According to the C++ standard, std::atomic
can be combined with any trivially copyable type. However, GCC produces the following error messages:
#include <atomic>
struct TriviallyCopyableType {
int a, b, c, d;
};
int main() {
std::atomic<TriviallyCopyableType> a;
a.store({}); // undefined reference to `__atomic_store_16'
a.is_lock_free(); // undefined reference to `__atomic_is_lock_free'
}
Clang and Microsoft's compiler do not complain. Am I doing something wrong? Is this a known problem? After all, atomic operations were implemented years ago in GCC 4.4. Are there any workarounds other than using a different compiler? Since Clang implements std::atomic<TriviallyCopyableType>
even lock-free, I do not want to use explicit locking.
This answer is compiled from the comments.
You need to explicitly link the atomic operations library with your program by specifying
-latomic
on the command line.-mcx16
may enable lock-free atomic operations on 128-bit data types.