6820066: Check that -XX:ParGCArrayScanChunk has a value larger than zero.

Summary: Check that -XX:ParGCArrayScanChunk has a value larger than zero.
Reviewed-by: johnc, jmasa, ysr

src/share/vm/gc_implementation/parallelScavenge/psPromotionManager.cpp

@@ -411,7 +411,7 @@ oop PSPromotionManager::copy_to_survivor_space(oop o) {
 template <class T> void PSPromotionManager::process_array_chunk_work(
                                                  oop obj,
                                                  int start, int end) {
-  assert(start < end, "invariant");
+  assert(start <= end, "invariant");
   T* const base      = (T*)objArrayOop(obj)->base();
   T* p               = base + start;
   T* const chunk_end = base + end;

src/share/vm/runtime/arguments.cpp

@@ -1668,13 +1668,13 @@ bool Arguments::verify_interval(uintx val, uintx min,
 }
 
 bool Arguments::verify_min_value(intx val, intx min, const char* name) {
-  // Returns true if given value is greater than specified min threshold
+  // Returns true if given value is at least specified min threshold
   // false, otherwise.
   if (val >= min ) {
       return true;
   }
   jio_fprintf(defaultStream::error_stream(),
-              "%s of " INTX_FORMAT " is invalid; must be greater than " INTX_FORMAT "\n",
+              "%s of " INTX_FORMAT " is invalid; must be at least " INTX_FORMAT "\n",
               name, val, min);
   return false;
 }
@@ -1901,6 +1901,8 @@ bool Arguments::check_vm_args_consistency() {
     status = false;
   }
 
+  status = status && verify_min_value(ParGCArrayScanChunk, 1, "ParGCArrayScanChunk");
+
 #ifndef SERIALGC
   if (UseG1GC) {
     status = status && verify_percentage(InitiatingHeapOccupancyPercent,