configure.ac: Test for __atomic_add_fetch in atomic checks

Some platforms have 64-bit __atomic_load_n but not 64-bit
__atomic_add_fetch, so test for both of them.

Bug: https://bugs.gentoo.org/655616
Reviewed-by: Matt Turner <mattst88@gmail.com>
Reviewed-by: Eric Engestrom <eric.engestrom@intel.com>
Reviewed-by: Dylan Baker <dylan@pnwbakers.com>
(cherry picked from commit baf16b2ea3)
This commit is contained in:
Andrew Galante 2018-06-11 15:05:25 -07:00 committed by Dylan Baker
parent b9725e3aa4
commit 87fb8bf6a8

View file

@ -442,7 +442,8 @@ int main() {
struct {
uint64_t *v;
} x;
return (int)__atomic_load_n(x.v, __ATOMIC_ACQUIRE);
return (int)__atomic_load_n(x.v, __ATOMIC_ACQUIRE) &
(int)__atomic_add_fetch(x.v, (uint64_t)1, __ATOMIC_ACQ_REL);
}]])], GCC_ATOMIC_BUILTINS_SUPPORTED=yes, GCC_ATOMIC_BUILTINS_SUPPORTED=no)
dnl If that didn't work, we try linking with -latomic, which is needed on some
@ -456,7 +457,8 @@ if test "x$GCC_ATOMIC_BUILTINS_SUPPORTED" != xyes; then
struct {
uint64_t *v;
} x;
return (int)__atomic_load_n(x.v, __ATOMIC_ACQUIRE);
return (int)__atomic_load_n(x.v, __ATOMIC_ACQUIRE) &
(int)__atomic_add_fetch(x.v, (uint64_t)1, __ATOMIC_ACQ_REL);
}]])], GCC_ATOMIC_BUILTINS_SUPPORTED=yes LIBATOMIC_LIBS="-latomic",
GCC_ATOMIC_BUILTINS_SUPPORTED=no)
LDFLAGS=$save_LDFLAGS