Since the direct I/O commit went in, buildfarm animals
curculio and morepork have been issuing warnings like
hashpage.c: In function '_hash_expandtable':
hashpage.c:995: warning: ignoring alignment for stack allocated 'zerobuf'
in places where there's a local variable of type PGIOAlignedBlock
or PGAlignedXLogBlock. I'm not sure why only those two animals
are unhappy, but I think they have a point: typical ABIs don't
guarantee alignment of function stack frames to better than
16 bytes or so. In principle the compiler could support a 4K
alignment request anyway by doing the equivalent of alloca(3),
but I do not think we can count on that to happen.
regards, tom lane
