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// RUN: %clangxx_tsan -O1 %s %link_libcxx_tsan -o %t && %run %t 2>&1
// This is a correct program and tsan should not report a race.
//
// Verify that there is a happens-before relationship between a
// memory_order_release store that happens as part of a successful
// compare_exchange_strong(), and an atomic_thread_fence(memory_order_acquire)
// that happens after a relaxed load.
#include <atomic>
#include <sanitizer/tsan_interface.h>
#include <stdbool.h>
#include <stdio.h>
#include <thread>
std::atomic<bool> a;
unsigned int b;
constexpr int loops = 100000;
void Thread1() {
for (int i = 0; i < loops; ++i) {
while (a.load(std::memory_order_acquire)) {
}
b = i;
bool expected = false;
a.compare_exchange_strong(expected, true, std::memory_order_acq_rel);
}
}
int main() {
std::thread t(Thread1);
unsigned int sum = 0;
for (int i = 0; i < loops; ++i) {
while (!a.load(std::memory_order_relaxed)) {
}
std::atomic_thread_fence(std::memory_order_acquire);
__tsan_acquire(&a);
sum += b;
a.store(false, std::memory_order_release);
}
t.join();
fprintf(stderr, "DONE: %u\n", sum);
return 0;
}
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