Mercurial > hg > truffle
view src/share/vm/interpreter/oopMapCache.hpp @ 5495:c78cf0abfdff
Removed unused import.
author | Thomas Wuerthinger <thomas.wuerthinger@oracle.com> |
---|---|
date | Wed, 06 Jun 2012 17:20:07 +0200 |
parents | c760f78e0a53 |
children | d2a62e0f25eb |
line wrap: on
line source
/* * Copyright (c) 1997, 2010, 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 = 2, // 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 #ifdef ENABLE_ZAP_DEAD_LOCALS bits_per_entry = 2, dead_bit_number = 1, #else bits_per_entry = 1, #endif oop_bit_number = 0 }; private: methodOop _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 methodOop method() const { return _method; } void set_method(methodOop 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; } int number_of_entries() const { return mask_size() / bits_per_entry; } // Test bit mask size and return either the in-line bit mask or allocated // bit mask. uintptr_t* bit_mask() { 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() { return (mask_size() + BitsPerWord - 1) / BitsPerWord; } uintptr_t entry_at(int offset) { int i = offset * bits_per_entry; return bit_mask()[i / BitsPerWord] >> (i % BitsPerWord); } void set_expression_stack_size(int sz) { _expression_stack_size = sz; } #ifdef ENABLE_ZAP_DEAD_LOCALS bool is_dead(int offset) { return (entry_at(offset) & (1 << dead_bit_number)) != 0; } #endif // Lookup bool match(methodHandle method, int bci) { return _method == method() && _bci == bci; } bool is_empty(); // 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); void oop_iterate(OopClosure * blk); void oop_iterate(OopClosure * blk, MemRegion mr); void verify(); void print(); bool is_oop (int offset) { return (entry_at(offset) & (1 << oop_bit_number )) != 0; } int expression_stack_size() { return _expression_stack_size; } #ifdef ENABLE_ZAP_DEAD_LOCALS void iterate_all(OffsetClosure* oop_closure, OffsetClosure* value_closure, OffsetClosure* dead_closure); #endif }; class OopMapCache : public CHeapObj { private: enum { _size = 32, // Use fixed size for now _probe_depth = 3 // probe depth in case of collisions }; OopMapCacheEntry* _array; unsigned int hash_value_for(methodHandle method, int bci); OopMapCacheEntry* entry_at(int i) const; Mutex _mut; 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(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(methodHandle method, int bci, InterpreterOopMap* entry); // Helpers // Iterate over the entries in the cached OopMapCacheEntry's void oop_iterate(OopClosure *blk); void oop_iterate(OopClosure *blk, MemRegion mr); void verify(); // Returns total no. of bytes allocated as part of OopMapCache's static long memory_usage() PRODUCT_RETURN0; }; #endif // SHARE_VM_INTERPRETER_OOPMAPCACHE_HPP