On 2024-Jul-01, Tom Lane wrote: > Alvaro Herrera <alvhe...@alvh.no-ip.org> writes: > >> because the failed assertion is: > >> #ifndef PG_HAVE_ATOMIC_U64_SIMULATION > >> AssertPointerAlignment(&currval, 8); > >> #endif > > Perhaps this assertion is what is wrong? If the platform has no > native 8-byte alignment requirement, why do we think that atomics > need it?
Oh, that's a good question. TBH I just copied the assertion from the other routines for 64-bit variables in the same file. But I think that's correct. We're gating the assertion on _not_ having emulation, which must mean we have native atomics; on MSVC, if I read the #ifdef maze correctly, that's implemented using _InterlockedCompareExchange, whose docs state: : The variables for this function must be aligned on a 64-bit boundary; : otherwise, this function will behave unpredictably on multiprocessor x86 : systems and any non-x86 systems. See _aligned_malloc. https://learn.microsoft.com/en-us/windows/win32/api/winnt/nf-winnt-interlockedcompareexchange64 So I think the assertion is correct. -- Álvaro Herrera PostgreSQL Developer — https://www.EnterpriseDB.com/ "[PostgreSQL] is a great group; in my opinion it is THE best open source development communities in existence anywhere." (Lamar Owen)
