1 /*
  2  * Copyright (c) 1997, 2022, Oracle and/or its affiliates. All rights reserved.
  3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  4  *
  5  * This code is free software; you can redistribute it and/or modify it
  6  * under the terms of the GNU General Public License version 2 only, as
  7  * published by the Free Software Foundation.
  8  *
  9  * This code is distributed in the hope that it will be useful, but WITHOUT
 10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 12  * version 2 for more details (a copy is included in the LICENSE file that
 13  * accompanied this code).
 14  *
 15  * You should have received a copy of the GNU General Public License version
 16  * 2 along with this work; if not, write to the Free Software Foundation,
 17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 18  *
 19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 20  * or visit www.oracle.com if you need additional information or have any
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 24 
 25 #ifndef SHARE_GC_SERIAL_MARKSWEEP_HPP
 26 #define SHARE_GC_SERIAL_MARKSWEEP_HPP
 27 
 28 #include "gc/shared/collectedHeap.hpp"
 29 #include "gc/shared/preservedMarks.inline.hpp"
 30 #include "gc/shared/referenceProcessor.hpp"
 31 #include "gc/shared/stringdedup/stringDedup.hpp"
 32 #include "gc/shared/taskqueue.hpp"
 33 #include "memory/iterator.hpp"
 34 #include "oops/markWord.hpp"
 35 #include "oops/oop.hpp"
 36 #include "runtime/timer.hpp"
 37 #include "utilities/growableArray.hpp"
 38 #include "utilities/stack.hpp"
 39 
 40 class DataLayout;
 41 class SerialOldTracer;
 42 class STWGCTimer;
 43 
 44 // MarkSweep takes care of global mark-compact garbage collection for a
 45 // SerialHeap using a four-phase pointer forwarding algorithm.  All
 46 // generations are assumed to support marking; those that can also support
 47 // compaction.
 48 //
 49 // Class unloading will only occur when a full gc is invoked.
 50 
 51 // declared at end
 52 class PreservedMark;
 53 class MarkAndPushClosure;
 54 
 55 class MarkSweep : AllStatic {
 56   //
 57   // Inline closure decls
 58   //
 59   class FollowRootClosure: public BasicOopIterateClosure {
 60    public:
 61     virtual void do_oop(oop* p);
 62     virtual void do_oop(narrowOop* p);
 63   };
 64 
 65   class FollowStackClosure: public VoidClosure {
 66    public:
 67     virtual void do_void();
 68   };
 69 
 70   // Used for java/lang/ref handling
 71   class IsAliveClosure: public BoolObjectClosure {
 72    public:
 73     virtual bool do_object_b(oop p);
 74   };
 75 
 76   class KeepAliveClosure: public OopClosure {
 77    protected:
 78     template <class T> void do_oop_work(T* p);
 79    public:
 80     virtual void do_oop(oop* p);
 81     virtual void do_oop(narrowOop* p);
 82   };
 83 
 84   //
 85   // Friend decls
 86   //
 87   friend class KeepAliveClosure;
 88 
 89   //
 90   // Vars
 91   //
 92  protected:
 93   // Total invocations of a MarkSweep collection
 94   static uint _total_invocations;
 95 
 96   // Traversal stacks used during phase1
 97   static Stack<oop, mtGC>                      _marking_stack;
 98   static Stack<ObjArrayTask, mtGC>             _objarray_stack;
 99 
100   // Space for storing/restoring mark word
101   static PreservedMarksSet               _preserved_overflow_stack_set;
102   static size_t                          _preserved_count;
103   static size_t                          _preserved_count_max;
104   static PreservedMark*                  _preserved_marks;
105 
106   static AlwaysTrueClosure               _always_true_closure;
107   static ReferenceProcessor*             _ref_processor;
108 
109   static STWGCTimer*                     _gc_timer;
110   static SerialOldTracer*                _gc_tracer;
111 
112   static StringDedup::Requests* _string_dedup_requests;
113 
114   // Non public closures
115   static KeepAliveClosure keep_alive;
116 
117  public:
118   static void initialize();
119 
120   // Public closures
121   static IsAliveClosure       is_alive;
122   static FollowRootClosure    follow_root_closure;
123   static MarkAndPushClosure   mark_and_push_closure;
124   static FollowStackClosure   follow_stack_closure;
125   static CLDToOopClosure      follow_cld_closure;
126 
127   // Accessors
128   static uint total_invocations() { return _total_invocations; }
129 
130   // Reference Processing
131   static ReferenceProcessor* ref_processor() { return _ref_processor; }
132 
133   static STWGCTimer* gc_timer() { return _gc_timer; }
134   static SerialOldTracer* gc_tracer() { return _gc_tracer; }
135 
136   static void preserve_mark(oop p, markWord mark);
137                                 // Save the mark word so it can be restored later
138   static void adjust_marks();   // Adjust the pointers in the preserved marks table
139   static void restore_marks();  // Restore the marks that we saved in preserve_mark
140 
141   template <bool ALT_FWD>
142   static size_t adjust_pointers(oop obj);
143 
144   static void follow_stack();   // Empty marking stack.
145 
146   template <bool ALT_FWD, class T>
147   static void adjust_pointer(T* p);
148 
149   // Check mark and maybe push on marking stack
150   template <class T> static void mark_and_push(T* p);
151 
152  private:
153   template <bool ALT_FWD>
154   static void adjust_marks_impl();
155 
156   // Call backs for marking
157   static void mark_object(oop obj);
158   // Mark pointer and follow contents.  Empty marking stack afterwards.
159   template <class T> static inline void follow_root(T* p);
160 
161   static inline void push_objarray(oop obj, size_t index);
162 
163   static void follow_object(oop obj);
164 
165   static void follow_array(objArrayOop array);
166 
167   static void follow_array_chunk(objArrayOop array, int index);
168 };
169 
170 class MarkAndPushClosure: public ClaimMetadataVisitingOopIterateClosure {
171 public:
172   MarkAndPushClosure(int claim) : ClaimMetadataVisitingOopIterateClosure(claim) {}
173 
174   template <typename T> void do_oop_work(T* p);
175   virtual void do_oop(      oop* p);
176   virtual void do_oop(narrowOop* p);
177 
178   void set_ref_discoverer(ReferenceDiscoverer* rd) {
179     set_ref_discoverer_internal(rd);
180   }
181 };
182 
183 template <bool ALT_FWD>
184 class AdjustPointerClosure: public BasicOopIterateClosure {
185  public:
186   template <typename T> void do_oop_work(T* p);
187   virtual void do_oop(oop* p);
188   virtual void do_oop(narrowOop* p);
189   virtual ReferenceIterationMode reference_iteration_mode() { return DO_FIELDS; }
190 };
191 
192 #endif // SHARE_GC_SERIAL_MARKSWEEP_HPP