The x32 ABI allows users to take advantage of the extra
registers on x86-64 without the bloat of 64-bit pointers and
longs.
This ought to be significant since Perl was designed when 32-bit
was prevalent; and the common structs for ops, hashes, scalars,
and arrays use longs (SSize_t/Size_t) for things which should
never need 64-bits when processing emails.
Debian's x32 port seems to work quite nicely under a chroot
on an amd64 Linux system. All tests pass under x32, now.