src/hotspot/share/gc/z/zMark.cpp

@@ -417,13 +417,20 @@
    // Increment live
    if (inc_live) {
      // Update live objects/bytes for page. We use the aligned object
      // size since that is the actual number of bytes used on the page
      // and alignment paddings can never be reclaimed.
+     const oop obj = to_oop(addr);
      const size_t size = ZUtils::object_size(addr);
      const size_t aligned_size = align_up(size, page->object_alignment());
      context->cache()->inc_live(page, aligned_size);
+     // Track objects that will expand by one HeapWord during relocation due to compact
+     // identity hashcode: their FROM size is one word smaller than their TO size.
+     if (UseCompactObjectHeaders && obj->mark().is_hashed_not_expanded()
+         && obj->klass()->expand_for_hash(obj, obj->mark())) {
+       page->inc_will_expand(1);
+     }
    }
  
    // Follow
    if (follow) {
      if (is_array(addr)) {