1/* GNU Objective C Runtime message lookup 2 Copyright (C) 1993, 1995, 1996, 1997, 1998, 3 2001, 2002, 2004 Free Software Foundation, Inc. 4 Contributed by Kresten Krab Thorup 5 6This file is part of GCC. 7 8GCC is free software; you can redistribute it and/or modify it under the 9terms of the GNU General Public License as published by the Free Software 10Foundation; either version 2, or (at your option) any later version. 11 12GCC is distributed in the hope that it will be useful, but WITHOUT ANY 13WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS 14FOR A PARTICULAR PURPOSE. See the GNU General Public License for more 15details. 16 17You should have received a copy of the GNU General Public License along with 18GCC; see the file COPYING. If not, write to the Free Software 19Foundation, 51 Franklin Street, Fifth Floor, 20Boston, MA 02110-1301, USA. */ 21 22/* As a special exception, if you link this library with files compiled with 23 GCC to produce an executable, this does not cause the resulting executable 24 to be covered by the GNU General Public License. This exception does not 25 however invalidate any other reasons why the executable file might be 26 covered by the GNU General Public License. */ 27 28/* FIXME: This file has no business including tm.h. */ 29/* FIXME: This should be using libffi instead of __builtin_apply 30 and friends. */ 31 32#include "tconfig.h" 33#include "coretypes.h" 34#include "tm.h" 35#include "objc/runtime.h" 36#include "objc/sarray.h" 37#include "objc/encoding.h" 38#include "runtime-info.h" 39 40/* This is how we hack STRUCT_VALUE to be 1 or 0. */ 41#define gen_rtx(args...) 1 42#define gen_rtx_MEM(args...) 1 43#define gen_rtx_REG(args...) 1 44#undef rtx 45#define rtx int 46 47#if ! defined (STRUCT_VALUE) || STRUCT_VALUE == 0 48#define INVISIBLE_STRUCT_RETURN 1 49#else 50#define INVISIBLE_STRUCT_RETURN 0 51#endif 52 53/* The uninstalled dispatch table */ 54struct sarray *__objc_uninstalled_dtable = 0; /* !T:MUTEX */ 55 56/* Hook for method forwarding. If it is set, is invoked to return a 57 function that performs the real forwarding. Otherwise the libgcc 58 based functions (__builtin_apply and friends) are used. */ 59IMP (*__objc_msg_forward) (SEL) = NULL; 60 61/* Send +initialize to class */ 62static void __objc_send_initialize (Class); 63 64static void __objc_install_dispatch_table_for_class (Class); 65 66/* Forward declare some functions */ 67static void __objc_init_install_dtable (id, SEL); 68 69/* Various forwarding functions that are used based upon the 70 return type for the selector. 71 __objc_block_forward for structures. 72 __objc_double_forward for floats/doubles. 73 __objc_word_forward for pointers or types that fit in registers. 74 */ 75static double __objc_double_forward (id, SEL, ...); 76static id __objc_word_forward (id, SEL, ...); 77typedef struct { id many[8]; } __big; 78#if INVISIBLE_STRUCT_RETURN 79static __big 80#else 81static id 82#endif 83__objc_block_forward (id, SEL, ...); 84static Method_t search_for_method_in_hierarchy (Class class, SEL sel); 85Method_t search_for_method_in_list (MethodList_t list, SEL op); 86id nil_method (id, SEL); 87 88/* Given a selector, return the proper forwarding implementation. */ 89inline 90IMP 91__objc_get_forward_imp (SEL sel) 92{ 93 /* If a custom forwarding hook was registered, try getting a forwarding 94 * function from it. */ 95 if (__objc_msg_forward) 96 { 97 IMP result; 98 if ((result = __objc_msg_forward (sel)) != NULL) 99 return result; 100 } 101 102 /* In all other cases, use the default forwarding functions built using 103 * __builtin_apply and friends. */ 104 { 105 const char *t = sel->sel_types; 106 107 if (t && (*t == '[' || *t == '(' || *t == '{') 108#ifdef OBJC_MAX_STRUCT_BY_VALUE 109 && objc_sizeof_type (t) > OBJC_MAX_STRUCT_BY_VALUE 110#endif 111 ) 112 return (IMP)__objc_block_forward; 113 else if (t && (*t == 'f' || *t == 'd')) 114 return (IMP)__objc_double_forward; 115 else 116 return (IMP)__objc_word_forward; 117 } 118} 119 120/* Given a class and selector, return the selector's implementation. */ 121inline 122IMP 123get_imp (Class class, SEL sel) 124{ 125 /* In a vanilla implementation we would first check if the dispatch 126 table is installed. Here instead, to get more speed in the 127 standard case (that the dispatch table is installed) we first try 128 to get the imp using brute force. Only if that fails, we do what 129 we should have been doing from the very beginning, that is, check 130 if the dispatch table needs to be installed, install it if it's 131 not installed, and retrieve the imp from the table if it's 132 installed. */ 133 void *res = sarray_get_safe (class->dtable, (size_t) sel->sel_id); 134 if (res == 0) 135 { 136 /* Not a valid method */ 137 if (class->dtable == __objc_uninstalled_dtable) 138 { 139 /* The dispatch table needs to be installed. */ 140 objc_mutex_lock (__objc_runtime_mutex); 141 142 /* Double-checked locking pattern: Check 143 __objc_uninstalled_dtable again in case another thread 144 installed the dtable while we were waiting for the lock 145 to be released. */ 146 if (class->dtable == __objc_uninstalled_dtable) 147 { 148 __objc_install_dispatch_table_for_class (class); 149 } 150 151 objc_mutex_unlock (__objc_runtime_mutex); 152 /* Call ourselves with the installed dispatch table 153 and get the real method */ 154 res = get_imp (class, sel); 155 } 156 else 157 { 158 /* The dispatch table has been installed. */ 159 160 /* Get the method from the dispatch table (we try to get it 161 again in case another thread has installed the dtable just 162 after we invoked sarray_get_safe, but before we checked 163 class->dtable == __objc_uninstalled_dtable). 164 */ 165 res = sarray_get_safe (class->dtable, (size_t) sel->sel_id); 166 if (res == 0) 167 { 168 /* The dispatch table has been installed, and the method 169 is not in the dispatch table. So the method just 170 doesn't exist for the class. Return the forwarding 171 implementation. */ 172 res = __objc_get_forward_imp (sel); 173 } 174 } 175 } 176 return res; 177} 178 179/* Query if an object can respond to a selector, returns YES if the 180object implements the selector otherwise NO. Does not check if the 181method can be forwarded. */ 182inline 183BOOL 184__objc_responds_to (id object, SEL sel) 185{ 186 void *res; 187 188 /* Install dispatch table if need be */ 189 if (object->class_pointer->dtable == __objc_uninstalled_dtable) 190 { 191 objc_mutex_lock (__objc_runtime_mutex); 192 if (object->class_pointer->dtable == __objc_uninstalled_dtable) 193 { 194 __objc_install_dispatch_table_for_class (object->class_pointer); 195 } 196 objc_mutex_unlock (__objc_runtime_mutex); 197 } 198 199 /* Get the method from the dispatch table */ 200 res = sarray_get_safe (object->class_pointer->dtable, (size_t) sel->sel_id); 201 return (res != 0); 202} 203 204/* This is the lookup function. All entries in the table are either a 205 valid method *or* zero. If zero then either the dispatch table 206 needs to be installed or it doesn't exist and forwarding is attempted. */ 207inline 208IMP 209objc_msg_lookup (id receiver, SEL op) 210{ 211 IMP result; 212 if (receiver) 213 { 214 result = sarray_get_safe (receiver->class_pointer->dtable, 215 (sidx)op->sel_id); 216 if (result == 0) 217 { 218 /* Not a valid method */ 219 if (receiver->class_pointer->dtable == __objc_uninstalled_dtable) 220 { 221 /* The dispatch table needs to be installed. 222 This happens on the very first method call to the class. */ 223 __objc_init_install_dtable (receiver, op); 224 225 /* Get real method for this in newly installed dtable */ 226 result = get_imp (receiver->class_pointer, op); 227 } 228 else 229 { 230 /* The dispatch table has been installed. Check again 231 if the method exists (just in case the dispatch table 232 has been installed by another thread after we did the 233 previous check that the method exists). 234 */ 235 result = sarray_get_safe (receiver->class_pointer->dtable, 236 (sidx)op->sel_id); 237 if (result == 0) 238 { 239 /* If the method still just doesn't exist for the 240 class, attempt to forward the method. */ 241 result = __objc_get_forward_imp (op); 242 } 243 } 244 } 245 return result; 246 } 247 else 248 return (IMP)nil_method; 249} 250 251IMP 252objc_msg_lookup_super (Super_t super, SEL sel) 253{ 254 if (super->self) 255 return get_imp (super->class, sel); 256 else 257 return (IMP)nil_method; 258} 259 260int method_get_sizeof_arguments (Method *); 261 262retval_t 263objc_msg_sendv (id object, SEL op, arglist_t arg_frame) 264{ 265 Method *m = class_get_instance_method (object->class_pointer, op); 266 const char *type; 267 *((id *) method_get_first_argument (m, arg_frame, &type)) = object; 268 *((SEL *) method_get_next_argument (arg_frame, &type)) = op; 269 return __builtin_apply ((apply_t) m->method_imp, 270 arg_frame, 271 method_get_sizeof_arguments (m)); 272} 273 274void 275__objc_init_dispatch_tables () 276{ 277 __objc_uninstalled_dtable = sarray_new (200, 0); 278} 279 280/* This function is called by objc_msg_lookup when the 281 dispatch table needs to be installed; thus it is called once 282 for each class, namely when the very first message is sent to it. */ 283static void 284__objc_init_install_dtable (id receiver, SEL op __attribute__ ((__unused__))) 285{ 286 objc_mutex_lock (__objc_runtime_mutex); 287 288 /* This may happen, if the programmer has taken the address of a 289 method before the dtable was initialized... too bad for him! */ 290 if (receiver->class_pointer->dtable != __objc_uninstalled_dtable) 291 { 292 objc_mutex_unlock (__objc_runtime_mutex); 293 return; 294 } 295 296 if (CLS_ISCLASS (receiver->class_pointer)) 297 { 298 /* receiver is an ordinary object */ 299 assert (CLS_ISCLASS (receiver->class_pointer)); 300 301 /* install instance methods table */ 302 __objc_install_dispatch_table_for_class (receiver->class_pointer); 303 304 /* call +initialize -- this will in turn install the factory 305 dispatch table if not already done :-) */ 306 __objc_send_initialize (receiver->class_pointer); 307 } 308 else 309 { 310 /* receiver is a class object */ 311 assert (CLS_ISCLASS ((Class)receiver)); 312 assert (CLS_ISMETA (receiver->class_pointer)); 313 314 /* Install real dtable for factory methods */ 315 __objc_install_dispatch_table_for_class (receiver->class_pointer); 316 317 __objc_send_initialize ((Class)receiver); 318 } 319 objc_mutex_unlock (__objc_runtime_mutex); 320} 321 322/* Install dummy table for class which causes the first message to 323 that class (or instances hereof) to be initialized properly */ 324void 325__objc_install_premature_dtable (Class class) 326{ 327 assert (__objc_uninstalled_dtable); 328 class->dtable = __objc_uninstalled_dtable; 329} 330 331/* Send +initialize to class if not already done */ 332static void 333__objc_send_initialize (Class class) 334{ 335 /* This *must* be a class object */ 336 assert (CLS_ISCLASS (class)); 337 assert (! CLS_ISMETA (class)); 338 339 if (! CLS_ISINITIALIZED (class)) 340 { 341 CLS_SETINITIALIZED (class); 342 CLS_SETINITIALIZED (class->class_pointer); 343 344 /* Create the garbage collector type memory description */ 345 __objc_generate_gc_type_description (class); 346 347 if (class->super_class) 348 __objc_send_initialize (class->super_class); 349 350 { 351 SEL op = sel_register_name ("initialize"); 352 IMP imp = 0; 353 MethodList_t method_list = class->class_pointer->methods; 354 355 while (method_list) { 356 int i; 357 Method_t method; 358 359 for (i = 0; i < method_list->method_count; i++) { 360 method = &(method_list->method_list[i]); 361 if (method->method_name 362 && method->method_name->sel_id == op->sel_id) { 363 imp = method->method_imp; 364 break; 365 } 366 } 367 368 if (imp) 369 break; 370 371 method_list = method_list->method_next; 372 373 } 374 if (imp) 375 (*imp) ((id) class, op); 376 377 } 378 } 379} 380 381/* Walk on the methods list of class and install the methods in the reverse 382 order of the lists. Since methods added by categories are before the methods 383 of class in the methods list, this allows categories to substitute methods 384 declared in class. However if more than one category replaces the same 385 method nothing is guaranteed about what method will be used. 386 Assumes that __objc_runtime_mutex is locked down. */ 387static void 388__objc_install_methods_in_dtable (Class class, MethodList_t method_list) 389{ 390 int i; 391 392 if (! method_list) 393 return; 394 395 if (method_list->method_next) 396 __objc_install_methods_in_dtable (class, method_list->method_next); 397 398 for (i = 0; i < method_list->method_count; i++) 399 { 400 Method_t method = &(method_list->method_list[i]); 401 sarray_at_put_safe (class->dtable, 402 (sidx) method->method_name->sel_id, 403 method->method_imp); 404 } 405} 406 407/* Assumes that __objc_runtime_mutex is locked down. */ 408static void 409__objc_install_dispatch_table_for_class (Class class) 410{ 411 Class super; 412 413 /* If the class has not yet had its class links resolved, we must 414 re-compute all class links */ 415 if (! CLS_ISRESOLV (class)) 416 __objc_resolve_class_links (); 417 418 super = class->super_class; 419 420 if (super != 0 && (super->dtable == __objc_uninstalled_dtable)) 421 __objc_install_dispatch_table_for_class (super); 422 423 /* Allocate dtable if necessary */ 424 if (super == 0) 425 { 426 objc_mutex_lock (__objc_runtime_mutex); 427 class->dtable = sarray_new (__objc_selector_max_index, 0); 428 objc_mutex_unlock (__objc_runtime_mutex); 429 } 430 else 431 class->dtable = sarray_lazy_copy (super->dtable); 432 433 __objc_install_methods_in_dtable (class, class->methods); 434} 435 436void 437__objc_update_dispatch_table_for_class (Class class) 438{ 439 Class next; 440 struct sarray *arr; 441 442 /* not yet installed -- skip it */ 443 if (class->dtable == __objc_uninstalled_dtable) 444 return; 445 446 objc_mutex_lock (__objc_runtime_mutex); 447 448 arr = class->dtable; 449 __objc_install_premature_dtable (class); /* someone might require it... */ 450 sarray_free (arr); /* release memory */ 451 452 /* could have been lazy... */ 453 __objc_install_dispatch_table_for_class (class); 454 455 if (class->subclass_list) /* Traverse subclasses */ 456 for (next = class->subclass_list; next; next = next->sibling_class) 457 __objc_update_dispatch_table_for_class (next); 458 459 objc_mutex_unlock (__objc_runtime_mutex); 460} 461 462 463/* This function adds a method list to a class. This function is 464 typically called by another function specific to the run-time. As 465 such this function does not worry about thread safe issues. 466 467 This one is only called for categories. Class objects have their 468 methods installed right away, and their selectors are made into 469 SEL's by the function __objc_register_selectors_from_class. */ 470void 471class_add_method_list (Class class, MethodList_t list) 472{ 473 /* Passing of a linked list is not allowed. Do multiple calls. */ 474 assert (! list->method_next); 475 476 __objc_register_selectors_from_list(list); 477 478 /* Add the methods to the class's method list. */ 479 list->method_next = class->methods; 480 class->methods = list; 481 482 /* Update the dispatch table of class */ 483 __objc_update_dispatch_table_for_class (class); 484} 485 486Method_t 487class_get_instance_method (Class class, SEL op) 488{ 489 return search_for_method_in_hierarchy (class, op); 490} 491 492Method_t 493class_get_class_method (MetaClass class, SEL op) 494{ 495 return search_for_method_in_hierarchy (class, op); 496} 497 498 499/* Search for a method starting from the current class up its hierarchy. 500 Return a pointer to the method's method structure if found. NULL 501 otherwise. */ 502 503static Method_t 504search_for_method_in_hierarchy (Class cls, SEL sel) 505{ 506 Method_t method = NULL; 507 Class class; 508 509 if (! sel_is_mapped (sel)) 510 return NULL; 511 512 /* Scan the method list of the class. If the method isn't found in the 513 list then step to its super class. */ 514 for (class = cls; ((! method) && class); class = class->super_class) 515 method = search_for_method_in_list (class->methods, sel); 516 517 return method; 518} 519 520 521 522/* Given a linked list of method and a method's name. Search for the named 523 method's method structure. Return a pointer to the method's method 524 structure if found. NULL otherwise. */ 525Method_t 526search_for_method_in_list (MethodList_t list, SEL op) 527{ 528 MethodList_t method_list = list; 529 530 if (! sel_is_mapped (op)) 531 return NULL; 532 533 /* If not found then we'll search the list. */ 534 while (method_list) 535 { 536 int i; 537 538 /* Search the method list. */ 539 for (i = 0; i < method_list->method_count; ++i) 540 { 541 Method_t method = &method_list->method_list[i]; 542 543 if (method->method_name) 544 if (method->method_name->sel_id == op->sel_id) 545 return method; 546 } 547 548 /* The method wasn't found. Follow the link to the next list of 549 methods. */ 550 method_list = method_list->method_next; 551 } 552 553 return NULL; 554} 555 556static retval_t __objc_forward (id object, SEL sel, arglist_t args); 557 558/* Forwarding pointers/integers through the normal registers */ 559static id 560__objc_word_forward (id rcv, SEL op, ...) 561{ 562 void *args, *res; 563 564 args = __builtin_apply_args (); 565 res = __objc_forward (rcv, op, args); 566 if (res) 567 __builtin_return (res); 568 else 569 return res; 570} 571 572/* Specific routine for forwarding floats/double because of 573 architectural differences on some processors. i386s for 574 example which uses a floating point stack versus general 575 registers for floating point numbers. This forward routine 576 makes sure that GCC restores the proper return values */ 577static double 578__objc_double_forward (id rcv, SEL op, ...) 579{ 580 void *args, *res; 581 582 args = __builtin_apply_args (); 583 res = __objc_forward (rcv, op, args); 584 __builtin_return (res); 585} 586 587#if INVISIBLE_STRUCT_RETURN 588static __big 589#else 590static id 591#endif 592__objc_block_forward (id rcv, SEL op, ...) 593{ 594 void *args, *res; 595 596 args = __builtin_apply_args (); 597 res = __objc_forward (rcv, op, args); 598 if (res) 599 __builtin_return (res); 600 else 601#if INVISIBLE_STRUCT_RETURN 602 return (__big) {{0, 0, 0, 0, 0, 0, 0, 0}}; 603#else 604 return nil; 605#endif 606} 607 608 609/* This function is installed in the dispatch table for all methods which are 610 not implemented. Thus, it is called when a selector is not recognized. */ 611static retval_t 612__objc_forward (id object, SEL sel, arglist_t args) 613{ 614 IMP imp; 615 static SEL frwd_sel = 0; /* !T:SAFE2 */ 616 SEL err_sel; 617 618 /* first try if the object understands forward:: */ 619 if (! frwd_sel) 620 frwd_sel = sel_get_any_uid ("forward::"); 621 622 if (__objc_responds_to (object, frwd_sel)) 623 { 624 imp = get_imp (object->class_pointer, frwd_sel); 625 return (*imp) (object, frwd_sel, sel, args); 626 } 627 628 /* If the object recognizes the doesNotRecognize: method then we're going 629 to send it. */ 630 err_sel = sel_get_any_uid ("doesNotRecognize:"); 631 if (__objc_responds_to (object, err_sel)) 632 { 633 imp = get_imp (object->class_pointer, err_sel); 634 return (*imp) (object, err_sel, sel); 635 } 636 637 /* The object doesn't recognize the method. Check for responding to 638 error:. If it does then sent it. */ 639 { 640 char msg[256 + strlen ((const char *) sel_get_name (sel)) 641 + strlen ((const char *) object->class_pointer->name)]; 642 643 sprintf (msg, "(%s) %s does not recognize %s", 644 (CLS_ISMETA (object->class_pointer) 645 ? "class" 646 : "instance" ), 647 object->class_pointer->name, sel_get_name (sel)); 648 649 err_sel = sel_get_any_uid ("error:"); 650 if (__objc_responds_to (object, err_sel)) 651 { 652 imp = get_imp (object->class_pointer, err_sel); 653 return (*imp) (object, sel_get_any_uid ("error:"), msg); 654 } 655 656 /* The object doesn't respond to doesNotRecognize: or error:; Therefore, 657 a default action is taken. */ 658 objc_error (object, OBJC_ERR_UNIMPLEMENTED, "%s\n", msg); 659 660 return 0; 661 } 662} 663 664void 665__objc_print_dtable_stats () 666{ 667 int total = 0; 668 669 objc_mutex_lock (__objc_runtime_mutex); 670 671#ifdef OBJC_SPARSE2 672 printf ("memory usage: (%s)\n", "2-level sparse arrays"); 673#else 674 printf ("memory usage: (%s)\n", "3-level sparse arrays"); 675#endif 676 677 printf ("arrays: %d = %ld bytes\n", narrays, 678 (long) narrays * sizeof (struct sarray)); 679 total += narrays * sizeof (struct sarray); 680 printf ("buckets: %d = %ld bytes\n", nbuckets, 681 (long) nbuckets * sizeof (struct sbucket)); 682 total += nbuckets * sizeof (struct sbucket); 683 684 printf ("idxtables: %d = %ld bytes\n", 685 idxsize, (long) idxsize * sizeof (void *)); 686 total += idxsize * sizeof (void *); 687 printf ("-----------------------------------\n"); 688 printf ("total: %d bytes\n", total); 689 printf ("===================================\n"); 690 691 objc_mutex_unlock (__objc_runtime_mutex); 692} 693 694/* Returns the uninstalled dispatch table indicator. 695 If a class' dispatch table points to __objc_uninstalled_dtable 696 then that means it needs its dispatch table to be installed. */ 697inline 698struct sarray * 699objc_get_uninstalled_dtable () 700{ 701 return __objc_uninstalled_dtable; 702} 703