Clock: Add a Cycles wrapper class and use where applicable

This patch addresses the comments and feedback on the preceding patch
that reworks the clocks and now more clearly shows where cycles
(relative cycle counts) are used to express time.

Instead of bumping the existing patch I chose to make this a separate
patch, merely to try and focus the discussion around a smaller set of
changes. The two patches will be pushed together though.

This changes done as part of this patch are mostly following directly
from the introduction of the wrapper class, and change enough code to
make things compile and run again. There are definitely more places
where int/uint/Tick is still used to represent cycles, and it will
take some time to chase them all down. Similarly, a lot of parameters
should be changed from Param.Tick and Param.Unsigned to
Param.Cycles.

In addition, the use of curTick is questionable as there should not be
an absolute cycle. Potential solutions can be built on top of this
patch. There is a similar situation in the o3 CPU where
lastRunningCycle is currently counting in Cycles, and is still an
absolute time. More discussion to be had in other words.

An additional change that would be appropriate in the future is to
perform a similar wrapping of Tick and probably also introduce a
Ticks class along with suitable operators for all these classes.

src/cpu/inorder/cpu.cc

@@ -209,7 +209,7 @@ InOrderCPU::CPUEvent::description() const
 }
 
 void
-InOrderCPU::CPUEvent::scheduleEvent(int delay)
+InOrderCPU::CPUEvent::scheduleEvent(Cycles delay)
 {
     assert(!scheduled() || squashed());
     cpu->reschedule(this, cpu->clockEdge(delay), true);
@@ -407,7 +407,7 @@ InOrderCPU::InOrderCPU(Params *params)
     lockFlag = false;
     
     // Schedule First Tick Event, CPU will reschedule itself from here on out.
-    scheduleTickEvent(0);
+    scheduleTickEvent(Cycles(0));
 }
 
 InOrderCPU::~InOrderCPU()
@@ -769,9 +769,9 @@ InOrderCPU::tick()
         } else {
             //Tick next_tick = curTick() + cycles(1);
             //tickEvent.schedule(next_tick);
-            schedule(&tickEvent, clockEdge(1));
+            schedule(&tickEvent, clockEdge(Cycles(1)));
             DPRINTF(InOrderCPU, "Scheduled CPU for next tick @ %i.\n", 
-                    clockEdge(1));
+                    clockEdge(Cycles(1)));
         }
     }
 
@@ -877,7 +877,7 @@ InOrderCPU::checkForInterrupts()
                 // Schedule Squash Through-out Resource Pool
                 resPool->scheduleEvent(
                     (InOrderCPU::CPUEventType)ResourcePool::SquashAll,
-                    dummyTrapInst[tid], 0);
+                    dummyTrapInst[tid], Cycles(0));
 
                 // Finally, Setup Trap to happen at end of cycle
                 trapContext(interrupt, tid, dummyTrapInst[tid]);
@@ -912,7 +912,8 @@ InOrderCPU::processInterrupts(Fault interrupt)
 }
 
 void
-InOrderCPU::trapContext(Fault fault, ThreadID tid, DynInstPtr inst, int delay)
+InOrderCPU::trapContext(Fault fault, ThreadID tid, DynInstPtr inst,
+                        Cycles delay)
 {
     scheduleCpuEvent(Trap, fault, tid, inst, delay);
     trapPending[tid] = true;
@@ -926,7 +927,8 @@ InOrderCPU::trap(Fault fault, ThreadID tid, DynInstPtr inst)
 }
 
 void 
-InOrderCPU::squashFromMemStall(DynInstPtr inst, ThreadID tid, int delay)
+InOrderCPU::squashFromMemStall(DynInstPtr inst, ThreadID tid,
+                               Cycles delay)
 {
     scheduleCpuEvent(SquashFromMemStall, NoFault, tid, inst, delay);
 }
@@ -954,7 +956,7 @@ InOrderCPU::squashDueToMemStall(int stage_num, InstSeqNum seq_num,
 void
 InOrderCPU::scheduleCpuEvent(CPUEventType c_event, Fault fault,
                              ThreadID tid, DynInstPtr inst, 
-                             unsigned delay, CPUEventPri event_pri)
+                             Cycles delay, CPUEventPri event_pri)
 {
     CPUEvent *cpu_event = new CPUEvent(this, c_event, fault, tid, inst,
                                        event_pri);
@@ -967,7 +969,8 @@ InOrderCPU::scheduleCpuEvent(CPUEventType c_event, Fault fault,
     // Broadcast event to the Resource Pool
     // Need to reset tid just in case this is a dummy instruction
     inst->setTid(tid);        
-    resPool->scheduleEvent(c_event, inst, 0, 0, tid);
+    // @todo: Is this really right? Should the delay not be passed on?
+    resPool->scheduleEvent(c_event, inst, Cycles(0), 0, tid);
 }
 
 bool
@@ -1071,7 +1074,7 @@ InOrderCPU::activateThreadInPipeline(ThreadID tid)
 }
 
 void
-InOrderCPU::deactivateContext(ThreadID tid, int delay)
+InOrderCPU::deactivateContext(ThreadID tid, Cycles delay)
 {
     DPRINTF(InOrderCPU,"[tid:%i]: Deactivating ...\n", tid);
 
@@ -1153,7 +1156,7 @@ InOrderCPU::tickThreadStats()
 }
 
 void
-InOrderCPU::activateContext(ThreadID tid, int delay)
+InOrderCPU::activateContext(ThreadID tid, Cycles delay)
 {
     DPRINTF(InOrderCPU,"[tid:%i]: Activating ...\n", tid);
 
@@ -1168,7 +1171,7 @@ InOrderCPU::activateContext(ThreadID tid, int delay)
 }
 
 void
-InOrderCPU::activateNextReadyContext(int delay)
+InOrderCPU::activateNextReadyContext(Cycles delay)
 {
     DPRINTF(InOrderCPU,"Activating next ready thread\n");
 
@@ -1719,7 +1722,8 @@ InOrderCPU::wakeup()
 }
 
 void
-InOrderCPU::syscallContext(Fault fault, ThreadID tid, DynInstPtr inst, int delay)
+InOrderCPU::syscallContext(Fault fault, ThreadID tid, DynInstPtr inst,
+                           Cycles delay)
 {
     // Syscall must be non-speculative, so squash from last stage
     unsigned squash_stage = NumStages - 1;
@@ -1730,7 +1734,8 @@ InOrderCPU::syscallContext(Fault fault, ThreadID tid, DynInstPtr inst, int delay
 
     // Schedule Squash Through-out Resource Pool
     resPool->scheduleEvent(
-        (InOrderCPU::CPUEventType)ResourcePool::SquashAll, inst, 0);
+        (InOrderCPU::CPUEventType)ResourcePool::SquashAll, inst,
+        Cycles(0));
     scheduleCpuEvent(Syscall, fault, tid, inst, delay, Syscall_Pri);
 }