Remove AIX support

There isn't a lot of user demand for AIX support, we have a bunch of
hacks to work around AIX-specific compiler bugs and idiosyncrasies,
and no one has stepped up to the plate to properly maintain it.
Remove support for AIX to get rid of that maintenance overhead. It's
still supported for stable versions.

The acute issue that triggered this decision was that after commit
8af2565248, the AIX buildfarm members have been hitting this
assertion:

    TRAP: failed Assert("(uintptr_t) buffer == TYPEALIGN(PG_IO_ALIGN_SIZE, buffer)"), File: "md.c", Line: 472, PID: 2949728

Apperently the "pg_attribute_aligned(a)" attribute doesn't work on AIX
for values larger than PG_IO_ALIGN_SIZE, for a static const variable.
That could be worked around, but we decided to just drop the AIX support
instead.

Discussion: https://www.postgresql.org/message-id/[email protected]
Reviewed-by: Andres Freund, Noah Misch, Thomas Munro

1 files changed, 28 insertions, 40 deletions

diff --git a/configure.ac b/configure.ac
index 6e64ece11da..d034bf742ad 100644
--- a/configure.ac
+++ b/configure.ac
@@ -62,7 +62,6 @@ PGAC_ARG_REQ(with, template, [NAME], [override operating system template],
 # --with-template not given
 
 case $host_os in
-     aix*) template=aix ;;
   cygwin*|msys*) template=cygwin ;;
   darwin*) template=darwin ;;
 dragonfly*) template=netbsd ;;
@@ -374,10 +373,10 @@ AC_DEFINE_UNQUOTED([XLOG_BLCKSZ], ${XLOG_BLCKSZ}, [
 # variable.
 PGAC_ARG_REQ(with, CC, [CMD], [set compiler (deprecated)], [CC=$with_CC])
 
-case $template in
-  aix) pgac_cc_list="gcc xlc"; pgac_cxx_list="g++ xlC";;
-    *) pgac_cc_list="gcc cc"; pgac_cxx_list="g++ c++";;
-esac
+# If you don't specify a list of compilers to test, the AC_PROG_CC and
+# AC_PROG_CXX macros test for a long list of unsupported compilers.
+pgac_cc_list="gcc cc"
+pgac_cxx_list="g++ c++"
 
 AC_PROG_CC([$pgac_cc_list])
 AC_PROG_CC_C99()
@@ -594,12 +593,6 @@ elif test "$ICC" = yes; then
   # Make sure strict aliasing is off (though this is said to be the default)
   PGAC_PROG_CC_CFLAGS_OPT([-fno-strict-aliasing])
   PGAC_PROG_CXX_CFLAGS_OPT([-fno-strict-aliasing])
-elif test "$PORTNAME" = "aix"; then
-  # AIX's xlc has to have strict aliasing turned off too
-  PGAC_PROG_CC_CFLAGS_OPT([-qnoansialias])
-  PGAC_PROG_CXX_CFLAGS_OPT([-qnoansialias])
-  PGAC_PROG_CC_CFLAGS_OPT([-qlonglong])
-  PGAC_PROG_CXX_CFLAGS_OPT([-qlonglong])
 fi
 
 # If the compiler knows how to hide symbols, add the switch needed for that to
@@ -618,16 +611,6 @@ if test "$GCC" = yes -o "$SUN_STUDIO_CC" = yes ; then
   PGAC_PROG_VARCXX_VARFLAGS_OPT(CXX, CXXFLAGS_SL_MODULE, [-fvisibility=hidden])
   PGAC_PROG_VARCXX_VARFLAGS_OPT(CXX, CXXFLAGS_SL_MODULE, [-fvisibility-inlines-hidden])
   have_visibility_attribute=$pgac_cv_prog_CC_cflags__fvisibility_hidden
-elif test "$PORTNAME" = "aix"; then
-  # Note that xlc accepts -fvisibility=hidden as a file.
-  PGAC_PROG_CC_VAR_OPT(CFLAGS_SL_MODULE, [-qvisibility=hidden])
-  PGAC_PROG_VARCXX_VARFLAGS_OPT(CXX, CXXFLAGS_SL_MODULE, [-qvisibility=hidden])
-  have_visibility_attribute=$pgac_cv_prog_CC_cflags__qvisibility_hidden
-  # Old xlc versions (<13.1) don't have support for -qvisibility. Use expfull to force
-  # all extension module symbols to be exported.
-  if test "$pgac_cv_prog_CC_cflags__qvisibility_hidden" != "yes"; then
-    CFLAGS_SL_MODULE="$CFLAGS_SL_MODULE -Wl,-b,expfull"
-  fi
 fi
 
 if test "$have_visibility_attribute" = "yes"; then
@@ -1407,8 +1390,7 @@ if test "$with_zstd" = yes ; then
   AC_CHECK_LIB(zstd, ZSTD_compress, [], [AC_MSG_ERROR([library 'zstd' is required for ZSTD support])])
 fi
 
-# Note: We can test for libldap_r only after we know PTHREAD_LIBS;
-# also, on AIX, we may need to have openssl in LIBS for this step.
+# Note: We can test for libldap_r only after we know PTHREAD_LIBS
 if test "$with_ldap" = yes ; then
   _LIBS="$LIBS"
   if test "$PORTNAME" != "win32"; then
@@ -1666,12 +1648,8 @@ PGAC_TYPE_LOCALE_T
 # spelling it understands, because it conflicts with
 # __declspec(restrict). Therefore we define pg_restrict to the
 # appropriate definition, which presumably won't conflict.
-#
-# Allow platforms with buggy compilers to force restrict to not be
-# used by setting $FORCE_DISABLE_RESTRICT=yes in the relevant
-# template.
 AC_C_RESTRICT
-if test "$ac_cv_c_restrict" = "no" -o "x$FORCE_DISABLE_RESTRICT" = "xyes"; then
+if test "$ac_cv_c_restrict" = "no"; then
   pg_restrict=""
 else
   pg_restrict="$ac_cv_c_restrict"
@@ -2022,18 +2000,28 @@ fi
 AC_CHECK_ALIGNOF(double)
 
 # Compute maximum alignment of any basic type.
-# We assume long's alignment is at least as strong as char, short, or int;
-# but we must check long long (if it is being used for int64) and double.
-# Note that we intentionally do not consider any types wider than 64 bits,
-# as allowing MAXIMUM_ALIGNOF to exceed 8 would be too much of a penalty
-# for disk and memory space.
-
-MAX_ALIGNOF=$ac_cv_alignof_long
-if test $MAX_ALIGNOF -lt $ac_cv_alignof_double ; then
-  MAX_ALIGNOF=$ac_cv_alignof_double
-fi
-if test x"$HAVE_LONG_LONG_INT_64" = xyes && test $MAX_ALIGNOF -lt $ac_cv_alignof_long_long_int ; then
-  MAX_ALIGNOF="$ac_cv_alignof_long_long_int"
+#
+# We require 'double' to have the strictest alignment among the basic types,
+# because otherwise the C ABI might impose 8-byte alignment on some of the
+# other C types that correspond to TYPALIGN_DOUBLE SQL types.  That could
+# cause a mismatch between the tuple layout and the C struct layout of a
+# catalog tuple.  We used to carefully order catalog columns such that any
+# fixed-width, attalign=4 columns were at offsets divisible by 8 regardless
+# of MAXIMUM_ALIGNOF to avoid that, but we no longer support any platforms
+# where TYPALIGN_DOUBLE != MAXIMUM_ALIGNOF.
+#
+# We assume without checking that long's alignment is at least as strong as
+# char, short, or int.  Note that we intentionally do not consider any types
+# wider than 64 bits, as allowing MAXIMUM_ALIGNOF to exceed 8 would be too
+# much of a penalty for disk and memory space.
+
+MAX_ALIGNOF=$ac_cv_alignof_double
+
+if test $ac_cv_alignof_long -gt $MAX_ALIGNOF ; then
+  AC_MSG_ERROR([alignment of 'long' is greater than the alignment of 'double'])
+fi
+if test x"$HAVE_LONG_LONG_INT_64" = xyes && test $ac_cv_alignof_long_long_int -gt $MAX_ALIGNOF ; then
+  AC_MSG_ERROR([alignment of 'long long int' is greater than the alignment of 'double'])
 fi
 AC_DEFINE_UNQUOTED(MAXIMUM_ALIGNOF, $MAX_ALIGNOF, [Define as the maximum alignment requirement of any C data type.])