cpu: Added correct return type for ROB::countInsts

- return size_t (unsigned) according to the .size() return type
- fixed typo in doc (source of warning with some compilers)

Change-Id: I48ee2e317cf41011a6fcb5ca45aef67e75329bfa
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/18948
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/cpu/base.hh

@@ -287,7 +287,9 @@ class BaseCPU : public ClockedObject
    virtual ThreadContext *getContext(int tn) { return threadContexts[tn]; }
 
    /// Get the number of thread contexts available
-   unsigned numContexts() { return threadContexts.size(); }
+   unsigned numContexts() {
+       return static_cast<unsigned>(threadContexts.size());
+   }
 
     /// Convert ContextID to threadID
     ThreadID contextToThread(ContextID cid)
@@ -399,7 +401,7 @@ class BaseCPU : public ClockedObject
      * uniform data format for all CPU models and promotes better code
      * reuse.
      *
-     * @param os The stream to serialize to.
+     * @param cp The stream to serialize to.
      */
     void serialize(CheckpointOut &cp) const override;
 
@@ -412,14 +414,13 @@ class BaseCPU : public ClockedObject
      * promotes better code reuse.
 
      * @param cp The checkpoint use.
-     * @param section The section name of this object.
      */
     void unserialize(CheckpointIn &cp) override;
 
     /**
      * Serialize a single thread.
      *
-     * @param os The stream to serialize to.
+     * @param cp The stream to serialize to.
      * @param tid ID of the current thread.
      */
     virtual void serializeThread(CheckpointOut &cp, ThreadID tid) const {};
@@ -428,7 +429,6 @@ class BaseCPU : public ClockedObject
      * Unserialize one thread.
      *
      * @param cp The checkpoint use.
-     * @param section The section name of this thread.
      * @param tid ID of the current thread.
      */
     virtual void unserializeThread(CheckpointIn &cp, ThreadID tid) {};

src/cpu/o3/rob.hh

@@ -258,7 +258,7 @@ class ROB
      *  threadEntries to get the instructions in the ROB unless you are
      *  double checking that variable.
      */
-    int countInsts(ThreadID tid);
+    size_t countInsts(ThreadID tid);
 
     /** Registers statistics. */
     void regStats();

src/cpu/o3/rob_impl.hh

@@ -153,7 +153,7 @@ void
 ROB<Impl>::resetEntries()
 {
     if (robPolicy != SMTQueuePolicy::Dynamic || numThreads > 1) {
-        int active_threads = activeThreads->size();
+        auto active_threads = activeThreads->size();
 
         list<ThreadID>::iterator threads = activeThreads->begin();
         list<ThreadID>::iterator end = activeThreads->end();
@@ -195,7 +195,7 @@ ROB<Impl>::countInsts()
 }
 
 template <class Impl>
-int
+size_t
 ROB<Impl>::countInsts(ThreadID tid)
 {
     return instList[tid].size();