--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/code/oopRecorder.hpp Sat Dec 01 00:00:00 2007 +0000
@@ -0,0 +1,136 @@
+/*
+ * Copyright 1998-2005 Sun Microsystems, Inc. All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ *
+ */
+
+// Recording and retrieval of oop relocations in compiled code.
+
+class CodeBlob;
+
+class OopRecorder : public ResourceObj {
+ public:
+ // A two-way mapping from positive indexes to oop handles.
+ // The zero index is reserved for a constant (sharable) null.
+ // Indexes may not be negative.
+
+ // Use the given arena to manage storage, if not NULL.
+ // By default, uses the current ResourceArea.
+ OopRecorder(Arena* arena = NULL);
+
+ // Generate a new index on which CodeBlob::oop_addr_at will work.
+ // allocate_index and find_index never return the same index,
+ // and allocate_index never returns the same index twice.
+ // In fact, two successive calls to allocate_index return successive ints.
+ int allocate_index(jobject h) {
+ return add_handle(h, false);
+ }
+
+ // For a given jobject, this will return the same index repeatedly.
+ // The index can later be given to oop_at to retrieve the oop.
+ // However, the oop must not be changed via CodeBlob::oop_addr_at.
+ int find_index(jobject h) {
+ int index = maybe_find_index(h);
+ if (index < 0) { // previously unallocated
+ index = add_handle(h, true);
+ }
+ return index;
+ }
+
+ // variant of find_index which does not allocate if not found (yields -1)
+ int maybe_find_index(jobject h);
+
+ // returns the size of the generated oop table, for sizing the CodeBlob.
+ // must be called after all oops are allocated!
+ int oop_size();
+
+ // Retrieve the oop handle at a given index.
+ jobject handle_at(int index);
+
+ int element_count() {
+ // there is always a NULL virtually present as first object
+ return _handles->length() + first_index;
+ }
+
+ // copy the generated oop table to CodeBlob
+ void copy_to(CodeBlob* code); // => code->copy_oops(_handles)
+
+ bool is_unused() { return _handles == NULL && !_complete; }
+#ifdef ASSERT
+ bool is_complete() { return _complete; }
+#endif
+
+ private:
+ // leaky hash table of handle => index, to help detect duplicate insertion
+ class IndexCache: public ResourceObj {
+ // This class is only used by the OopRecorder class.
+ friend class OopRecorder;
+ enum {
+ _log_cache_size = 9,
+ _cache_size = (1<<_log_cache_size),
+ // Index entries are ints. The LSBit is a collision indicator.
+ _collision_bit_shift = 0,
+ _collision_bit = 1,
+ _index_shift = _collision_bit_shift+1
+ };
+ int _cache[_cache_size];
+ static juint cache_index(jobject handle) {
+ juint ci = (int) (intptr_t) handle;
+ ci ^= ci >> (BitsPerByte*2);
+ ci += ci >> (BitsPerByte*1);
+ return ci & (_cache_size-1);
+ }
+ int* cache_location(jobject handle) {
+ return &_cache[ cache_index(handle) ];
+ }
+ static bool cache_location_collision(int* cloc) {
+ return ((*cloc) & _collision_bit) != 0;
+ }
+ static int cache_location_index(int* cloc) {
+ return (*cloc) >> _index_shift;
+ }
+ static void set_cache_location_index(int* cloc, int index) {
+ int cval0 = (*cloc);
+ int cval1 = (index << _index_shift);
+ if (cval0 != 0 && cval1 != cval0) cval1 += _collision_bit;
+ (*cloc) = cval1;
+ }
+ IndexCache();
+ };
+
+ // Helper function; returns false for NULL or Universe::non_oop_word().
+ inline bool is_real_jobject(jobject h);
+
+ void maybe_initialize();
+ int add_handle(jobject h, bool make_findable);
+
+ enum { null_index = 0, first_index = 1, index_cache_threshold = 20 };
+
+ GrowableArray<jobject>* _handles; // ordered list (first is always NULL)
+ GrowableArray<int>* _no_finds; // all unfindable indexes; usually empty
+ IndexCache* _indexes; // map: jobject -> its probable index
+ Arena* _arena;
+ bool _complete;
+
+#ifdef ASSERT
+ static int _find_index_calls, _hit_indexes, _missed_indexes;
+#endif
+};