[pbsd]

>Even after the static variable has been initialised, the overhead of accessing it is still considerable: a function call to __cxa_guard_acquire(), plus atomic_load_explicit(&__b_guard, memory_order::acquire) in __cxa_guard_acquire().

No. The lock calls are only done during initialization, in case two threads run the initialization concurrently while the guard variable is 0. Once the variable is initialized, this will always be skipped by "je .L3".

[menaerus]

Right, I was scratching my head exactly for that reason too. Even if the analysis was correct it would still be a solution for the problem that doesn't exist.