8259778: Merge MutableSpace and ImmutableSpace

Reviewed-by: sspitsyn, dholmes, tschatzl

src/hotspot/share/gc/parallel/mutableSpace.cpp

@@ -35,7 +35,14 @@
 #include "utilities/align.hpp"
 #include "utilities/macros.hpp"
 
-MutableSpace::MutableSpace(size_t alignment): ImmutableSpace(), _alignment(alignment), _top(NULL) {
+MutableSpace::MutableSpace(size_t alignment) :
+  _mangler(NULL),
+  _last_setup_region(),
+  _alignment(alignment),
+  _bottom(NULL),
+  _top(NULL),
+  _end(NULL)
+{
   assert(MutableSpace::alignment() % os::vm_page_size() == 0,
          "Space should be aligned");
   _mangler = new MutableSpaceMangler(this);

src/hotspot/share/gc/parallel/mutableSpace.hpp

@@ -25,35 +25,40 @@
 #ifndef SHARE_GC_PARALLEL_MUTABLESPACE_HPP
 #define SHARE_GC_PARALLEL_MUTABLESPACE_HPP
 
-#include "gc/parallel/immutableSpace.hpp"
+#include "memory/allocation.hpp"
+#include "memory/iterator.hpp"
 #include "memory/memRegion.hpp"
 #include "utilities/copy.hpp"
+#include "utilities/globalDefinitions.hpp"
+#include "utilities/macros.hpp"
 
 class WorkGang;
 
-// A MutableSpace is a subtype of ImmutableSpace that supports the
-// concept of allocation. This includes the concepts that a space may
-// be only partially full, and the query methods that go with such
-// an assumption. MutableSpace is also responsible for minimizing the
+// A MutableSpace supports the concept of allocation. This includes the
+// concepts that a space may be only partially full, and the query methods
+// that go with such an assumption.
+//
+// MutableSpace is also responsible for minimizing the
 // page allocation time by having the memory pretouched (with
 // AlwaysPretouch) and for optimizing page placement on NUMA systems
 // by make the underlying region interleaved (with UseNUMA).
 //
-// Invariant: (ImmutableSpace +) bottom() <= top() <= end()
-// top() is inclusive and end() is exclusive.
+// Invariant: bottom() <= top() <= end()
+// top() and end() are exclusive.
 
 class MutableSpaceMangler;
 
-class MutableSpace: public ImmutableSpace {
+class MutableSpace: public CHeapObj<mtGC> {
   friend class VMStructs;
 
   // Helper for mangling unused space in debug builds
   MutableSpaceMangler* _mangler;
   // The last region which page had been setup to be interleaved.
   MemRegion _last_setup_region;
   size_t _alignment;
- protected:
+  HeapWord* _bottom;
   HeapWord* volatile _top;
+  HeapWord* _end;
 
   MutableSpaceMangler* mangler() { return _mangler; }
 
@@ -67,17 +72,25 @@ class MutableSpace: public ImmutableSpace {
   MutableSpace(size_t page_size);
 
   // Accessors
+  HeapWord* bottom() const                 { return _bottom; }
   HeapWord* top() const                    { return _top;    }
+  HeapWord* end() const                    { return _end; }
+
+  void set_bottom(HeapWord* value)         { _bottom = value; }
   virtual void set_top(HeapWord* value)    { _top = value;   }
+  void set_end(HeapWord* value)            { _end = value; }
 
   HeapWord* volatile* top_addr()           { return &_top; }
   HeapWord** end_addr()                    { return &_end; }
 
-  virtual void set_bottom(HeapWord* value) { _bottom = value; }
-  virtual void set_end(HeapWord* value)    { _end = value; }
-
   size_t alignment()                       { return _alignment; }
 
+  MemRegion region() const { return MemRegion(bottom(), end()); }
+
+  size_t capacity_in_bytes() const { return capacity_in_words() * HeapWordSize; }
+  size_t capacity_in_words() const { return pointer_delta(end(), bottom()); }
+  virtual size_t capacity_in_words(Thread*) const { return capacity_in_words(); }
+
   // Returns a subregion containing all objects in this space.
   MemRegion used_region() { return MemRegion(bottom(), top()); }
 
@@ -92,10 +105,6 @@ class MutableSpace: public ImmutableSpace {
                           WorkGang* pretouch_gang = NULL);
 
   virtual void clear(bool mangle_space);
-  // Does the usual initialization but optionally resets top to bottom.
-#if 0  // MANGLE_SPACE
-  void initialize(MemRegion mr, bool clear_space, bool reset_top);
-#endif
   virtual void update() { }
   virtual void accumulate_statistics() { }
 

src/hotspot/share/gc/parallel/spaceCounters.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2002, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2002, 2021, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -25,7 +25,6 @@
 #ifndef SHARE_GC_PARALLEL_SPACECOUNTERS_HPP
 #define SHARE_GC_PARALLEL_SPACECOUNTERS_HPP
 
-#include "gc/parallel/immutableSpace.hpp"
 #include "gc/parallel/mutableSpace.hpp"
 #include "gc/shared/generationCounters.hpp"
 #include "runtime/perfData.hpp"

src/hotspot/share/gc/parallel/vmStructs_parallelgc.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2007, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2007, 2021, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -25,7 +25,6 @@
 #ifndef SHARE_GC_PARALLEL_VMSTRUCTS_PARALLELGC_HPP
 #define SHARE_GC_PARALLEL_VMSTRUCTS_PARALLELGC_HPP
 
-#include "gc/parallel/immutableSpace.hpp"
 #include "gc/parallel/mutableSpace.hpp"
 #include "gc/parallel/parallelScavengeHeap.hpp"
 #include "gc/parallel/psOldGen.hpp"
@@ -46,9 +45,8 @@
   nonstatic_field(PSVirtualSpace,              _committed_low_addr,                           char*)                                 \
   nonstatic_field(PSVirtualSpace,              _committed_high_addr,                          char*)                                 \
                                                                                                                                      \
-  nonstatic_field(ImmutableSpace,              _bottom,                                       HeapWord*)                             \
-  nonstatic_field(ImmutableSpace,              _end,                                          HeapWord*)                             \
-                                                                                                                                     \
+  nonstatic_field(MutableSpace,                _bottom,                                       HeapWord*)                             \
+  nonstatic_field(MutableSpace,                _end,                                          HeapWord*)                             \
   volatile_nonstatic_field(MutableSpace,       _top,                                          HeapWord*)                             \
                                                                                                                                      \
   nonstatic_field(PSYoungGen,                  _reserved,                                     MemRegion)                             \
@@ -81,8 +79,7 @@
            declare_type(ParallelScavengeHeap,         CollectedHeap)      \
                                                                           \
   declare_toplevel_type(PSVirtualSpace)                                   \
-  declare_toplevel_type(ImmutableSpace)                                   \
-           declare_type(MutableSpace, ImmutableSpace)                     \
+  declare_toplevel_type(MutableSpace)                                     \
   declare_toplevel_type(PSYoungGen)                                       \
   declare_toplevel_type(PSOldGen)                                         \
                                                                           \
@@ -91,7 +88,6 @@
   /*****************************/                                         \
                                                                           \
   declare_toplevel_type(PSVirtualSpace*)                                  \
-  declare_toplevel_type(ImmutableSpace*)                                  \
   declare_toplevel_type(MutableSpace*)                                    \
   declare_toplevel_type(PSYoungGen*)                                      \
   declare_toplevel_type(PSOldGen*)                                        \