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Convert deprecated functions to use modern atomic variable handling
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Replaced deprecated atomic functions with the recommended C11 equivalents.
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@AZero13
AZero13 committed Dec 16, 2023
1 parent ee39300 commit b0bc0cd
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Showing 22 changed files with 141 additions and 203 deletions.
2 changes: 1 addition & 1 deletion src/BlocksRuntime/Block_private.h
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Original file line number Diff line number Diff line change
Expand Up @@ -88,7 +88,7 @@ enum {
struct Block_byref {
void *isa;
struct Block_byref *forwarding;
volatile int32_t flags; // contains ref count
_Atomic(int32_t) flags; // contains ref count
uint32_t size;
};

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40 changes: 14 additions & 26 deletions src/BlocksRuntime/runtime.c
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Original file line number Diff line number Diff line change
Expand Up @@ -32,20 +32,7 @@
#define __has_builtin(builtin) 0
#endif

#if __has_builtin(__sync_bool_compare_and_swap)
#define OSAtomicCompareAndSwapInt(_Old, _New, _Ptr) \
__sync_bool_compare_and_swap(_Ptr, _Old, _New)
#else
#define _CRT_SECURE_NO_WARNINGS 1
#include <Windows.h>
static __inline bool OSAtomicCompareAndSwapInt(int oldi, int newi,
int volatile *dst) {
// fixme barrier is overkill -- see objc-os.h
int original = InterlockedCompareExchange((LONG volatile *)dst, newi, oldi);
return (original == oldi);
}
#endif

#include <stdatomic.h>
/***********************
Globals
************************/
Expand All @@ -64,21 +51,22 @@ Internal Utilities
********************************************************************************/


static int32_t latching_incr_int(volatile int32_t *where) {
static int32_t latching_incr_int(_Atomic(int32_t) *where) {
while (1) {
int32_t old_value = *where;
int32_t old_value = atomic_load_explicit(where, memory_order_relaxed);
if ((old_value & BLOCK_REFCOUNT_MASK) == BLOCK_REFCOUNT_MASK) {
return BLOCK_REFCOUNT_MASK;
}
if (OSAtomicCompareAndSwapInt(old_value, old_value+2, where)) {

if (atomic_compare_exchange_weak(where, &old_value, old_value + 2)) {
return old_value+2;
}
}
}

static bool latching_incr_int_not_deallocating(volatile int32_t *where) {
static bool latching_incr_int_not_deallocating(_Atomic(int32_t) *where) {
while (1) {
int32_t old_value = *where;
int32_t old_value = atomic_load_explicit(where, memory_order_relaxed);
if (old_value & BLOCK_DEALLOCATING) {
// if deallocating we can't do this
return false;
Expand All @@ -87,7 +75,7 @@ static bool latching_incr_int_not_deallocating(volatile int32_t *where) {
// if latched, we're leaking this block, and we succeed
return true;
}
if (OSAtomicCompareAndSwapInt(old_value, old_value+2, where)) {
if (atomic_compare_exchange_weak(where, &old_value, old_value + 2)) {
// otherwise, we must store a new retained value without the deallocating bit set
return true;
}
Expand All @@ -96,9 +84,9 @@ static bool latching_incr_int_not_deallocating(volatile int32_t *where) {


// return should_deallocate?
static bool latching_decr_int_should_deallocate(volatile int32_t *where) {
static bool latching_decr_int_should_deallocate(_Atomic(int32_t) *where) {
while (1) {
int32_t old_value = *where;
int32_t old_value = atomic_load_explicit(where, memory_order_relaxed);
if ((old_value & BLOCK_REFCOUNT_MASK) == BLOCK_REFCOUNT_MASK) {
return false; // latched high
}
Expand All @@ -111,24 +99,24 @@ static bool latching_decr_int_should_deallocate(volatile int32_t *where) {
new_value = old_value - 1;
result = true;
}
if (OSAtomicCompareAndSwapInt(old_value, new_value, where)) {
if (atomic_compare_exchange_weak(where, &old_value, new_value)) {
return result;
}
}
}

// hit zero?
static bool latching_decr_int_now_zero(volatile int32_t *where) {
static bool latching_decr_int_now_zero(_Atomic(int32_t) *where) {
while (1) {
int32_t old_value = *where;
int32_t old_value = atomic_load_explicit(where, memory_order_relaxed);
if ((old_value & BLOCK_REFCOUNT_MASK) == BLOCK_REFCOUNT_MASK) {
return false; // latched high
}
if ((old_value & BLOCK_REFCOUNT_MASK) == 0) {
return false; // underflow, latch low
}
int32_t new_value = old_value - 2;
if (OSAtomicCompareAndSwapInt(old_value, new_value, where)) {
if (atomic_compare_exchange_weak(where, &old_value, new_value)) {
return (new_value & BLOCK_REFCOUNT_MASK) == 0;
}
}
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36 changes: 19 additions & 17 deletions src/allocator.c
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Original file line number Diff line number Diff line change
Expand Up @@ -542,31 +542,33 @@ _dispatch_alloc_maybe_madvise_page(dispatch_continuation_t c)
}
// They are all unallocated, so we could madvise the page. Try to
// take ownership of them all.
int last_locked = 0;
do {
if (!os_atomic_cmpxchg(&page_bitmaps[last_locked], BITMAP_C(0),
for (i = 0; i < BITMAPS_PER_PAGE; i++) {
if (!os_atomic_cmpxchg(&page_bitmaps[i], BITMAP_C(0),
BITMAP_ALL_ONES, relaxed)) {
// We didn't get one; since there is a cont allocated in
// the page, we can't madvise. Give up and unlock all.
goto unlock;
break;
}
} while (++last_locked < (signed)BITMAPS_PER_PAGE);
}

if (i >= BITMAPS_PER_PAGE) {
#if DISPATCH_DEBUG
//fprintf(stderr, "%s: madvised page %p for cont %p (next = %p), "
// "[%u+1]=%u bitmaps at %p\n", __func__, page, c, c->do_next,
// last_locked-1, BITMAPS_PER_PAGE, &page_bitmaps[0]);
// Scribble to expose use-after-free bugs
// madvise (syscall) flushes these stores
memset(page, DISPATCH_ALLOCATOR_SCRIBBLE, DISPATCH_ALLOCATOR_PAGE_SIZE);
// fprintf(stderr, "%s: madvised page %p for cont %p (next = %p), "
// "[%u+1]=%u bitmaps at %p\n", __func__, page, c, c->do_next,
// last_locked-1, BITMAPS_PER_PAGE, &page_bitmaps[0]);
// Scribble to expose use-after-free bugs
// madvise (syscall) flushes these stores
memset(page, DISPATCH_ALLOCATOR_SCRIBBLE, DISPATCH_ALLOCATOR_PAGE_SIZE);
#endif
(void)dispatch_assume_zero(madvise(page, DISPATCH_ALLOCATOR_PAGE_SIZE,
MADV_FREE));
// madvise the page
(void)dispatch_assume_zero(madvise(page, DISPATCH_ALLOCATOR_PAGE_SIZE,
MADV_FREE));
}

unlock:
while (last_locked > 1) {
page_bitmaps[--last_locked] = BITMAP_C(0);
while (i > 1) {
page_bitmaps[--i] = BITMAP_C(0);
}
if (last_locked) {
if (i) {
os_atomic_store(&page_bitmaps[0], BITMAP_C(0), relaxed);
}
return;
Expand Down
68 changes: 33 additions & 35 deletions tests/Foundation/bench.mm
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Original file line number Diff line number Diff line change
Expand Up @@ -83,8 +83,8 @@ virtual void virtfunc(void) {
return arg;
}

static volatile int32_t global;
static volatile int64_t w_global;
static atomic_int global;
static _Atomic(int64_t) w_global;

#if TARGET_OS_EMBEDDED
static const size_t cnt = 5000000;
Expand Down Expand Up @@ -191,7 +191,7 @@ static void __attribute__((noinline))
main(void)
{
pthread_mutex_t plock = PTHREAD_MUTEX_INITIALIZER;
OSSpinLock slock = OS_SPINLOCK_INIT;
os_unfair_lock slock = OS_UNFAIR_LOCK_INIT;
BasicObject *bo;
BasicClass *bc;
pthread_t pthr_pause;
Expand Down Expand Up @@ -219,8 +219,7 @@ static void __attribute__((noinline))
cycles_per_nanosecond = (long double)freq / (long double)NSEC_PER_SEC;

#if BENCH_SLOW
NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
assert(pool);
@autoreleasepool {
#endif

/* Malloc has different logic for threaded apps. */
Expand Down Expand Up @@ -371,9 +370,7 @@ static void __attribute__((noinline))
}
print_result2(s, "\"description\" ObjC call:");

[pool release];

pool = NULL;
} // For the autorelease pool
#endif

s = mach_absolute_time();
Expand Down Expand Up @@ -554,30 +551,30 @@ __asm__ __volatile__ ("svc 0x80" : "+r" (_r0)

s = mach_absolute_time();
for (i = cnt; i; i--) {
__sync_lock_test_and_set(&global, 0);
atomic_xchg(&global, 0);
}
print_result(s, "Atomic xchg:");

s = mach_absolute_time();
for (i = cnt; i; i--) {
__sync_val_compare_and_swap(&global, 1, 0);
atomic_cmpxchg(&global, 1, 0);
}
print_result(s, "Atomic cmpxchg:");

s = mach_absolute_time();
for (i = cnt; i; i--) {
__sync_fetch_and_add(&global, 1);
atomic_fetch_add(&global, 1);
}
print_result(s, "Atomic increment:");

{
global = 0;
volatile int32_t *g = &global;
global = ATOMIC_VAR_INIT(0);
atomic_int *g = &global;

s = mach_absolute_time();
for (i = cnt; i; i--) {
uint32_t result;
__sync_and_and_fetch(g, 1);
atomic_fetch_and(g, 1);
result = *g;
if (result) {
abort();
Expand All @@ -587,57 +584,58 @@ __asm__ __volatile__ ("svc 0x80" : "+r" (_r0)
}

{
global = 0;
volatile int32_t *g = &global;
global = ATOMIC_VAR_INIT(0);
atomic_int *g = &global;

s = mach_absolute_time();
for (i = cnt; i; i--) {
uint32_t result;
result = __sync_and_and_fetch(g, 1);
result = atomic_fetch_and(g, 1);
if (result) {
abort();
}
}
print_result(s, "Atomic and-and-fetch, using result:");
}

global = 0;
global = ATOMIC_VAR_INIT(0);

s = mach_absolute_time();
for (i = cnt; i; i--) {
OSAtomicIncrement32Barrier(&global);
__c11_atomic_fetch_add(&global, 1, memory_order_seq_cst);
}
print_result(s, "OSAtomicIncrement32Barrier:");
print_result(s, "atomic_fetch_add with memory_order_seq_cst barrier:");

global = 0;
global = ATOMIC_VAR_INIT(0);

s = mach_absolute_time();
for (i = cnt; i; i--) {
OSAtomicIncrement32(&global);
__c11_atomic_fetch_add(&global, 1, memory_order_relaxed);
}
print_result(s, "OSAtomicIncrement32:");
print_result(s, "atomic_fetch_add with memory_order_relaxed barrier:");

w_global = 0;
w_global = ATOMIC_VAR_INIT(0);

s = mach_absolute_time();
for (i = cnt; i; i--) {
OSAtomicIncrement64Barrier(&w_global);
__c11_atomic_fetch_add(&wglobal, 1, memory_order_seq_cst);
}
print_result(s, "OSAtomicIncrement64Barrier:");
print_result(s, "64-bit atomic_fetch_add with memory_order_seq_cst barrier:");

w_global = 0;
w_global = ATOMIC_VAR_INIT(0);

s = mach_absolute_time();
for (i = cnt; i; i--) {
OSAtomicIncrement64(&w_global);
__c11_atomic_fetch_add(&wglobal, 1, memory_order_relaxed);
}
print_result(s, "OSAtomicIncrement64:");
print_result(s, "64-bit atomic_fetch_add with memory_order_seq_cst barrier:");

global = 0;
global = ATOMIC_VAR_INIT(0);

s = mach_absolute_time();
for (i = cnt; i; i--) {
while (!__sync_bool_compare_and_swap(&global, 0, 1)) {
atomic_int zero = ATOMIC_VAR_INIT(0);
while (!atomic_compare_exchange_weak(&global, &zero, 1)) {
do {
#if defined(__i386__) || defined(__x86_64__)
__asm__ __volatile__ ("pause");
Expand All @@ -646,16 +644,16 @@ __asm__ __volatile__ ("svc 0x80" : "+r" (_r0)
#endif
} while (global);
}
global = 0;
global = ATOMIC_VAR_INIT(0);
}
print_result(s, "Inlined spin lock/unlock:");

s = mach_absolute_time();
for (i = cnt; i; i--) {
OSSpinLockLock(&slock);
OSSpinLockUnlock(&slock);
os_unfair_lock_lock(&slock);
os_unfair_lock_unlock(&slock);
}
print_result(s, "OSSpinLock/Unlock:");
print_result(s, "os_unfair_lock_lock/unlock:");

s = mach_absolute_time();
for (i = cnt; i; i--) {
Expand Down
11 changes: 5 additions & 6 deletions tests/Foundation/dispatch_apply_gc.m
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Original file line number Diff line number Diff line change
Expand Up @@ -30,26 +30,25 @@
#else
const size_t final = 1000, desclen = 8892;
#endif
NSAutoreleasePool *pool = nil;

static void
work(void* ctxt __attribute__((unused)))
{
pool = [[NSAutoreleasePool alloc] init];
@autoreleasepool {
NSMutableArray *a = [NSMutableArray array];
OSSpinLock sl = OS_SPINLOCK_INIT, *l = &sl;
os_unfair_lock sl = OS_UNFAIR_LOCK_INIT, *l = &sl;

dispatch_apply(final, dispatch_get_global_queue(0, 0), ^(size_t i){
NSDecimalNumber *n = [NSDecimalNumber decimalNumberWithDecimal:
[[NSNumber numberWithInteger:i] decimalValue]];
OSSpinLockLock(l);
os_unfair_lock_lock(l);
[a addObject:n];
OSSpinLockUnlock(l);
os_unfair_lock_unlock(l);
});
test_long("count", [a count], final);
test_long("description length", [[a description] length], desclen);
a = nil;
[pool drain];
}
test_stop_after_delay((void*)(intptr_t)1);
}

Expand Down
4 changes: 2 additions & 2 deletions tests/Foundation/nsoperation.m
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Original file line number Diff line number Diff line change
Expand Up @@ -54,7 +54,7 @@ - (void)main
{
dispatch_test_start("NSOperation");

NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
@ autoreleasepool {

NSOperationQueue *queue = [[[NSOperationQueue alloc] init] autorelease];
test_ptr_notnull("NSOperationQueue", queue);
Expand All @@ -67,7 +67,7 @@ - (void)main

[[NSRunLoop mainRunLoop] run];

[pool release];
}

return 0;
}
3 changes: 0 additions & 3 deletions tests/dispatch_after.c
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Original file line number Diff line number Diff line change
Expand Up @@ -25,9 +25,6 @@
#endif
#include <stdlib.h>
#include <assert.h>
#ifdef __APPLE__
#include <libkern/OSAtomic.h>
#endif

#include <bsdtests.h>
#include <Block.h>
Expand Down
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