1/*
2 * Copyright (c) 2015, 2019, 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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23 */
24
25#ifndef SHARE_CODE_DEPENDENCYCONTEXT_HPP
26#define SHARE_CODE_DEPENDENCYCONTEXT_HPP
27
28#include "memory/allocation.hpp"
29#include "oops/oop.hpp"
30#include "runtime/handles.hpp"
31#include "runtime/perfData.hpp"
32#include "runtime/safepoint.hpp"
33
34class nmethod;
35class DepChange;
36
37//
38// nmethodBucket is used to record dependent nmethods for
39// deoptimization. nmethod dependencies are actually <klass, method>
40// pairs but we really only care about the klass part for purposes of
41// finding nmethods which might need to be deoptimized. Instead of
42// recording the method, a count of how many times a particular nmethod
43// was recorded is kept. This ensures that any recording errors are
44// noticed since an nmethod should be removed as many times are it's
45// added.
46//
47class nmethodBucket: public CHeapObj<mtClass> {
48 friend class VMStructs;
49 private:
50 nmethod* _nmethod;
51 volatile int _count;
52 nmethodBucket* volatile _next;
53 nmethodBucket* volatile _purge_list_next;
54
55 public:
56 nmethodBucket(nmethod* nmethod, nmethodBucket* next) :
57 _nmethod(nmethod), _count(1), _next(next), _purge_list_next(NULL) {}
58
59 int count() { return _count; }
60 int increment() { _count += 1; return _count; }
61 int decrement();
62 nmethodBucket* next();
63 nmethodBucket* next_not_unloading();
64 void set_next(nmethodBucket* b);
65 nmethodBucket* purge_list_next();
66 void set_purge_list_next(nmethodBucket* b);
67 nmethod* get_nmethod() { return _nmethod; }
68};
69
70//
71// Utility class to manipulate nmethod dependency context.
72// Dependency context can be attached either to an InstanceKlass (_dep_context field)
73// or CallSiteContext oop for call_site_target dependencies (see javaClasses.hpp).
74// DependencyContext class operates on some location which holds a nmethodBucket* value
75// and uint64_t integer recording the safepoint counter at the last cleanup.
76//
77class DependencyContext : public StackObj {
78 friend class VMStructs;
79 friend class TestDependencyContext;
80 private:
81 nmethodBucket* volatile* _dependency_context_addr;
82 volatile uint64_t* _last_cleanup_addr;
83
84 bool claim_cleanup();
85 void set_dependencies(nmethodBucket* b);
86 nmethodBucket* dependencies();
87 nmethodBucket* dependencies_not_unloading();
88
89 static PerfCounter* _perf_total_buckets_allocated_count;
90 static PerfCounter* _perf_total_buckets_deallocated_count;
91 static PerfCounter* _perf_total_buckets_stale_count;
92 static PerfCounter* _perf_total_buckets_stale_acc_count;
93 static nmethodBucket* volatile _purge_list;
94 static uint64_t _cleaning_epoch_monotonic;
95 static volatile uint64_t _cleaning_epoch;
96
97 public:
98#ifdef ASSERT
99 // Safepoints are forbidden during DC lifetime. GC can invalidate
100 // _dependency_context_addr if it relocates the holder
101 // (e.g. CallSiteContext Java object).
102 SafepointStateTracker _safepoint_tracker;
103
104 DependencyContext(nmethodBucket* volatile* bucket_addr, volatile uint64_t* last_cleanup_addr)
105 : _dependency_context_addr(bucket_addr),
106 _last_cleanup_addr(last_cleanup_addr),
107 _safepoint_tracker(SafepointSynchronize::safepoint_state_tracker()) {}
108
109 ~DependencyContext() {
110 assert(!_safepoint_tracker.safepoint_state_changed(), "must be the same safepoint");
111 }
112#else
113 DependencyContext(nmethodBucket* volatile* bucket_addr, volatile uint64_t* last_cleanup_addr)
114 : _dependency_context_addr(bucket_addr),
115 _last_cleanup_addr(last_cleanup_addr) {}
116#endif // ASSERT
117
118 static void init();
119
120 int mark_dependent_nmethods(DepChange& changes);
121 void add_dependent_nmethod(nmethod* nm);
122 void remove_dependent_nmethod(nmethod* nm);
123 int remove_all_dependents();
124 void clean_unloading_dependents();
125 static void purge_dependency_contexts();
126 static void release(nmethodBucket* b);
127 static void cleaning_start();
128 static void cleaning_end();
129
130#ifndef PRODUCT
131 void print_dependent_nmethods(bool verbose);
132 bool is_dependent_nmethod(nmethod* nm);
133#endif //PRODUCT
134};
135#endif // SHARE_CODE_DEPENDENCYCONTEXT_HPP
136