systemc: Modify reportifyException to keep sc_reports in scope.

reportifyException was sometimes indirectly creating temporary
sc_report objects which would go out of scope when they were
returned. The later code which tried to print them would then read
garbage.

Change-Id: I0a744eb029c62bf2ffee83db0a0e6dcbe3e60f7d
Reviewed-on: https://gem5-review.googlesource.com/c/13190
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>

src/systemc/core/sc_main.cc

@@ -81,8 +81,7 @@ class ScMainFiber : public Fiber
                 resultStr = r.what();
             } catch (...) {
                 // There was some other type of exception we need to wrap.
-                const sc_report *r = ::sc_gem5::reportifyException();
-                resultStr = r->what();
+                resultStr = ::sc_gem5::reportifyException().what();
             }
             ::sc_gem5::Kernel::scMainFinished(true);
             ::sc_gem5::scheduler.clear();

src/systemc/core/scheduler.cc

@@ -418,11 +418,10 @@ Scheduler::schedulePause()
 }
 
 void
-Scheduler::throwToScMain(const ::sc_core::sc_report *r)
+Scheduler::throwToScMain()
 {
-    if (!r)
-        r = reportifyException();
-    _throwToScMain = r;
+    ::sc_core::sc_report report = reportifyException();
+    _throwToScMain = &report;
     status(StatusOther);
     scMain->run();
 }
@@ -462,7 +461,7 @@ throwingReportHandler(const ::sc_core::sc_report &r,
 
 } // anonymous namespace
 
-const ::sc_core::sc_report *
+const ::sc_core::sc_report
 reportifyException()
 {
     ::sc_core::sc_report_handler_proc old_handler =
@@ -488,7 +487,7 @@ reportifyException()
         }
     } catch (const ::sc_core::sc_report &r) {
         ::sc_core::sc_report_handler::set_handler(old_handler);
-        return &r;
+        return r;
     }
     panic("No exception thrown in reportifyException.");
 }

src/systemc/core/scheduler.hh

@@ -365,7 +365,7 @@ class Scheduler
 
     uint64_t changeStamp() { return _changeStamp; }
 
-    void throwToScMain(const ::sc_core::sc_report *r=nullptr);
+    void throwToScMain();
 
     Status status() { return _status; }
     void status(Status s) { _status = s; }
@@ -511,7 +511,7 @@ Scheduler::TimeSlot::process()
     scheduler.completeTimeSlot(this);
 }
 
-const ::sc_core::sc_report *reportifyException();
+const ::sc_core::sc_report reportifyException();
 
 } // namespace sc_gem5