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darling-objc4/runtime/NSObject.mm
Thomas A 5a22f74c04 Fix Building For i386/Non-OBJC2
2022-04-29 10:13:27 -07:00

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/*
* Copyright (c) 2010-2012 Apple Inc. All rights reserved.
*
* @APPLE_LICENSE_HEADER_START@
*
* This file contains Original Code and/or Modifications of Original Code
* as defined in and that are subject to the Apple Public Source License
* Version 2.0 (the 'License'). You may not use this file except in
* compliance with the License. Please obtain a copy of the License at
* http://www.opensource.apple.com/apsl/ and read it before using this
* file.
*
* The Original Code and all software distributed under the License are
* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
* Please see the License for the specific language governing rights and
* limitations under the License.
*
* @APPLE_LICENSE_HEADER_END@
*/
#include "objc-private.h"
#include "NSObject.h"
#include "objc-weak.h"
#include "DenseMapExtras.h"
#include <malloc/malloc.h>
#include <stdint.h>
#include <stdbool.h>
#include <mach/mach.h>
#include <mach-o/dyld.h>
#include <mach-o/nlist.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <Block.h>
#include <map>
#include <execinfo.h>
#include "NSObject-internal.h"
#include <os/feature_private.h>
extern "C" {
#include <os/reason_private.h>
#include <os/variant_private.h>
}
#ifdef DARLING
#if __OBJC2__
#define DARLING_GET_SUPER_CLASS getSuperclass()
#else
#define DARLING_GET_SUPER_CLASS superclass
#endif
#endif
@interface NSInvocation
- (SEL)selector;
@end
OBJC_EXTERN const uint32_t objc_debug_autoreleasepoolpage_magic_offset = __builtin_offsetof(AutoreleasePoolPageData, magic);
OBJC_EXTERN const uint32_t objc_debug_autoreleasepoolpage_next_offset = __builtin_offsetof(AutoreleasePoolPageData, next);
OBJC_EXTERN const uint32_t objc_debug_autoreleasepoolpage_thread_offset = __builtin_offsetof(AutoreleasePoolPageData, thread);
OBJC_EXTERN const uint32_t objc_debug_autoreleasepoolpage_parent_offset = __builtin_offsetof(AutoreleasePoolPageData, parent);
OBJC_EXTERN const uint32_t objc_debug_autoreleasepoolpage_child_offset = __builtin_offsetof(AutoreleasePoolPageData, child);
OBJC_EXTERN const uint32_t objc_debug_autoreleasepoolpage_depth_offset = __builtin_offsetof(AutoreleasePoolPageData, depth);
OBJC_EXTERN const uint32_t objc_debug_autoreleasepoolpage_hiwat_offset = __builtin_offsetof(AutoreleasePoolPageData, hiwat);
OBJC_EXTERN const uint32_t objc_debug_autoreleasepoolpage_begin_offset = sizeof(AutoreleasePoolPageData);
#if __OBJC2__
#if SUPPORT_AUTORELEASEPOOL_DEDUP_PTRS
OBJC_EXTERN const uintptr_t objc_debug_autoreleasepoolpage_ptr_mask = (AutoreleasePoolPageData::AutoreleasePoolEntry){ .ptr = ~(uintptr_t)0 }.ptr;
#else
OBJC_EXTERN const uintptr_t objc_debug_autoreleasepoolpage_ptr_mask = ~(uintptr_t)0;
#endif
OBJC_EXTERN const uint32_t objc_class_abi_version = OBJC_CLASS_ABI_VERSION_MAX;
#endif
/***********************************************************************
* Weak ivar support
**********************************************************************/
static id defaultBadAllocHandler(Class cls)
{
_objc_fatal("attempt to allocate object of class '%s' failed",
cls->nameForLogging());
}
id(*badAllocHandler)(Class) = &defaultBadAllocHandler;
id _objc_callBadAllocHandler(Class cls)
{
// fixme add re-entrancy protection in case allocation fails inside handler
return (*badAllocHandler)(cls);
}
void _objc_setBadAllocHandler(id(*newHandler)(Class))
{
badAllocHandler = newHandler;
}
static id _initializeSwiftRefcountingThenCallRetain(id objc);
static void _initializeSwiftRefcountingThenCallRelease(id objc);
explicit_atomic<id(*)(id)> swiftRetain{&_initializeSwiftRefcountingThenCallRetain};
explicit_atomic<void(*)(id)> swiftRelease{&_initializeSwiftRefcountingThenCallRelease};
static void _initializeSwiftRefcounting() {
void *const token = dlopen("/usr/lib/swift/libswiftCore.dylib", RTLD_LAZY | RTLD_LOCAL);
ASSERT(token);
swiftRetain.store((id(*)(id))dlsym(token, "swift_retain"), memory_order_relaxed);
ASSERT(swiftRetain.load(memory_order_relaxed));
swiftRelease.store((void(*)(id))dlsym(token, "swift_release"), memory_order_relaxed);
ASSERT(swiftRelease.load(memory_order_relaxed));
dlclose(token);
}
static id _initializeSwiftRefcountingThenCallRetain(id objc) {
_initializeSwiftRefcounting();
return swiftRetain.load(memory_order_relaxed)(objc);
}
static void _initializeSwiftRefcountingThenCallRelease(id objc) {
_initializeSwiftRefcounting();
swiftRelease.load(memory_order_relaxed)(objc);
}
namespace objc {
extern int PageCountWarning;
}
namespace {
#if TARGET_OS_IPHONE && !TARGET_OS_SIMULATOR
uint32_t numFaults = 0;
#endif
// The order of these bits is important.
#define SIDE_TABLE_WEAKLY_REFERENCED (1UL<<0)
#define SIDE_TABLE_DEALLOCATING (1UL<<1) // MSB-ward of weak bit
#define SIDE_TABLE_RC_ONE (1UL<<2) // MSB-ward of deallocating bit
#define SIDE_TABLE_RC_PINNED (1UL<<(WORD_BITS-1))
#define SIDE_TABLE_RC_SHIFT 2
#define SIDE_TABLE_FLAG_MASK (SIDE_TABLE_RC_ONE-1)
struct RefcountMapValuePurgeable {
static inline bool isPurgeable(size_t x) {
return x == 0;
}
};
// RefcountMap disguises its pointers because we
// don't want the table to act as a root for `leaks`.
typedef objc::DenseMap<DisguisedPtr<objc_object>,size_t,RefcountMapValuePurgeable> RefcountMap;
// Template parameters.
enum HaveOld { DontHaveOld = false, DoHaveOld = true };
enum HaveNew { DontHaveNew = false, DoHaveNew = true };
struct SideTable {
spinlock_t slock;
RefcountMap refcnts;
weak_table_t weak_table;
SideTable() {
memset(&weak_table, 0, sizeof(weak_table));
}
~SideTable() {
_objc_fatal("Do not delete SideTable.");
}
void lock() { slock.lock(); }
void unlock() { slock.unlock(); }
void forceReset() { slock.forceReset(); }
// Address-ordered lock discipline for a pair of side tables.
template<HaveOld, HaveNew>
static void lockTwo(SideTable *lock1, SideTable *lock2);
template<HaveOld, HaveNew>
static void unlockTwo(SideTable *lock1, SideTable *lock2);
};
template<>
void SideTable::lockTwo<DoHaveOld, DoHaveNew>
(SideTable *lock1, SideTable *lock2)
{
spinlock_t::lockTwo(&lock1->slock, &lock2->slock);
}
template<>
void SideTable::lockTwo<DoHaveOld, DontHaveNew>
(SideTable *lock1, SideTable *)
{
lock1->lock();
}
template<>
void SideTable::lockTwo<DontHaveOld, DoHaveNew>
(SideTable *, SideTable *lock2)
{
lock2->lock();
}
template<>
void SideTable::unlockTwo<DoHaveOld, DoHaveNew>
(SideTable *lock1, SideTable *lock2)
{
spinlock_t::unlockTwo(&lock1->slock, &lock2->slock);
}
template<>
void SideTable::unlockTwo<DoHaveOld, DontHaveNew>
(SideTable *lock1, SideTable *)
{
lock1->unlock();
}
template<>
void SideTable::unlockTwo<DontHaveOld, DoHaveNew>
(SideTable *, SideTable *lock2)
{
lock2->unlock();
}
static objc::ExplicitInit<StripedMap<SideTable>> SideTablesMap;
static StripedMap<SideTable>& SideTables() {
return SideTablesMap.get();
}
// anonymous namespace
};
void SideTableLockAll() {
SideTables().lockAll();
}
void SideTableUnlockAll() {
SideTables().unlockAll();
}
void SideTableForceResetAll() {
SideTables().forceResetAll();
}
void SideTableDefineLockOrder() {
SideTables().defineLockOrder();
}
void SideTableLocksPrecedeLock(const void *newlock) {
SideTables().precedeLock(newlock);
}
void SideTableLocksSucceedLock(const void *oldlock) {
SideTables().succeedLock(oldlock);
}
void SideTableLocksPrecedeLocks(StripedMap<spinlock_t>& newlocks) {
int i = 0;
const void *newlock;
while ((newlock = newlocks.getLock(i++))) {
SideTables().precedeLock(newlock);
}
}
void SideTableLocksSucceedLocks(StripedMap<spinlock_t>& oldlocks) {
int i = 0;
const void *oldlock;
while ((oldlock = oldlocks.getLock(i++))) {
SideTables().succeedLock(oldlock);
}
}
// Call out to the _setWeaklyReferenced method on obj, if implemented.
static void callSetWeaklyReferenced(id obj) {
if (!obj)
return;
Class cls = obj->getIsa();
if (slowpath(cls->hasCustomRR() && !object_isClass(obj))) {
ASSERT(((objc_class *)cls)->isInitializing() || ((objc_class *)cls)->isInitialized());
void (*setWeaklyReferenced)(id, SEL) = (void(*)(id, SEL))
class_getMethodImplementation(cls, @selector(_setWeaklyReferenced));
if ((IMP)setWeaklyReferenced != _objc_msgForward) {
(*setWeaklyReferenced)(obj, @selector(_setWeaklyReferenced));
}
}
}
//
// The -fobjc-arc flag causes the compiler to issue calls to objc_{retain/release/autorelease/retain_block}
//
id objc_retainBlock(id x) {
return (id)_Block_copy(x);
}
//
// The following SHOULD be called by the compiler directly, but the request hasn't been made yet :-)
//
BOOL objc_should_deallocate(id object) {
return YES;
}
id
objc_retain_autorelease(id obj)
{
return objc_autorelease(objc_retain(obj));
}
void
objc_storeStrong(id *location, id obj)
{
id prev = *location;
if (obj == prev) {
return;
}
objc_retain(obj);
*location = obj;
objc_release(prev);
}
// Update a weak variable.
// If HaveOld is true, the variable has an existing value
// that needs to be cleaned up. This value might be nil.
// If HaveNew is true, there is a new value that needs to be
// assigned into the variable. This value might be nil.
// If CrashIfDeallocating is true, the process is halted if newObj is
// deallocating or newObj's class does not support weak references.
// If CrashIfDeallocating is false, nil is stored instead.
enum CrashIfDeallocating {
DontCrashIfDeallocating = false, DoCrashIfDeallocating = true
};
template <HaveOld haveOld, HaveNew haveNew,
enum CrashIfDeallocating crashIfDeallocating>
static id
storeWeak(id *location, objc_object *newObj)
{
ASSERT(haveOld || haveNew);
if (!haveNew) ASSERT(newObj == nil);
Class previouslyInitializedClass = nil;
id oldObj;
SideTable *oldTable;
SideTable *newTable;
// Acquire locks for old and new values.
// Order by lock address to prevent lock ordering problems.
// Retry if the old value changes underneath us.
retry:
if (haveOld) {
oldObj = *location;
oldTable = &SideTables()[oldObj];
} else {
oldTable = nil;
}
if (haveNew) {
newTable = &SideTables()[newObj];
} else {
newTable = nil;
}
SideTable::lockTwo<haveOld, haveNew>(oldTable, newTable);
if (haveOld && *location != oldObj) {
SideTable::unlockTwo<haveOld, haveNew>(oldTable, newTable);
goto retry;
}
// Prevent a deadlock between the weak reference machinery
// and the +initialize machinery by ensuring that no
// weakly-referenced object has an un-+initialized isa.
if (haveNew && newObj) {
Class cls = newObj->getIsa();
if (cls != previouslyInitializedClass &&
!((objc_class *)cls)->isInitialized())
{
SideTable::unlockTwo<haveOld, haveNew>(oldTable, newTable);
class_initialize(cls, (id)newObj);
// If this class is finished with +initialize then we're good.
// If this class is still running +initialize on this thread
// (i.e. +initialize called storeWeak on an instance of itself)
// then we may proceed but it will appear initializing and
// not yet initialized to the check above.
// Instead set previouslyInitializedClass to recognize it on retry.
previouslyInitializedClass = cls;
goto retry;
}
}
// Clean up old value, if any.
if (haveOld) {
weak_unregister_no_lock(&oldTable->weak_table, oldObj, location);
}
// Assign new value, if any.
if (haveNew) {
newObj = (objc_object *)
weak_register_no_lock(&newTable->weak_table, (id)newObj, location,
crashIfDeallocating ? CrashIfDeallocating : ReturnNilIfDeallocating);
// weak_register_no_lock returns nil if weak store should be rejected
// Set is-weakly-referenced bit in refcount table.
if (!newObj->isTaggedPointerOrNil()) {
newObj->setWeaklyReferenced_nolock();
}
// Do not set *location anywhere else. That would introduce a race.
*location = (id)newObj;
}
else {
// No new value. The storage is not changed.
}
SideTable::unlockTwo<haveOld, haveNew>(oldTable, newTable);
// This must be called without the locks held, as it can invoke
// arbitrary code. In particular, even if _setWeaklyReferenced
// is not implemented, resolveInstanceMethod: may be, and may
// call back into the weak reference machinery.
callSetWeaklyReferenced((id)newObj);
return (id)newObj;
}
/**
* This function stores a new value into a __weak variable. It would
* be used anywhere a __weak variable is the target of an assignment.
*
* @param location The address of the weak pointer itself
* @param newObj The new object this weak ptr should now point to
*
* @return \e newObj
*/
id
objc_storeWeak(id *location, id newObj)
{
return storeWeak<DoHaveOld, DoHaveNew, DoCrashIfDeallocating>
(location, (objc_object *)newObj);
}
/**
* This function stores a new value into a __weak variable.
* If the new object is deallocating or the new object's class
* does not support weak references, stores nil instead.
*
* @param location The address of the weak pointer itself
* @param newObj The new object this weak ptr should now point to
*
* @return The value stored (either the new object or nil)
*/
id
objc_storeWeakOrNil(id *location, id newObj)
{
return storeWeak<DoHaveOld, DoHaveNew, DontCrashIfDeallocating>
(location, (objc_object *)newObj);
}
/**
* Initialize a fresh weak pointer to some object location.
* It would be used for code like:
*
* (The nil case)
* __weak id weakPtr;
* (The non-nil case)
* NSObject *o = ...;
* __weak id weakPtr = o;
*
* This function IS NOT thread-safe with respect to concurrent
* modifications to the weak variable. (Concurrent weak clear is safe.)
*
* @param location Address of __weak ptr.
* @param newObj Object ptr.
*/
id
objc_initWeak(id *location, id newObj)
{
if (!newObj) {
*location = nil;
return nil;
}
return storeWeak<DontHaveOld, DoHaveNew, DoCrashIfDeallocating>
(location, (objc_object*)newObj);
}
id
objc_initWeakOrNil(id *location, id newObj)
{
if (!newObj) {
*location = nil;
return nil;
}
return storeWeak<DontHaveOld, DoHaveNew, DontCrashIfDeallocating>
(location, (objc_object*)newObj);
}
/**
* Destroys the relationship between a weak pointer
* and the object it is referencing in the internal weak
* table. If the weak pointer is not referencing anything,
* there is no need to edit the weak table.
*
* This function IS NOT thread-safe with respect to concurrent
* modifications to the weak variable. (Concurrent weak clear is safe.)
*
* @param location The weak pointer address.
*/
void
objc_destroyWeak(id *location)
{
(void)storeWeak<DoHaveOld, DontHaveNew, DontCrashIfDeallocating>
(location, nil);
}
/*
Once upon a time we eagerly cleared *location if we saw the object
was deallocating. This confuses code like NSPointerFunctions which
tries to pre-flight the raw storage and assumes if the storage is
zero then the weak system is done interfering. That is false: the
weak system is still going to check and clear the storage later.
This can cause objc_weak_error complaints and crashes.
So we now don't touch the storage until deallocation completes.
*/
id
objc_loadWeakRetained(id *location)
{
id obj;
id result;
Class cls;
SideTable *table;
retry:
// fixme std::atomic this load
obj = *location;
if (obj->isTaggedPointerOrNil()) return obj;
table = &SideTables()[obj];
table->lock();
if (*location != obj) {
table->unlock();
goto retry;
}
result = obj;
cls = obj->ISA();
if (! cls->hasCustomRR()) {
// Fast case. We know +initialize is complete because
// default-RR can never be set before then.
ASSERT(cls->isInitialized());
if (! obj->rootTryRetain()) {
result = nil;
}
}
else {
// Slow case. We must check for +initialize and call it outside
// the lock if necessary in order to avoid deadlocks.
// Use lookUpImpOrForward so we can avoid the assert in
// class_getInstanceMethod, since we intentionally make this
// callout with the lock held.
if (cls->isInitialized() || _thisThreadIsInitializingClass(cls)) {
BOOL (*tryRetain)(id, SEL) = (BOOL(*)(id, SEL))
#if defined(DARLING) && defined(__i386__)
class_getMethodImplementation(cls, @selector(retainWeakReference));
#else
lookUpImpOrForwardTryCache(obj, @selector(retainWeakReference), cls);
#endif
if ((IMP)tryRetain == _objc_msgForward) {
result = nil;
}
else if (! (*tryRetain)(obj, @selector(retainWeakReference))) {
result = nil;
}
}
else {
table->unlock();
class_initialize(cls, obj);
goto retry;
}
}
table->unlock();
return result;
}
/**
* This loads the object referenced by a weak pointer and returns it, after
* retaining and autoreleasing the object to ensure that it stays alive
* long enough for the caller to use it. This function would be used
* anywhere a __weak variable is used in an expression.
*
* @param location The weak pointer address
*
* @return The object pointed to by \e location, or \c nil if \e location is \c nil.
*/
id
objc_loadWeak(id *location)
{
if (!*location) return nil;
return objc_autorelease(objc_loadWeakRetained(location));
}
/**
* This function copies a weak pointer from one location to another,
* when the destination doesn't already contain a weak pointer. It
* would be used for code like:
*
* __weak id src = ...;
* __weak id dst = src;
*
* This function IS NOT thread-safe with respect to concurrent
* modifications to the destination variable. (Concurrent weak clear is safe.)
*
* @param dst The destination variable.
* @param src The source variable.
*/
void
objc_copyWeak(id *dst, id *src)
{
id obj = objc_loadWeakRetained(src);
objc_initWeak(dst, obj);
objc_release(obj);
}
/**
* Move a weak pointer from one location to another.
* Before the move, the destination must be uninitialized.
* After the move, the source is nil.
*
* This function IS NOT thread-safe with respect to concurrent
* modifications to either weak variable. (Concurrent weak clear is safe.)
*
*/
void
objc_moveWeak(id *dst, id *src)
{
id obj;
SideTable *table;
retry:
obj = *src;
if (obj == nil) {
*dst = nil;
return;
}
table = &SideTables()[obj];
table->lock();
if (*src != obj) {
table->unlock();
goto retry;
}
weak_unregister_no_lock(&table->weak_table, obj, src);
weak_register_no_lock(&table->weak_table, obj, dst, DontCheckDeallocating);
*dst = obj;
*src = nil;
table->unlock();
}
/***********************************************************************
Autorelease pool implementation
A thread's autorelease pool is a stack of pointers.
Each pointer is either an object to release, or POOL_BOUNDARY which is
an autorelease pool boundary.
A pool token is a pointer to the POOL_BOUNDARY for that pool. When
the pool is popped, every object hotter than the sentinel is released.
The stack is divided into a doubly-linked list of pages. Pages are added
and deleted as necessary.
Thread-local storage points to the hot page, where newly autoreleased
objects are stored.
**********************************************************************/
BREAKPOINT_FUNCTION(void objc_autoreleaseNoPool(id obj));
BREAKPOINT_FUNCTION(void objc_autoreleasePoolInvalid(const void *token));
class AutoreleasePoolPage : private AutoreleasePoolPageData
{
friend struct thread_data_t;
public:
static size_t const SIZE =
#if PROTECT_AUTORELEASEPOOL
PAGE_MAX_SIZE; // must be multiple of vm page size
#else
PAGE_MIN_SIZE; // size and alignment, power of 2
#endif
private:
static pthread_key_t const key = AUTORELEASE_POOL_KEY;
static uint8_t const SCRIBBLE = 0xA3; // 0xA3A3A3A3 after releasing
static size_t const COUNT = SIZE / sizeof(id);
static size_t const MAX_FAULTS = 2;
// EMPTY_POOL_PLACEHOLDER is stored in TLS when exactly one pool is
// pushed and it has never contained any objects. This saves memory
// when the top level (i.e. libdispatch) pushes and pops pools but
// never uses them.
# define EMPTY_POOL_PLACEHOLDER ((id*)1)
# define POOL_BOUNDARY nil
// SIZE-sizeof(*this) bytes of contents follow
static void * operator new(size_t size) {
return malloc_zone_memalign(malloc_default_zone(), SIZE, SIZE);
}
static void operator delete(void * p) {
return free(p);
}
inline void protect() {
#if PROTECT_AUTORELEASEPOOL
mprotect(this, SIZE, PROT_READ);
check();
#endif
}
inline void unprotect() {
#if PROTECT_AUTORELEASEPOOL
check();
mprotect(this, SIZE, PROT_READ | PROT_WRITE);
#endif
}
void checkTooMuchAutorelease()
{
#if TARGET_OS_IPHONE && !TARGET_OS_SIMULATOR
bool objcModeNoFaults = DisableFaults || getpid() == 1 ||
!os_variant_has_internal_diagnostics("com.apple.obj-c");
if (!objcModeNoFaults) {
if (depth+1 >= (uint32_t)objc::PageCountWarning && numFaults < MAX_FAULTS) { //depth is 0 when first page is allocated
os_fault_with_payload(OS_REASON_LIBSYSTEM,
OS_REASON_LIBSYSTEM_CODE_FAULT,
NULL, 0, "Large Autorelease Pool", 0);
numFaults++;
}
}
#endif
}
AutoreleasePoolPage(AutoreleasePoolPage *newParent) :
AutoreleasePoolPageData(begin(),
objc_thread_self(),
newParent,
newParent ? 1+newParent->depth : 0,
newParent ? newParent->hiwat : 0)
{
if (objc::PageCountWarning != -1) {
checkTooMuchAutorelease();
}
if (parent) {
parent->check();
ASSERT(!parent->child);
parent->unprotect();
parent->child = this;
parent->protect();
}
protect();
}
~AutoreleasePoolPage()
{
check();
unprotect();
ASSERT(empty());
// Not recursive: we don't want to blow out the stack
// if a thread accumulates a stupendous amount of garbage
ASSERT(!child);
}
template<typename Fn>
void
busted(Fn log) const
{
magic_t right;
log("autorelease pool page %p corrupted\n"
" magic 0x%08x 0x%08x 0x%08x 0x%08x\n"
" should be 0x%08x 0x%08x 0x%08x 0x%08x\n"
" pthread %p\n"
" should be %p\n",
this,
magic.m[0], magic.m[1], magic.m[2], magic.m[3],
right.m[0], right.m[1], right.m[2], right.m[3],
this->thread, objc_thread_self());
}
__attribute__((noinline, cold, noreturn))
void
busted_die() const
{
busted(_objc_fatal);
__builtin_unreachable();
}
inline void
check(bool die = true) const
{
if (!magic.check() || thread != objc_thread_self()) {
if (die) {
busted_die();
} else {
busted(_objc_inform);
}
}
}
inline void
fastcheck() const
{
#if CHECK_AUTORELEASEPOOL
check();
#else
if (! magic.fastcheck()) {
busted_die();
}
#endif
}
id * begin() {
return (id *) ((uint8_t *)this+sizeof(*this));
}
id * end() {
return (id *) ((uint8_t *)this+SIZE);
}
bool empty() {
return next == begin();
}
bool full() {
return next == end();
}
bool lessThanHalfFull() {
return (next - begin() < (end() - begin()) / 2);
}
id *add(id obj)
{
ASSERT(!full());
unprotect();
id *ret;
#if SUPPORT_AUTORELEASEPOOL_DEDUP_PTRS
if (!DisableAutoreleaseCoalescing || !DisableAutoreleaseCoalescingLRU) {
if (!DisableAutoreleaseCoalescingLRU) {
if (!empty() && (obj != POOL_BOUNDARY)) {
AutoreleasePoolEntry *topEntry = (AutoreleasePoolEntry *)next - 1;
for (uintptr_t offset = 0; offset < 4; offset++) {
AutoreleasePoolEntry *offsetEntry = topEntry - offset;
if (offsetEntry <= (AutoreleasePoolEntry*)begin() || *(id *)offsetEntry == POOL_BOUNDARY) {
break;
}
if (offsetEntry->ptr == (uintptr_t)obj && offsetEntry->count < AutoreleasePoolEntry::maxCount) {
if (offset > 0) {
AutoreleasePoolEntry found = *offsetEntry;
memmove(offsetEntry, offsetEntry + 1, offset * sizeof(*offsetEntry));
*topEntry = found;
}
topEntry->count++;
ret = (id *)topEntry; // need to reset ret
goto done;
}
}
}
} else {
if (!empty() && (obj != POOL_BOUNDARY)) {
AutoreleasePoolEntry *prevEntry = (AutoreleasePoolEntry *)next - 1;
if (prevEntry->ptr == (uintptr_t)obj && prevEntry->count < AutoreleasePoolEntry::maxCount) {
prevEntry->count++;
ret = (id *)prevEntry; // need to reset ret
goto done;
}
}
}
}
#endif
ret = next; // faster than `return next-1` because of aliasing
*next++ = obj;
#if SUPPORT_AUTORELEASEPOOL_DEDUP_PTRS
// Make sure obj fits in the bits available for it
ASSERT(((AutoreleasePoolEntry *)ret)->ptr == (uintptr_t)obj);
#endif
done:
protect();
return ret;
}
void releaseAll()
{
releaseUntil(begin());
}
void releaseUntil(id *stop)
{
// Not recursive: we don't want to blow out the stack
// if a thread accumulates a stupendous amount of garbage
while (this->next != stop) {
// Restart from hotPage() every time, in case -release
// autoreleased more objects
AutoreleasePoolPage *page = hotPage();
// fixme I think this `while` can be `if`, but I can't prove it
while (page->empty()) {
page = page->parent;
setHotPage(page);
}
page->unprotect();
#if SUPPORT_AUTORELEASEPOOL_DEDUP_PTRS
AutoreleasePoolEntry* entry = (AutoreleasePoolEntry*) --page->next;
// create an obj with the zeroed out top byte and release that
id obj = (id)entry->ptr;
int count = (int)entry->count; // grab these before memset
#else
id obj = *--page->next;
#endif
memset((void*)page->next, SCRIBBLE, sizeof(*page->next));
page->protect();
if (obj != POOL_BOUNDARY) {
#if SUPPORT_AUTORELEASEPOOL_DEDUP_PTRS
// release count+1 times since it is count of the additional
// autoreleases beyond the first one
for (int i = 0; i < count + 1; i++) {
objc_release(obj);
}
#else
objc_release(obj);
#endif
}
}
setHotPage(this);
#if DEBUG
// we expect any children to be completely empty
for (AutoreleasePoolPage *page = child; page; page = page->child) {
ASSERT(page->empty());
}
#endif
}
void kill()
{
// Not recursive: we don't want to blow out the stack
// if a thread accumulates a stupendous amount of garbage
AutoreleasePoolPage *page = this;
while (page->child) page = page->child;
AutoreleasePoolPage *deathptr;
do {
deathptr = page;
page = page->parent;
if (page) {
page->unprotect();
page->child = nil;
page->protect();
}
delete deathptr;
} while (deathptr != this);
}
static void tls_dealloc(void *p)
{
if (p == (void*)EMPTY_POOL_PLACEHOLDER) {
// No objects or pool pages to clean up here.
return;
}
// reinstate TLS value while we work
setHotPage((AutoreleasePoolPage *)p);
if (AutoreleasePoolPage *page = coldPage()) {
if (!page->empty()) objc_autoreleasePoolPop(page->begin()); // pop all of the pools
if (slowpath(DebugMissingPools || DebugPoolAllocation)) {
// pop() killed the pages already
} else {
page->kill(); // free all of the pages
}
}
// clear TLS value so TLS destruction doesn't loop
setHotPage(nil);
}
static AutoreleasePoolPage *pageForPointer(const void *p)
{
return pageForPointer((uintptr_t)p);
}
static AutoreleasePoolPage *pageForPointer(uintptr_t p)
{
AutoreleasePoolPage *result;
uintptr_t offset = p % SIZE;
ASSERT(offset >= sizeof(AutoreleasePoolPage));
result = (AutoreleasePoolPage *)(p - offset);
result->fastcheck();
return result;
}
static inline bool haveEmptyPoolPlaceholder()
{
id *tls = (id *)tls_get_direct(key);
return (tls == EMPTY_POOL_PLACEHOLDER);
}
static inline id* setEmptyPoolPlaceholder()
{
ASSERT(tls_get_direct(key) == nil);
tls_set_direct(key, (void *)EMPTY_POOL_PLACEHOLDER);
return EMPTY_POOL_PLACEHOLDER;
}
static inline AutoreleasePoolPage *hotPage()
{
AutoreleasePoolPage *result = (AutoreleasePoolPage *)
tls_get_direct(key);
if ((id *)result == EMPTY_POOL_PLACEHOLDER) return nil;
if (result) result->fastcheck();
return result;
}
static inline void setHotPage(AutoreleasePoolPage *page)
{
if (page) page->fastcheck();
tls_set_direct(key, (void *)page);
}
static inline AutoreleasePoolPage *coldPage()
{
AutoreleasePoolPage *result = hotPage();
if (result) {
while (result->parent) {
result = result->parent;
result->fastcheck();
}
}
return result;
}
static inline id *autoreleaseFast(id obj)
{
AutoreleasePoolPage *page = hotPage();
if (page && !page->full()) {
return page->add(obj);
} else if (page) {
return autoreleaseFullPage(obj, page);
} else {
return autoreleaseNoPage(obj);
}
}
static __attribute__((noinline))
id *autoreleaseFullPage(id obj, AutoreleasePoolPage *page)
{
// The hot page is full.
// Step to the next non-full page, adding a new page if necessary.
// Then add the object to that page.
ASSERT(page == hotPage());
ASSERT(page->full() || DebugPoolAllocation);
do {
if (page->child) page = page->child;
else page = new AutoreleasePoolPage(page);
} while (page->full());
setHotPage(page);
return page->add(obj);
}
static __attribute__((noinline))
id *autoreleaseNoPage(id obj)
{
// "No page" could mean no pool has been pushed
// or an empty placeholder pool has been pushed and has no contents yet
ASSERT(!hotPage());
bool pushExtraBoundary = false;
if (haveEmptyPoolPlaceholder()) {
// We are pushing a second pool over the empty placeholder pool
// or pushing the first object into the empty placeholder pool.
// Before doing that, push a pool boundary on behalf of the pool
// that is currently represented by the empty placeholder.
pushExtraBoundary = true;
}
else if (obj != POOL_BOUNDARY && DebugMissingPools) {
// We are pushing an object with no pool in place,
// and no-pool debugging was requested by environment.
_objc_inform("MISSING POOLS: (%p) Object %p of class %s "
"autoreleased with no pool in place - "
"just leaking - break on "
"objc_autoreleaseNoPool() to debug",
objc_thread_self(), (void*)obj, object_getClassName(obj));
objc_autoreleaseNoPool(obj);
return nil;
}
else if (obj == POOL_BOUNDARY && !DebugPoolAllocation) {
// We are pushing a pool with no pool in place,
// and alloc-per-pool debugging was not requested.
// Install and return the empty pool placeholder.
return setEmptyPoolPlaceholder();
}
// We are pushing an object or a non-placeholder'd pool.
// Install the first page.
AutoreleasePoolPage *page = new AutoreleasePoolPage(nil);
setHotPage(page);
// Push a boundary on behalf of the previously-placeholder'd pool.
if (pushExtraBoundary) {
page->add(POOL_BOUNDARY);
}
// Push the requested object or pool.
return page->add(obj);
}
static __attribute__((noinline))
id *autoreleaseNewPage(id obj)
{
AutoreleasePoolPage *page = hotPage();
if (page) return autoreleaseFullPage(obj, page);
else return autoreleaseNoPage(obj);
}
public:
static inline id autorelease(id obj)
{
ASSERT(!obj->isTaggedPointerOrNil());
id *dest __unused = autoreleaseFast(obj);
#if SUPPORT_AUTORELEASEPOOL_DEDUP_PTRS
ASSERT(!dest || dest == EMPTY_POOL_PLACEHOLDER || (id)((AutoreleasePoolEntry *)dest)->ptr == obj);
#else
ASSERT(!dest || dest == EMPTY_POOL_PLACEHOLDER || *dest == obj);
#endif
return obj;
}
static inline void *push()
{
id *dest;
if (slowpath(DebugPoolAllocation)) {
// Each autorelease pool starts on a new pool page.
dest = autoreleaseNewPage(POOL_BOUNDARY);
} else {
dest = autoreleaseFast(POOL_BOUNDARY);
}
ASSERT(dest == EMPTY_POOL_PLACEHOLDER || *dest == POOL_BOUNDARY);
return dest;
}
__attribute__((noinline, cold))
static void badPop(void *token)
{
// Error. For bincompat purposes this is not
// fatal in executables built with old SDKs.
if (DebugPoolAllocation || sdkIsAtLeast(10_12, 10_0, 10_0, 3_0, 2_0)) {
// OBJC_DEBUG_POOL_ALLOCATION or new SDK. Bad pop is fatal.
_objc_fatal
("Invalid or prematurely-freed autorelease pool %p.", token);
}
// Old SDK. Bad pop is warned once.
static bool complained = false;
if (!complained) {
complained = true;
_objc_inform_now_and_on_crash
("Invalid or prematurely-freed autorelease pool %p. "
"Set a breakpoint on objc_autoreleasePoolInvalid to debug. "
"Proceeding anyway because the app is old. Memory errors "
"are likely.",
token);
}
objc_autoreleasePoolInvalid(token);
}
template<bool allowDebug>
static void
popPage(void *token, AutoreleasePoolPage *page, id *stop)
{
if (allowDebug && PrintPoolHiwat) printHiwat();
page->releaseUntil(stop);
// memory: delete empty children
if (allowDebug && DebugPoolAllocation && page->empty()) {
// special case: delete everything during page-per-pool debugging
AutoreleasePoolPage *parent = page->parent;
page->kill();
setHotPage(parent);
} else if (allowDebug && DebugMissingPools && page->empty() && !page->parent) {
// special case: delete everything for pop(top)
// when debugging missing autorelease pools
page->kill();
setHotPage(nil);
} else if (page->child) {
// hysteresis: keep one empty child if page is more than half full
if (page->lessThanHalfFull()) {
page->child->kill();
}
else if (page->child->child) {
page->child->child->kill();
}
}
}
__attribute__((noinline, cold))
static void
popPageDebug(void *token, AutoreleasePoolPage *page, id *stop)
{
popPage<true>(token, page, stop);
}
static inline void
pop(void *token)
{
AutoreleasePoolPage *page;
id *stop;
if (token == (void*)EMPTY_POOL_PLACEHOLDER) {
// Popping the top-level placeholder pool.
page = hotPage();
if (!page) {
// Pool was never used. Clear the placeholder.
return setHotPage(nil);
}
// Pool was used. Pop its contents normally.
// Pool pages remain allocated for re-use as usual.
page = coldPage();
token = page->begin();
} else {
page = pageForPointer(token);
}
stop = (id *)token;
if (*stop != POOL_BOUNDARY) {
if (stop == page->begin() && !page->parent) {
// Start of coldest page may correctly not be POOL_BOUNDARY:
// 1. top-level pool is popped, leaving the cold page in place
// 2. an object is autoreleased with no pool
} else {
// Error. For bincompat purposes this is not
// fatal in executables built with old SDKs.
return badPop(token);
}
}
if (slowpath(PrintPoolHiwat || DebugPoolAllocation || DebugMissingPools)) {
return popPageDebug(token, page, stop);
}
return popPage<false>(token, page, stop);
}
static void init()
{
int r __unused = pthread_key_init_np(AutoreleasePoolPage::key,
AutoreleasePoolPage::tls_dealloc);
ASSERT(r == 0);
}
__attribute__((noinline, cold))
void print()
{
_objc_inform("[%p] ................ PAGE %s %s %s", this,
full() ? "(full)" : "",
this == hotPage() ? "(hot)" : "",
this == coldPage() ? "(cold)" : "");
check(false);
for (id *p = begin(); p < next; p++) {
if (*p == POOL_BOUNDARY) {
_objc_inform("[%p] ################ POOL %p", p, p);
} else {
#if SUPPORT_AUTORELEASEPOOL_DEDUP_PTRS
AutoreleasePoolEntry *entry = (AutoreleasePoolEntry *)p;
if (entry->count > 0) {
id obj = (id)entry->ptr;
_objc_inform("[%p] %#16lx %s autorelease count %u",
p, (unsigned long)obj, object_getClassName(obj),
entry->count + 1);
goto done;
}
#endif
_objc_inform("[%p] %#16lx %s",
p, (unsigned long)*p, object_getClassName(*p));
done:;
}
}
}
__attribute__((noinline, cold))
static void printAll()
{
_objc_inform("##############");
_objc_inform("AUTORELEASE POOLS for thread %p", objc_thread_self());
AutoreleasePoolPage *page;
ptrdiff_t objects = 0;
for (page = coldPage(); page; page = page->child) {
objects += page->next - page->begin();
}
_objc_inform("%llu releases pending.", (unsigned long long)objects);
if (haveEmptyPoolPlaceholder()) {
_objc_inform("[%p] ................ PAGE (placeholder)",
EMPTY_POOL_PLACEHOLDER);
_objc_inform("[%p] ################ POOL (placeholder)",
EMPTY_POOL_PLACEHOLDER);
}
else {
for (page = coldPage(); page; page = page->child) {
page->print();
}
}
_objc_inform("##############");
}
#if SUPPORT_AUTORELEASEPOOL_DEDUP_PTRS
__attribute__((noinline, cold))
unsigned sumOfExtraReleases()
{
unsigned sumOfExtraReleases = 0;
for (id *p = begin(); p < next; p++) {
if (*p != POOL_BOUNDARY) {
sumOfExtraReleases += ((AutoreleasePoolEntry *)p)->count;
}
}
return sumOfExtraReleases;
}
#endif
__attribute__((noinline, cold))
static void printHiwat()
{
// Check and propagate high water mark
// Ignore high water marks under 256 to suppress noise.
AutoreleasePoolPage *p = hotPage();
uint32_t mark = p->depth*COUNT + (uint32_t)(p->next - p->begin());
if (mark > p->hiwat + 256) {
#if SUPPORT_AUTORELEASEPOOL_DEDUP_PTRS
unsigned sumOfExtraReleases = 0;
#endif
for( ; p; p = p->parent) {
p->unprotect();
p->hiwat = mark;
p->protect();
#if SUPPORT_AUTORELEASEPOOL_DEDUP_PTRS
sumOfExtraReleases += p->sumOfExtraReleases();
#endif
}
_objc_inform("POOL HIGHWATER: new high water mark of %u "
"pending releases for thread %p:",
mark, objc_thread_self());
#if SUPPORT_AUTORELEASEPOOL_DEDUP_PTRS
if (sumOfExtraReleases > 0) {
_objc_inform("POOL HIGHWATER: extra sequential autoreleases of objects: %u",
sumOfExtraReleases);
}
#endif
void *stack[128];
int count = backtrace(stack, sizeof(stack)/sizeof(stack[0]));
char **sym = backtrace_symbols(stack, count);
for (int i = 0; i < count; i++) {
_objc_inform("POOL HIGHWATER: %s", sym[i]);
}
free(sym);
}
}
#undef POOL_BOUNDARY
};
/***********************************************************************
* Slow paths for inline control
**********************************************************************/
#if SUPPORT_NONPOINTER_ISA
NEVER_INLINE id
objc_object::rootRetain_overflow(bool tryRetain)
{
return rootRetain(tryRetain, RRVariant::Full);
}
NEVER_INLINE uintptr_t
objc_object::rootRelease_underflow(bool performDealloc)
{
return rootRelease(performDealloc, RRVariant::Full);
}
// Slow path of clearDeallocating()
// for objects with nonpointer isa
// that were ever weakly referenced
// or whose retain count ever overflowed to the side table.
NEVER_INLINE void
objc_object::clearDeallocating_slow()
{
ASSERT(isa.nonpointer && (isa.weakly_referenced || isa.has_sidetable_rc));
SideTable& table = SideTables()[this];
table.lock();
if (isa.weakly_referenced) {
weak_clear_no_lock(&table.weak_table, (id)this);
}
if (isa.has_sidetable_rc) {
table.refcnts.erase(this);
}
table.unlock();
}
#endif
__attribute__((noinline,used))
id
objc_object::rootAutorelease2()
{
ASSERT(!isTaggedPointer());
return AutoreleasePoolPage::autorelease((id)this);
}
BREAKPOINT_FUNCTION(
void objc_overrelease_during_dealloc_error(void)
);
NEVER_INLINE uintptr_t
objc_object::overrelease_error()
{
_objc_inform_now_and_on_crash("%s object %p overreleased while already deallocating; break on objc_overrelease_during_dealloc_error to debug", object_getClassName((id)this), this);
objc_overrelease_during_dealloc_error();
return 0; // allow rootRelease() to tail-call this
}
/***********************************************************************
* Retain count operations for side table.
**********************************************************************/
#if DEBUG
// Used to assert that an object is not present in the side table.
bool
objc_object::sidetable_present()
{
bool result = false;
SideTable& table = SideTables()[this];
table.lock();
RefcountMap::iterator it = table.refcnts.find(this);
if (it != table.refcnts.end()) result = true;
if (weak_is_registered_no_lock(&table.weak_table, (id)this)) result = true;
table.unlock();
return result;
}
#endif
#if SUPPORT_NONPOINTER_ISA
void
objc_object::sidetable_lock()
{
SideTable& table = SideTables()[this];
table.lock();
}
void
objc_object::sidetable_unlock()
{
SideTable& table = SideTables()[this];
table.unlock();
}
// Move the entire retain count to the side table,
// as well as isDeallocating and weaklyReferenced.
void
objc_object::sidetable_moveExtraRC_nolock(size_t extra_rc,
bool isDeallocating,
bool weaklyReferenced)
{
ASSERT(!isa.nonpointer); // should already be changed to raw pointer
SideTable& table = SideTables()[this];
size_t& refcntStorage = table.refcnts[this];
size_t oldRefcnt = refcntStorage;
// not deallocating - that was in the isa
ASSERT((oldRefcnt & SIDE_TABLE_DEALLOCATING) == 0);
ASSERT((oldRefcnt & SIDE_TABLE_WEAKLY_REFERENCED) == 0);
uintptr_t carry;
size_t refcnt = addc(oldRefcnt, (extra_rc - 1) << SIDE_TABLE_RC_SHIFT, 0, &carry);
if (carry) refcnt = SIDE_TABLE_RC_PINNED;
if (isDeallocating) refcnt |= SIDE_TABLE_DEALLOCATING;
if (weaklyReferenced) refcnt |= SIDE_TABLE_WEAKLY_REFERENCED;
refcntStorage = refcnt;
}
// Move some retain counts to the side table from the isa field.
// Returns true if the object is now pinned.
bool
objc_object::sidetable_addExtraRC_nolock(size_t delta_rc)
{
ASSERT(isa.nonpointer);
SideTable& table = SideTables()[this];
size_t& refcntStorage = table.refcnts[this];
size_t oldRefcnt = refcntStorage;
// isa-side bits should not be set here
ASSERT((oldRefcnt & SIDE_TABLE_DEALLOCATING) == 0);
ASSERT((oldRefcnt & SIDE_TABLE_WEAKLY_REFERENCED) == 0);
if (oldRefcnt & SIDE_TABLE_RC_PINNED) return true;
uintptr_t carry;
size_t newRefcnt =
addc(oldRefcnt, delta_rc << SIDE_TABLE_RC_SHIFT, 0, &carry);
if (carry) {
refcntStorage =
SIDE_TABLE_RC_PINNED | (oldRefcnt & SIDE_TABLE_FLAG_MASK);
return true;
}
else {
refcntStorage = newRefcnt;
return false;
}
}
// Move some retain counts from the side table to the isa field.
// Returns the actual count subtracted, which may be less than the request.
objc_object::SidetableBorrow
objc_object::sidetable_subExtraRC_nolock(size_t delta_rc)
{
ASSERT(isa.nonpointer);
SideTable& table = SideTables()[this];
RefcountMap::iterator it = table.refcnts.find(this);
if (it == table.refcnts.end() || it->second == 0) {
// Side table retain count is zero. Can't borrow.
return { 0, 0 };
}
size_t oldRefcnt = it->second;
// isa-side bits should not be set here
ASSERT((oldRefcnt & SIDE_TABLE_DEALLOCATING) == 0);
ASSERT((oldRefcnt & SIDE_TABLE_WEAKLY_REFERENCED) == 0);
size_t newRefcnt = oldRefcnt - (delta_rc << SIDE_TABLE_RC_SHIFT);
ASSERT(oldRefcnt > newRefcnt); // shouldn't underflow
it->second = newRefcnt;
return { delta_rc, newRefcnt >> SIDE_TABLE_RC_SHIFT };
}
size_t
objc_object::sidetable_getExtraRC_nolock()
{
ASSERT(isa.nonpointer);
SideTable& table = SideTables()[this];
RefcountMap::iterator it = table.refcnts.find(this);
if (it == table.refcnts.end()) return 0;
else return it->second >> SIDE_TABLE_RC_SHIFT;
}
void
objc_object::sidetable_clearExtraRC_nolock()
{
ASSERT(isa.nonpointer);
SideTable& table = SideTables()[this];
RefcountMap::iterator it = table.refcnts.find(this);
table.refcnts.erase(it);
}
// SUPPORT_NONPOINTER_ISA
#endif
id
objc_object::sidetable_retain(bool locked)
{
#if SUPPORT_NONPOINTER_ISA
ASSERT(!isa.nonpointer);
#endif
SideTable& table = SideTables()[this];
if (!locked) table.lock();
size_t& refcntStorage = table.refcnts[this];
if (! (refcntStorage & SIDE_TABLE_RC_PINNED)) {
refcntStorage += SIDE_TABLE_RC_ONE;
}
table.unlock();
return (id)this;
}
bool
objc_object::sidetable_tryRetain()
{
#if SUPPORT_NONPOINTER_ISA
ASSERT(!isa.nonpointer);
#endif
SideTable& table = SideTables()[this];
// NO SPINLOCK HERE
// _objc_rootTryRetain() is called exclusively by _objc_loadWeak(),
// which already acquired the lock on our behalf.
// fixme can't do this efficiently with os_lock_handoff_s
// if (table.slock == 0) {
// _objc_fatal("Do not call -_tryRetain.");
// }
bool result = true;
auto it = table.refcnts.try_emplace(this, SIDE_TABLE_RC_ONE);
auto &refcnt = it.first->second;
if (it.second) {
// there was no entry
} else if (refcnt & SIDE_TABLE_DEALLOCATING) {
result = false;
} else if (! (refcnt & SIDE_TABLE_RC_PINNED)) {
refcnt += SIDE_TABLE_RC_ONE;
}
return result;
}
uintptr_t
objc_object::sidetable_retainCount()
{
SideTable& table = SideTables()[this];
size_t refcnt_result = 1;
table.lock();
RefcountMap::iterator it = table.refcnts.find(this);
if (it != table.refcnts.end()) {
// this is valid for SIDE_TABLE_RC_PINNED too
refcnt_result += it->second >> SIDE_TABLE_RC_SHIFT;
}
table.unlock();
return refcnt_result;
}
bool
objc_object::sidetable_isDeallocating()
{
SideTable& table = SideTables()[this];
// NO SPINLOCK HERE
// _objc_rootIsDeallocating() is called exclusively by _objc_storeWeak(),
// which already acquired the lock on our behalf.
// fixme can't do this efficiently with os_lock_handoff_s
// if (table.slock == 0) {
// _objc_fatal("Do not call -_isDeallocating.");
// }
RefcountMap::iterator it = table.refcnts.find(this);
return (it != table.refcnts.end()) && (it->second & SIDE_TABLE_DEALLOCATING);
}
bool
objc_object::sidetable_isWeaklyReferenced()
{
bool result = false;
SideTable& table = SideTables()[this];
table.lock();
RefcountMap::iterator it = table.refcnts.find(this);
if (it != table.refcnts.end()) {
result = it->second & SIDE_TABLE_WEAKLY_REFERENCED;
}
table.unlock();
return result;
}
#if OBJC_WEAK_FORMATION_CALLOUT_DEFINED
//Clients can dlsym() for this symbol to see if an ObjC supporting
//-_setWeaklyReferenced is present
OBJC_EXPORT const uintptr_t _objc_has_weak_formation_callout = 0;
static_assert(SUPPORT_NONPOINTER_ISA, "Weak formation callout must only be defined when nonpointer isa is supported.");
#else
static_assert(!SUPPORT_NONPOINTER_ISA, "If weak callout is not present then we must not support nonpointer isas.");
#endif
void
objc_object::sidetable_setWeaklyReferenced_nolock()
{
#if SUPPORT_NONPOINTER_ISA
ASSERT(!isa.nonpointer);
#endif
SideTable& table = SideTables()[this];
table.refcnts[this] |= SIDE_TABLE_WEAKLY_REFERENCED;
}
// rdar://20206767
// return uintptr_t instead of bool so that the various raw-isa
// -release paths all return zero in eax
uintptr_t
objc_object::sidetable_release(bool locked, bool performDealloc)
{
#if SUPPORT_NONPOINTER_ISA
ASSERT(!isa.nonpointer);
#endif
SideTable& table = SideTables()[this];
bool do_dealloc = false;
if (!locked) table.lock();
auto it = table.refcnts.try_emplace(this, SIDE_TABLE_DEALLOCATING);
auto &refcnt = it.first->second;
if (it.second) {
do_dealloc = true;
} else if (refcnt < SIDE_TABLE_DEALLOCATING) {
// SIDE_TABLE_WEAKLY_REFERENCED may be set. Don't change it.
do_dealloc = true;
refcnt |= SIDE_TABLE_DEALLOCATING;
} else if (! (refcnt & SIDE_TABLE_RC_PINNED)) {
refcnt -= SIDE_TABLE_RC_ONE;
}
table.unlock();
if (do_dealloc && performDealloc) {
((void(*)(objc_object *, SEL))objc_msgSend)(this, @selector(dealloc));
}
return do_dealloc;
}
void
objc_object::sidetable_clearDeallocating()
{
SideTable& table = SideTables()[this];
// clear any weak table items
// clear extra retain count and deallocating bit
// (fixme warn or abort if extra retain count == 0 ?)
table.lock();
RefcountMap::iterator it = table.refcnts.find(this);
if (it != table.refcnts.end()) {
if (it->second & SIDE_TABLE_WEAKLY_REFERENCED) {
weak_clear_no_lock(&table.weak_table, (id)this);
}
table.refcnts.erase(it);
}
table.unlock();
}
/***********************************************************************
* Optimized retain/release/autorelease entrypoints
**********************************************************************/
#if __OBJC2__
__attribute__((aligned(16), flatten, noinline))
id
objc_retain(id obj)
{
if (obj->isTaggedPointerOrNil()) return obj;
return obj->retain();
}
__attribute__((aligned(16), flatten, noinline))
void
objc_release(id obj)
{
if (obj->isTaggedPointerOrNil()) return;
return obj->release();
}
__attribute__((aligned(16), flatten, noinline))
id
objc_autorelease(id obj)
{
if (obj->isTaggedPointerOrNil()) return obj;
return obj->autorelease();
}
// OBJC2
#else
// not OBJC2
id objc_retain(id obj) { return [obj retain]; }
void objc_release(id obj) { [obj release]; }
id objc_autorelease(id obj) { return [obj autorelease]; }
#endif
/***********************************************************************
* Basic operations for root class implementations a.k.a. _objc_root*()
**********************************************************************/
bool
_objc_rootTryRetain(id obj)
{
ASSERT(obj);
return obj->rootTryRetain();
}
bool
_objc_rootIsDeallocating(id obj)
{
ASSERT(obj);
return obj->rootIsDeallocating();
}
void
objc_clear_deallocating(id obj)
{
ASSERT(obj);
if (obj->isTaggedPointer()) return;
obj->clearDeallocating();
}
bool
_objc_rootReleaseWasZero(id obj)
{
ASSERT(obj);
return obj->rootReleaseShouldDealloc();
}
NEVER_INLINE id
_objc_rootAutorelease(id obj)
{
ASSERT(obj);
return obj->rootAutorelease();
}
uintptr_t
_objc_rootRetainCount(id obj)
{
ASSERT(obj);
return obj->rootRetainCount();
}
NEVER_INLINE id
_objc_rootRetain(id obj)
{
ASSERT(obj);
return obj->rootRetain();
}
NEVER_INLINE void
_objc_rootRelease(id obj)
{
ASSERT(obj);
obj->rootRelease();
}
// Call [cls alloc] or [cls allocWithZone:nil], with appropriate
// shortcutting optimizations.
static ALWAYS_INLINE id
callAlloc(Class cls, bool checkNil, bool allocWithZone=false)
{
#if __OBJC2__
if (slowpath(checkNil && !cls)) return nil;
if (fastpath(!cls->ISA()->hasCustomAWZ())) {
return _objc_rootAllocWithZone(cls, nil);
}
#endif
// No shortcuts available.
if (allocWithZone) {
return ((id(*)(id, SEL, struct _NSZone *))objc_msgSend)(cls, @selector(allocWithZone:), nil);
}
return ((id(*)(id, SEL))objc_msgSend)(cls, @selector(alloc));
}
// Base class implementation of +alloc. cls is not nil.
// Calls [cls allocWithZone:nil].
id
_objc_rootAlloc(Class cls)
{
return callAlloc(cls, false/*checkNil*/, true/*allocWithZone*/);
}
// Calls [cls alloc].
id
objc_alloc(Class cls)
{
return callAlloc(cls, true/*checkNil*/, false/*allocWithZone*/);
}
// Calls [cls allocWithZone:nil].
id
objc_allocWithZone(Class cls)
{
return callAlloc(cls, true/*checkNil*/, true/*allocWithZone*/);
}
// Calls [[cls alloc] init].
id
objc_alloc_init(Class cls)
{
return [callAlloc(cls, true/*checkNil*/, false/*allocWithZone*/) init];
}
// Calls [cls new]
id
objc_opt_new(Class cls)
{
#if __OBJC2__
if (fastpath(cls && !cls->ISA()->hasCustomCore())) {
return [callAlloc(cls, false/*checkNil*/) init];
}
#endif
return ((id(*)(id, SEL))objc_msgSend)(cls, @selector(new));
}
// Calls [obj self]
id
objc_opt_self(id obj)
{
#if __OBJC2__
if (fastpath(obj->isTaggedPointerOrNil() || !obj->ISA()->hasCustomCore())) {
return obj;
}
#endif
return ((id(*)(id, SEL))objc_msgSend)(obj, @selector(self));
}
// Calls [obj class]
Class
objc_opt_class(id obj)
{
#if __OBJC2__
if (slowpath(!obj)) return nil;
Class cls = obj->getIsa();
if (fastpath(!cls->hasCustomCore())) {
return cls->isMetaClass() ? obj : cls;
}
#endif
return ((Class(*)(id, SEL))objc_msgSend)(obj, @selector(class));
}
// Calls [obj isKindOfClass]
BOOL
objc_opt_isKindOfClass(id obj, Class otherClass)
{
#if __OBJC2__
if (slowpath(!obj)) return NO;
Class cls = obj->getIsa();
if (fastpath(!cls->hasCustomCore())) {
for (Class tcls = cls; tcls; tcls = tcls->DARLING_GET_SUPER_CLASS) {
if (tcls == otherClass) return YES;
}
return NO;
}
#endif
return ((BOOL(*)(id, SEL, Class))objc_msgSend)(obj, @selector(isKindOfClass:), otherClass);
}
// Calls [obj respondsToSelector]
BOOL
objc_opt_respondsToSelector(id obj, SEL sel)
{
#if __OBJC2__
if (slowpath(!obj)) return NO;
Class cls = obj->getIsa();
if (fastpath(!cls->hasCustomCore())) {
return class_respondsToSelector_inst(obj, sel, cls);
}
#endif
return ((BOOL(*)(id, SEL, SEL))objc_msgSend)(obj, @selector(respondsToSelector:), sel);
}
void
_objc_rootDealloc(id obj)
{
ASSERT(obj);
obj->rootDealloc();
}
void
_objc_rootFinalize(id obj __unused)
{
ASSERT(obj);
_objc_fatal("_objc_rootFinalize called with garbage collection off");
}
id
_objc_rootInit(id obj)
{
// In practice, it will be hard to rely on this function.
// Many classes do not properly chain -init calls.
return obj;
}
malloc_zone_t *
_objc_rootZone(id obj)
{
(void)obj;
#if __OBJC2__
// allocWithZone under __OBJC2__ ignores the zone parameter
return malloc_default_zone();
#else
malloc_zone_t *rval = malloc_zone_from_ptr(obj);
return rval ? rval : malloc_default_zone();
#endif
}
uintptr_t
_objc_rootHash(id obj)
{
return (uintptr_t)obj;
}
void *
objc_autoreleasePoolPush(void)
{
return AutoreleasePoolPage::push();
}
NEVER_INLINE
void
objc_autoreleasePoolPop(void *ctxt)
{
AutoreleasePoolPage::pop(ctxt);
}
void *
_objc_autoreleasePoolPush(void)
{
return objc_autoreleasePoolPush();
}
void
_objc_autoreleasePoolPop(void *ctxt)
{
objc_autoreleasePoolPop(ctxt);
}
void
_objc_autoreleasePoolPrint(void)
{
AutoreleasePoolPage::printAll();
}
// Same as objc_release but suitable for tail-calling
// if you need the value back and don't want to push a frame before this point.
__attribute__((noinline))
static id
objc_releaseAndReturn(id obj)
{
objc_release(obj);
return obj;
}
// Same as objc_retainAutorelease but suitable for tail-calling
// if you don't want to push a frame before this point.
__attribute__((noinline))
static id
objc_retainAutoreleaseAndReturn(id obj)
{
return objc_retainAutorelease(obj);
}
// Prepare a value at +1 for return through a +0 autoreleasing convention.
id
objc_autoreleaseReturnValue(id obj)
{
if (prepareOptimizedReturn(ReturnAtPlus1)) return obj;
return objc_autorelease(obj);
}
// Prepare a value at +0 for return through a +0 autoreleasing convention.
id
objc_retainAutoreleaseReturnValue(id obj)
{
if (prepareOptimizedReturn(ReturnAtPlus0)) return obj;
// not objc_autoreleaseReturnValue(objc_retain(obj))
// because we don't need another optimization attempt
return objc_retainAutoreleaseAndReturn(obj);
}
// Accept a value returned through a +0 autoreleasing convention for use at +1.
id
objc_retainAutoreleasedReturnValue(id obj)
{
if (acceptOptimizedReturn() == ReturnAtPlus1) return obj;
return objc_retain(obj);
}
// Accept a value returned through a +0 autoreleasing convention for use at +0.
id
objc_unsafeClaimAutoreleasedReturnValue(id obj)
{
if (acceptOptimizedReturn() == ReturnAtPlus0) return obj;
return objc_releaseAndReturn(obj);
}
id
objc_retainAutorelease(id obj)
{
return objc_autorelease(objc_retain(obj));
}
void
_objc_deallocOnMainThreadHelper(void *context)
{
id obj = (id)context;
[obj dealloc];
}
// convert objc_objectptr_t to id, callee must take ownership.
id objc_retainedObject(objc_objectptr_t pointer) { return (id)pointer; }
// convert objc_objectptr_t to id, without ownership transfer.
id objc_unretainedObject(objc_objectptr_t pointer) { return (id)pointer; }
// convert id to objc_objectptr_t, no ownership transfer.
objc_objectptr_t objc_unretainedPointer(id object) { return object; }
void arr_init(void)
{
AutoreleasePoolPage::init();
SideTablesMap.init();
_objc_associations_init();
}
#ifdef DARLING
// see libdispatch
#if __has_attribute(objc_nonlazy_class)
#define NONLAZY_CLASS __attribute__((objc_nonlazy_class))
#define NONLAZY_CLASS_LOAD
#else
#define NONLAZY_CLASS
#define NONLAZY_CLASS_LOAD + (void)load {}
#endif
#endif
#if SUPPORT_TAGGED_POINTERS
// Placeholder for old debuggers. When they inspect an
// extended tagged pointer object they will see this isa.
@interface __NSUnrecognizedTaggedPointer : NSObject
@end
#ifdef DARLING
NONLAZY_CLASS
#else
__attribute__((objc_nonlazy_class))
#endif
@implementation __NSUnrecognizedTaggedPointer
#ifdef DARLING
NONLAZY_CLASS_LOAD
#endif
-(id) retain { return self; }
-(oneway void) release { }
-(id) autorelease { return self; }
@end
#endif
#ifdef DARLING
NONLAZY_CLASS
#else
__attribute__((objc_nonlazy_class))
#endif
@implementation NSObject
#ifdef DARLING
NONLAZY_CLASS_LOAD
#endif
+ (void)initialize {
}
+ (id)self {
return (id)self;
}
- (id)self {
return self;
}
+ (Class)class {
return self;
}
- (Class)class {
return object_getClass(self);
}
+ (Class)superclass {
return self->DARLING_GET_SUPER_CLASS;
}
- (Class)superclass {
return [self class]->DARLING_GET_SUPER_CLASS;
}
+ (BOOL)isMemberOfClass:(Class)cls {
return self->ISA() == cls;
}
- (BOOL)isMemberOfClass:(Class)cls {
return [self class] == cls;
}
+ (BOOL)isKindOfClass:(Class)cls {
for (Class tcls = self->ISA(); tcls; tcls = tcls->DARLING_GET_SUPER_CLASS) {
if (tcls == cls) return YES;
}
return NO;
}
- (BOOL)isKindOfClass:(Class)cls {
for (Class tcls = [self class]; tcls; tcls = tcls->DARLING_GET_SUPER_CLASS) {
if (tcls == cls) return YES;
}
return NO;
}
+ (BOOL)isSubclassOfClass:(Class)cls {
for (Class tcls = self; tcls; tcls = tcls->DARLING_GET_SUPER_CLASS) {
if (tcls == cls) return YES;
}
return NO;
}
+ (BOOL)isAncestorOfObject:(NSObject *)obj {
for (Class tcls = [obj class]; tcls; tcls = tcls->DARLING_GET_SUPER_CLASS) {
if (tcls == self) return YES;
}
return NO;
}
+ (BOOL)instancesRespondToSelector:(SEL)sel {
return class_respondsToSelector_inst(nil, sel, self);
}
+ (BOOL)respondsToSelector:(SEL)sel {
return class_respondsToSelector_inst(self, sel, self->ISA());
}
- (BOOL)respondsToSelector:(SEL)sel {
return class_respondsToSelector_inst(self, sel, [self class]);
}
+ (BOOL)conformsToProtocol:(Protocol *)protocol {
if (!protocol) return NO;
for (Class tcls = self; tcls; tcls = tcls->DARLING_GET_SUPER_CLASS) {
if (class_conformsToProtocol(tcls, protocol)) return YES;
}
return NO;
}
- (BOOL)conformsToProtocol:(Protocol *)protocol {
if (!protocol) return NO;
for (Class tcls = [self class]; tcls; tcls = tcls->DARLING_GET_SUPER_CLASS) {
if (class_conformsToProtocol(tcls, protocol)) return YES;
}
return NO;
}
+ (NSUInteger)hash {
return _objc_rootHash(self);
}
- (NSUInteger)hash {
return _objc_rootHash(self);
}
+ (BOOL)isEqual:(id)obj {
return obj == (id)self;
}
- (BOOL)isEqual:(id)obj {
return obj == self;
}
+ (BOOL)isFault {
return NO;
}
- (BOOL)isFault {
return NO;
}
+ (BOOL)isProxy {
return NO;
}
- (BOOL)isProxy {
return NO;
}
+ (IMP)instanceMethodForSelector:(SEL)sel {
if (!sel) [self doesNotRecognizeSelector:sel];
return class_getMethodImplementation(self, sel);
}
+ (IMP)methodForSelector:(SEL)sel {
if (!sel) [self doesNotRecognizeSelector:sel];
return object_getMethodImplementation((id)self, sel);
}
- (IMP)methodForSelector:(SEL)sel {
if (!sel) [self doesNotRecognizeSelector:sel];
return object_getMethodImplementation(self, sel);
}
+ (BOOL)resolveClassMethod:(SEL)sel {
return NO;
}
+ (BOOL)resolveInstanceMethod:(SEL)sel {
return NO;
}
// Replaced by CF (throws an NSException)
+ (void)doesNotRecognizeSelector:(SEL)sel {
_objc_fatal("+[%s %s]: unrecognized selector sent to instance %p",
class_getName(self), sel_getName(sel), self);
}
// Replaced by CF (throws an NSException)
- (void)doesNotRecognizeSelector:(SEL)sel {
_objc_fatal("-[%s %s]: unrecognized selector sent to instance %p",
object_getClassName(self), sel_getName(sel), self);
}
+ (id)performSelector:(SEL)sel {
if (!sel) [self doesNotRecognizeSelector:sel];
return ((id(*)(id, SEL))objc_msgSend)((id)self, sel);
}
+ (id)performSelector:(SEL)sel withObject:(id)obj {
if (!sel) [self doesNotRecognizeSelector:sel];
return ((id(*)(id, SEL, id))objc_msgSend)((id)self, sel, obj);
}
+ (id)performSelector:(SEL)sel withObject:(id)obj1 withObject:(id)obj2 {
if (!sel) [self doesNotRecognizeSelector:sel];
return ((id(*)(id, SEL, id, id))objc_msgSend)((id)self, sel, obj1, obj2);
}
- (id)performSelector:(SEL)sel {
if (!sel) [self doesNotRecognizeSelector:sel];
return ((id(*)(id, SEL))objc_msgSend)(self, sel);
}
- (id)performSelector:(SEL)sel withObject:(id)obj {
if (!sel) [self doesNotRecognizeSelector:sel];
return ((id(*)(id, SEL, id))objc_msgSend)(self, sel, obj);
}
- (id)performSelector:(SEL)sel withObject:(id)obj1 withObject:(id)obj2 {
if (!sel) [self doesNotRecognizeSelector:sel];
return ((id(*)(id, SEL, id, id))objc_msgSend)(self, sel, obj1, obj2);
}
// Replaced by CF (returns an NSMethodSignature)
+ (NSMethodSignature *)instanceMethodSignatureForSelector:(SEL)sel {
_objc_fatal("+[NSObject instanceMethodSignatureForSelector:] "
"not available without CoreFoundation");
}
// Replaced by CF (returns an NSMethodSignature)
+ (NSMethodSignature *)methodSignatureForSelector:(SEL)sel {
_objc_fatal("+[NSObject methodSignatureForSelector:] "
"not available without CoreFoundation");
}
// Replaced by CF (returns an NSMethodSignature)
- (NSMethodSignature *)methodSignatureForSelector:(SEL)sel {
_objc_fatal("-[NSObject methodSignatureForSelector:] "
"not available without CoreFoundation");
}
+ (void)forwardInvocation:(NSInvocation *)invocation {
[self doesNotRecognizeSelector:(invocation ? [invocation selector] : 0)];
}
- (void)forwardInvocation:(NSInvocation *)invocation {
[self doesNotRecognizeSelector:(invocation ? [invocation selector] : 0)];
}
+ (id)forwardingTargetForSelector:(SEL)sel {
return nil;
}
- (id)forwardingTargetForSelector:(SEL)sel {
return nil;
}
// Replaced by CF (returns an NSString)
+ (NSString *)description {
return nil;
}
// Replaced by CF (returns an NSString)
- (NSString *)description {
return nil;
}
+ (NSString *)debugDescription {
return [self description];
}
- (NSString *)debugDescription {
return [self description];
}
+ (id)new {
return [callAlloc(self, false/*checkNil*/) init];
}
+ (id)retain {
return (id)self;
}
// Replaced by ObjectAlloc
- (id)retain {
return _objc_rootRetain(self);
}
+ (BOOL)_tryRetain {
return YES;
}
// Replaced by ObjectAlloc
- (BOOL)_tryRetain {
return _objc_rootTryRetain(self);
}
+ (BOOL)_isDeallocating {
return NO;
}
- (BOOL)_isDeallocating {
return _objc_rootIsDeallocating(self);
}
+ (BOOL)allowsWeakReference {
return YES;
}
+ (BOOL)retainWeakReference {
return YES;
}
- (BOOL)allowsWeakReference {
return ! [self _isDeallocating];
}
- (BOOL)retainWeakReference {
return [self _tryRetain];
}
+ (oneway void)release {
}
// Replaced by ObjectAlloc
- (oneway void)release {
_objc_rootRelease(self);
}
+ (id)autorelease {
return (id)self;
}
// Replaced by ObjectAlloc
- (id)autorelease {
return _objc_rootAutorelease(self);
}
+ (NSUInteger)retainCount {
return ULONG_MAX;
}
- (NSUInteger)retainCount {
return _objc_rootRetainCount(self);
}
+ (id)alloc {
return _objc_rootAlloc(self);
}
// Replaced by ObjectAlloc
+ (id)allocWithZone:(struct _NSZone *)zone {
return _objc_rootAllocWithZone(self, (malloc_zone_t *)zone);
}
// Replaced by CF (throws an NSException)
+ (id)init {
return (id)self;
}
- (id)init {
return _objc_rootInit(self);
}
// Replaced by CF (throws an NSException)
+ (void)dealloc {
}
// Replaced by NSZombies
- (void)dealloc {
_objc_rootDealloc(self);
}
// Previously used by GC. Now a placeholder for binary compatibility.
- (void) finalize {
}
+ (struct _NSZone *)zone {
return (struct _NSZone *)_objc_rootZone(self);
}
- (struct _NSZone *)zone {
return (struct _NSZone *)_objc_rootZone(self);
}
+ (id)copy {
return (id)self;
}
+ (id)copyWithZone:(struct _NSZone *)zone {
return (id)self;
}
- (id)copy {
return [(id)self copyWithZone:nil];
}
+ (id)mutableCopy {
return (id)self;
}
+ (id)mutableCopyWithZone:(struct _NSZone *)zone {
return (id)self;
}
- (id)mutableCopy {
return [(id)self mutableCopyWithZone:nil];
}
@end
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