From 80ccc989a892e4d9f4e2c9395a100cfabbdcda64 Mon Sep 17 00:00:00 2001 From: Roman Kennke Date: Fri, 15 Mar 2024 11:08:21 +0000 Subject: [PATCH] 8328075: Shenandoah: Avoid forwarding when objects don't move in full-GC Reviewed-by: wkemper, shade, kdnilsen, ysr --- src/hotspot/share/gc/shenandoah/shenandoahFullGC.cpp | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/src/hotspot/share/gc/shenandoah/shenandoahFullGC.cpp b/src/hotspot/share/gc/shenandoah/shenandoahFullGC.cpp index d66bf052da4..2aeec0911d0 100644 --- a/src/hotspot/share/gc/shenandoah/shenandoahFullGC.cpp +++ b/src/hotspot/share/gc/shenandoah/shenandoahFullGC.cpp @@ -364,11 +364,13 @@ public: _compact_point = _to_region->bottom(); } - // Object fits into current region, record new location: + // Object fits into current region, record new location, if object does not move: assert(_compact_point + obj_size <= _to_region->end(), "must fit"); shenandoah_assert_not_forwarded(nullptr, p); - _preserved_marks->push_if_necessary(p, p->mark()); - p->forward_to(cast_to_oop(_compact_point)); + if (_compact_point != cast_from_oop(p)) { + _preserved_marks->push_if_necessary(p, p->mark()); + p->forward_to(cast_to_oop(_compact_point)); + } _compact_point += obj_size; } }; @@ -864,6 +866,7 @@ public: if (p->is_forwarded()) { HeapWord* compact_from = cast_from_oop(p); HeapWord* compact_to = cast_from_oop(p->forwardee()); + assert(compact_from != compact_to, "Forwarded object should move"); Copy::aligned_conjoint_words(compact_from, compact_to, size); oop new_obj = cast_to_oop(compact_to);