author | dholmes |
Mon, 21 Mar 2011 22:16:19 -0400 | |
changeset 8735 | 9829dda3b405 |
parent 7397 | 5b173b4ca846 |
child 13728 | 882756847a04 |
permissions | -rw-r--r-- |
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/* |
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* Copyright (c) 1998, 2010, Oracle and/or its affiliates. All rights reserved. |
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
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* |
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* This code is free software; you can redistribute it and/or modify it |
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* under the terms of the GNU General Public License version 2 only, as |
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* published by the Free Software Foundation. |
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* |
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* This code is distributed in the hope that it will be useful, but WITHOUT |
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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* version 2 for more details (a copy is included in the LICENSE file that |
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* accompanied this code). |
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* |
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* You should have received a copy of the GNU General Public License version |
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* 2 along with this work; if not, write to the Free Software Foundation, |
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
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* |
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
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* or visit www.oracle.com if you need additional information or have any |
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* questions. |
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* |
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*/ |
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#ifndef SHARE_VM_CODE_OOPRECORDER_HPP |
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#define SHARE_VM_CODE_OOPRECORDER_HPP |
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#include "runtime/handles.hpp" |
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#include "utilities/growableArray.hpp" |
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// Recording and retrieval of oop relocations in compiled code. |
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class CodeBlob; |
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class OopRecorder : public ResourceObj { |
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public: |
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// A two-way mapping from positive indexes to oop handles. |
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// The zero index is reserved for a constant (sharable) null. |
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// Indexes may not be negative. |
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// Use the given arena to manage storage, if not NULL. |
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// By default, uses the current ResourceArea. |
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OopRecorder(Arena* arena = NULL); |
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// Generate a new index on which CodeBlob::oop_addr_at will work. |
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// allocate_index and find_index never return the same index, |
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// and allocate_index never returns the same index twice. |
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// In fact, two successive calls to allocate_index return successive ints. |
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int allocate_index(jobject h) { |
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return add_handle(h, false); |
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} |
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// For a given jobject, this will return the same index repeatedly. |
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// The index can later be given to oop_at to retrieve the oop. |
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// However, the oop must not be changed via CodeBlob::oop_addr_at. |
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int find_index(jobject h) { |
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int index = maybe_find_index(h); |
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if (index < 0) { // previously unallocated |
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index = add_handle(h, true); |
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} |
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return index; |
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} |
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// variant of find_index which does not allocate if not found (yields -1) |
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int maybe_find_index(jobject h); |
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// returns the size of the generated oop table, for sizing the CodeBlob. |
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// must be called after all oops are allocated! |
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int oop_size(); |
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// Retrieve the oop handle at a given index. |
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jobject handle_at(int index); |
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int element_count() { |
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// there is always a NULL virtually present as first object |
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return _handles->length() + first_index; |
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} |
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// copy the generated oop table to nmethod |
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void copy_to(nmethod* nm); // => nm->copy_oops(_handles) |
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bool is_unused() { return _handles == NULL && !_complete; } |
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#ifdef ASSERT |
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bool is_complete() { return _complete; } |
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#endif |
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private: |
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// leaky hash table of handle => index, to help detect duplicate insertion |
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class IndexCache: public ResourceObj { |
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// This class is only used by the OopRecorder class. |
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friend class OopRecorder; |
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enum { |
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_log_cache_size = 9, |
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_cache_size = (1<<_log_cache_size), |
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// Index entries are ints. The LSBit is a collision indicator. |
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_collision_bit_shift = 0, |
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_collision_bit = 1, |
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_index_shift = _collision_bit_shift+1 |
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}; |
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int _cache[_cache_size]; |
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static juint cache_index(jobject handle) { |
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juint ci = (int) (intptr_t) handle; |
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ci ^= ci >> (BitsPerByte*2); |
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ci += ci >> (BitsPerByte*1); |
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return ci & (_cache_size-1); |
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} |
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int* cache_location(jobject handle) { |
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return &_cache[ cache_index(handle) ]; |
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} |
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static bool cache_location_collision(int* cloc) { |
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return ((*cloc) & _collision_bit) != 0; |
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} |
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static int cache_location_index(int* cloc) { |
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return (*cloc) >> _index_shift; |
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} |
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static void set_cache_location_index(int* cloc, int index) { |
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int cval0 = (*cloc); |
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int cval1 = (index << _index_shift); |
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if (cval0 != 0 && cval1 != cval0) cval1 += _collision_bit; |
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(*cloc) = cval1; |
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} |
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IndexCache(); |
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}; |
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// Helper function; returns false for NULL or Universe::non_oop_word(). |
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inline bool is_real_jobject(jobject h); |
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void maybe_initialize(); |
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int add_handle(jobject h, bool make_findable); |
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enum { null_index = 0, first_index = 1, index_cache_threshold = 20 }; |
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GrowableArray<jobject>* _handles; // ordered list (first is always NULL) |
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GrowableArray<int>* _no_finds; // all unfindable indexes; usually empty |
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IndexCache* _indexes; // map: jobject -> its probable index |
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Arena* _arena; |
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bool _complete; |
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#ifdef ASSERT |
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static int _find_index_calls, _hit_indexes, _missed_indexes; |
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#endif |
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}; |
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#endif // SHARE_VM_CODE_OOPRECORDER_HPP |