int __atomic_inc(volatile int *ptr)
{
int32_t oldValue;
do {
oldValue = *ptr;
} while (__atomic_cmpxchg(oldValue, oldValue+1, ptr));
return oldValue;
}
int __atomic_dec(volatile int *ptr)
{
int oldValue;
do {
oldValue = *ptr;
} while (__atomic_cmpxchg(oldValue, oldValue-1, ptr));
return oldValue;
}
int __atomic_swap(int _new, volatile int *ptr)
{
int oldValue;
do {
oldValue = *ptr;
} while (__atomic_cmpxchg(oldValue, _new, ptr));
return oldValue;
}
extern "C" int __cxa_guard_acquire(_guard_t* gv)
{
// 0 -> pending, return 1
// pending -> waiting, wait and return 0
// waiting: untouched, wait and return 0
// ready: untouched, return 0
retry:
if (__atomic_cmpxchg(0, pending, &gv->state) == 0) {
ANDROID_MEMBAR_FULL();
return 1;
}
__atomic_cmpxchg(pending, waiting, &gv->state); // Indicate there is a waiter
__futex_wait(&gv->state, waiting, NULL);
if (gv->state != ready) // __cxa_guard_abort was called, let every thread try since there is no return code for this condition
goto retry;
ANDROID_MEMBAR_FULL();
return 0;
}
extern "C" void __cxa_guard_release(_guard_t* gv)
{
// pending -> ready
// waiting -> ready, and wake
ANDROID_MEMBAR_FULL();
if (__atomic_cmpxchg(pending, ready, &gv->state) == 0) {
return;
}
gv->state = ready;
__futex_wake(&gv->state, 0x7fffffff);
}
/*
* Start tests, show results.
*/
bool dvmTestAtomicSpeed() {
pthread_t threads[THREAD_COUNT];
void *(*startRoutine)(void *) = atomicTest;
int64_t startWhen, endWhen;
#if defined(__ARM_ARCH__)
dvmFprintf(stdout, "__ARM_ARCH__ is %d\n", __ARM_ARCH__);
#endif
#if defined(ANDROID_SMP)
dvmFprintf(stdout, "ANDROID_SMP is %d\n", ANDROID_SMP);
#endif
dvmFprintf(stdout, "Creating threads\n");
int i;
for (i = 0; i < THREAD_COUNT; i++) {
void *arg = (void *) i;
if (pthread_create(&threads[i], NULL, startRoutine, arg) != 0) {
dvmFprintf(stderr, "thread create failed\n");
}
}
/* wait for all the threads to reach the starting line */
while (1) {
pthread_mutex_lock(&waitLock);
if (threadsStarted == THREAD_COUNT) {
dvmFprintf(stdout, "Starting test\n");
startWhen = getRelativeTimeNsec();
pthread_cond_broadcast(&waitCond);
pthread_mutex_unlock(&waitLock);
break;
}
pthread_mutex_unlock(&waitLock);
usleep(100000);
}
for (i = 0; i < THREAD_COUNT; i++) {
void *retval;
if (pthread_join(threads[i], &retval) != 0) {
dvmFprintf(stderr, "thread join (%d) failed\n", i);
}
}
endWhen = getRelativeTimeNsec();
dvmFprintf(stdout, "All threads stopped, time is %.6fms\n",
(endWhen - startWhen) / 1000000.0);
/*
* Show results; expecting:
*
* incTest = 5000000
* decTest = -5000000
* addTest = 7500000
* casTest = 10000000
* wideCasTest = 0x6600000077000000
*/
dvmFprintf(stdout, "incTest = %d\n", incTest);
dvmFprintf(stdout, "decTest = %d\n", decTest);
dvmFprintf(stdout, "addTest = %d\n", addTest);
dvmFprintf(stdout, "casTest = %d\n", casTest);
dvmFprintf(stdout, "wideCasTest = 0x%llx\n", wideCasTest);
/* do again, serially (SMP check) */
startWhen = getRelativeTimeNsec();
for (i = 0; i < THREAD_COUNT; i++) {
doAtomicTest(i);
}
endWhen = getRelativeTimeNsec();
dvmFprintf(stdout, "Same iterations done serially: time is %.6fms\n",
(endWhen - startWhen) / 1000000.0);
/*
* Hard to do a meaningful thrash test on these, so just do a simple
* function test.
*/
andTest = 0xffd7fa96;
orTest = 0x122221ff;
android_atomic_and(0xfffdaf96, &andTest);
android_atomic_or(0xdeaaeb00, &orTest);
if (android_atomic_release_cas(failingCasTest + 1, failingCasTest - 1,
&failingCasTest) == 0)
dvmFprintf(stdout, "failing test did not fail!\n");
dvmFprintf(stdout, "andTest = %#x\n", andTest);
dvmFprintf(stdout, "orTest = %#x\n", orTest);
dvmFprintf(stdout, "failingCasTest = %d\n", failingCasTest);
#ifdef TEST_BIONIC
/*
* Quick function test on the bionic ops.
*/
int prev;
int tester = 7;
prev = __atomic_inc(&tester);
__atomic_inc(&tester);
__atomic_inc(&tester);
dvmFprintf(stdout, "bionic 3 inc: %d -> %d\n", prev, tester);
prev = __atomic_dec(&tester);
__atomic_dec(&tester);
__atomic_dec(&tester);
dvmFprintf(stdout, "bionic 3 dec: %d -> %d\n", prev, tester);
prev = __atomic_swap(27, &tester);
dvmFprintf(stdout, "bionic swap: %d -> %d\n", prev, tester);
int swapok = __atomic_cmpxchg(27, 72, &tester);
dvmFprintf(stdout, "bionic cmpxchg: %d (%d)\n", tester, swapok);
#endif
testAtomicSpeed();
return 0;
}