1 /*
   2  * Copyright (c) 1997, 2010, 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 #ifndef SHARE_VM_RUNTIME_STACKVALUE_HPP
  26 #define SHARE_VM_RUNTIME_STACKVALUE_HPP
  27 
  28 #include "code/location.hpp"
  29 #include "runtime/handles.hpp"
  30 #include "utilities/top.hpp"
  31 
  32 class StackValue : public ResourceObj {
  33  private:
  34   BasicType _type;
  35   intptr_t  _i; // Blank java stack slot value
  36   Handle    _o; // Java stack slot value interpreted as a Handle
  37  public:
  38 
  39   StackValue(intptr_t value) {
  40     _type  = T_INT;
  41     _i     = value;
  42   }
  43 
  44   StackValue(Handle value, intptr_t scalar_replaced = 0) {
  45     _type    = T_OBJECT;
  46     _i       = scalar_replaced;
  47     _o       = value;
  48     assert(_i == 0 || _o.is_null(), "not null object should not be marked as scalar replaced");
  49   }
  50 
  51   StackValue() {
  52     _type   = T_CONFLICT;
  53     _i      = 0;
  54   }
  55 
  56   // Only used during deopt- preserve object type.
  57   StackValue(intptr_t o, BasicType t) {
  58     assert(t == T_OBJECT, "should not be used");
  59     _type   = t;
  60     _i      = o;
  61   }
  62 
  63   Handle get_obj() const {
  64     assert(type() == T_OBJECT, "type check");
  65     return _o;
  66   }
  67 
  68   bool obj_is_scalar_replaced() const {
  69     assert(type() == T_OBJECT, "type check");
  70     return _i != 0;
  71   }
  72 
  73   void set_obj(Handle value) {
  74     assert(type() == T_OBJECT, "type check");
  75     _o = value;
  76   }
  77 
  78   intptr_t get_int() const {
  79     assert(type() == T_INT, "type check");
  80     return _i;
  81   }
  82 
  83   // For special case in deopt.
  84   intptr_t get_int(BasicType t) const {
  85     assert(t == T_OBJECT && type() == T_OBJECT, "type check");
  86     return _i;
  87   }
  88 
  89   void set_int(intptr_t value) {
  90     assert(type() == T_INT, "type check");
  91     _i = value;
  92   }
  93 
  94   BasicType type() const { return  _type; }
  95 
  96   bool equal(StackValue *value) {
  97     if (_type != value->_type) return false;
  98     if (_type == T_OBJECT)
  99       return (_o == value->_o);
 100     else {
 101       assert(_type == T_INT, "sanity check");
 102       // [phh] compare only low addressed portions of intptr_t slots
 103       return (*(int *)&_i == *(int *)&value->_i);
 104     }
 105   }
 106 
 107   static StackValue* create_stack_value(const frame* fr, const RegisterMap* reg_map, ScopeValue* sv);
 108   static BasicLock*  resolve_monitor_lock(const frame* fr, Location location);
 109 
 110 #ifndef PRODUCT
 111  public:
 112   // Printing
 113   void print_on(outputStream* st) const;
 114 #endif
 115 };
 116 
 117 #endif // SHARE_VM_RUNTIME_STACKVALUE_HPP