mirror of
https://git.postgresql.org/git/postgresql.git
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2e8ce9ae46
Almost ten years ago, commit e48322a6d6 broke
the logic in ACX_PTHREAD by looping through all the possible flags rather
than stopping with the first one that would work. This meant that
$acx_pthread_ok was no longer meaningful after the loop; it would usually
be "no", whether or not we'd found working thread flags. The reason nobody
noticed is that Postgres doesn't actually use any of the symbols set up
by the code after the loop. Rather than complicate things some more to
make it work as designed, let's just remove all that dead code, and thereby
save a few cycles in each configure run.
172 lines
6.9 KiB
Plaintext
172 lines
6.9 KiB
Plaintext
dnl This is based on an old macro from the GNU Autoconf Macro Archive at:
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dnl http://www.gnu.org/software/ac-archive/htmldoc/acx_pthread.html
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dnl but it's been rather heavily hacked --- beware of blindly dropping in
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dnl upstream changes!
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dnl
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AC_DEFUN([ACX_PTHREAD], [
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AC_REQUIRE([AC_CANONICAL_HOST])
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AC_LANG_SAVE
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AC_LANG_C
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acx_pthread_ok=no
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# We used to check for pthread.h first, but this fails if pthread.h
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# requires special compiler flags (e.g. on True64 or Sequent).
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# It gets checked for in the link test anyway.
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# First of all, check if the user has set any of the PTHREAD_LIBS,
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# etcetera environment variables, and if threads linking works using
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# them:
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if test x"$PTHREAD_LIBS$PTHREAD_CFLAGS" != x; then
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save_CFLAGS="$CFLAGS"
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CFLAGS="$CFLAGS $PTHREAD_CFLAGS"
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save_LIBS="$LIBS"
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LIBS="$PTHREAD_LIBS $LIBS"
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AC_MSG_CHECKING([for pthread_join in LIBS=$PTHREAD_LIBS with CFLAGS=$PTHREAD_CFLAGS])
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AC_TRY_LINK_FUNC(pthread_join, acx_pthread_ok=yes)
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AC_MSG_RESULT($acx_pthread_ok)
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if test x"$acx_pthread_ok" = xno; then
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PTHREAD_LIBS=""
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PTHREAD_CFLAGS=""
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fi
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LIBS="$save_LIBS"
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CFLAGS="$save_CFLAGS"
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fi
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# We must check for the threads library under a number of different
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# names; the ordering is very important because some systems
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# (e.g. DEC) have both -lpthread and -lpthreads, where one of the
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# libraries is broken (non-POSIX).
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# Create a list of thread flags to try. Items starting with a "-" are
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# C compiler flags, and other items are library names, except for "none"
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# which indicates that we try without any flags at all, and "pthread-config"
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# which is a program returning the flags for the Pth emulation library.
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acx_pthread_flags="pthreads none -Kthread -kthread lthread -pthread -pthreads -mthreads pthread --thread-safe -mt pthread-config pthreadGC2"
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# The ordering *is* (sometimes) important. Some notes on the
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# individual items follow:
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# pthreads: AIX (must check this before -lpthread)
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# none: in case threads are in libc; should be tried before -Kthread and
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# other compiler flags to prevent continual compiler warnings
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# -Kthread: Sequent (threads in libc, but -Kthread needed for pthread.h)
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# -kthread: FreeBSD kernel threads (preferred to -pthread since SMP-able)
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# lthread: LinuxThreads port on FreeBSD (also preferred to -pthread)
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# -pthread: Linux/gcc (kernel threads), BSD/gcc (userland threads)
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# -pthreads: Solaris/gcc
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# -mthreads: Mingw32/gcc, Lynx/gcc
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# -mt: Sun Workshop C (may only link SunOS threads [-lthread], but it
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# doesn't hurt to check since this sometimes defines pthreads too;
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# also defines -D_REENTRANT)
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# pthread: Linux, etcetera
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# --thread-safe: KAI C++
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# pthread-config: use pthread-config program (for GNU Pth library)
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case "${host_cpu}-${host_os}" in
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*solaris*)
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# On Solaris (at least, for some versions), libc contains stubbed
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# (non-functional) versions of the pthreads routines, so link-based
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# tests will erroneously succeed. (We need to link with -pthread or
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# -lpthread.) (The stubs are missing pthread_cleanup_push, or rather
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# a function called by this macro, so we could check for that, but
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# who knows whether they'll stub that too in a future libc.) So,
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# we'll just look for -pthreads and -lpthread first:
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acx_pthread_flags="-pthread -pthreads pthread -mt $acx_pthread_flags"
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;;
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esac
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if test x"$acx_pthread_ok" = xno; then
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for flag in $acx_pthread_flags; do
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tryPTHREAD_CFLAGS=""
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tryPTHREAD_LIBS=""
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case $flag in
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none)
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AC_MSG_CHECKING([whether pthreads work without any flags])
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;;
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-*)
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AC_MSG_CHECKING([whether pthreads work with $flag])
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tryPTHREAD_CFLAGS="$flag"
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;;
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pthread-config)
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# skip this if we already have flags defined, for PostgreSQL
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if test x"$PTHREAD_CFLAGS" != x -o x"$PTHREAD_LIBS" != x; then continue; fi
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AC_CHECK_PROG(acx_pthread_config, pthread-config, yes, no)
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if test x"$acx_pthread_config" = xno; then continue; fi
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tryPTHREAD_CFLAGS="`pthread-config --cflags`"
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tryPTHREAD_LIBS="`pthread-config --ldflags` `pthread-config --libs`"
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;;
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*)
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AC_MSG_CHECKING([for the pthreads library -l$flag])
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tryPTHREAD_LIBS="-l$flag"
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;;
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esac
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save_LIBS="$LIBS"
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save_CFLAGS="$CFLAGS"
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LIBS="$tryPTHREAD_LIBS $PTHREAD_LIBS $LIBS"
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CFLAGS="$CFLAGS $PTHREAD_CFLAGS $tryPTHREAD_CFLAGS"
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# Check for various functions. We must include pthread.h,
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# since some functions may be macros. (On the Sequent, we
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# need a special flag -Kthread to make this header compile.)
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# We check for pthread_join because it is in -lpthread on IRIX
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# while pthread_create is in libc. We check for pthread_attr_init
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# due to DEC craziness with -lpthreads. We check for
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# pthread_cleanup_push because it is one of the few pthread
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# functions on Solaris that doesn't have a non-functional libc stub.
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# We try pthread_create on general principles.
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AC_TRY_LINK([#include <pthread.h>],
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[pthread_t th; pthread_join(th, 0);
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pthread_attr_init(0); pthread_cleanup_push(0, 0);
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pthread_create(0,0,0,0); pthread_cleanup_pop(0); ],
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[acx_pthread_ok=yes], [acx_pthread_ok=no])
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if test "x$acx_pthread_ok" = xyes; then
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# Don't use options that are ignored by the compiler.
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# We find them by checking stderror.
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cat >conftest.$ac_ext <<_ACEOF
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int
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main (int argc, char **argv)
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{
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(void) argc;
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(void) argv;
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return 0;
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}
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_ACEOF
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rm -f conftest.$ac_objext conftest$ac_exeext
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# Check both linking and compiling, because they might tolerate different options.
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if test "`(eval $ac_link 2>&1 1>&5)`" = "" && test "`(eval $ac_compile 2>&1 1>&5)`" = ""; then
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# The original macro breaks out of the loop at this point,
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# but we continue trying flags because Linux needs -lpthread
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# too to build libpq successfully. The test above only
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# tests for building binaries, not shared libraries.
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PTHREAD_LIBS=" $tryPTHREAD_LIBS $PTHREAD_LIBS"
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PTHREAD_CFLAGS="$PTHREAD_CFLAGS $tryPTHREAD_CFLAGS"
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else acx_pthread_ok=no
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fi
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fi
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LIBS="$save_LIBS"
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CFLAGS="$save_CFLAGS"
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AC_MSG_RESULT($acx_pthread_ok)
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done
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fi
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# The original macro has a bunch of other tests here, which we have removed
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# because (a) Postgres doesn't need them, and (b) $acx_pthread_ok is not
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# meaningful at this point.
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AC_SUBST(PTHREAD_LIBS)
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AC_SUBST(PTHREAD_CFLAGS)
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AC_LANG_RESTORE
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])dnl ACX_PTHREAD
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