1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/share/vm/code/oopRecorder.hpp Sat Dec 01 00:00:00 2007 +0000
1.3 @@ -0,0 +1,136 @@
1.4 +/*
1.5 + * Copyright 1998-2005 Sun Microsystems, Inc. All Rights Reserved.
1.6 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.7 + *
1.8 + * This code is free software; you can redistribute it and/or modify it
1.9 + * under the terms of the GNU General Public License version 2 only, as
1.10 + * published by the Free Software Foundation.
1.11 + *
1.12 + * This code is distributed in the hope that it will be useful, but WITHOUT
1.13 + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.14 + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.15 + * version 2 for more details (a copy is included in the LICENSE file that
1.16 + * accompanied this code).
1.17 + *
1.18 + * You should have received a copy of the GNU General Public License version
1.19 + * 2 along with this work; if not, write to the Free Software Foundation,
1.20 + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.21 + *
1.22 + * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
1.23 + * CA 95054 USA or visit www.sun.com if you need additional information or
1.24 + * have any questions.
1.25 + *
1.26 + */
1.27 +
1.28 +// Recording and retrieval of oop relocations in compiled code.
1.29 +
1.30 +class CodeBlob;
1.31 +
1.32 +class OopRecorder : public ResourceObj {
1.33 + public:
1.34 + // A two-way mapping from positive indexes to oop handles.
1.35 + // The zero index is reserved for a constant (sharable) null.
1.36 + // Indexes may not be negative.
1.37 +
1.38 + // Use the given arena to manage storage, if not NULL.
1.39 + // By default, uses the current ResourceArea.
1.40 + OopRecorder(Arena* arena = NULL);
1.41 +
1.42 + // Generate a new index on which CodeBlob::oop_addr_at will work.
1.43 + // allocate_index and find_index never return the same index,
1.44 + // and allocate_index never returns the same index twice.
1.45 + // In fact, two successive calls to allocate_index return successive ints.
1.46 + int allocate_index(jobject h) {
1.47 + return add_handle(h, false);
1.48 + }
1.49 +
1.50 + // For a given jobject, this will return the same index repeatedly.
1.51 + // The index can later be given to oop_at to retrieve the oop.
1.52 + // However, the oop must not be changed via CodeBlob::oop_addr_at.
1.53 + int find_index(jobject h) {
1.54 + int index = maybe_find_index(h);
1.55 + if (index < 0) { // previously unallocated
1.56 + index = add_handle(h, true);
1.57 + }
1.58 + return index;
1.59 + }
1.60 +
1.61 + // variant of find_index which does not allocate if not found (yields -1)
1.62 + int maybe_find_index(jobject h);
1.63 +
1.64 + // returns the size of the generated oop table, for sizing the CodeBlob.
1.65 + // must be called after all oops are allocated!
1.66 + int oop_size();
1.67 +
1.68 + // Retrieve the oop handle at a given index.
1.69 + jobject handle_at(int index);
1.70 +
1.71 + int element_count() {
1.72 + // there is always a NULL virtually present as first object
1.73 + return _handles->length() + first_index;
1.74 + }
1.75 +
1.76 + // copy the generated oop table to CodeBlob
1.77 + void copy_to(CodeBlob* code); // => code->copy_oops(_handles)
1.78 +
1.79 + bool is_unused() { return _handles == NULL && !_complete; }
1.80 +#ifdef ASSERT
1.81 + bool is_complete() { return _complete; }
1.82 +#endif
1.83 +
1.84 + private:
1.85 + // leaky hash table of handle => index, to help detect duplicate insertion
1.86 + class IndexCache: public ResourceObj {
1.87 + // This class is only used by the OopRecorder class.
1.88 + friend class OopRecorder;
1.89 + enum {
1.90 + _log_cache_size = 9,
1.91 + _cache_size = (1<<_log_cache_size),
1.92 + // Index entries are ints. The LSBit is a collision indicator.
1.93 + _collision_bit_shift = 0,
1.94 + _collision_bit = 1,
1.95 + _index_shift = _collision_bit_shift+1
1.96 + };
1.97 + int _cache[_cache_size];
1.98 + static juint cache_index(jobject handle) {
1.99 + juint ci = (int) (intptr_t) handle;
1.100 + ci ^= ci >> (BitsPerByte*2);
1.101 + ci += ci >> (BitsPerByte*1);
1.102 + return ci & (_cache_size-1);
1.103 + }
1.104 + int* cache_location(jobject handle) {
1.105 + return &_cache[ cache_index(handle) ];
1.106 + }
1.107 + static bool cache_location_collision(int* cloc) {
1.108 + return ((*cloc) & _collision_bit) != 0;
1.109 + }
1.110 + static int cache_location_index(int* cloc) {
1.111 + return (*cloc) >> _index_shift;
1.112 + }
1.113 + static void set_cache_location_index(int* cloc, int index) {
1.114 + int cval0 = (*cloc);
1.115 + int cval1 = (index << _index_shift);
1.116 + if (cval0 != 0 && cval1 != cval0) cval1 += _collision_bit;
1.117 + (*cloc) = cval1;
1.118 + }
1.119 + IndexCache();
1.120 + };
1.121 +
1.122 + // Helper function; returns false for NULL or Universe::non_oop_word().
1.123 + inline bool is_real_jobject(jobject h);
1.124 +
1.125 + void maybe_initialize();
1.126 + int add_handle(jobject h, bool make_findable);
1.127 +
1.128 + enum { null_index = 0, first_index = 1, index_cache_threshold = 20 };
1.129 +
1.130 + GrowableArray<jobject>* _handles; // ordered list (first is always NULL)
1.131 + GrowableArray<int>* _no_finds; // all unfindable indexes; usually empty
1.132 + IndexCache* _indexes; // map: jobject -> its probable index
1.133 + Arena* _arena;
1.134 + bool _complete;
1.135 +
1.136 +#ifdef ASSERT
1.137 + static int _find_index_calls, _hit_indexes, _missed_indexes;
1.138 +#endif
1.139 +};
