RFR (XS) 8243307: Shenandoah: remove ShCollectionSet::live_data

[Aleksey Shipilev]

RFE:
  https://bugs.openjdk.java.net/browse/JDK-8243307

ShCollectionSet::live_data is not used, yet computed on hot path during the pause. We should
eliminate it.

Fix:

diff -r 53c60b2ed2d5 src/hotspot/share/gc/shenandoah/shenandoahCollectionSet.cpp
--- a/src/hotspot/share/gc/shenandoah/shenandoahCollectionSet.cpp       Tue Apr 21 21:20:19 2020 +0200
+++ b/src/hotspot/share/gc/shenandoah/shenandoahCollectionSet.cpp       Tue Apr 21 21:21:56 2020 +0200
@@ -43,3 +43,2 @@
   _garbage(0),
-  _live_data(0),
   _used(0),
@@ -87,5 +86,4 @@
   _cset_map[r->index()] = 1;
-  _region_count ++;
+  _region_count++;
   _garbage += r->garbage();
-  _live_data += r->get_live_data_bytes();
   _used += r->used();
@@ -107,3 +105,2 @@
   _garbage = 0;
-  _live_data = 0;
   _used = 0;
diff -r 53c60b2ed2d5 src/hotspot/share/gc/shenandoah/shenandoahCollectionSet.hpp
--- a/src/hotspot/share/gc/shenandoah/shenandoahCollectionSet.hpp       Tue Apr 21 21:20:19 2020 +0200
+++ b/src/hotspot/share/gc/shenandoah/shenandoahCollectionSet.hpp       Tue Apr 21 21:21:56 2020 +0200
@@ -45,3 +45,2 @@
   size_t                _garbage;
-  size_t                _live_data;
   size_t                _used;
@@ -80,3 +79,2 @@
   size_t used()      const { return _used; }
-  size_t live_data() const { return _live_data; }
   size_t garbage()   const { return _garbage;   }

Testing: hotspot_gc_shenandoah

-- 
Thanks,
-Aleksey