7193946: Move warnings associated with UseMemSetInBOT flag

Summary: The warnings associated with the UseMemSetInBOT flag are duplicated in CMS and G1. The separate warnings have been removed and single instance of the warning has been placed in a common location.
Reviewed-by: brutisso, ysr

src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp

@@ -789,14 +789,6 @@ CMSCollector::CMSCollector(ConcurrentMarkSweepGeneration* cmsGen,
   _gc_counters = new CollectorCounters("CMS", 1);
   _completed_initialization = true;
   _inter_sweep_timer.start();  // start of time
-#ifdef SPARC
-  // Issue a stern warning, but allow use for experimentation and debugging.
-  if (VM_Version::is_sun4v() && UseMemSetInBOT) {
-    assert(!FLAG_IS_DEFAULT(UseMemSetInBOT), "Error");
-    warning("Experimental flag -XX:+UseMemSetInBOT is known to cause instability"
-            " on sun4v; please understand that you are using at your own risk!");
-  }
-#endif
 }
 
 const char* ConcurrentMarkSweepGeneration::name() const {

src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp

@@ -1954,14 +1954,6 @@ G1CollectedHeap::G1CollectedHeap(G1CollectorPolicy* policy_) :
   NOT_PRODUCT(reset_evacuation_should_fail();)
 
   guarantee(_task_queues != NULL, "task_queues allocation failure.");
-#ifdef SPARC
-  // Issue a stern warning, but allow use for experimentation and debugging.
-  if (VM_Version::is_sun4v() && UseMemSetInBOT) {
-    assert(!FLAG_IS_DEFAULT(UseMemSetInBOT), "Error");
-    warning("Experimental flag -XX:+UseMemSetInBOT is known to cause instability"
-            " on sun4v; please understand that you are using at your own risk!");
-  }
-#endif
 }
 
 jint G1CollectedHeap::initialize() {

src/share/vm/runtime/arguments.cpp

@@ -1978,6 +1978,19 @@ bool Arguments::check_vm_args_consistency() {
   status = status && verify_min_value(ClassMetaspaceSize, 1*M,
                                       "ClassMetaspaceSize");
 
+#ifdef SPARC
+  if (UseConcMarkSweepGC || UseG1GC) {
+    // Issue a stern warning if the user has explicitly set
+    // UseMemSetInBOT (it is known to cause issues), but allow
+    // use for experimentation and debugging.
+    if (VM_Version::is_sun4v() && UseMemSetInBOT) {
+      assert(!FLAG_IS_DEFAULT(UseMemSetInBOT), "Error");
+      warning("Experimental flag -XX:+UseMemSetInBOT is known to cause instability"
+          " on sun4v; please understand that you are using at your own risk!");
+    }
+  }
+#endif // SPARC
+
   return status;
 }