8364650: G1: Use InvalidCSetIndex instead of UINT_MAX for "invalid" sentinel value of young_index_in_cset

Reviewed-by: ayang, iwalulya

Author: Thomas Schatzl

src/hotspot/share/gc/g1/g1HeapRegion.cpp

@@ -245,7 +245,7 @@ G1HeapRegion::G1HeapRegion(uint hrm_index,
   _parsable_bottom(nullptr),
   _garbage_bytes(0),
   _incoming_refs(0),
-  _young_index_in_cset(-1),
+  _young_index_in_cset(InvalidCSetIndex),
   _surv_rate_group(nullptr),
   _age_index(G1SurvRateGroup::InvalidAgeIndex),
   _node_index(G1NUMA::UnknownNodeIndex),

src/hotspot/share/gc/g1/g1HeapRegion.hpp

@@ -496,10 +496,10 @@ class G1HeapRegion : public CHeapObj<mtGC> {
   void set_index_in_opt_cset(uint index) { _index_in_opt_cset = index; }
   void clear_index_in_opt_cset() { _index_in_opt_cset = InvalidCSetIndex; }
 
-  uint  young_index_in_cset() const { return _young_index_in_cset; }
+  uint young_index_in_cset() const { return _young_index_in_cset; }
   void clear_young_index_in_cset() { _young_index_in_cset = 0; }
   void set_young_index_in_cset(uint index) {
-    assert(index != UINT_MAX, "just checking");
+    assert(index != InvalidCSetIndex, "just checking");
     assert(index != 0, "just checking");
     assert(is_young(), "pre-condition");
     _young_index_in_cset = index;