From e02b2a3d3b0d2d56e7a968269da022cbe68f7ca2 Mon Sep 17 00:00:00 2001
From: Gabe Black <gabeblack@google.com>
Date: Mon, 16 Jul 2018 16:44:07 -0700
Subject: systemc: Handle suspended processes and handle sensitivity overload.

This change keeps track of whether a process would have become ready
but was suspended so that it can become ready when the process is
resumed.

Also, this makes a process ignore its static sensitivity while a
dynamic sensitivity is in place.

Change-Id: If3f6c62f370051e574f81bf227746db8c43527e2
Reviewed-on: https://gem5-review.googlesource.com/11715
Reviewed-by: Gabe Black <gabeblack@google.com>
Maintainer: Gabe Black <gabeblack@google.com>
---
 src/systemc/core/process.cc   | 36 +++++++++++++++++++++++++-----------
 src/systemc/core/process.hh   | 14 ++++++++++++--
 src/systemc/core/scheduler.cc |  4 ++--
 3 files changed, 39 insertions(+), 15 deletions(-)

diff --git a/src/systemc/core/process.cc b/src/systemc/core/process.cc
index a949c9dee..63d2ff94b 100644
--- a/src/systemc/core/process.cc
+++ b/src/systemc/core/process.cc
@@ -36,14 +36,6 @@
 namespace sc_gem5
 {
 
-void
-Sensitivity::satisfy()
-{
-    warn_once("Ignoring suspended status for now.\n");
-    process->setDynamic(nullptr);
-    scheduler.ready(process);
-}
-
 SensitivityTimeout::SensitivityTimeout(Process *p, ::sc_core::sc_time t) :
     Sensitivity(p), timeoutEvent(this), timeout(t)
 {
@@ -88,7 +80,7 @@ SensitivityEventAndList::notifyWork(Event *e)
     e->delSensitivity(this);
     count++;
     if (count == list->events.size())
-        satisfy();
+        process->satisfySensitivity(this);
 }
 
 SensitivityEventOrList::SensitivityEventOrList(
@@ -150,7 +142,7 @@ Process::suspend(bool inc_kids)
 
     if (!_suspended) {
         _suspended = true;
-        //TODO Suspend this process.
+        _suspendedReady = false;
     }
 
     if (procKind() != ::sc_core::SC_METHOD_PROC_ &&
@@ -167,7 +159,9 @@ Process::resume(bool inc_kids)
 
     if (_suspended) {
         _suspended = false;
-        //TODO Resume this process.
+        if (_suspendedReady)
+            ready();
+        _suspendedReady = false;
     }
 }
 
@@ -309,6 +303,26 @@ Process::setDynamic(Sensitivity *s)
     dynamicSensitivity = s;
 }
 
+void
+Process::satisfySensitivity(Sensitivity *s)
+{
+    // If there's a dynamic sensitivity and this wasn't it, ignore.
+    if (dynamicSensitivity && dynamicSensitivity != s)
+        return;
+
+    setDynamic(nullptr);
+    ready();
+}
+
+void
+Process::ready()
+{
+    if (suspended())
+        _suspendedReady = true;
+    else
+        scheduler.ready(this);
+}
+
 Process::Process(const char *name, ProcessFuncWrapper *func, bool _dynamic) :
     ::sc_core::sc_object(name), excWrapper(nullptr), func(func),
     _running(false), _dynamic(_dynamic), _isUnwinding(false),
diff --git a/src/systemc/core/process.hh b/src/systemc/core/process.hh
index cd92992eb..579ea602f 100644
--- a/src/systemc/core/process.hh
+++ b/src/systemc/core/process.hh
@@ -51,13 +51,12 @@ class Sensitivity
 {
   protected:
     Process *process;
-    void satisfy();
 
   public:
     Sensitivity(Process *p) : process(p) {}
     virtual ~Sensitivity() {}
 
-    virtual void notifyWork(Event *e) { satisfy(); }
+    virtual void notifyWork(Event *e);
     void notify(Event *e);
     void notify() { notify(nullptr); }
 
@@ -290,6 +289,10 @@ class Process : public ::sc_core::sc_object, public ListNode
     void addStatic(PendingSensitivity *);
     void setDynamic(Sensitivity *);
 
+    void satisfySensitivity(Sensitivity *);
+
+    void ready();
+
     virtual Fiber *fiber() { return Fiber::primaryFiber(); }
 
     static Process *newest() { return _newest; }
@@ -317,6 +320,7 @@ class Process : public ::sc_core::sc_object, public ListNode
     bool _terminated;
 
     bool _suspended;
+    bool _suspendedReady;
     bool _disabled;
 
     bool _syncReset;
@@ -331,6 +335,12 @@ class Process : public ::sc_core::sc_object, public ListNode
     Sensitivity *dynamicSensitivity;
 };
 
+inline void
+Sensitivity::notifyWork(Event *e)
+{
+    process->satisfySensitivity(this);
+}
+
 inline void
 Sensitivity::notify(Event *e)
 {
diff --git a/src/systemc/core/scheduler.cc b/src/systemc/core/scheduler.cc
index 8ea090f57..230ed0af2 100644
--- a/src/systemc/core/scheduler.cc
+++ b/src/systemc/core/scheduler.cc
@@ -51,7 +51,7 @@ Scheduler::prepareForInit()
 
     for (Process *p = initList.getNext(); p; p = initList.getNext()) {
         p->finalize();
-        ready(p);
+        p->ready();
     }
 
     initReady = true;
@@ -64,7 +64,7 @@ Scheduler::reg(Process *p)
         // If we're past initialization, finalize static sensitivity.
         p->finalize();
         // Mark the process as ready.
-        ready(p);
+        p->ready();
     } else {
         // Otherwise, record that this process should be initialized once we
         // get there.
-- 
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