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1/*2 * runtime.c3 *4 * Copyright 2008-2010 Apple, Inc. Permission is hereby granted, free of charge,5 * to any person obtaining a copy of this software and associated documentation6 * files (the "Software"), to deal in the Software without restriction,7 * including without limitation the rights to use, copy, modify, merge, publish,8 * distribute, sublicense, and/or sell copies of the Software, and to permit9 * persons to whom the Software is furnished to do so, subject to the following10 * conditions:11 * 12 * The above copyright notice and this permission notice shall be included in13 * all copies or substantial portions of the Software.14 * 15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR16 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,17 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE18 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER19 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,20 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE21 * SOFTWARE.22 *23 */24 25#include "Block_private.h"26#include <stdio.h>27#include <stdlib.h>28#include <string.h>29#include <stdint.h>30 31#include "config.h"32 33#ifdef HAVE_AVAILABILITY_MACROS_H34#include <AvailabilityMacros.h>35#endif /* HAVE_AVAILABILITY_MACROS_H */36 37#ifdef HAVE_TARGET_CONDITIONALS_H38#include <TargetConditionals.h>39#endif /* HAVE_TARGET_CONDITIONALS_H */40 41#if defined(HAVE_OSATOMIC_COMPARE_AND_SWAP_INT) && defined(HAVE_OSATOMIC_COMPARE_AND_SWAP_LONG)42 43#ifdef HAVE_LIBKERN_OSATOMIC_H44#include <libkern/OSAtomic.h>45#endif /* HAVE_LIBKERN_OSATOMIC_H */46 47#elif defined(__WIN32__) || defined(_WIN32)48#define _CRT_SECURE_NO_WARNINGS 149#include <windows.h>50 51static __inline bool OSAtomicCompareAndSwapLong(long oldl, long newl, long volatile *dst) {52 /* fixme barrier is overkill -- see objc-os.h */53 long original = InterlockedCompareExchange(dst, newl, oldl);54 return (original == oldl);55}56 57static __inline bool OSAtomicCompareAndSwapInt(int oldi, int newi, int volatile *dst) {58 /* fixme barrier is overkill -- see objc-os.h */59 int original = InterlockedCompareExchange(dst, newi, oldi);60 return (original == oldi);61}62 63/*64 * Check to see if the GCC atomic built-ins are available. If we're on65 * a 64-bit system, make sure we have an 8-byte atomic function66 * available.67 *68 */69 70#elif defined(HAVE_SYNC_BOOL_COMPARE_AND_SWAP_INT) && defined(HAVE_SYNC_BOOL_COMPARE_AND_SWAP_LONG)71 72static __inline bool OSAtomicCompareAndSwapLong(long oldl, long newl, long volatile *dst) {73 return __sync_bool_compare_and_swap(dst, oldl, newl);74}75 76static __inline bool OSAtomicCompareAndSwapInt(int oldi, int newi, int volatile *dst) {77 return __sync_bool_compare_and_swap(dst, oldi, newi);78}79 80#else81#error unknown atomic compare-and-swap primitive82#endif /* HAVE_OSATOMIC_COMPARE_AND_SWAP_INT && HAVE_OSATOMIC_COMPARE_AND_SWAP_LONG */83 84 85/*86 * Globals:87 */88 89static void *_Block_copy_class = _NSConcreteMallocBlock;90static void *_Block_copy_finalizing_class = _NSConcreteMallocBlock;91static int _Block_copy_flag = BLOCK_NEEDS_FREE;92static int _Byref_flag_initial_value = BLOCK_NEEDS_FREE | 2;93 94static const int WANTS_ONE = (1 << 16);95 96static bool isGC = false;97 98/*99 * Internal Utilities:100 */101 102#if 0103static unsigned long int latching_incr_long(unsigned long int *where) {104 while (1) {105 unsigned long int old_value = *(volatile unsigned long int *)where;106 if ((old_value & BLOCK_REFCOUNT_MASK) == BLOCK_REFCOUNT_MASK) {107 return BLOCK_REFCOUNT_MASK;108 }109 if (OSAtomicCompareAndSwapLong(old_value, old_value+1, (volatile long int *)where)) {110 return old_value+1;111 }112 }113}114#endif /* if 0 */115 116static int latching_incr_int(int *where) {117 while (1) {118 int old_value = *(volatile int *)where;119 if ((old_value & BLOCK_REFCOUNT_MASK) == BLOCK_REFCOUNT_MASK) {120 return BLOCK_REFCOUNT_MASK;121 }122 if (OSAtomicCompareAndSwapInt(old_value, old_value+1, (volatile int *)where)) {123 return old_value+1;124 }125 }126}127 128#if 0129static int latching_decr_long(unsigned long int *where) {130 while (1) {131 unsigned long int old_value = *(volatile int *)where;132 if ((old_value & BLOCK_REFCOUNT_MASK) == BLOCK_REFCOUNT_MASK) {133 return BLOCK_REFCOUNT_MASK;134 }135 if ((old_value & BLOCK_REFCOUNT_MASK) == 0) {136 return 0;137 }138 if (OSAtomicCompareAndSwapLong(old_value, old_value-1, (volatile long int *)where)) {139 return old_value-1;140 }141 }142}143#endif /* if 0 */144 145static int latching_decr_int(int *where) {146 while (1) {147 int old_value = *(volatile int *)where;148 if ((old_value & BLOCK_REFCOUNT_MASK) == BLOCK_REFCOUNT_MASK) {149 return BLOCK_REFCOUNT_MASK;150 }151 if ((old_value & BLOCK_REFCOUNT_MASK) == 0) {152 return 0;153 }154 if (OSAtomicCompareAndSwapInt(old_value, old_value-1, (volatile int *)where)) {155 return old_value-1;156 }157 }158}159 160 161/*162 * GC support stub routines:163 */164#if 0165#pragma mark GC Support Routines166#endif /* if 0 */167 168 169static void *_Block_alloc_default(const unsigned long size, const bool initialCountIsOne, const bool isObject) {170 return malloc(size);171}172 173static void _Block_assign_default(void *value, void **destptr) {174 *destptr = value;175}176 177static void _Block_setHasRefcount_default(const void *ptr, const bool hasRefcount) {178}179 180static void _Block_do_nothing(const void *aBlock) { }181 182static void _Block_retain_object_default(const void *ptr) {183 if (!ptr) return;184}185 186static void _Block_release_object_default(const void *ptr) {187 if (!ptr) return;188}189 190static void _Block_assign_weak_default(const void *ptr, void *dest) {191 *(void **)dest = (void *)ptr;192}193 194static void _Block_memmove_default(void *dst, void *src, unsigned long size) {195 memmove(dst, src, (size_t)size);196}197 198static void _Block_memmove_gc_broken(void *dest, void *src, unsigned long size) {199 void **destp = (void **)dest;200 void **srcp = (void **)src;201 while (size) {202 _Block_assign_default(*srcp, destp);203 destp++;204 srcp++;205 size -= sizeof(void *);206 }207}208 209/*210 * GC support callout functions - initially set to stub routines:211 */212 213static void *(*_Block_allocator)(const unsigned long, const bool isOne, const bool isObject) = _Block_alloc_default;214static void (*_Block_deallocator)(const void *) = (void (*)(const void *))free;215static void (*_Block_assign)(void *value, void **destptr) = _Block_assign_default;216static void (*_Block_setHasRefcount)(const void *ptr, const bool hasRefcount) = _Block_setHasRefcount_default;217static void (*_Block_retain_object)(const void *ptr) = _Block_retain_object_default;218static void (*_Block_release_object)(const void *ptr) = _Block_release_object_default;219static void (*_Block_assign_weak)(const void *dest, void *ptr) = _Block_assign_weak_default;220static void (*_Block_memmove)(void *dest, void *src, unsigned long size) = _Block_memmove_default;221 222 223/*224 * GC support SPI functions - called from ObjC runtime and CoreFoundation:225 */226 227/* Public SPI228 * Called from objc-auto to turn on GC.229 * version 3, 4 arg, but changed 1st arg230 */231void _Block_use_GC( void *(*alloc)(const unsigned long, const bool isOne, const bool isObject),232 void (*setHasRefcount)(const void *, const bool),233 void (*gc_assign)(void *, void **),234 void (*gc_assign_weak)(const void *, void *),235 void (*gc_memmove)(void *, void *, unsigned long)) {236 237 isGC = true;238 _Block_allocator = alloc;239 _Block_deallocator = _Block_do_nothing;240 _Block_assign = gc_assign;241 _Block_copy_flag = BLOCK_IS_GC;242 _Block_copy_class = _NSConcreteAutoBlock;243 /* blocks with ctors & dtors need to have the dtor run from a class with a finalizer */244 _Block_copy_finalizing_class = _NSConcreteFinalizingBlock;245 _Block_setHasRefcount = setHasRefcount;246 _Byref_flag_initial_value = BLOCK_IS_GC; // no refcount247 _Block_retain_object = _Block_do_nothing;248 _Block_release_object = _Block_do_nothing;249 _Block_assign_weak = gc_assign_weak;250 _Block_memmove = gc_memmove;251}252 253/* transitional */254void _Block_use_GC5( void *(*alloc)(const unsigned long, const bool isOne, const bool isObject),255 void (*setHasRefcount)(const void *, const bool),256 void (*gc_assign)(void *, void **),257 void (*gc_assign_weak)(const void *, void *)) {258 /* until objc calls _Block_use_GC it will call us; supply a broken internal memmove implementation until then */259 _Block_use_GC(alloc, setHasRefcount, gc_assign, gc_assign_weak, _Block_memmove_gc_broken);260}261 262 263/*264 * Called from objc-auto to alternatively turn on retain/release.265 * Prior to this the only "object" support we can provide is for those266 * super special objects that live in libSystem, namely dispatch queues.267 * Blocks and Block_byrefs have their own special entry points.268 *269 */270void _Block_use_RR( void (*retain)(const void *),271 void (*release)(const void *)) {272 _Block_retain_object = retain;273 _Block_release_object = release;274}275 276/*277 * Internal Support routines for copying:278 */279 280#if 0281#pragma mark Copy/Release support282#endif /* if 0 */283 284/* Copy, or bump refcount, of a block. If really copying, call the copy helper if present. */285static void *_Block_copy_internal(const void *arg, const int flags) {286 struct Block_layout *aBlock;287 const bool wantsOne = (WANTS_ONE & flags) == WANTS_ONE;288 289 //printf("_Block_copy_internal(%p, %x)\n", arg, flags); 290 if (!arg) return NULL;291 292 293 // The following would be better done as a switch statement294 aBlock = (struct Block_layout *)arg;295 if (aBlock->flags & BLOCK_NEEDS_FREE) {296 // latches on high297 latching_incr_int(&aBlock->flags);298 return aBlock;299 }300 else if (aBlock->flags & BLOCK_IS_GC) {301 // GC refcounting is expensive so do most refcounting here.302 if (wantsOne && ((latching_incr_int(&aBlock->flags) & BLOCK_REFCOUNT_MASK) == 1)) {303 // Tell collector to hang on this - it will bump the GC refcount version304 _Block_setHasRefcount(aBlock, true);305 }306 return aBlock;307 }308 else if (aBlock->flags & BLOCK_IS_GLOBAL) {309 return aBlock;310 }311 312 // Its a stack block. Make a copy.313 if (!isGC) {314 struct Block_layout *result = malloc(aBlock->descriptor->size);315 if (!result) return (void *)0;316 memmove(result, aBlock, aBlock->descriptor->size); // bitcopy first317 // reset refcount318 result->flags &= ~(BLOCK_REFCOUNT_MASK); // XXX not needed319 result->flags |= BLOCK_NEEDS_FREE | 1;320 result->isa = _NSConcreteMallocBlock;321 if (result->flags & BLOCK_HAS_COPY_DISPOSE) {322 //printf("calling block copy helper %p(%p, %p)...\n", aBlock->descriptor->copy, result, aBlock);323 (*aBlock->descriptor->copy)(result, aBlock); // do fixup324 }325 return result;326 }327 else {328 // Under GC want allocation with refcount 1 so we ask for "true" if wantsOne329 // This allows the copy helper routines to make non-refcounted block copies under GC330 unsigned long int flags = aBlock->flags;331 bool hasCTOR = (flags & BLOCK_HAS_CTOR) != 0;332 struct Block_layout *result = _Block_allocator(aBlock->descriptor->size, wantsOne, hasCTOR);333 if (!result) return (void *)0;334 memmove(result, aBlock, aBlock->descriptor->size); // bitcopy first335 // reset refcount336 // if we copy a malloc block to a GC block then we need to clear NEEDS_FREE.337 flags &= ~(BLOCK_NEEDS_FREE|BLOCK_REFCOUNT_MASK); // XXX not needed338 if (wantsOne)339 flags |= BLOCK_IS_GC | 1;340 else341 flags |= BLOCK_IS_GC;342 result->flags = flags;343 if (flags & BLOCK_HAS_COPY_DISPOSE) {344 //printf("calling block copy helper...\n");345 (*aBlock->descriptor->copy)(result, aBlock); // do fixup346 }347 if (hasCTOR) {348 result->isa = _NSConcreteFinalizingBlock;349 }350 else {351 result->isa = _NSConcreteAutoBlock;352 }353 return result;354 }355}356 357 358/*359 * Runtime entry points for maintaining the sharing knowledge of byref data blocks.360 *361 * A closure has been copied and its fixup routine is asking us to fix up the reference to the shared byref data362 * Closures that aren't copied must still work, so everyone always accesses variables after dereferencing the forwarding ptr.363 * We ask if the byref pointer that we know about has already been copied to the heap, and if so, increment it.364 * Otherwise we need to copy it and update the stack forwarding pointer365 * XXX We need to account for weak/nonretained read-write barriers.366 */367 368static void _Block_byref_assign_copy(void *dest, const void *arg, const int flags) {369 struct Block_byref **destp = (struct Block_byref **)dest;370 struct Block_byref *src = (struct Block_byref *)arg;371 372 //printf("_Block_byref_assign_copy called, byref destp %p, src %p, flags %x\n", destp, src, flags);373 //printf("src dump: %s\n", _Block_byref_dump(src));374 if (src->forwarding->flags & BLOCK_IS_GC) {375 ; // don't need to do any more work376 }377 else if ((src->forwarding->flags & BLOCK_REFCOUNT_MASK) == 0) {378 //printf("making copy\n");379 // src points to stack380 bool isWeak = ((flags & (BLOCK_FIELD_IS_BYREF|BLOCK_FIELD_IS_WEAK)) == (BLOCK_FIELD_IS_BYREF|BLOCK_FIELD_IS_WEAK));381 // if its weak ask for an object (only matters under GC)382 struct Block_byref *copy = (struct Block_byref *)_Block_allocator(src->size, false, isWeak);383 copy->flags = src->flags | _Byref_flag_initial_value; // non-GC one for caller, one for stack384 copy->forwarding = copy; // patch heap copy to point to itself (skip write-barrier)385 src->forwarding = copy; // patch stack to point to heap copy386 copy->size = src->size;387 if (isWeak) {388 copy->isa = &_NSConcreteWeakBlockVariable; // mark isa field so it gets weak scanning389 }390 if (src->flags & BLOCK_HAS_COPY_DISPOSE) {391 // Trust copy helper to copy everything of interest392 // If more than one field shows up in a byref block this is wrong XXX393 copy->byref_keep = src->byref_keep;394 copy->byref_destroy = src->byref_destroy;395 (*src->byref_keep)(copy, src);396 }397 else {398 // just bits. Blast 'em using _Block_memmove in case they're __strong399 _Block_memmove(400 (void *)©->byref_keep,401 (void *)&src->byref_keep,402 src->size - sizeof(struct Block_byref_header));403 }404 }405 // already copied to heap406 else if ((src->forwarding->flags & BLOCK_NEEDS_FREE) == BLOCK_NEEDS_FREE) {407 latching_incr_int(&src->forwarding->flags);408 }409 // assign byref data block pointer into new Block410 _Block_assign(src->forwarding, (void **)destp);411}412 413// Old compiler SPI414static void _Block_byref_release(const void *arg) {415 struct Block_byref *shared_struct = (struct Block_byref *)arg;416 int refcount;417 418 // dereference the forwarding pointer since the compiler isn't doing this anymore (ever?)419 shared_struct = shared_struct->forwarding;420 421 //printf("_Block_byref_release %p called, flags are %x\n", shared_struct, shared_struct->flags);422 // To support C++ destructors under GC we arrange for there to be a finalizer for this423 // by using an isa that directs the code to a finalizer that calls the byref_destroy method.424 if ((shared_struct->flags & BLOCK_NEEDS_FREE) == 0) {425 return; // stack or GC or global426 }427 refcount = shared_struct->flags & BLOCK_REFCOUNT_MASK;428 if (refcount <= 0) {429 printf("_Block_byref_release: Block byref data structure at %p underflowed\n", arg);430 }431 else if ((latching_decr_int(&shared_struct->flags) & BLOCK_REFCOUNT_MASK) == 0) {432 //printf("disposing of heap based byref block\n");433 if (shared_struct->flags & BLOCK_HAS_COPY_DISPOSE) {434 //printf("calling out to helper\n");435 (*shared_struct->byref_destroy)(shared_struct);436 }437 _Block_deallocator((struct Block_layout *)shared_struct);438 }439}440 441 442/*443 *444 * API supporting SPI445 * _Block_copy, _Block_release, and (old) _Block_destroy446 *447 */448 449#if 0450#pragma mark SPI/API451#endif /* if 0 */452 453void *_Block_copy(const void *arg) {454 return _Block_copy_internal(arg, WANTS_ONE);455}456 457 458// API entry point to release a copied Block459void _Block_release(void *arg) {460 struct Block_layout *aBlock = (struct Block_layout *)arg;461 int32_t newCount;462 if (!aBlock) return;463 newCount = latching_decr_int(&aBlock->flags) & BLOCK_REFCOUNT_MASK;464 if (newCount > 0) return;465 // Hit zero466 if (aBlock->flags & BLOCK_IS_GC) {467 // Tell GC we no longer have our own refcounts. GC will decr its refcount468 // and unless someone has done a CFRetain or marked it uncollectable it will469 // now be subject to GC reclamation.470 _Block_setHasRefcount(aBlock, false);471 }472 else if (aBlock->flags & BLOCK_NEEDS_FREE) {473 if (aBlock->flags & BLOCK_HAS_COPY_DISPOSE)(*aBlock->descriptor->dispose)(aBlock);474 _Block_deallocator(aBlock);475 }476 else if (aBlock->flags & BLOCK_IS_GLOBAL) {477 ;478 }479 else {480 printf("Block_release called upon a stack Block: %p, ignored\n", (void *)aBlock);481 }482}483 484 485 486// Old Compiler SPI point to release a copied Block used by the compiler in dispose helpers487static void _Block_destroy(const void *arg) {488 struct Block_layout *aBlock;489 if (!arg) return;490 aBlock = (struct Block_layout *)arg;491 if (aBlock->flags & BLOCK_IS_GC) {492 // assert(aBlock->Block_flags & BLOCK_HAS_CTOR);493 return; // ignore, we are being called because of a DTOR494 }495 _Block_release(aBlock);496}497 498 499 500/*501 *502 * SPI used by other layers503 *504 */505 506// SPI, also internal. Called from NSAutoBlock only under GC507void *_Block_copy_collectable(const void *aBlock) {508 return _Block_copy_internal(aBlock, 0);509}510 511 512// SPI513unsigned long int Block_size(void *arg) {514 return ((struct Block_layout *)arg)->descriptor->size;515}516 517 518#if 0519#pragma mark Compiler SPI entry points520#endif /* if 0 */521 522 523/*******************************************************524 525Entry points used by the compiler - the real API!526 527 528A Block can reference four different kinds of things that require help when the Block is copied to the heap.5291) C++ stack based objects5302) References to Objective-C objects5313) Other Blocks5324) __block variables533 534In these cases helper functions are synthesized by the compiler for use in Block_copy and Block_release, called the copy and dispose helpers. The copy helper emits a call to the C++ const copy constructor for C++ stack based objects and for the rest calls into the runtime support function _Block_object_assign. The dispose helper has a call to the C++ destructor for case 1 and a call into _Block_object_dispose for the rest.535 536The flags parameter of _Block_object_assign and _Block_object_dispose is set to537 * BLOCK_FIELD_IS_OBJECT (3), for the case of an Objective-C Object,538 * BLOCK_FIELD_IS_BLOCK (7), for the case of another Block, and539 * BLOCK_FIELD_IS_BYREF (8), for the case of a __block variable.540If the __block variable is marked weak the compiler also or's in BLOCK_FIELD_IS_WEAK (16).541 542So the Block copy/dispose helpers should only ever generate the four flag values of 3, 7, 8, and 24.543 544When a __block variable is either a C++ object, an Objective-C object, or another Block then the compiler also generates copy/dispose helper functions. Similarly to the Block copy helper, the "__block" copy helper (formerly and still a.k.a. "byref" copy helper) will do a C++ copy constructor (not a const one though!) and the dispose helper will do the destructor. And similarly the helpers will call into the same two support functions with the same values for objects and Blocks with the additional BLOCK_BYREF_CALLER (128) bit of information supplied.545 546So the __block copy/dispose helpers will generate flag values of 3 or 7 for objects and Blocks respectively, with BLOCK_FIELD_IS_WEAK (16) or'ed as appropriate and always 128 or'd in, for the following set of possibilities:547 __block id 128+3548 __weak block id 128+3+16549 __block (^Block) 128+7550 __weak __block (^Block) 128+7+16551 552The implementation of the two routines would be improved by switch statements enumerating the eight cases.553 554********************************************************/555 556/*557 * When Blocks or Block_byrefs hold objects then their copy routine helpers use this entry point558 * to do the assignment.559 */560void _Block_object_assign(void *destAddr, const void *object, const int flags) {561 //printf("_Block_object_assign(*%p, %p, %x)\n", destAddr, object, flags);562 if ((flags & BLOCK_BYREF_CALLER) == BLOCK_BYREF_CALLER) {563 if ((flags & BLOCK_FIELD_IS_WEAK) == BLOCK_FIELD_IS_WEAK) {564 _Block_assign_weak(object, destAddr);565 }566 else {567 // do *not* retain or *copy* __block variables whatever they are568 _Block_assign((void *)object, destAddr);569 }570 }571 else if ((flags & BLOCK_FIELD_IS_BYREF) == BLOCK_FIELD_IS_BYREF) {572 // copying a __block reference from the stack Block to the heap573 // flags will indicate if it holds a __weak reference and needs a special isa574 _Block_byref_assign_copy(destAddr, object, flags);575 }576 // (this test must be before next one)577 else if ((flags & BLOCK_FIELD_IS_BLOCK) == BLOCK_FIELD_IS_BLOCK) {578 // copying a Block declared variable from the stack Block to the heap579 _Block_assign(_Block_copy_internal(object, flags), destAddr);580 }581 // (this test must be after previous one)582 else if ((flags & BLOCK_FIELD_IS_OBJECT) == BLOCK_FIELD_IS_OBJECT) {583 //printf("retaining object at %p\n", object);584 _Block_retain_object(object);585 //printf("done retaining object at %p\n", object);586 _Block_assign((void *)object, destAddr);587 }588}589 590// When Blocks or Block_byrefs hold objects their destroy helper routines call this entry point591// to help dispose of the contents592// Used initially only for __attribute__((NSObject)) marked pointers.593void _Block_object_dispose(const void *object, const int flags) {594 //printf("_Block_object_dispose(%p, %x)\n", object, flags);595 if (flags & BLOCK_FIELD_IS_BYREF) {596 // get rid of the __block data structure held in a Block597 _Block_byref_release(object);598 }599 else if ((flags & (BLOCK_FIELD_IS_BLOCK|BLOCK_BYREF_CALLER)) == BLOCK_FIELD_IS_BLOCK) {600 // get rid of a referenced Block held by this Block601 // (ignore __block Block variables, compiler doesn't need to call us)602 _Block_destroy(object);603 }604 else if ((flags & (BLOCK_FIELD_IS_WEAK|BLOCK_FIELD_IS_BLOCK|BLOCK_BYREF_CALLER)) == BLOCK_FIELD_IS_OBJECT) {605 // get rid of a referenced object held by this Block606 // (ignore __block object variables, compiler doesn't need to call us)607 _Block_release_object(object);608 }609}610 611 612/*613 * Debugging support:614 */615#if 0616#pragma mark Debugging617#endif /* if 0 */618 619 620const char *_Block_dump(const void *block) {621 struct Block_layout *closure = (struct Block_layout *)block;622 static char buffer[512];623 char *cp = buffer;624 if (closure == NULL) {625 sprintf(cp, "NULL passed to _Block_dump\n");626 return buffer;627 }628 if (! (closure->flags & BLOCK_HAS_DESCRIPTOR)) {629 printf("Block compiled by obsolete compiler, please recompile source for this Block\n");630 exit(1);631 }632 cp += sprintf(cp, "^%p (new layout) =\n", (void *)closure);633 if (closure->isa == NULL) {634 cp += sprintf(cp, "isa: NULL\n");635 }636 else if (closure->isa == _NSConcreteStackBlock) {637 cp += sprintf(cp, "isa: stack Block\n");638 }639 else if (closure->isa == _NSConcreteMallocBlock) {640 cp += sprintf(cp, "isa: malloc heap Block\n");641 }642 else if (closure->isa == _NSConcreteAutoBlock) {643 cp += sprintf(cp, "isa: GC heap Block\n");644 }645 else if (closure->isa == _NSConcreteGlobalBlock) {646 cp += sprintf(cp, "isa: global Block\n");647 }648 else if (closure->isa == _NSConcreteFinalizingBlock) {649 cp += sprintf(cp, "isa: finalizing Block\n");650 }651 else {652 cp += sprintf(cp, "isa?: %p\n", (void *)closure->isa);653 }654 cp += sprintf(cp, "flags:");655 if (closure->flags & BLOCK_HAS_DESCRIPTOR) {656 cp += sprintf(cp, " HASDESCRIPTOR");657 }658 if (closure->flags & BLOCK_NEEDS_FREE) {659 cp += sprintf(cp, " FREEME");660 }661 if (closure->flags & BLOCK_IS_GC) {662 cp += sprintf(cp, " ISGC");663 }664 if (closure->flags & BLOCK_HAS_COPY_DISPOSE) {665 cp += sprintf(cp, " HASHELP");666 }667 if (closure->flags & BLOCK_HAS_CTOR) {668 cp += sprintf(cp, " HASCTOR");669 }670 cp += sprintf(cp, "\nrefcount: %u\n", closure->flags & BLOCK_REFCOUNT_MASK);671 cp += sprintf(cp, "invoke: %p\n", (void *)(uintptr_t)closure->invoke);672 {673 struct Block_descriptor *dp = closure->descriptor;674 cp += sprintf(cp, "descriptor: %p\n", (void *)dp);675 cp += sprintf(cp, "descriptor->reserved: %lu\n", dp->reserved);676 cp += sprintf(cp, "descriptor->size: %lu\n", dp->size);677 678 if (closure->flags & BLOCK_HAS_COPY_DISPOSE) {679 cp += sprintf(cp, "descriptor->copy helper: %p\n", (void *)(uintptr_t)dp->copy);680 cp += sprintf(cp, "descriptor->dispose helper: %p\n", (void *)(uintptr_t)dp->dispose);681 }682 }683 return buffer;684}685 686 687const char *_Block_byref_dump(struct Block_byref *src) {688 static char buffer[256];689 char *cp = buffer;690 cp += sprintf(cp, "byref data block %p contents:\n", (void *)src);691 cp += sprintf(cp, " forwarding: %p\n", (void *)src->forwarding);692 cp += sprintf(cp, " flags: 0x%x\n", src->flags);693 cp += sprintf(cp, " size: %d\n", src->size);694 if (src->flags & BLOCK_HAS_COPY_DISPOSE) {695 cp += sprintf(cp, " copy helper: %p\n", (void *)(uintptr_t)src->byref_keep);696 cp += sprintf(cp, " dispose helper: %p\n", (void *)(uintptr_t)src->byref_destroy);697 }698 return buffer;699}700 701