8241534: Shenandoah: region status should include update watermark

Reviewed-by: rkennke

src/hotspot/share/gc/shenandoah/shenandoahHeap.cpp

@@ -991,7 +991,7 @@ void ShenandoahHeap::print_heap_regions_on(outputStream* st) const {
   st->print_cr("Heap Regions:");
   st->print_cr("EU=empty-uncommitted, EC=empty-committed, R=regular, H=humongous start, HC=humongous continuation, CS=collection set, T=trash, P=pinned");
   st->print_cr("BTE=bottom/top/end, U=used, T=TLAB allocs, G=GCLAB allocs, S=shared allocs, L=live data");
-  st->print_cr("R=root, CP=critical pins, TAMS=top-at-mark-start (previous, next)");
+  st->print_cr("R=root, CP=critical pins, TAMS=top-at-mark-start, UWM=update watermark");
   st->print_cr("SN=alloc sequence number");
 
   for (size_t i = 0; i < num_regions(); i++) {

src/hotspot/share/gc/shenandoah/shenandoahHeapRegion.cpp

@@ -413,6 +413,8 @@ void ShenandoahHeapRegion::print_on(outputStream* st) const {
             p2i(bottom()), p2i(top()), p2i(end()));
   st->print("|TAMS " INTPTR_FORMAT_W(12),
             p2i(_heap->marking_context()->top_at_mark_start(const_cast<ShenandoahHeapRegion*>(this))));
+  st->print("|UWM " INTPTR_FORMAT_W(12),
+            p2i(_update_watermark));
   st->print("|U " SIZE_FORMAT_W(5) "%1s", byte_size_in_proper_unit(used()),                proper_unit_for_byte_size(used()));
   st->print("|T " SIZE_FORMAT_W(5) "%1s", byte_size_in_proper_unit(get_tlab_allocs()),     proper_unit_for_byte_size(get_tlab_allocs()));
   st->print("|G " SIZE_FORMAT_W(5) "%1s", byte_size_in_proper_unit(get_gclab_allocs()),    proper_unit_for_byte_size(get_gclab_allocs()));