Mercurial > hg > truffle
annotate src/share/vm/code/oopRecorder.hpp @ 1616:38e8278318ca
6656830: assert((*p)->is_oop(),"expected an oop while scanning weak refs")
Reviewed-by: dcubed, kvn, twisti
author | never |
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date | Mon, 21 Jun 2010 14:26:17 -0700 |
parents | e9ff18c4ace7 |
children | f95d63e2154a |
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0 | 1 /* |
1579 | 2 * Copyright (c) 1998, 2010, Oracle and/or its affiliates. All rights reserved. |
0 | 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 * | |
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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20 * or visit www.oracle.com if you need additional information or have any |
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21 * questions. |
0 | 22 * |
23 */ | |
24 | |
25 // Recording and retrieval of oop relocations in compiled code. | |
26 | |
27 class CodeBlob; | |
28 | |
29 class OopRecorder : public ResourceObj { | |
30 public: | |
31 // A two-way mapping from positive indexes to oop handles. | |
32 // The zero index is reserved for a constant (sharable) null. | |
33 // Indexes may not be negative. | |
34 | |
35 // Use the given arena to manage storage, if not NULL. | |
36 // By default, uses the current ResourceArea. | |
37 OopRecorder(Arena* arena = NULL); | |
38 | |
39 // Generate a new index on which CodeBlob::oop_addr_at will work. | |
40 // allocate_index and find_index never return the same index, | |
41 // and allocate_index never returns the same index twice. | |
42 // In fact, two successive calls to allocate_index return successive ints. | |
43 int allocate_index(jobject h) { | |
44 return add_handle(h, false); | |
45 } | |
46 | |
47 // For a given jobject, this will return the same index repeatedly. | |
48 // The index can later be given to oop_at to retrieve the oop. | |
49 // However, the oop must not be changed via CodeBlob::oop_addr_at. | |
50 int find_index(jobject h) { | |
51 int index = maybe_find_index(h); | |
52 if (index < 0) { // previously unallocated | |
53 index = add_handle(h, true); | |
54 } | |
55 return index; | |
56 } | |
57 | |
58 // variant of find_index which does not allocate if not found (yields -1) | |
59 int maybe_find_index(jobject h); | |
60 | |
61 // returns the size of the generated oop table, for sizing the CodeBlob. | |
62 // must be called after all oops are allocated! | |
63 int oop_size(); | |
64 | |
65 // Retrieve the oop handle at a given index. | |
66 jobject handle_at(int index); | |
67 | |
68 int element_count() { | |
69 // there is always a NULL virtually present as first object | |
70 return _handles->length() + first_index; | |
71 } | |
72 | |
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73 // copy the generated oop table to nmethod |
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74 void copy_to(nmethod* nm); // => nm->copy_oops(_handles) |
0 | 75 |
76 bool is_unused() { return _handles == NULL && !_complete; } | |
77 #ifdef ASSERT | |
78 bool is_complete() { return _complete; } | |
79 #endif | |
80 | |
81 private: | |
82 // leaky hash table of handle => index, to help detect duplicate insertion | |
83 class IndexCache: public ResourceObj { | |
84 // This class is only used by the OopRecorder class. | |
85 friend class OopRecorder; | |
86 enum { | |
87 _log_cache_size = 9, | |
88 _cache_size = (1<<_log_cache_size), | |
89 // Index entries are ints. The LSBit is a collision indicator. | |
90 _collision_bit_shift = 0, | |
91 _collision_bit = 1, | |
92 _index_shift = _collision_bit_shift+1 | |
93 }; | |
94 int _cache[_cache_size]; | |
95 static juint cache_index(jobject handle) { | |
96 juint ci = (int) (intptr_t) handle; | |
97 ci ^= ci >> (BitsPerByte*2); | |
98 ci += ci >> (BitsPerByte*1); | |
99 return ci & (_cache_size-1); | |
100 } | |
101 int* cache_location(jobject handle) { | |
102 return &_cache[ cache_index(handle) ]; | |
103 } | |
104 static bool cache_location_collision(int* cloc) { | |
105 return ((*cloc) & _collision_bit) != 0; | |
106 } | |
107 static int cache_location_index(int* cloc) { | |
108 return (*cloc) >> _index_shift; | |
109 } | |
110 static void set_cache_location_index(int* cloc, int index) { | |
111 int cval0 = (*cloc); | |
112 int cval1 = (index << _index_shift); | |
113 if (cval0 != 0 && cval1 != cval0) cval1 += _collision_bit; | |
114 (*cloc) = cval1; | |
115 } | |
116 IndexCache(); | |
117 }; | |
118 | |
119 // Helper function; returns false for NULL or Universe::non_oop_word(). | |
120 inline bool is_real_jobject(jobject h); | |
121 | |
122 void maybe_initialize(); | |
123 int add_handle(jobject h, bool make_findable); | |
124 | |
125 enum { null_index = 0, first_index = 1, index_cache_threshold = 20 }; | |
126 | |
127 GrowableArray<jobject>* _handles; // ordered list (first is always NULL) | |
128 GrowableArray<int>* _no_finds; // all unfindable indexes; usually empty | |
129 IndexCache* _indexes; // map: jobject -> its probable index | |
130 Arena* _arena; | |
131 bool _complete; | |
132 | |
133 #ifdef ASSERT | |
134 static int _find_index_calls, _hit_indexes, _missed_indexes; | |
135 #endif | |
136 }; |