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.
