glog/m4/ac_have_sync_val_compare_and_swap.m4
6232847ecb Fix __sync_val_compare_and_swap detection
We should use the second argument of AC_TRY_LINK.
Otherwise, the main function defined twice and this test does never succeed.



git-svn-id: https://google-glog.googlecode.com/svn/trunk@102 eb4d4688-79bd-11dd-afb4-1d65580434c0
2012-01-12 06:15:52 +00:00

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AC_DEFUN([AX_C___SYNC_VAL_COMPARE_AND_SWAP], [
AC_MSG_CHECKING(for __sync_val_compare_and_swap)
AC_CACHE_VAL(ac_cv___sync_val_compare_and_swap, [
AC_TRY_LINK(
[],
[int a; if (__sync_val_compare_and_swap(&a, 0, 1)) return 1; return 0;],
ac_cv___sync_val_compare_and_swap=yes,
ac_cv___sync_val_compare_and_swap=no
)])
if test "$ac_cv___sync_val_compare_and_swap" = "yes"; then
AC_DEFINE(HAVE___SYNC_VAL_COMPARE_AND_SWAP, 1, [define if your compiler has __sync_val_compare_and_swap])
fi
AC_MSG_RESULT($ac_cv___sync_val_compare_and_swap)
])