duke@435: /*
stefank@2314:  * Copyright (c) 1997, 2010, Oracle and/or its affiliates. All rights reserved.
duke@435:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@435:  *
duke@435:  * This code is free software; you can redistribute it and/or modify it
duke@435:  * under the terms of the GNU General Public License version 2 only, as
duke@435:  * published by the Free Software Foundation.
duke@435:  *
duke@435:  * This code is distributed in the hope that it will be useful, but WITHOUT
duke@435:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@435:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
duke@435:  * version 2 for more details (a copy is included in the LICENSE file that
duke@435:  * accompanied this code).
duke@435:  *
duke@435:  * You should have received a copy of the GNU General Public License version
duke@435:  * 2 along with this work; if not, write to the Free Software Foundation,
duke@435:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@435:  *
trims@1907:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
trims@1907:  * or visit www.oracle.com if you need additional information or have any
trims@1907:  * questions.
duke@435:  *
duke@435:  */
duke@435: 
stefank@2314: #ifndef SHARE_VM_INTERPRETER_OOPMAPCACHE_HPP
stefank@2314: #define SHARE_VM_INTERPRETER_OOPMAPCACHE_HPP
stefank@2314: 
stefank@2314: #include "oops/generateOopMap.hpp"
stefank@2325: #include "runtime/mutex.hpp"
stefank@2314: 
duke@435: // A Cache for storing (method, bci) -> oopMap.
duke@435: // The memory management system uses the cache when locating object
duke@435: // references in an interpreted frame.
duke@435: //
duke@435: // OopMapCache's are allocated lazily per instanceKlass.
duke@435: 
duke@435: // The oopMap (InterpreterOopMap) is stored as a bit mask. If the
duke@435: // bit_mask can fit into two words it is stored in
duke@435: // the _bit_mask array, otherwise it is allocated on the heap.
duke@435: // For OopMapCacheEntry the bit_mask is allocated in the C heap
duke@435: // because these entries persist between garbage collections.
duke@435: // For InterpreterOopMap the bit_mask is allocated in
duke@435: // a resource area for better performance.  InterpreterOopMap
duke@435: // should only be created and deleted during same garbage collection.
duke@435: //
duke@435: // If ENABBLE_ZAP_DEAD_LOCALS is defined, two bits are used
duke@435: // per entry instead of one. In all cases,
duke@435: // the first bit is set to indicate oops as opposed to other
duke@435: // values. If the second bit is available,
duke@435: // it is set for dead values. We get the following encoding:
duke@435: //
duke@435: // 00 live value
duke@435: // 01 live oop
duke@435: // 10 dead value
duke@435: // 11 <unused>                                   (we cannot distinguish between dead oops or values with the current oop map generator)
duke@435: 
duke@435: 
duke@435: class OffsetClosure  {
duke@435:  public:
duke@435:   virtual void offset_do(int offset) = 0;
duke@435: };
duke@435: 
duke@435: 
duke@435: class InterpreterOopMap: ResourceObj {
duke@435:   friend class OopMapCache;
duke@435: 
duke@435:  public:
duke@435:   enum {
duke@435:     N                = 2,                // the number of words reserved
duke@435:                                          // for inlined mask storage
duke@435:     small_mask_limit = N * BitsPerWord,  // the maximum number of bits
duke@435:                                          // available for small masks,
duke@435:                                          // small_mask_limit can be set to 0
duke@435:                                          // for testing bit_mask allocation
duke@435: 
duke@435: #ifdef ENABLE_ZAP_DEAD_LOCALS
duke@435:     bits_per_entry   = 2,
duke@435:     dead_bit_number  = 1,
duke@435: #else
duke@435:     bits_per_entry   = 1,
duke@435: #endif
duke@435:     oop_bit_number   = 0
duke@435:   };
duke@435: 
duke@435:  private:
duke@435:   methodOop      _method;         // the method for which the mask is valid
duke@435:   unsigned short _bci;            // the bci    for which the mask is valid
duke@435:   int            _mask_size;      // the mask size in bits
duke@435:   int            _expression_stack_size; // the size of the expression stack in slots
duke@435: 
duke@435:  protected:
duke@435:   intptr_t       _bit_mask[N];    // the bit mask if
duke@435:                                   // mask_size <= small_mask_limit,
duke@435:                                   // ptr to bit mask otherwise
duke@435:                                   // "protected" so that sub classes can
duke@435:                                   // access it without using trickery in
duke@435:                                   // methd bit_mask().
duke@435: #ifdef ASSERT
duke@435:   bool _resource_allocate_bit_mask;
duke@435: #endif
duke@435: 
duke@435:   // access methods
duke@435:   methodOop      method() const                  { return _method; }
duke@435:   void           set_method(methodOop v)         { _method = v; }
duke@435:   int            bci() const                     { return _bci; }
duke@435:   void           set_bci(int v)                  { _bci = v; }
duke@435:   int            mask_size() const               { return _mask_size; }
duke@435:   void           set_mask_size(int v)            { _mask_size = v; }
duke@435:   int            number_of_entries() const       { return mask_size() / bits_per_entry; }
duke@435:   // Test bit mask size and return either the in-line bit mask or allocated
duke@435:   // bit mask.
duke@435:   uintptr_t*  bit_mask()                         { return (uintptr_t*)(mask_size() <= small_mask_limit ? (intptr_t)_bit_mask : _bit_mask[0]); }
duke@435: 
duke@435:   // return the word size of_bit_mask.  mask_size() <= 4 * MAX_USHORT
duke@435:   size_t mask_word_size() {
duke@435:     return (mask_size() + BitsPerWord - 1) / BitsPerWord;
duke@435:   }
duke@435: 
duke@435:   uintptr_t entry_at(int offset)            { int i = offset * bits_per_entry; return bit_mask()[i / BitsPerWord] >> (i % BitsPerWord); }
duke@435: 
duke@435:   void set_expression_stack_size(int sz)    { _expression_stack_size = sz; }
duke@435: 
duke@435: #ifdef ENABLE_ZAP_DEAD_LOCALS
duke@435:   bool is_dead(int offset)                       { return (entry_at(offset) & (1 << dead_bit_number)) != 0; }
duke@435: #endif
duke@435: 
duke@435:   // Lookup
duke@435:   bool match(methodHandle method, int bci)       { return _method == method() && _bci == bci; }
duke@435:   bool is_empty();
duke@435: 
duke@435:   // Initialization
duke@435:   void initialize();
duke@435: 
duke@435:  public:
duke@435:   InterpreterOopMap();
duke@435:   ~InterpreterOopMap();
duke@435: 
duke@435:   // Copy the OopMapCacheEntry in parameter "from" into this
duke@435:   // InterpreterOopMap.  If the _bit_mask[0] in "from" points to
duke@435:   // allocated space (i.e., the bit mask was to large to hold
duke@435:   // in-line), allocate the space from a Resource area.
duke@435:   void resource_copy(OopMapCacheEntry* from);
duke@435: 
duke@435:   void iterate_oop(OffsetClosure* oop_closure);
duke@435:   void oop_iterate(OopClosure * blk);
duke@435:   void oop_iterate(OopClosure * blk, MemRegion mr);
duke@435:   void verify();
duke@435:   void print();
duke@435: 
duke@435:   bool is_oop  (int offset)                      { return (entry_at(offset) & (1 << oop_bit_number )) != 0; }
duke@435: 
duke@435:   int expression_stack_size()                    { return _expression_stack_size; }
duke@435: 
duke@435: #ifdef ENABLE_ZAP_DEAD_LOCALS
duke@435:   void iterate_all(OffsetClosure* oop_closure, OffsetClosure* value_closure, OffsetClosure* dead_closure);
duke@435: #endif
duke@435: };
duke@435: 
duke@435: class OopMapCache : public CHeapObj {
duke@435:  private:
duke@435:   enum { _size        = 32,     // Use fixed size for now
duke@435:          _probe_depth = 3       // probe depth in case of collisions
duke@435:   };
duke@435: 
duke@435:   OopMapCacheEntry* _array;
duke@435: 
duke@435:   unsigned int hash_value_for(methodHandle method, int bci);
duke@435:   OopMapCacheEntry* entry_at(int i) const;
duke@435: 
duke@435:   Mutex _mut;
duke@435: 
duke@435:   void flush();
duke@435: 
duke@435:  public:
duke@435:   OopMapCache();
duke@435:   ~OopMapCache();                                // free up memory
duke@435: 
duke@435:   // flush cache entry is occupied by an obsolete method
duke@435:   void flush_obsolete_entries();
duke@435: 
duke@435:   // Returns the oopMap for (method, bci) in parameter "entry".
duke@435:   // Returns false if an oop map was not found.
duke@435:   void lookup(methodHandle method, int bci, InterpreterOopMap* entry);
duke@435: 
duke@435:   // Compute an oop map without updating the cache or grabbing any locks (for debugging)
duke@435:   static void compute_one_oop_map(methodHandle method, int bci, InterpreterOopMap* entry);
duke@435: 
duke@435:   // Helpers
duke@435:   // Iterate over the entries in the cached OopMapCacheEntry's
duke@435:   void oop_iterate(OopClosure *blk);
duke@435:   void oop_iterate(OopClosure *blk, MemRegion mr);
duke@435:   void verify();
duke@435: 
duke@435:   // Returns total no. of bytes allocated as part of OopMapCache's
duke@435:   static long memory_usage()                     PRODUCT_RETURN0;
duke@435: };
stefank@2314: 
stefank@2314: #endif // SHARE_VM_INTERPRETER_OOPMAPCACHE_HPP