gcc/emutls.c

   1 /* TLS emulation.
   2    Copyright (C) 2006 Free Software Foundation, Inc.
   3    Contributed by Jakub Jelinek <jakub@redhat.com>.
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 2, or (at your option) any later
  10 version.
  11
  12 In addition to the permissions in the GNU General Public License, the
  13 Free Software Foundation gives you unlimited permission to link the
  14 compiled version of this file into combinations with other programs,
  15 and to distribute those combinations without any restriction coming
  16 from the use of this file.  (The General Public License restrictions
  17 do apply in other respects; for example, they cover modification of
  18 the file, and distribution when not linked into a combine
  19 executable.)
  20
  21 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  22 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  23 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  24 for more details.
  25
  26 You should have received a copy of the GNU General Public License
  27 along with GCC; see the file COPYING.  If not, write to the Free
  28 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
  29 02110-1301, USA.  */
  30
  31 #include "tconfig.h"
  32 #include "tsystem.h"
  33 #include "coretypes.h"
  34 #include "tm.h"
  35 #include "gthr.h"
  36
  37 typedef unsigned int word __attribute__((mode(word)));
  38 typedef unsigned int pointer __attribute__((mode(pointer)));
  39
  40 struct __emutls_object
  41 {
  42   word size;
  43   word align;
  44   union {
  45     pointer offset;
  46     void *ptr;
  47   } loc;
  48   void *templ;
  49 };
  50
  51 struct __emutls_array
  52 {
  53   pointer size;
  54   void **data[];
  55 };
  56
  57 #ifdef __GTHREADS
  58 #ifdef __GTHREAD_MUTEX_INIT
  59 static __gthread_mutex_t emutls_mutex = __GTHREAD_MUTEX_INIT;
  60 #else
  61 static __gthread_mutex_t emutls_mutex;
  62 #endif
  63 static __gthread_key_t emutls_key;
  64 static pointer emutls_size;
  65
  66 static void
  67 emutls_destroy (void *ptr)
  68 {
  69   struct __emutls_array *arr = ptr;
  70   pointer size = arr->size;
  71   pointer i;
  72
  73   for (i = 0; i < size; ++i)
  74     {
  75       if (arr->data[i])
  76         free (arr->data[i][-1]);
  77     }
  78
  79   free (ptr);
  80 }
  81
  82 static void
  83 emutls_init (void)
  84 {
  85 #ifndef __GTHREAD_MUTEX_INIT
  86   __GTHREAD_MUTEX_INIT_FUNCTION (&emutls_mutex);
  87 #endif
  88   if (__gthread_key_create (&emutls_key, emutls_destroy) != 0)
  89     abort ();
  90 }
  91 #endif
  92
  93 static void *
  94 emutls_alloc (struct __emutls_object *obj)
  95 {
  96   void *ptr;
  97   void *ret;
  98
  99   /* We could use here posix_memalign if available and adjust
 100      emutls_destroy accordingly.  */
 101   if (obj->align <= sizeof (void *))
 102     {
 103       ptr = malloc (obj->size + sizeof (void *));
 104       if (ptr == NULL)
 105         abort ();
 106       ((void **) ptr)[0] = ptr;
 107       ret = ptr + sizeof (void *);
 108     }
 109   else
 110     {
 111       ptr = malloc (obj->size + sizeof (void *) + obj->align - 1);
 112       if (ptr == NULL)
 113         abort ();
 114       ret = (void *) (((pointer) (ptr + sizeof (void *) + obj->align - 1))
 115                       & ~(pointer)(obj->align - 1));
 116       ((void **) ret)[-1] = ptr;
 117     }
 118
 119   if (obj->templ)
 120     memcpy (ret, obj->templ, obj->size);
 121   else
 122     memset (ret, 0, obj->size);
 123
 124   return ret;
 125 }
 126
 127 void *
 128 __emutls_get_address (struct __emutls_object *obj)
 129 {
 130   if (! __gthread_active_p ())
 131     {
 132       if (__builtin_expect (obj->loc.ptr == NULL, 0))
 133         obj->loc.ptr = emutls_alloc (obj);
 134       return obj->loc.ptr;
 135     }
 136
 137 #ifndef __GTHREADS
 138   abort ();
 139 #else
 140   pointer offset = obj->loc.offset;
 141
 142   if (__builtin_expect (offset == 0, 0))
 143     {
 144       static __gthread_once_t once = __GTHREAD_ONCE_INIT;
 145       __gthread_once (&once, emutls_init);
 146       __gthread_mutex_lock (&emutls_mutex);
 147       offset = ++emutls_size;
 148       obj->loc.offset = offset;
 149       __gthread_mutex_unlock (&emutls_mutex);
 150     }
 151
 152   struct __emutls_array *arr = __gthread_getspecific (emutls_key);
 153   if (__builtin_expect (arr == NULL, 0))
 154     {
 155       pointer size = offset + 32;
 156       arr = calloc (size, sizeof (void *));
 157       if (arr == NULL)
 158         abort ();
 159       arr->size = size;
 160       __gthread_setspecific (emutls_key, (void *) arr);
 161     }
 162   else if (__builtin_expect (offset >= arr->size, 0))
 163     {
 164       pointer orig_size = arr->size;
 165       pointer size = orig_size * 2;
 166       if (offset >= size)
 167         size = offset + 32;
 168       arr = realloc (arr, size * sizeof (void *));
 169       if (arr == NULL)
 170         abort ();
 171       arr->size = size;
 172       memset (arr->data + orig_size - 1, 0,
 173               (size - orig_size) * sizeof (void *));
 174       __gthread_setspecific (emutls_key, (void *) arr);
 175     }
 176
 177   void *ret = arr->data[offset - 1];
 178   if (__builtin_expect (ret == NULL, 0))
 179     {
 180       ret = emutls_alloc (obj);
 181       arr->data[offset - 1] = ret;
 182     }
 183   return ret;
 184 #endif
 185 }
 186
 187 void
 188 __emutls_register_common (struct __emutls_object *obj,
 189                           word size, word align, void *templ)
 190 {
 191   if (obj->size < size)
 192     {
 193       obj->size = size;
 194       obj->templ = NULL;
 195     }
 196   if (obj->align < align)
 197     obj->align = align;
 198   if (templ && size == obj->size)
 199     obj->templ = templ;
 200 }