libgcc/config/rs6000/cxa_atexit.c

   1 /* Copyright (C) 1999-2024 Free Software Foundation, Inc.
   2
   3    NOTE: This source is derived from an old version taken from the GNU C
   4    Library (glibc).
   5
   6 This file is part of GCC.
   7
   8 GCC is free software; you can redistribute it and/or modify it under
   9 the terms of the GNU General Public License as published by the Free
  10 Software Foundation; either version 3, or (at your option) any later
  11 version.
  12
  13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  16 for more details.
  17
  18 Under Section 7 of GPL version 3, you are granted additional
  19 permissions described in the GCC Runtime Library Exception, version
  20 3.1, as published by the Free Software Foundation.
  21
  22 You should have received a copy of the GNU General Public License and
  23 a copy of the GCC Runtime Library Exception along with this program;
  24 see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
  25 <http://www.gnu.org/licenses/>.  */
  26
  27 #include <assert.h>
  28 #include <stdlib.h>
  29
  30 #include "exit.h"
  31
  32 #undef __cxa_atexit
  33
  34 #define atomic_write_barrier() __asm__ ("eieio" ::: "memory")
  35
  36 int
  37 attribute_hidden
  38 __internal_atexit (void (*func) (void *), void *arg, void *d,
  39                    struct exit_function_list **listp)
  40 {
  41   struct exit_function *new = __new_exitfn (listp);
  42
  43   if (new == NULL)
  44     return -1;
  45
  46 #ifdef PTR_MANGLE
  47   PTR_MANGLE (func);
  48 #endif
  49   new->func.cxa.fn = (void (*) (void *, int)) func;
  50   new->func.cxa.arg = arg;
  51   new->func.cxa.dso_handle = d;
  52   atomic_write_barrier ();
  53   new->flavor = ef_cxa;
  54   return 0;
  55 }
  56
  57
  58 /* Register a function to be called by exit or when a shared library
  59    is unloaded.  This function is only called from code generated by
  60    the C++ compiler.  */
  61 int
  62 __cxa_atexit (void (*func) (void *), void *arg, void *d)
  63 {
  64   return __internal_atexit (func, arg, d, &__exit_funcs);
  65 }
  66 INTDEF(__cxa_atexit)
  67
  68
  69 static struct exit_function_list initial;
  70 struct exit_function_list *__exit_funcs = &initial;
  71 uint64_t __new_exitfn_called;
  72
  73 struct exit_function *
  74 __new_exitfn (struct exit_function_list **listp)
  75 {
  76   struct exit_function_list *p = NULL;
  77   struct exit_function_list *l;
  78   struct exit_function *r = NULL;
  79   size_t i = 0;
  80
  81   for (l = *listp; l != NULL; p = l, l = l->next)
  82     {
  83       for (i = l->idx; i > 0; --i)
  84         if (l->fns[i - 1].flavor != ef_free)
  85           break;
  86
  87       if (i > 0)
  88         break;
  89
  90       /* This block is completely unused.  */
  91       l->idx = 0;
  92     }
  93
  94   if (l == NULL || i == sizeof (l->fns) / sizeof (l->fns[0]))
  95     {
  96       /* The last entry in a block is used.  Use the first entry in
  97          the previous block if it exists.  Otherwise create a new one.  */
  98       if (p == NULL)
  99         {
 100           assert (l != NULL);
 101           p = (struct exit_function_list *)
 102             calloc (1, sizeof (struct exit_function_list));
 103           if (p != NULL)
 104             {
 105               p->next = *listp;
 106               *listp = p;
 107             }
 108         }
 109
 110       if (p != NULL)
 111         {
 112           r = &p->fns[0];
 113           p->idx = 1;
 114         }
 115     }
 116   else
 117     {
 118       /* There is more room in the block.  */
 119       r = &l->fns[i];
 120       l->idx = i + 1;
 121     }
 122
 123   /* Mark entry as used, but we don't know the flavor now.  */
 124   if (r != NULL)
 125     {
 126       r->flavor = ef_us;
 127       ++__new_exitfn_called;
 128     }
 129
 130   return r;
 131 }