| /* |
| * Copyright (c) 1997, 2017, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| * |
| */ |
| |
| #ifndef SHARE_VM_INTERPRETER_OOPMAPCACHE_HPP |
| #define SHARE_VM_INTERPRETER_OOPMAPCACHE_HPP |
| |
| #include "oops/generateOopMap.hpp" |
| #include "runtime/mutex.hpp" |
| |
| // A Cache for storing (method, bci) -> oopMap. |
| // The memory management system uses the cache when locating object |
| // references in an interpreted frame. |
| // |
| // OopMapCache's are allocated lazily per InstanceKlass. |
| |
| // The oopMap (InterpreterOopMap) is stored as a bit mask. If the |
| // bit_mask can fit into two words it is stored in |
| // the _bit_mask array, otherwise it is allocated on the heap. |
| // For OopMapCacheEntry the bit_mask is allocated in the C heap |
| // because these entries persist between garbage collections. |
| // For InterpreterOopMap the bit_mask is allocated in |
| // a resource area for better performance. InterpreterOopMap |
| // should only be created and deleted during same garbage collection. |
| // |
| // If ENABBLE_ZAP_DEAD_LOCALS is defined, two bits are used |
| // per entry instead of one. In all cases, |
| // the first bit is set to indicate oops as opposed to other |
| // values. If the second bit is available, |
| // it is set for dead values. We get the following encoding: |
| // |
| // 00 live value |
| // 01 live oop |
| // 10 dead value |
| // 11 <unused> (we cannot distinguish between dead oops or values with the current oop map generator) |
| |
| |
| class OffsetClosure { |
| public: |
| virtual void offset_do(int offset) = 0; |
| }; |
| |
| |
| class InterpreterOopMap: ResourceObj { |
| friend class OopMapCache; |
| |
| public: |
| enum { |
| N = 4, // the number of words reserved |
| // for inlined mask storage |
| small_mask_limit = N * BitsPerWord, // the maximum number of bits |
| // available for small masks, |
| // small_mask_limit can be set to 0 |
| // for testing bit_mask allocation |
| |
| bits_per_entry = 2, |
| dead_bit_number = 1, |
| oop_bit_number = 0 |
| }; |
| |
| private: |
| Method* _method; // the method for which the mask is valid |
| unsigned short _bci; // the bci for which the mask is valid |
| int _mask_size; // the mask size in bits |
| int _expression_stack_size; // the size of the expression stack in slots |
| |
| protected: |
| intptr_t _bit_mask[N]; // the bit mask if |
| // mask_size <= small_mask_limit, |
| // ptr to bit mask otherwise |
| // "protected" so that sub classes can |
| // access it without using trickery in |
| // methd bit_mask(). |
| #ifdef ASSERT |
| bool _resource_allocate_bit_mask; |
| #endif |
| |
| // access methods |
| Method* method() const { return _method; } |
| void set_method(Method* v) { _method = v; } |
| int bci() const { return _bci; } |
| void set_bci(int v) { _bci = v; } |
| int mask_size() const { return _mask_size; } |
| void set_mask_size(int v) { _mask_size = v; } |
| // Test bit mask size and return either the in-line bit mask or allocated |
| // bit mask. |
| uintptr_t* bit_mask() const { return (uintptr_t*)(mask_size() <= small_mask_limit ? (intptr_t)_bit_mask : _bit_mask[0]); } |
| |
| // return the word size of_bit_mask. mask_size() <= 4 * MAX_USHORT |
| size_t mask_word_size() const { |
| return (mask_size() + BitsPerWord - 1) / BitsPerWord; |
| } |
| |
| uintptr_t entry_at(int offset) const { int i = offset * bits_per_entry; return bit_mask()[i / BitsPerWord] >> (i % BitsPerWord); } |
| |
| void set_expression_stack_size(int sz) { _expression_stack_size = sz; } |
| |
| // Lookup |
| bool match(const methodHandle& method, int bci) const { return _method == method() && _bci == bci; } |
| bool is_empty() const; |
| |
| // Initialization |
| void initialize(); |
| |
| public: |
| InterpreterOopMap(); |
| ~InterpreterOopMap(); |
| |
| // Copy the OopMapCacheEntry in parameter "from" into this |
| // InterpreterOopMap. If the _bit_mask[0] in "from" points to |
| // allocated space (i.e., the bit mask was to large to hold |
| // in-line), allocate the space from a Resource area. |
| void resource_copy(OopMapCacheEntry* from); |
| |
| void iterate_oop(OffsetClosure* oop_closure) const; |
| void print() const; |
| |
| int number_of_entries() const { return mask_size() / bits_per_entry; } |
| bool is_dead(int offset) const { return (entry_at(offset) & (1 << dead_bit_number)) != 0; } |
| bool is_oop (int offset) const { return (entry_at(offset) & (1 << oop_bit_number )) != 0; } |
| |
| int expression_stack_size() const { return _expression_stack_size; } |
| |
| }; |
| |
| class OopMapCache : public CHeapObj<mtClass> { |
| static OopMapCacheEntry* volatile _old_entries; |
| private: |
| enum { _size = 32, // Use fixed size for now |
| _probe_depth = 3 // probe depth in case of collisions |
| }; |
| |
| OopMapCacheEntry* volatile * _array; |
| |
| unsigned int hash_value_for(const methodHandle& method, int bci) const; |
| OopMapCacheEntry* entry_at(int i) const; |
| bool put_at(int i, OopMapCacheEntry* entry, OopMapCacheEntry* old); |
| |
| static void enqueue_for_cleanup(OopMapCacheEntry* entry); |
| |
| void flush(); |
| |
| public: |
| OopMapCache(); |
| ~OopMapCache(); // free up memory |
| |
| // flush cache entry is occupied by an obsolete method |
| void flush_obsolete_entries(); |
| |
| // Returns the oopMap for (method, bci) in parameter "entry". |
| // Returns false if an oop map was not found. |
| void lookup(const methodHandle& method, int bci, InterpreterOopMap* entry); |
| |
| // Compute an oop map without updating the cache or grabbing any locks (for debugging) |
| static void compute_one_oop_map(const methodHandle& method, int bci, InterpreterOopMap* entry); |
| static void cleanup_old_entries(); |
| }; |
| |
| #endif // SHARE_VM_INTERPRETER_OOPMAPCACHE_HPP |