8211955: GC abstraction for LAB reserve

Reviewed-by: pliden, shade

src/hotspot/share/gc/shared/collectedHeap.cpp

@@ -445,6 +445,15 @@ void CollectedHeap::fill_with_dummy_object(HeapWord* start, HeapWord* end, bool
   CollectedHeap::fill_with_object(start, end, zap);
 }
 
+size_t CollectedHeap::min_dummy_object_size() const {
+  return oopDesc::header_size();
+}
+
+size_t CollectedHeap::tlab_alloc_reserve() const {
+  size_t min_size = min_dummy_object_size();
+  return min_size > (size_t)MinObjAlignment ? align_object_size(min_size) : 0;
+}
+
 HeapWord* CollectedHeap::allocate_new_tlab(size_t min_size,
                                            size_t requested_size,
                                            size_t* actual_size) {

src/hotspot/share/gc/shared/collectedHeap.hpp

@@ -309,6 +309,8 @@ class CollectedHeap : public CHeapObj<mtInternal> {
   }
 
   virtual void fill_with_dummy_object(HeapWord* start, HeapWord* end, bool zap);
+  virtual size_t min_dummy_object_size() const;
+  size_t tlab_alloc_reserve() const;
 
   // Return the address "addr" aligned by "alignment_in_bytes" if such
   // an address is below "end".  Return NULL otherwise.

src/hotspot/share/gc/shared/plab.cpp

@@ -27,7 +27,6 @@
 #include "gc/shared/plab.inline.hpp"
 #include "gc/shared/threadLocalAllocBuffer.hpp"
 #include "logging/log.hpp"
-#include "oops/arrayOop.hpp"
 #include "oops/oop.inline.hpp"
 
 size_t PLAB::min_size() {
@@ -43,8 +42,7 @@ PLAB::PLAB(size_t desired_plab_sz_) :
   _word_sz(desired_plab_sz_), _bottom(NULL), _top(NULL),
   _end(NULL), _hard_end(NULL), _allocated(0), _wasted(0), _undo_wasted(0)
 {
-  // ArrayOopDesc::header_size depends on command line initialization.
-  AlignmentReserve = oopDesc::header_size() > MinObjAlignment ? align_object_size(arrayOopDesc::header_size(T_INT)) : 0;
+  AlignmentReserve = Universe::heap()->tlab_alloc_reserve();
   assert(min_size() > AlignmentReserve,
          "Minimum PLAB size " SIZE_FORMAT " must be larger than alignment reserve " SIZE_FORMAT " "
          "to be able to contain objects", min_size(), AlignmentReserve);

src/hotspot/share/gc/shared/threadLocalAllocBuffer.cpp

@@ -23,6 +23,7 @@
  */
 
 #include "precompiled.hpp"
+#include "gc/shared/collectedHeap.hpp"
 #include "gc/shared/threadLocalAllocBuffer.inline.hpp"
 #include "logging/log.hpp"
 #include "memory/resourceArea.hpp"
@@ -461,3 +462,8 @@ void ThreadLocalAllocStats::publish() {
     _perf_max_slow_allocations    ->set_value(_max_slow_allocations);
   }
 }
+
+size_t ThreadLocalAllocBuffer::end_reserve() {
+  size_t reserve_size = Universe::heap()->tlab_alloc_reserve();
+  return MAX2(reserve_size, (size_t)_reserve_for_allocation_prefetch);
+}

src/hotspot/share/gc/shared/threadLocalAllocBuffer.hpp

@@ -26,7 +26,6 @@
 #define SHARE_VM_GC_SHARED_THREADLOCALALLOCBUFFER_HPP
 
 #include "gc/shared/gcUtil.hpp"
-#include "oops/typeArrayOop.hpp"
 #include "runtime/perfData.hpp"
 #include "runtime/vm_version.hpp"
 
@@ -138,10 +137,7 @@ public:
   inline HeapWord* allocate(size_t size);
 
   // Reserve space at the end of TLAB
-  static size_t end_reserve() {
-    int reserve_size = typeArrayOopDesc::header_size(T_INT);
-    return MAX2(reserve_size, _reserve_for_allocation_prefetch);
-  }
+  static size_t end_reserve();
   static size_t alignment_reserve()              { return align_object_size(end_reserve()); }
   static size_t alignment_reserve_in_bytes()     { return alignment_reserve() * HeapWordSize; }