From e9f6ba05264ecb2f1ca3983ea503778f301bf280 Mon Sep 17 00:00:00 2001
From: Roman Kennke <rkennke@openjdk.org>
Date: Tue, 3 Dec 2024 16:45:50 +0000
Subject: [PATCH] 8345293: Fix generational Shenandoah with compact headers

Reviewed-by: shade, stuefe, ysr
---
 src/hotspot/share/gc/shenandoah/shenandoahHeap.inline.hpp | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/hotspot/share/gc/shenandoah/shenandoahHeap.inline.hpp b/src/hotspot/share/gc/shenandoah/shenandoahHeap.inline.hpp
index b2c8e0405e0..2b34b2d5cfc 100644
--- a/src/hotspot/share/gc/shenandoah/shenandoahHeap.inline.hpp
+++ b/src/hotspot/share/gc/shenandoah/shenandoahHeap.inline.hpp
@@ -332,6 +332,11 @@ void ShenandoahHeap::increase_object_age(oop obj, uint additional_age) {
 uint ShenandoahHeap::get_object_age(oop obj) {
   markWord w = obj->mark();
   assert(!w.is_marked(), "must not be forwarded");
+  if (UseObjectMonitorTable) {
+    assert(LockingMode == LM_LIGHTWEIGHT, "Must use LW locking, too");
+    assert(w.age() <= markWord::max_age, "Impossible!");
+    return w.age();
+  }
   if (w.has_monitor()) {
     w = w.monitor()->header();
   } else if (w.is_being_inflated() || w.has_displaced_mark_helper()) {