misc: Fix 'unused variable' clang errors with gem5.fast

Change-Id: I2bb8ac10e8db69fa82abe41577cd8e5db575e93d
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/70297
Maintainer: Bobby Bruce <bbruce@ucdavis.edu>
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Reviewed-by: Daniel Carvalho <odanrc@yahoo.com.br>

src/cpu/activity.cc

@@ -151,6 +151,7 @@ ActivityRecorder::dump()
 void
 ActivityRecorder::validate()
 {
+#ifdef DEBUG
     int count = 0;
     for (int i = 0; i <= longestLatency; ++i) {
         if (activityBuffer[-i]) {
@@ -165,6 +166,7 @@ ActivityRecorder::validate()
     }
 
     assert(count == activityCount);
+#endif
 }
 
 } // namespace gem5

src/cpu/minor/execute.cc

@@ -568,10 +568,6 @@ Execute::issue(ThreadID thread_id)
     /* Number of memory ops issues this cycle to check for memoryIssueLimit */
     unsigned num_mem_insts_issued = 0;
 
-    /* Number of instructions discarded this cycle in order to enforce a
-     *  discardLimit. @todo, add that parameter? */
-    unsigned num_insts_discarded = 0;
-
     do {
         MinorDynInstPtr inst = insts_in->insts[thread.inputIndex];
         Fault fault = inst->fault;
@@ -800,9 +796,7 @@ Execute::issue(ThreadID thread_id)
             if (issued_mem_ref)
                 num_mem_insts_issued++;
 
-            if (discarded) {
-                num_insts_discarded++;
-            } else if (!inst->isBubble()) {
+            if (!discarded && !inst->isBubble()) {
                 num_insts_issued++;
 
                 if (num_insts_issued == issueLimit)

src/cpu/simple/atomic.cc

@@ -462,7 +462,7 @@ AtomicSimpleCPU::writeMem(uint8_t *data, unsigned size, Addr addr,
     Addr frag_addr = addr;
     int frag_size = 0;
     int size_left = size;
-    int curr_frag_id = 0;
+    [[maybe_unused]] int curr_frag_id = 0;
     bool predicate;
     Fault fault = NoFault;