systemc: Rework how delta and timed notifications/timeouts are tracked.

Rather than delegating them entirely to the gem5 event queue and using
priorities to ensure the right thing happens, this change adds a few
new structures which keep track of them and give the scheduler more
control over what happens and in what order. The old scheme was mostly
correct, but there were some competing situations which made it next
to impossible to make everything happen at the right time.

Change-Id: I43f4dd6ddfa488a31073c0318bb41369b1a6117d
Reviewed-on: https://gem5-review.googlesource.com/12213
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>

1 files changed, 10 insertions, 21 deletions

diff --git a/src/systemc/core/event.cc b/src/systemc/core/event.cc
index 05670fe59..6e35da1c8 100644
--- a/src/systemc/core/event.cc
+++ b/src/systemc/core/event.cc
@@ -44,7 +44,8 @@ namespace sc_gem5
 Event::Event(sc_core::sc_event *_sc_event) : Event(_sc_event, "") {}
 
 Event::Event(sc_core::sc_event *_sc_event, const char *_basename) :
-    _sc_event(_sc_event), _basename(_basename), delayedNotifyEvent(this)
+    _sc_event(_sc_event), _basename(_basename),
+    delayedNotify([this]() { this->notify(); })
 {
     Module *p = currentModule();
 
@@ -90,8 +91,8 @@ Event::~Event()
     std::swap(*it, allEvents.back());
     allEvents.pop_back();
 
-    if (delayedNotifyEvent.scheduled())
-        scheduler.deschedule(&delayedNotifyEvent);
+    if (delayedNotify.scheduled())
+        scheduler.deschedule(&delayedNotify);
 }
 
 const std::string &
@@ -127,34 +128,22 @@ Event::notify()
 }
 
 void
-Event::delayedNotify()
-{
-    scheduler.eventHappened();
-    notify();
-}
-
-void
 Event::notify(const sc_core::sc_time &t)
 {
-    //XXX We're assuming the systemc time resolution is in ps.
-    Tick new_tick = t.value() * SimClock::Int::ps + scheduler.getCurTick();
-    if (delayedNotifyEvent.scheduled()) {
-        Tick old_tick = delayedNotifyEvent.when();
-
-        if (new_tick >= old_tick)
+    if (delayedNotify.scheduled()) {
+        if (scheduler.delayed(t) >= delayedNotify.when())
             return;
 
-        scheduler.deschedule(&delayedNotifyEvent);
+        scheduler.deschedule(&delayedNotify);
     }
-
-    scheduler.schedule(&delayedNotifyEvent, new_tick);
+    scheduler.schedule(&delayedNotify, t);
 }
 
 void
 Event::cancel()
 {
-    if (delayedNotifyEvent.scheduled())
-        scheduler.deschedule(&delayedNotifyEvent);
+    if (delayedNotify.scheduled())
+        scheduler.deschedule(&delayedNotify);
 }
 
 bool