1 /*
2 * Copyright (c) 1998, 2018, 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
21 * questions.
22 *
23 */
24
25 #ifndef SHARE_VM_OOPS_COMPILEDICHOLDEROOP_HPP
26 #define SHARE_VM_OOPS_COMPILEDICHOLDEROOP_HPP
27
28 #include "oops/oop.hpp"
29 #include "oops/klass.hpp"
30 #include "oops/method.hpp"
31
32 // A CompiledICHolder* is a helper object for the inline cache implementation.
33 // It holds:
34 // (1) (method+klass pair) when converting from compiled to an interpreted call
35 // (2) (klass+klass pair) when calling itable stub from megamorphic compiled call
36 //
37 // These are always allocated in the C heap and are freed during a
38 // safepoint by the ICBuffer logic. It's unsafe to free them earlier
39 // since they might be in use.
40 //
41
42
43 class CompiledICHolder : public CHeapObj<mtCompiler> {
44 friend class VMStructs;
45 private:
46 static volatile int _live_count; // allocated
47 static volatile int _live_not_claimed_count; // allocated but not yet in use so not
48 // reachable by iterating over nmethods
49
50 Metadata* _holder_metadata;
51 Klass* _holder_klass; // to avoid name conflict with oopDesc::_klass
52 CompiledICHolder* _next;
53 bool _is_metadata_method;
54
55 public:
56 // Constructor
57 CompiledICHolder(Metadata* metadata, Klass* klass, bool is_method = true)
58 : _holder_metadata(metadata), _holder_klass(klass), _is_metadata_method(is_method) {
59 #ifdef ASSERT
60 Atomic::inc(&_live_count);
61 Atomic::inc(&_live_not_claimed_count);
62 #endif
63 }
64
65 ~CompiledICHolder() {
66 #ifdef ASSERT
67 assert(_live_count > 0, "underflow");
68 Atomic::dec(&_live_count);
69 #endif
70 }
71
72 static int live_count() { return _live_count; }
73 static int live_not_claimed_count() { return _live_not_claimed_count; }
74
75 // accessors
76 Klass* holder_klass() const { return _holder_klass; }
77 Metadata* holder_metadata() const { return _holder_metadata; }
78
79 void set_holder_metadata(Metadata* m) { _holder_metadata = m; }
80 void set_holder_klass(Klass* k) { _holder_klass = k; }
81
82 static int holder_metadata_offset() { return offset_of(CompiledICHolder, _holder_metadata); }
83 static int holder_klass_offset() { return offset_of(CompiledICHolder, _holder_klass); }
84
85 CompiledICHolder* next() { return _next; }
86 void set_next(CompiledICHolder* n) { _next = n; }
87
88 inline bool is_loader_alive(BoolObjectClosure* is_alive) {
89 Klass* k = _is_metadata_method ? ((Method*)_holder_metadata)->method_holder() : (Klass*)_holder_metadata;
90 if (!k->is_loader_alive(is_alive)) {
91 return false;
92 }
93 if (!_holder_klass->is_loader_alive(is_alive)) {
94 return false;
95 }
96 return true;
97 }
98
99 // Verify
100 void verify_on(outputStream* st);
101
102 // Printing
103 void print_on(outputStream* st) const;
104 void print_value_on(outputStream* st) const;
105
106 const char* internal_name() const { return "{compiledICHolder}"; }
107
108 void claim() {
109 #ifdef ASSERT
110 Atomic::dec(&_live_not_claimed_count);
111 #endif
112 }
113 };
114
115 #endif // SHARE_VM_OOPS_COMPILEDICHOLDEROOP_HPP