc/core/sc_main_fiber.hh"
 #include "systemc/ext/core/messages.hh"
 #include "systemc/ext/core/sc_main.hh"
 #include "systemc/ext/utils/sc_report.hh"
@@ -46,8 +47,7 @@ namespace sc_gem5
 Scheduler::Scheduler() :
     eq(nullptr), readyEvent(this, false, ReadyPriority),
     pauseEvent(this, false, PausePriority),
-    stopEvent(this, false, StopPriority),
-    scMain(nullptr), _throwToScMain(nullptr),
+    stopEvent(this, false, StopPriority), _throwToScMain(nullptr),
     starvationEvent(this, false, StarvationPriority),
     _elaborationDone(false), _started(false), _stopNow(false),
     _status(StatusOther), maxTickEvent(this, false, MaxTickPriority),
@@ -349,8 +349,8 @@ Scheduler::pause()
     status(StatusPaused);
     kernel->status(::sc_core::SC_PAUSED);
     runOnce = false;
-    if (scMain && !scMain->finished())
-        scMain->run();
+    if (scMainFiber.called() && !scMainFiber.finished())
+        scMainFiber.run();
 }
 
 void
@@ -362,17 +362,13 @@ Scheduler::stop()
     clear();
 
     runOnce = false;
-    if (scMain && !scMain->finished())
-        scMain->run();
+    if (scMainFiber.called() && !scMainFiber.finished())
+        scMainFiber.run();
 }
 
 void
 Scheduler::start(Tick max_tick, bool run_to_time)
 {
-    // We should be running from sc_main. Keep track of that Fiber to return
-    // to later.
-    scMain = Fiber::currentFiber();
-
     _started = true;
     status(StatusOther);
     runToTime = run_to_time;
@@ -431,7 +427,7 @@ Scheduler::throwToScMain()
     ::sc_core::sc_report report = reportifyException();
     _throwToScMain = &report;
     status(StatusOther);
-    scMain->run();
+    scMainFiber.run();
 }
 
 void
diff --git a/src/systemc/core/scheduler.hh b/src/systemc/core/scheduler.hh
index 2ae03ea1b..64841086d 100644
--- a/src/systemc/core/scheduler.hh
+++ b/src/systemc/core/scheduler.hh
@@ -333,8 +333,6 @@ class Scheduler
     // Run delta events.
     void runDelta();
 
-    void setScMainFiber(Fiber *sc_main) { scMain = sc_main; }
-
     void start(Tick max_tick, bool run_to_time);
     void oneCycle();
 
@@ -426,7 +424,6 @@ class Scheduler
     EventWrapper<Scheduler, &Scheduler::pause> pauseEvent;
     EventWrapper<Scheduler, &Scheduler::stop> stopEvent;
 
-    Fiber *scMain;
     const ::sc_core::sc_report *_throwToScMain;
 
     bool