Horton

Re: Cleaning up historical portability baggage

Thomas Munro <thomas.munro@gmail.com>

View thread View on postgr.es
From: Thomas Munro <thomas.munro@gmail.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Peter Eisentraut <peter.eisentraut@enterprisedb.com>, Andres Freund <andres@anarazel.de>, Andrew Dunstan <andrew@dunslane.net>, Robert Haas <robertmhaas@gmail.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2022-08-12T21:48:24Z
Lists: pgsql-hackers 
On Sat, Aug 13, 2022 at 8:08 AM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> I wrote:
> > I see that prairiedog was the only buildfarm animal failing the
> > HAVE_PPC_LWARX_MUTEX_HINT test, and it seems pretty unlikely that
> > there are any assemblers remaining in the wild that can't parse that.
>
> Actually, after further investigation and testing, I think we could
> drop the conditionality around PPC spinlock sequences altogether.
> The commentary in pg_config_manual.h claims that "some pre-POWER4
> machines" will fail on LWSYNC or LWARX with hint, but I've now
> confirmed that the oldest PPC chips in my possession (prairiedog's
> ppc7400, as well as a couple of ppc7450 machines) are all fine with
> both.  Indeed, prairiedog would have been failing for some time now
> if it didn't like LWSYNC, because port/atomics/arch-ppc.h is using
> that unconditionally in some places :-(.  I think we can safely
> assume that such machines no longer exist in the wild, or at least
> are not going to be used to run Postgres v16.

Yeah, POWER3 was superseded in 2001.  Looking around, Linux distros
that someone might seriously run a database on already require much
more recent POWER generations to even boot up, and although there is
(for example) a separate unofficial powerpc port for Debian and of
course NetBSD and others that can target older Macs and IBM servers
etc, apparently no one has run our test suite on 21+ year old hardware
and reported that it (presumably) SIGILLs already, per that
observation (I think ports/packages that fail to work probably just
get marked broken).  As for vintage Apple hardware, clearly the G4
cube was far more collectable than those weird slightly inflated
looking G3 machines :-)

I'm curious, though... if we used compiler builtins, would
-march/-mcpu etc know about this kind of thing, for people who wanted
to compile on ancient hardware, or, I guess more interestingly, newer
tricks that we haven't got around to learning about yet?

Commits

  1. Make sure IOV_MAX is defined.

  2. Doc: Abstract AF_UNIX sockets don't work on Windows.

  3. Clean up inconsistent use of fflush().

  4. Remove configure probe for sockaddr_in6 and require AF_INET6.

  5. Remove configure probes for sockaddr_storage members.

  6. Remove configure probe for netinet/tcp.h.

  7. Fix macro problem with gai_strerror on Windows.

  8. Remove configure probe for net/if.h.

  9. mstcpip.h is not missing on MinGW.

  10. Remove dead ifaddr.c fallback code.

  11. Remove configure probe for gethostbyname_r.

  12. Remove replacement code for getaddrinfo.

  13. Remove configure probe for struct sockaddr_storage.

  14. Remove HAVE_UNIX_SOCKETS.

  15. Remove configurability of PPC spinlock assembly code.

  16. Remove configure probe for shl_load library.

  17. Remove configure probe for sys/select.h.

  18. Remove configure probes for sys/un.h and struct sockaddr_un.

  19. Remove configure probes for sys/ipc.h, sys/sem.h, sys/shm.h.

  20. Remove configure probe for sys/resource.h and refactor.

  21. Remove configure probe for sys/uio.h.

  22. Fix obsolete comments in instr_time.h.

  23. aix: fix misreading of condition in 8f12a4e7add

  24. aix: Remove checks for very old OS versions

  25. windows: Remove HAVE_MINIDUMP_TYPE test

  26. solaris: Remove unnecessary gcc / gnu ld vs sun studio differences

  27. Trust a few system headers to stand on their own

  28. Rely on __func__ being supported

  29. Simplify replacement code for strtof.

  30. Simplify gettimeofday for Windows.

  31. Simplify gettimeofday() fallback logic.

  32. Remove fallbacks for strtoll, strtoull.

  33. Remove configure probe for fdatasync.

  34. Remove configure probe for clock_gettime.

  35. Simplify replacement code for preadv and pwritev.

  36. Remove dead pread and pwrite replacement code.

  37. Remove dead setenv, unsetenv replacement code.

  38. Remove configure probes for poll and poll.h.

  39. Remove configure probe for link.

  40. Remove configure probes for symlink/readlink, and dead code.

  41. Remove configure probe for setsid.

  42. Remove configure probe for shm_open.

  43. Remove configure probe and related tests for getrlimit.

  44. Remove configure probe for dlopen, and refactor.

  45. Remove dead getpwuid_r replacement code.

  46. Remove dead handling for pre-POSIX sigwait().

  47. Remove dead getrusage replacement code.

  48. Cygwin and Mingw floating-point fixes.

  49. Support platforms where strtoll/strtoull are spelled __strtoll/__strtoull.

  50. Arrange to supply declarations for strtoll/strtoull if needed.

  51. Lock down regression testing temporary clusters on Windows.

  52. Secure Unix-domain sockets of "make check" temporary clusters.

  53. Add configure checks for strtoll, strtoull (or strto[u]q). Disable

  54. Portability fix for old SunOS releases: fflush(NULL)