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.

1 files changed, 14 insertions, 13 deletions

diff --git a/src/cpu/o3/cpu.cc b/src/cpu/o3/cpu.cc
index 95683a77a..fdd45fdda 100644
--- a/src/cpu/o3/cpu.cc
+++ b/src/cpu/o3/cpu.cc
@@ -256,7 +256,8 @@ FullO3CPU<Impl>::FullO3CPU(DerivO3CPUParams *params)
       globalSeqNum(1),
       system(params->system),
       drainCount(0),
-      deferRegistration(params->defer_registration)
+      deferRegistration(params->defer_registration),
+      lastRunningCycle(curCycle())
 {
     if (!deferRegistration) {
         _status = Running;
@@ -386,8 +387,6 @@ FullO3CPU<Impl>::FullO3CPU(DerivO3CPUParams *params)
     // Setup the ROB for whichever stages need it.
     commit.setROB(&rob);
 
-    lastRunningCycle = curCycle();
-
     lastActivatedCycle = 0;
 #if 0
     // Give renameMap & rename stage access to the freeList;
@@ -629,7 +628,7 @@ FullO3CPU<Impl>::tick()
             lastRunningCycle = curCycle();
             timesIdled++;
         } else {
-            schedule(tickEvent, clockEdge(1));
+            schedule(tickEvent, clockEdge(Cycles(1)));
             DPRINTF(O3CPU, "Scheduling next tick!\n");
         }
     }
@@ -741,12 +740,12 @@ FullO3CPU<Impl>::totalOps() const
 
 template <class Impl>
 void
-FullO3CPU<Impl>::activateContext(ThreadID tid, int delay)
+FullO3CPU<Impl>::activateContext(ThreadID tid, Cycles delay)
 {
     // Needs to set each stage to running as well.
     if (delay){
         DPRINTF(O3CPU, "[tid:%i]: Scheduling thread context to activate "
-                "on cycle %d\n", tid, curTick() + ticks(delay));
+                "on cycle %d\n", tid, clockEdge(delay));
         scheduleActivateThreadEvent(tid, delay);
     } else {
         activateThread(tid);
@@ -762,7 +761,8 @@ FullO3CPU<Impl>::activateContext(ThreadID tid, int delay)
         activityRec.activity();
         fetch.wakeFromQuiesce();
 
-        Tick cycles = curCycle() - lastRunningCycle;
+        Cycles cycles(curCycle() - lastRunningCycle);
+        // @todo: This is an oddity that is only here to match the stats
         if (cycles != 0)
             --cycles;
         quiesceCycles += cycles;
@@ -776,12 +776,12 @@ FullO3CPU<Impl>::activateContext(ThreadID tid, int delay)
 template <class Impl>
 bool
 FullO3CPU<Impl>::scheduleDeallocateContext(ThreadID tid, bool remove,
-                                           int delay)
+                                           Cycles delay)
 {
     // Schedule removal of thread data from CPU
     if (delay){
         DPRINTF(O3CPU, "[tid:%i]: Scheduling thread context to deallocate "
-                "on cycle %d\n", tid, curTick() + ticks(delay));
+                "on tick %d\n", tid, clockEdge(delay));
         scheduleDeallocateContextEvent(tid, remove, delay);
         return false;
     } else {
@@ -797,7 +797,7 @@ void
 FullO3CPU<Impl>::suspendContext(ThreadID tid)
 {
     DPRINTF(O3CPU,"[tid: %i]: Suspending Thread Context.\n", tid);
-    bool deallocated = scheduleDeallocateContext(tid, false, 1);
+    bool deallocated = scheduleDeallocateContext(tid, false, Cycles(1));
     // If this was the last thread then unschedule the tick event.
     if ((activeThreads.size() == 1 && !deallocated) ||
         activeThreads.size() == 0)
@@ -814,7 +814,7 @@ FullO3CPU<Impl>::haltContext(ThreadID tid)
 {
     //For now, this is the same as deallocate
     DPRINTF(O3CPU,"[tid:%i]: Halt Context called. Deallocating", tid);
-    scheduleDeallocateContext(tid, true, 1);
+    scheduleDeallocateContext(tid, true, Cycles(1));
 }
 
 template <class Impl>
@@ -854,7 +854,7 @@ FullO3CPU<Impl>::insertThread(ThreadID tid)
 
     src_tc->setStatus(ThreadContext::Active);
 
-    activateContext(tid,1);
+    activateContext(tid, Cycles(1));
 
     //Reset ROB/IQ/LSQ Entries
     commit.rob->resetEntries();
@@ -1672,7 +1672,8 @@ FullO3CPU<Impl>::wakeCPU()
 
     DPRINTF(Activity, "Waking up CPU\n");
 
-    Tick cycles = curCycle() - lastRunningCycle;
+    Cycles cycles(curCycle() - lastRunningCycle);
+    // @todo: This is an oddity that is only here to match the stats
     if (cycles != 0)
         --cycles;
     idleCycles += cycles;