On 27.11.25 03:53, Thomas Munro wrote:
> I wondered about this in the context of special alignment
> requirements[1]. palloc() aligns to MAXALIGN, which we artificially
> constrain for various reasons that we can't easily change (at least
> not without splitting on-disk MAXALIGN from allocation MAXALIGN, and
> if we do that we'll waste more memory). That's less than
> alignof(max_align_t) on common systems, so then we have to do some
> weird stuff to handle __int128 that doesn't fit too well into modern
> <stdalign.h> thinking and also disables optimal codegen.
On macOS ARM, I have MAXALIGN == alignof(max_align_t) == 8, but
alignof(__int128) == 16. (macOS Intel has 16/16.) Also, as a
consequence of that, the result of malloc() is not guaranteed to be
aligned sufficiently for __int128 (need to use aligned_alloc()). So it
seems to me that the current behavior of palloc() is pretty consistent
with that.
