aboutsummaryrefslogtreecommitdiff
path: root/libobjc/sendmsg.c
blob: 8b1845104e50e18727d1f000ca65f378d63a83d8 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
/* GNU Objective C Runtime message lookup 
   Copyright (C) 1993, 1995, 1996, 1997, 1998,
   2001, 2002, 2004, 2009 Free Software Foundation, Inc.
   Contributed by Kresten Krab Thorup

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it under the
terms of the GNU General Public License as published by the Free Software
Foundation; either version 3, or (at your option) any later version.

GCC is distributed in the hope that it will be useful, but WITHOUT ANY
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
details.

Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.

You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
<http://www.gnu.org/licenses/>.  */


/* FIXME: This file has no business including tm.h.  */
/* FIXME: This should be using libffi instead of __builtin_apply
   and friends.  */

#include "tconfig.h"
#include "coretypes.h"
#include "tm.h"
#include "objc/runtime.h"
#include "objc/sarray.h"
#include "objc/encoding.h"
#include "runtime-info.h"

/* This is how we hack STRUCT_VALUE to be 1 or 0.   */
#define gen_rtx(args...) 1
#define gen_rtx_MEM(args...) 1
#define gen_rtx_REG(args...) 1
/* Alread defined in gcc/coretypes.h. So prevent double definition warning.  */
#undef rtx
#define rtx int

#if ! defined (STRUCT_VALUE) || STRUCT_VALUE == 0
#define INVISIBLE_STRUCT_RETURN 1
#else
#define INVISIBLE_STRUCT_RETURN 0
#endif

/* The uninstalled dispatch table */
struct sarray *__objc_uninstalled_dtable = 0;   /* !T:MUTEX */

/* Two hooks for method forwarding. If either is set, it is invoked
 * to return a function that performs the real forwarding.  If both
 * are set, the result of __objc_msg_forward2 will be preferred over
 * that of __objc_msg_forward.  If both return NULL or are unset,
 * the libgcc based functions (__builtin_apply and friends) are
 * used.
 */
IMP (*__objc_msg_forward) (SEL) = NULL;
IMP (*__objc_msg_forward2) (id, SEL) = NULL;

/* Send +initialize to class */
static void __objc_send_initialize (Class);

static void __objc_install_dispatch_table_for_class (Class);

/* Forward declare some functions */
static void __objc_init_install_dtable (id, SEL);

/* Various forwarding functions that are used based upon the
   return type for the selector.
   __objc_block_forward for structures.
   __objc_double_forward for floats/doubles.
   __objc_word_forward for pointers or types that fit in registers. */
static double __objc_double_forward (id, SEL, ...);
static id __objc_word_forward (id, SEL, ...);
typedef struct { id many[8]; } __big;
#if INVISIBLE_STRUCT_RETURN 
static __big 
#else
static id
#endif
__objc_block_forward (id, SEL, ...);
static Method_t search_for_method_in_hierarchy (Class class, SEL sel);
Method_t search_for_method_in_list (MethodList_t list, SEL op);
id nil_method (id, SEL);

/* Given a selector, return the proper forwarding implementation. */
inline
IMP
__objc_get_forward_imp (id rcv, SEL sel)
{
  /* If a custom forwarding hook was registered, try getting a forwarding
     function from it. There are two forward routine hooks, one that
     takes the receiver as an argument and one that does not. */
  if (__objc_msg_forward2)
    {
      IMP result;
      if ((result = __objc_msg_forward2 (rcv, sel)) != NULL)
       return result;
    }
  if (__objc_msg_forward)
    {
      IMP result;
      if ((result = __objc_msg_forward (sel)) != NULL) 
        return result;
    }

  /* In all other cases, use the default forwarding functions built using
     __builtin_apply and friends.  */
    {
      const char *t = sel->sel_types;

      if (t && (*t == '[' || *t == '(' || *t == '{')
#ifdef OBJC_MAX_STRUCT_BY_VALUE
          && objc_sizeof_type (t) > OBJC_MAX_STRUCT_BY_VALUE
#endif
          )
        return (IMP)__objc_block_forward;
      else if (t && (*t == 'f' || *t == 'd'))
        return (IMP)__objc_double_forward;
      else
        return (IMP)__objc_word_forward;
    }
}

/* Given a class and selector, return the selector's implementation.  */
inline
IMP
get_imp (Class class, SEL sel)
{
  /* In a vanilla implementation we would first check if the dispatch
     table is installed.  Here instead, to get more speed in the
     standard case (that the dispatch table is installed) we first try
     to get the imp using brute force.  Only if that fails, we do what
     we should have been doing from the very beginning, that is, check
     if the dispatch table needs to be installed, install it if it's
     not installed, and retrieve the imp from the table if it's
     installed.  */
  void *res = sarray_get_safe (class->dtable, (size_t) sel->sel_id);
  if (res == 0)
    {
      /* Not a valid method */
      if (class->dtable == __objc_uninstalled_dtable)
	{
	  /* The dispatch table needs to be installed. */
	  objc_mutex_lock (__objc_runtime_mutex);

	   /* Double-checked locking pattern: Check
	      __objc_uninstalled_dtable again in case another thread
	      installed the dtable while we were waiting for the lock
	      to be released.  */
         if (class->dtable == __objc_uninstalled_dtable)
           {
             __objc_install_dispatch_table_for_class (class);
           }

	  objc_mutex_unlock (__objc_runtime_mutex);
	  /* Call ourselves with the installed dispatch table
	     and get the real method */
	  res = get_imp (class, sel);
	}
      else
	{
	  /* The dispatch table has been installed.  */

         /* Get the method from the dispatch table (we try to get it
	    again in case another thread has installed the dtable just
	    after we invoked sarray_get_safe, but before we checked
	    class->dtable == __objc_uninstalled_dtable).
         */
	  res = sarray_get_safe (class->dtable, (size_t) sel->sel_id);
	  if (res == 0)
	    {
	      /* The dispatch table has been installed, and the method
		 is not in the dispatch table.  So the method just
		 doesn't exist for the class.  Return the forwarding
		 implementation. */
             res = __objc_get_forward_imp ((id)class, sel);
	    }
	}
    }
  return res;
}

/* Query if an object can respond to a selector, returns YES if the
object implements the selector otherwise NO.  Does not check if the
method can be forwarded. */
inline
BOOL
__objc_responds_to (id object, SEL sel)
{
  void *res;

  /* Install dispatch table if need be */
  if (object->class_pointer->dtable == __objc_uninstalled_dtable)
    {
      objc_mutex_lock (__objc_runtime_mutex);
      if (object->class_pointer->dtable == __objc_uninstalled_dtable)
	{
	  __objc_install_dispatch_table_for_class (object->class_pointer);
	}
      objc_mutex_unlock (__objc_runtime_mutex);
    }

  /* Get the method from the dispatch table */
  res = sarray_get_safe (object->class_pointer->dtable, (size_t) sel->sel_id);
  return (res != 0);
}

/* This is the lookup function.  All entries in the table are either a 
   valid method *or* zero.  If zero then either the dispatch table
   needs to be installed or it doesn't exist and forwarding is attempted. */
inline
IMP
objc_msg_lookup (id receiver, SEL op)
{
  IMP result;
  if (receiver)
    {
      result = sarray_get_safe (receiver->class_pointer->dtable, 
				(sidx)op->sel_id);
      if (result == 0)
	{
	  /* Not a valid method */
	  if (receiver->class_pointer->dtable == __objc_uninstalled_dtable)
	    {
	      /* The dispatch table needs to be installed.
		 This happens on the very first method call to the class. */
	      __objc_init_install_dtable (receiver, op);

	      /* Get real method for this in newly installed dtable */
	      result = get_imp (receiver->class_pointer, op);
	    }
	  else
	    {
	      /* The dispatch table has been installed.  Check again
		 if the method exists (just in case the dispatch table
		 has been installed by another thread after we did the
		 previous check that the method exists).
	      */
	      result = sarray_get_safe (receiver->class_pointer->dtable,
					(sidx)op->sel_id);
	      if (result == 0)
		{
		  /* If the method still just doesn't exist for the
		     class, attempt to forward the method. */
		  result = __objc_get_forward_imp (receiver, op);
		}
	    }
	}
      return result;
    }
  else
    return (IMP)nil_method;
}

IMP
objc_msg_lookup_super (Super_t super, SEL sel)
{
  if (super->self)
    return get_imp (super->class, sel);
  else
    return (IMP)nil_method;
}

int method_get_sizeof_arguments (Method *);

retval_t
objc_msg_sendv (id object, SEL op, arglist_t arg_frame)
{
  Method *m = class_get_instance_method (object->class_pointer, op);
  const char *type;
  *((id *) method_get_first_argument (m, arg_frame, &type)) = object;
  *((SEL *) method_get_next_argument (arg_frame, &type)) = op;
  return __builtin_apply ((apply_t) m->method_imp, 
			  arg_frame,
			  method_get_sizeof_arguments (m));
}

void
__objc_init_dispatch_tables ()
{
  __objc_uninstalled_dtable = sarray_new (200, 0);
}

/* This function is called by objc_msg_lookup when the
   dispatch table needs to be installed; thus it is called once
   for each class, namely when the very first message is sent to it. */
static void
__objc_init_install_dtable (id receiver, SEL op __attribute__ ((__unused__)))
{
  objc_mutex_lock (__objc_runtime_mutex);
  
  /* This may happen, if the programmer has taken the address of a 
     method before the dtable was initialized... too bad for him! */
  if (receiver->class_pointer->dtable != __objc_uninstalled_dtable)
    {
      objc_mutex_unlock (__objc_runtime_mutex);
      return;
    }
  
  if (CLS_ISCLASS (receiver->class_pointer))
    {
      /* receiver is an ordinary object */
      assert (CLS_ISCLASS (receiver->class_pointer));

      /* install instance methods table */
      __objc_install_dispatch_table_for_class (receiver->class_pointer);

      /* call +initialize -- this will in turn install the factory 
	 dispatch table if not already done :-) */
      __objc_send_initialize (receiver->class_pointer);
    }
  else
    {
      /* receiver is a class object */
      assert (CLS_ISCLASS ((Class)receiver));
      assert (CLS_ISMETA (receiver->class_pointer));

      /* Install real dtable for factory methods */
      __objc_install_dispatch_table_for_class (receiver->class_pointer);

      __objc_send_initialize ((Class)receiver);
    }
  objc_mutex_unlock (__objc_runtime_mutex);
}

/* Install dummy table for class which causes the first message to
   that class (or instances hereof) to be initialized properly */
void
__objc_install_premature_dtable (Class class)
{
  assert (__objc_uninstalled_dtable);
  class->dtable = __objc_uninstalled_dtable;
}   

/* Send +initialize to class if not already done */
static void
__objc_send_initialize (Class class)
{
  /* This *must* be a class object */
  assert (CLS_ISCLASS (class));
  assert (! CLS_ISMETA (class));

  if (! CLS_ISINITIALIZED (class))
    {
      CLS_SETINITIALIZED (class);
      CLS_SETINITIALIZED (class->class_pointer);

      /* Create the garbage collector type memory description */
      __objc_generate_gc_type_description (class);

      if (class->super_class)
	__objc_send_initialize (class->super_class);

      {
	SEL 	     op = sel_register_name ("initialize");
	IMP	     imp = 0;
        MethodList_t method_list = class->class_pointer->methods;

        while (method_list) {
	  int i;
          Method_t method;

          for (i = 0; i < method_list->method_count; i++) {
	    method = &(method_list->method_list[i]);
            if (method->method_name
                && method->method_name->sel_id == op->sel_id) {
	      imp = method->method_imp;
              break;
            }
          }

          if (imp)
            break;

          method_list = method_list->method_next;

	}
	if (imp)
	    (*imp) ((id) class, op);
		
      }
    }
}

/* Walk on the methods list of class and install the methods in the reverse
   order of the lists. Since methods added by categories are before the methods
   of class in the methods list, this allows categories to substitute methods
   declared in class. However if more than one category replaces the same
   method nothing is guaranteed about what method will be used.
   Assumes that __objc_runtime_mutex is locked down. */
static void
__objc_install_methods_in_dtable (Class class, MethodList_t method_list)
{
  int i;

  if (! method_list)
    return;

  if (method_list->method_next)
    __objc_install_methods_in_dtable (class, method_list->method_next);

  for (i = 0; i < method_list->method_count; i++)
    {
      Method_t method = &(method_list->method_list[i]);
      sarray_at_put_safe (class->dtable,
			  (sidx) method->method_name->sel_id,
			  method->method_imp);
    }
}

/* Assumes that __objc_runtime_mutex is locked down. */
static void
__objc_install_dispatch_table_for_class (Class class)
{
  Class super;

  /* If the class has not yet had its class links resolved, we must 
     re-compute all class links */
  if (! CLS_ISRESOLV (class))
    __objc_resolve_class_links ();

  super = class->super_class;

  if (super != 0 && (super->dtable == __objc_uninstalled_dtable))
    __objc_install_dispatch_table_for_class (super);

  /* Allocate dtable if necessary */
  if (super == 0)
    {
      objc_mutex_lock (__objc_runtime_mutex);
      class->dtable = sarray_new (__objc_selector_max_index, 0);
      objc_mutex_unlock (__objc_runtime_mutex);
    }
  else
    class->dtable = sarray_lazy_copy (super->dtable);

  __objc_install_methods_in_dtable (class, class->methods);
}

void
__objc_update_dispatch_table_for_class (Class class)
{
  Class next;
  struct sarray *arr;

  /* not yet installed -- skip it */
  if (class->dtable == __objc_uninstalled_dtable) 
    return;

  objc_mutex_lock (__objc_runtime_mutex);

  arr = class->dtable;
  __objc_install_premature_dtable (class); /* someone might require it... */
  sarray_free (arr);			   /* release memory */

  /* could have been lazy... */
  __objc_install_dispatch_table_for_class (class); 

  if (class->subclass_list)	/* Traverse subclasses */
    for (next = class->subclass_list; next; next = next->sibling_class)
      __objc_update_dispatch_table_for_class (next);

  objc_mutex_unlock (__objc_runtime_mutex);
}


/* This function adds a method list to a class.  This function is
   typically called by another function specific to the run-time.  As
   such this function does not worry about thread safe issues.

   This one is only called for categories. Class objects have their
   methods installed right away, and their selectors are made into
   SEL's by the function __objc_register_selectors_from_class. */
void
class_add_method_list (Class class, MethodList_t list)
{
  /* Passing of a linked list is not allowed.  Do multiple calls.  */
  assert (! list->method_next);

  __objc_register_selectors_from_list(list);

  /* Add the methods to the class's method list.  */
  list->method_next = class->methods;
  class->methods = list;

  /* Update the dispatch table of class */
  __objc_update_dispatch_table_for_class (class);
}

Method_t
class_get_instance_method (Class class, SEL op)
{
  return search_for_method_in_hierarchy (class, op);
}

Method_t
class_get_class_method (MetaClass class, SEL op)
{
  return search_for_method_in_hierarchy (class, op);
}


/* Search for a method starting from the current class up its hierarchy.
   Return a pointer to the method's method structure if found.  NULL
   otherwise. */   

static Method_t
search_for_method_in_hierarchy (Class cls, SEL sel)
{
  Method_t method = NULL;
  Class class;

  if (! sel_is_mapped (sel))
    return NULL;

  /* Scan the method list of the class.  If the method isn't found in the
     list then step to its super class. */
  for (class = cls; ((! method) && class); class = class->super_class)
    method = search_for_method_in_list (class->methods, sel);

  return method;
}



/* Given a linked list of method and a method's name.  Search for the named
   method's method structure.  Return a pointer to the method's method
   structure if found.  NULL otherwise. */  
Method_t
search_for_method_in_list (MethodList_t list, SEL op)
{
  MethodList_t method_list = list;

  if (! sel_is_mapped (op))
    return NULL;

  /* If not found then we'll search the list.  */
  while (method_list)
    {
      int i;

      /* Search the method list.  */
      for (i = 0; i < method_list->method_count; ++i)
        {
          Method_t method = &method_list->method_list[i];

          if (method->method_name)
            if (method->method_name->sel_id == op->sel_id)
              return method;
        }

      /* The method wasn't found.  Follow the link to the next list of
         methods.  */
      method_list = method_list->method_next;
    }

  return NULL;
}

static retval_t __objc_forward (id object, SEL sel, arglist_t args);

/* Forwarding pointers/integers through the normal registers */
static id
__objc_word_forward (id rcv, SEL op, ...)
{
  void *args, *res;

  args = __builtin_apply_args ();
  res = __objc_forward (rcv, op, args);
  if (res)
    __builtin_return (res);
  else
    return res;
}

/* Specific routine for forwarding floats/double because of
   architectural differences on some processors.  i386s for
   example which uses a floating point stack versus general
   registers for floating point numbers.  This forward routine 
   makes sure that GCC restores the proper return values */
static double
__objc_double_forward (id rcv, SEL op, ...)
{
  void *args, *res;

  args = __builtin_apply_args ();
  res = __objc_forward (rcv, op, args);
  __builtin_return (res);
}

#if INVISIBLE_STRUCT_RETURN
static __big
#else
static id
#endif
__objc_block_forward (id rcv, SEL op, ...)
{
  void *args, *res;

  args = __builtin_apply_args ();
  res = __objc_forward (rcv, op, args);
  if (res)
    __builtin_return (res);
  else
#if INVISIBLE_STRUCT_RETURN
    return (__big) {{0, 0, 0, 0, 0, 0, 0, 0}};
#else
    return nil;
#endif
}


/* This function is installed in the dispatch table for all methods which are
   not implemented.  Thus, it is called when a selector is not recognized. */
static retval_t
__objc_forward (id object, SEL sel, arglist_t args)
{
  IMP imp;
  static SEL frwd_sel = 0;                      /* !T:SAFE2 */
  SEL err_sel;

  /* first try if the object understands forward:: */
  if (! frwd_sel)
    frwd_sel = sel_get_any_uid ("forward::");

  if (__objc_responds_to (object, frwd_sel))
    {
      imp = get_imp (object->class_pointer, frwd_sel);
      return (*imp) (object, frwd_sel, sel, args);
    }

  /* If the object recognizes the doesNotRecognize: method then we're going
     to send it. */
  err_sel = sel_get_any_uid ("doesNotRecognize:");
  if (__objc_responds_to (object, err_sel))
    {
      imp = get_imp (object->class_pointer, err_sel);
      return (*imp) (object, err_sel, sel);
    }
  
  /* The object doesn't recognize the method.  Check for responding to
     error:.  If it does then sent it. */
  {
    char msg[256 + strlen ((const char *) sel_get_name (sel))
             + strlen ((const char *) object->class_pointer->name)];

    sprintf (msg, "(%s) %s does not recognize %s",
	     (CLS_ISMETA (object->class_pointer)
	      ? "class"
	      : "instance" ),
             object->class_pointer->name, sel_get_name (sel));

    err_sel = sel_get_any_uid ("error:");
    if (__objc_responds_to (object, err_sel))
      {
	imp = get_imp (object->class_pointer, err_sel);
	return (*imp) (object, sel_get_any_uid ("error:"), msg);
      }

    /* The object doesn't respond to doesNotRecognize: or error:;  Therefore,
       a default action is taken. */
    objc_error (object, OBJC_ERR_UNIMPLEMENTED, "%s\n", msg);

    return 0;
  }
}

void
__objc_print_dtable_stats ()
{
  int total = 0;

  objc_mutex_lock (__objc_runtime_mutex);

#ifdef OBJC_SPARSE2
  printf ("memory usage: (%s)\n", "2-level sparse arrays");
#else
  printf ("memory usage: (%s)\n", "3-level sparse arrays");
#endif

  printf ("arrays: %d = %ld bytes\n", narrays, 
	  (long) ((size_t) narrays * sizeof (struct sarray)));
  total += narrays * sizeof (struct sarray);
  printf ("buckets: %d = %ld bytes\n", nbuckets, 
	  (long) ((size_t) nbuckets * sizeof (struct sbucket)));
  total += nbuckets * sizeof (struct sbucket);

  printf ("idxtables: %d = %ld bytes\n",
	  idxsize, (long) ((size_t) idxsize * sizeof (void *)));
  total += idxsize * sizeof (void *);
  printf ("-----------------------------------\n");
  printf ("total: %d bytes\n", total);
  printf ("===================================\n");

  objc_mutex_unlock (__objc_runtime_mutex);
}

/* Returns the uninstalled dispatch table indicator.
 If a class' dispatch table points to __objc_uninstalled_dtable
 then that means it needs its dispatch table to be installed. */
inline
struct sarray *
objc_get_uninstalled_dtable ()
{
  return __objc_uninstalled_dtable;
}