1 /*
   2  * Copyright (c) 1997, 2009, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 class StackValue : public ResourceObj {
  26  private:
  27   BasicType _type;
  28   intptr_t  _i; // Blank java stack slot value
  29   Handle    _o; // Java stack slot value interpreted as a Handle
  30  public:
  31 
  32   StackValue(intptr_t value) {
  33     _type  = T_INT;
  34     _i     = value;
  35   }
  36 
  37   StackValue(Handle value, intptr_t scalar_replaced = 0) {
  38     _type    = T_OBJECT;
  39     _i       = scalar_replaced;
  40     _o       = value;
  41     assert(_i == 0 || _o.is_null(), "not null object should not be marked as scalar replaced");
  42   }
  43 
  44   StackValue() {
  45     _type   = T_CONFLICT;
  46     _i      = 0;
  47   }
  48 
  49   // Only used during deopt- preserve object type.
  50   StackValue(intptr_t o, BasicType t) {
  51     assert(t == T_OBJECT, "should not be used");
  52     _type   = t;
  53     _i      = o;
  54   }
  55 
  56   Handle get_obj() const {
  57     assert(type() == T_OBJECT, "type check");
  58     return _o;
  59   }
  60 
  61   bool obj_is_scalar_replaced() const {
  62     assert(type() == T_OBJECT, "type check");
  63     return _i != 0;
  64   }
  65 
  66   void set_obj(Handle value) {
  67     assert(type() == T_OBJECT, "type check");
  68     _o = value;
  69   }
  70 
  71   intptr_t get_int() const {
  72     assert(type() == T_INT, "type check");
  73     return _i;
  74   }
  75 
  76   // For special case in deopt.
  77   intptr_t get_int(BasicType t) const {
  78     assert(t == T_OBJECT && type() == T_OBJECT, "type check");
  79     return _i;
  80   }
  81 
  82   void set_int(intptr_t value) {
  83     assert(type() == T_INT, "type check");
  84     _i = value;
  85   }
  86 
  87   BasicType type() const { return  _type; }
  88 
  89   bool equal(StackValue *value) {
  90     if (_type != value->_type) return false;
  91     if (_type == T_OBJECT)
  92       return (_o == value->_o);
  93     else {
  94       assert(_type == T_INT, "sanity check");
  95       // [phh] compare only low addressed portions of intptr_t slots
  96       return (*(int *)&_i == *(int *)&value->_i);
  97     }
  98   }
  99 
 100   static StackValue* create_stack_value(const frame* fr, const RegisterMap* reg_map, ScopeValue* sv);
 101   static BasicLock*  resolve_monitor_lock(const frame* fr, Location location);
 102 
 103 #ifndef PRODUCT
 104  public:
 105   // Printing
 106   void print_on(outputStream* st) const;
 107 #endif
 108 };