1 /*
   2  * Copyright 1997-2009 Sun Microsystems, Inc.  All Rights Reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  20  * CA 95054 USA or visit www.sun.com if you need additional information or
  21  * have any questions.
  22  *
  23  */
  24 
  25 // PcDescs map a physical PC (given as offset from start of nmethod) to
  26 // the corresponding source scope and byte code index.
  27 
  28 class nmethod;
  29 
  30 class PcDesc VALUE_OBJ_CLASS_SPEC {
  31   friend class VMStructs;
  32  private:
  33   int _pc_offset;           // offset from start of nmethod
  34   int _scope_decode_offset; // offset for scope in nmethod
  35   int _obj_decode_offset;
  36 
  37   union PcDescFlags {
  38     int word;
  39     struct {
  40       unsigned int reexecute: 1;
  41     } bits;
  42     operator ==(const PcDescFlags& other) { return word == other.word; }
  43   } _flags;
  44 
  45  public:
  46   int pc_offset() const           { return _pc_offset;   }
  47   int scope_decode_offset() const { return _scope_decode_offset; }
  48   int obj_decode_offset() const   { return _obj_decode_offset; }
  49 
  50   void set_pc_offset(int x)           { _pc_offset           = x; }
  51   void set_scope_decode_offset(int x) { _scope_decode_offset = x; }
  52   void set_obj_decode_offset(int x)   { _obj_decode_offset   = x; }
  53 
  54   // Constructor (only used for static in nmethod.cpp)
  55   // Also used by ScopeDesc::sender()]
  56   PcDesc(int pc_offset, int scope_decode_offset, int obj_decode_offset);
  57 
  58   enum {
  59     // upper and lower exclusive limits real offsets:
  60     lower_offset_limit = -1,
  61     upper_offset_limit = (unsigned int)-1 >> 1
  62   };
  63 
  64   // Flags
  65   bool     should_reexecute()              const { return _flags.bits.reexecute; }
  66   void set_should_reexecute(bool z)              { _flags.bits.reexecute = z;    }
  67 
  68   // Does pd refer to the same information as pd?
  69   bool is_same_info(const PcDesc* pd) {
  70     return _scope_decode_offset == pd->_scope_decode_offset &&
  71       _obj_decode_offset == pd->_obj_decode_offset &&
  72       _flags == pd->_flags;
  73   }
  74 
  75   // Returns the real pc
  76   address real_pc(const nmethod* code) const;
  77 
  78   void print(nmethod* code);
  79   bool verify(nmethod* code);
  80 };