libguile/inline.h

   1 /* classes: h_files */
   2
   3 #ifndef SCM_INLINE_H
   4 #define SCM_INLINE_H
   5
   6 /* Copyright (C) 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
   7  *
   8  * This library is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; either
  11  * version 2.1 of the License, or (at your option) any later version.
  12  *
  13  * This library is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with this library; if not, write to the Free Software
  20  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  21  */
  22
  23 /* This file is for inline functions.  On platforms that don't support
  24    inlining functions, they are turned into ordinary functions.  See
  25    "inline.c".
  26 */
  27
  28 #include "libguile/__scm.h"
  29
  30 #if (SCM_DEBUG_CELL_ACCESSES == 1)
  31 #include <stdio.h>
  32 #endif
  33
  34 #include "libguile/pairs.h"
  35 #include "libguile/gc.h"
  36 #include "libguile/threads.h"
  37 #include "libguile/unif.h"
  38
  39
  40 SCM_API SCM scm_cell (scm_t_bits car, scm_t_bits cdr);
  41 SCM_API SCM scm_double_cell (scm_t_bits car, scm_t_bits cbr,
  42                              scm_t_bits ccr, scm_t_bits cdr);
  43
  44 SCM_API SCM scm_array_handle_ref (scm_t_array_handle *h, ssize_t pos);
  45 SCM_API void scm_array_handle_set (scm_t_array_handle *h, ssize_t pos, SCM val);
  46
  47
  48 #if defined SCM_C_INLINE || defined SCM_INLINE_C_INCLUDING_INLINE_H
  49 /* either inlining, or being included from inline.c.  We use (and
  50    repeat) this long #if test here and below so that we don't have to
  51    introduce any extraneous symbols into the public namespace.  We
  52    only need SCM_C_INLINE to be seen publically . */
  53
  54 extern unsigned scm_newcell2_count;
  55 extern unsigned scm_newcell_count;
  56
  57 #if defined SCM_C_INLINE && ! defined SCM_INLINE_C_INCLUDING_INLINE_H
  58 /* definitely inlining */
  59 #ifdef __GNUC__
  60 extern
  61 #else
  62 static
  63 #endif
  64 SCM_C_INLINE
  65 #endif
  66 SCM
  67 scm_cell (scm_t_bits car, scm_t_bits cdr)
  68 {
  69   SCM z;
  70   /* We retrieve the SCM pointer only once since the call to
  71      SCM_FREELIST_LOC will be slightly expensive when we support
  72      preemptive multithreading.  SCM_FREELIST_LOC will then retrieve
  73      the thread specific freelist.
  74
  75      Until then, SCM_FREELIST_DOC expands to (&scm_i_freelist) and the
  76      following code will compile to the same as if we had worked
  77      directly on the scm_i_freelist variable.
  78    */
  79   SCM *freelist = SCM_FREELIST_LOC (scm_i_freelist);
  80
  81   if (scm_gc_running_p)
  82     {
  83       abort();
  84     }
  85
  86   if (scm_is_null (*freelist))
  87     z = scm_gc_for_newcell (&scm_i_master_freelist, freelist);
  88   else
  89     {
  90       z = *freelist;
  91       *freelist = SCM_FREE_CELL_CDR (*freelist);
  92     }
  93
  94   /*
  95     We update scm_cells_allocated from this function. If we don't
  96     update this explicitly, we will have to walk a freelist somewhere
  97     later on, which seems a lot more expensive.
  98    */
  99   scm_cells_allocated += 1;
 100
 101 #if (SCM_DEBUG_CELL_ACCESSES == 1)
 102     if (scm_debug_cell_accesses_p)
 103       {
 104         if (SCM_GC_MARK_P (z))
 105           {
 106             fprintf(stderr, "scm_cell tried to allocate a marked cell.\n");
 107             abort();
 108           }
 109         else if (SCM_GC_CELL_WORD(z, 0) != scm_tc_free_cell)
 110           {
 111             fprintf(stderr, "cell from freelist is not a free cell.\n");
 112             abort();
 113           }
 114       }
 115
 116     /*
 117       Always set mark. Otherwise cells that are alloced before
 118       scm_debug_cell_accesses_p is toggled seem invalid.
 119     */
 120     SCM_SET_GC_MARK (z);
 121
 122     /*
 123       TODO: figure out if this use of mark bits is valid with
 124       threading. What if another thread is doing GC at this point
 125       ... ?
 126      */
 127
 128 #endif
 129
 130
 131   /* Initialize the type slot last so that the cell is ignored by the
 132      GC until it is completely initialized.  This is only relevant
 133      when the GC can actually run during this code, which it can't for
 134      cooperating threads, but it might be important when we get true
 135      preemptive threads.
 136   */
 137   SCM_GC_SET_CELL_WORD (z, 1, cdr);
 138   SCM_GC_SET_CELL_WORD (z, 0, car);
 139
 140 #if 0 /*fixme* Hmm... let's consider this later. */
 141 #if !defined(SCM_USE_COOP_THREADS) && !defined(SCM_USE_NULL_THREADS) && !defined(SCM_USE_COPT_THREADS)
 142   /* When we are using preemtive threads, we might need to make
 143      sure that the initial values for the slots are protected until
 144      the cell is completely initialized.
 145   */
 146 #error review me
 147   scm_remember_upto_here_1 (SCM_PACK (cdr));
 148 #endif
 149 #endif
 150
 151 #if (SCM_DEBUG_CELL_ACCESSES == 1)
 152   if (scm_expensive_debug_cell_accesses_p )
 153     scm_i_expensive_validation_check (z);
 154 #endif
 155
 156   return z;
 157 }
 158
 159 #if defined SCM_C_INLINE && ! defined SCM_INLINE_C_INCLUDING_INLINE_H
 160 /* definitely inlining */
 161 #ifdef __GNUC__
 162 extern
 163 #else
 164 static
 165 #endif
 166 SCM_C_INLINE
 167 #endif
 168 SCM
 169 scm_double_cell (scm_t_bits car, scm_t_bits cbr,
 170                  scm_t_bits ccr, scm_t_bits cdr)
 171 {
 172   SCM z;
 173   SCM *freelist = SCM_FREELIST_LOC (scm_i_freelist2);
 174
 175   if (scm_gc_running_p)
 176     {
 177       abort();
 178     }
 179
 180   if (scm_is_null (*freelist))
 181     z = scm_gc_for_newcell (&scm_i_master_freelist2, freelist);
 182   else
 183     {
 184       z = *freelist;
 185       *freelist = SCM_FREE_CELL_CDR (*freelist);
 186     }
 187
 188   scm_cells_allocated += 2;
 189
 190   /* Initialize the type slot last so that the cell is ignored by the
 191      GC until it is completely initialized.  This is only relevant
 192      when the GC can actually run during this code, which it can't for
 193      cooperating threads, but it might be important when we get true
 194      preemptive threads.
 195   */
 196   SCM_GC_SET_CELL_WORD (z, 1, cbr);
 197   SCM_GC_SET_CELL_WORD (z, 2, ccr);
 198   SCM_GC_SET_CELL_WORD (z, 3, cdr);
 199   SCM_GC_SET_CELL_WORD (z, 0, car);
 200
 201 #if 0 /*fixme* Hmm... let's consider this later. */
 202 #if !defined(SCM_USE_COOP_THREADS) && !defined(SCM_USE_NULL_THREADS) && !defined(SCM_USE_COPT_THREADS)
 203   /* When we are using non-cooperating threads, we might need to make
 204      sure that the initial values for the slots are protected until
 205      the cell is completely initialized.
 206   */
 207 #error review me
 208   scm_remember_upto_here_3 (SCM_PACK (cbr), SCM_PACK (ccr), SCM_PACK (cdr));
 209 #endif
 210 #endif
 211
 212
 213 #if (SCM_DEBUG_CELL_ACCESSES == 1)
 214   if (scm_debug_cell_accesses_p)
 215     {
 216       if (SCM_GC_MARK_P (z))
 217         {
 218           fprintf(stderr,
 219                   "scm_double_cell tried to allocate a marked cell.\n");
 220           abort();
 221         }
 222     }
 223
 224   /* see above. */
 225   SCM_SET_GC_MARK (z);
 226
 227 #endif
 228
 229   /* When this function is inlined, it's possible that the last
 230      SCM_GC_SET_CELL_WORD above will be adjacent to a following
 231      initialization of z.  E.g., it occurred in scm_make_real.  GCC
 232      from around version 3 (e.g., certainly 3.2) began taking
 233      advantage of strict C aliasing rules which say that it's OK to
 234      interchange the initialization above and the one below when the
 235      pointer types appear to differ sufficiently.  We don't want that,
 236      of course.  GCC allows this behaviour to be disabled with the
 237      -fno-strict-aliasing option, but would also need to be supplied
 238      by Guile users.  Instead, the following statements prevent the
 239      reordering.
 240    */
 241 #ifdef __GNUC__
 242   asm volatile ("" : : : "memory");
 243 #else
 244   /* portable version, just in case any other compiler does the same
 245      thing.  */
 246   scm_remember_upto_here_1 (z);
 247 #endif
 248
 249   return z;
 250 }
 251
 252 #if defined SCM_C_INLINE && ! defined SCM_INLINE_C_INCLUDING_INLINE_H
 253 /* definitely inlining */
 254 #ifdef __GNUC__
 255 extern
 256 #else
 257 static
 258 #endif
 259 SCM_C_INLINE
 260 #endif
 261 SCM
 262 scm_array_handle_ref (scm_t_array_handle *h, ssize_t p)
 263 {
 264   return h->ref (h, p);
 265 }
 266
 267 #if defined SCM_C_INLINE && ! defined SCM_INLINE_C_INCLUDING_INLINE_H
 268 /* definitely inlining */
 269 #ifdef __GNUC__
 270 extern
 271 #else
 272 static
 273 #endif
 274 SCM_C_INLINE
 275 #endif
 276 void
 277 scm_array_handle_set (scm_t_array_handle *h, ssize_t p, SCM v)
 278 {
 279   h->set (h, p, v);
 280 }
 281
 282 #endif
 283 #endif