aoqi@0: /*
aoqi@0:  * Copyright (c) 1997, 2012, Oracle and/or its affiliates. All rights reserved.
aoqi@0:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
aoqi@0:  *
aoqi@0:  * This code is free software; you can redistribute it and/or modify it
aoqi@0:  * under the terms of the GNU General Public License version 2 only, as
aoqi@0:  * published by the Free Software Foundation.
aoqi@0:  *
aoqi@0:  * This code is distributed in the hope that it will be useful, but WITHOUT
aoqi@0:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
aoqi@0:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
aoqi@0:  * version 2 for more details (a copy is included in the LICENSE file that
aoqi@0:  * accompanied this code).
aoqi@0:  *
aoqi@0:  * You should have received a copy of the GNU General Public License version
aoqi@0:  * 2 along with this work; if not, write to the Free Software Foundation,
aoqi@0:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
aoqi@0:  *
aoqi@0:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
aoqi@0:  * or visit www.oracle.com if you need additional information or have any
aoqi@0:  * questions.
aoqi@0:  *
aoqi@0:  */
aoqi@0: 
aoqi@0: #ifndef SHARE_VM_INTERPRETER_OOPMAPCACHE_HPP
aoqi@0: #define SHARE_VM_INTERPRETER_OOPMAPCACHE_HPP
aoqi@0: 
aoqi@0: #include "oops/generateOopMap.hpp"
aoqi@0: #include "runtime/mutex.hpp"
aoqi@0: 
aoqi@0: // A Cache for storing (method, bci) -> oopMap.
aoqi@0: // The memory management system uses the cache when locating object
aoqi@0: // references in an interpreted frame.
aoqi@0: //
aoqi@0: // OopMapCache's are allocated lazily per InstanceKlass.
aoqi@0: 
aoqi@0: // The oopMap (InterpreterOopMap) is stored as a bit mask. If the
aoqi@0: // bit_mask can fit into two words it is stored in
aoqi@0: // the _bit_mask array, otherwise it is allocated on the heap.
aoqi@0: // For OopMapCacheEntry the bit_mask is allocated in the C heap
aoqi@0: // because these entries persist between garbage collections.
aoqi@0: // For InterpreterOopMap the bit_mask is allocated in
aoqi@0: // a resource area for better performance.  InterpreterOopMap
aoqi@0: // should only be created and deleted during same garbage collection.
aoqi@0: //
aoqi@0: // If ENABBLE_ZAP_DEAD_LOCALS is defined, two bits are used
aoqi@0: // per entry instead of one. In all cases,
aoqi@0: // the first bit is set to indicate oops as opposed to other
aoqi@0: // values. If the second bit is available,
aoqi@0: // it is set for dead values. We get the following encoding:
aoqi@0: //
aoqi@0: // 00 live value
aoqi@0: // 01 live oop
aoqi@0: // 10 dead value
aoqi@0: // 11 <unused>                                   (we cannot distinguish between dead oops or values with the current oop map generator)
aoqi@0: 
aoqi@0: 
aoqi@0: class OffsetClosure  {
aoqi@0:  public:
aoqi@0:   virtual void offset_do(int offset) = 0;
aoqi@0: };
aoqi@0: 
aoqi@0: 
aoqi@0: class InterpreterOopMap: ResourceObj {
aoqi@0:   friend class OopMapCache;
aoqi@0: 
aoqi@0:  public:
aoqi@0:   enum {
aoqi@0:     N                = 2,                // the number of words reserved
aoqi@0:                                          // for inlined mask storage
aoqi@0:     small_mask_limit = N * BitsPerWord,  // the maximum number of bits
aoqi@0:                                          // available for small masks,
aoqi@0:                                          // small_mask_limit can be set to 0
aoqi@0:                                          // for testing bit_mask allocation
aoqi@0: 
aoqi@0: #ifdef ENABLE_ZAP_DEAD_LOCALS
aoqi@0:     bits_per_entry   = 2,
aoqi@0:     dead_bit_number  = 1,
aoqi@0: #else
aoqi@0:     bits_per_entry   = 1,
aoqi@0: #endif
aoqi@0:     oop_bit_number   = 0
aoqi@0:   };
aoqi@0: 
aoqi@0:  private:
aoqi@0:   Method*        _method;         // the method for which the mask is valid
aoqi@0:   unsigned short _bci;            // the bci    for which the mask is valid
aoqi@0:   int            _mask_size;      // the mask size in bits
aoqi@0:   int            _expression_stack_size; // the size of the expression stack in slots
aoqi@0: 
aoqi@0:  protected:
aoqi@0:   intptr_t       _bit_mask[N];    // the bit mask if
aoqi@0:                                   // mask_size <= small_mask_limit,
aoqi@0:                                   // ptr to bit mask otherwise
aoqi@0:                                   // "protected" so that sub classes can
aoqi@0:                                   // access it without using trickery in
aoqi@0:                                   // methd bit_mask().
aoqi@0: #ifdef ASSERT
aoqi@0:   bool _resource_allocate_bit_mask;
aoqi@0: #endif
aoqi@0: 
aoqi@0:   // access methods
aoqi@0:   Method*        method() const                  { return _method; }
aoqi@0:   void           set_method(Method* v)         { _method = v; }
aoqi@0:   int            bci() const                     { return _bci; }
aoqi@0:   void           set_bci(int v)                  { _bci = v; }
aoqi@0:   int            mask_size() const               { return _mask_size; }
aoqi@0:   void           set_mask_size(int v)            { _mask_size = v; }
aoqi@0:   int            number_of_entries() const       { return mask_size() / bits_per_entry; }
aoqi@0:   // Test bit mask size and return either the in-line bit mask or allocated
aoqi@0:   // bit mask.
aoqi@0:   uintptr_t*  bit_mask()                         { return (uintptr_t*)(mask_size() <= small_mask_limit ? (intptr_t)_bit_mask : _bit_mask[0]); }
aoqi@0: 
aoqi@0:   // return the word size of_bit_mask.  mask_size() <= 4 * MAX_USHORT
aoqi@0:   size_t mask_word_size() {
aoqi@0:     return (mask_size() + BitsPerWord - 1) / BitsPerWord;
aoqi@0:   }
aoqi@0: 
aoqi@0:   uintptr_t entry_at(int offset)            { int i = offset * bits_per_entry; return bit_mask()[i / BitsPerWord] >> (i % BitsPerWord); }
aoqi@0: 
aoqi@0:   void set_expression_stack_size(int sz)    { _expression_stack_size = sz; }
aoqi@0: 
aoqi@0: #ifdef ENABLE_ZAP_DEAD_LOCALS
aoqi@0:   bool is_dead(int offset)                       { return (entry_at(offset) & (1 << dead_bit_number)) != 0; }
aoqi@0: #endif
aoqi@0: 
aoqi@0:   // Lookup
aoqi@0:   bool match(methodHandle method, int bci)       { return _method == method() && _bci == bci; }
aoqi@0:   bool is_empty();
aoqi@0: 
aoqi@0:   // Initialization
aoqi@0:   void initialize();
aoqi@0: 
aoqi@0:  public:
aoqi@0:   InterpreterOopMap();
aoqi@0:   ~InterpreterOopMap();
aoqi@0: 
aoqi@0:   // Copy the OopMapCacheEntry in parameter "from" into this
aoqi@0:   // InterpreterOopMap.  If the _bit_mask[0] in "from" points to
aoqi@0:   // allocated space (i.e., the bit mask was to large to hold
aoqi@0:   // in-line), allocate the space from a Resource area.
aoqi@0:   void resource_copy(OopMapCacheEntry* from);
aoqi@0: 
aoqi@0:   void iterate_oop(OffsetClosure* oop_closure);
aoqi@0:   void print();
aoqi@0: 
aoqi@0:   bool is_oop  (int offset)                      { return (entry_at(offset) & (1 << oop_bit_number )) != 0; }
aoqi@0: 
aoqi@0:   int expression_stack_size()                    { return _expression_stack_size; }
aoqi@0: 
aoqi@0: #ifdef ENABLE_ZAP_DEAD_LOCALS
aoqi@0:   void iterate_all(OffsetClosure* oop_closure, OffsetClosure* value_closure, OffsetClosure* dead_closure);
aoqi@0: #endif
aoqi@0: };
aoqi@0: 
aoqi@0: class OopMapCache : public CHeapObj<mtClass> {
aoqi@0:  private:
aoqi@0:   enum { _size        = 32,     // Use fixed size for now
aoqi@0:          _probe_depth = 3       // probe depth in case of collisions
aoqi@0:   };
aoqi@0: 
aoqi@0:   OopMapCacheEntry* _array;
aoqi@0: 
aoqi@0:   unsigned int hash_value_for(methodHandle method, int bci);
aoqi@0:   OopMapCacheEntry* entry_at(int i) const;
aoqi@0: 
aoqi@0:   Mutex _mut;
aoqi@0: 
aoqi@0:   void flush();
aoqi@0: 
aoqi@0:  public:
aoqi@0:   OopMapCache();
aoqi@0:   ~OopMapCache();                                // free up memory
aoqi@0: 
aoqi@0:   // flush cache entry is occupied by an obsolete method
aoqi@0:   void flush_obsolete_entries();
aoqi@0: 
aoqi@0:   // Returns the oopMap for (method, bci) in parameter "entry".
aoqi@0:   // Returns false if an oop map was not found.
aoqi@0:   void lookup(methodHandle method, int bci, InterpreterOopMap* entry);
aoqi@0: 
aoqi@0:   // Compute an oop map without updating the cache or grabbing any locks (for debugging)
aoqi@0:   static void compute_one_oop_map(methodHandle method, int bci, InterpreterOopMap* entry);
aoqi@0: 
aoqi@0:   // Returns total no. of bytes allocated as part of OopMapCache's
aoqi@0:   static long memory_usage()                     PRODUCT_RETURN0;
aoqi@0: };
aoqi@0: 
aoqi@0: #endif // SHARE_VM_INTERPRETER_OOPMAPCACHE_HPP