gdb/frame-info.h

   1 /* Frame info pointer
   2
   3    Copyright (C) 2022-2023 Free Software Foundation, Inc.
   4
   5    This file is part of GDB.
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 3 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
  19
  20 #ifndef GDB_FRAME_INFO_H
  21 #define GDB_FRAME_INFO_H
  22
  23 #include "gdbsupport/intrusive_list.h"
  24 #include "frame-id.h"
  25
  26 struct frame_info;
  27
  28 /* A wrapper for "frame_info *".  frame_info objects are invalidated
  29    whenever reinit_frame_cache is called.  This class arranges to
  30    invalidate the pointer when appropriate.  This is done to help
  31    detect a GDB bug that was relatively common.
  32
  33    A small amount of code must still operate on raw pointers, so a
  34    "get" method is provided.  However, you should normally not use
  35    this in new code.  */
  36
  37 class frame_info_ptr : public intrusive_list_node<frame_info_ptr>
  38 {
  39 public:
  40   /* Create a frame_info_ptr from a raw pointer.  */
  41   explicit frame_info_ptr (struct frame_info *ptr)
  42     : m_ptr (ptr)
  43   {
  44     frame_list.push_back (*this);
  45   }
  46
  47   /* Create a null frame_info_ptr.  */
  48   frame_info_ptr ()
  49   {
  50     frame_list.push_back (*this);
  51   }
  52
  53   frame_info_ptr (std::nullptr_t)
  54   {
  55     frame_list.push_back (*this);
  56   }
  57
  58   frame_info_ptr (const frame_info_ptr &other)
  59     : m_ptr (other.m_ptr),
  60       m_cached_id (other.m_cached_id),
  61       m_cached_level (other.m_cached_level)
  62   {
  63     frame_list.push_back (*this);
  64   }
  65
  66   frame_info_ptr (frame_info_ptr &&other)
  67     : m_ptr (other.m_ptr),
  68       m_cached_id (other.m_cached_id),
  69       m_cached_level (other.m_cached_level)
  70   {
  71     other.m_ptr = nullptr;
  72     other.m_cached_id = null_frame_id;
  73     other.m_cached_level = invalid_level;
  74     frame_list.push_back (*this);
  75   }
  76
  77   ~frame_info_ptr ()
  78   {
  79     /* If this node has static storage, it may be deleted after
  80        frame_list.  Attempting to erase ourselves would then trigger
  81        internal errors, so make sure we are still linked first.  */
  82     if (is_linked ())
  83       frame_list.erase (frame_list.iterator_to (*this));
  84   }
  85
  86   frame_info_ptr &operator= (const frame_info_ptr &other)
  87   {
  88     m_ptr = other.m_ptr;
  89     m_cached_id = other.m_cached_id;
  90     m_cached_level = other.m_cached_level;
  91     return *this;
  92   }
  93
  94   frame_info_ptr &operator= (std::nullptr_t)
  95   {
  96     m_ptr = nullptr;
  97     m_cached_id = null_frame_id;
  98     m_cached_level = invalid_level;
  99     return *this;
 100   }
 101
 102   frame_info_ptr &operator= (frame_info_ptr &&other)
 103   {
 104     m_ptr = other.m_ptr;
 105     m_cached_id = other.m_cached_id;
 106     m_cached_level = other.m_cached_level;
 107     other.m_ptr = nullptr;
 108     other.m_cached_id = null_frame_id;
 109     other.m_cached_level = invalid_level;
 110     return *this;
 111   }
 112
 113   frame_info *operator-> () const
 114   {
 115     return m_ptr;
 116   }
 117
 118   /* Fetch the underlying pointer.  Note that new code should
 119      generally not use this -- avoid it if at all possible.  */
 120   frame_info *get () const
 121   {
 122     return m_ptr;
 123   }
 124
 125   /* This exists for compatibility with pre-existing code that checked
 126      a "frame_info *" using "!".  */
 127   bool operator! () const
 128   {
 129     return m_ptr == nullptr;
 130   }
 131
 132   /* This exists for compatibility with pre-existing code that checked
 133      a "frame_info *" like "if (ptr)".  */
 134   explicit operator bool () const
 135   {
 136     return m_ptr != nullptr;
 137   }
 138
 139   /* Invalidate this pointer.  */
 140   void invalidate ()
 141   {
 142     m_ptr = nullptr;
 143   }
 144
 145   /* Cache the frame_id that the pointer will use to reinflate.  */
 146   void prepare_reinflate ();
 147
 148   /* Use the cached frame_id to reinflate the pointer.  */
 149   void reinflate ();
 150
 151 private:
 152   /* We sometimes need to construct frame_info_ptr objects around the
 153      sentinel_frame, which has level -1.  Therefore, make the invalid frame
 154      level value -2.  */
 155   static constexpr int invalid_level = -2;
 156
 157   /* The underlying pointer.  */
 158   frame_info *m_ptr = nullptr;
 159
 160   /* The frame_id of the underlying pointer.  */
 161   frame_id m_cached_id = null_frame_id;
 162
 163   /* The frame level of the underlying pointer.  */
 164   int m_cached_level = invalid_level;
 165
 166   /* All frame_info_ptr objects are kept on an intrusive list.
 167      This keeps their construction and destruction costs
 168      reasonably small.  */
 169   static intrusive_list<frame_info_ptr> frame_list;
 170
 171   /* A friend so it can invalidate the pointers.  */
 172   friend void reinit_frame_cache ();
 173 };
 174
 175 static inline bool
 176 operator== (const frame_info *self, const frame_info_ptr &other)
 177 {
 178   return self == other.get ();
 179 }
 180
 181 static inline bool
 182 operator== (const frame_info_ptr &self, const frame_info_ptr &other)
 183 {
 184   return self.get () == other.get ();
 185 }
 186
 187 static inline bool
 188 operator== (const frame_info_ptr &self, const frame_info *other)
 189 {
 190   return self.get () == other;
 191 }
 192
 193 static inline bool
 194 operator!= (const frame_info *self, const frame_info_ptr &other)
 195 {
 196   return self != other.get ();
 197 }
 198
 199 static inline bool
 200 operator!= (const frame_info_ptr &self, const frame_info_ptr &other)
 201 {
 202   return self.get () != other.get ();
 203 }
 204
 205 static inline bool
 206 operator!= (const frame_info_ptr &self, const frame_info *other)
 207 {
 208   return self.get () != other;
 209 }
 210
 211 #endif /* GDB_FRAME_INFO_H */