1dnl Check whether the target supports TLS. 2AC_DEFUN([GCC_CHECK_TLS], [ 3 GCC_ENABLE(tls, yes, [], [Use thread-local storage]) 4 AC_CACHE_CHECK([whether the target supports thread-local storage], 5 have_tls, [ 6 AC_RUN_IFELSE([__thread int a; int b; int main() { return a = b; }], 7 [dnl If the test case passed with dynamic linking, try again with 8 dnl static linking, but only if static linking is supported (not 9 dnl on Solaris 10). This fails with some older Red Hat releases. 10 save_LDFLAGS="$LDFLAGS" 11 LDFLAGS="-static $LDFLAGS" 12 AC_LINK_IFELSE([int main() { return 0; }], 13 AC_RUN_IFELSE([__thread int a; int b; int main() { return a = b; }], 14 [have_tls=yes], [have_tls=no],[]), 15 [have_tls=yes]) 16 LDFLAGS="$save_LDFLAGS"], 17 [have_tls=no], 18 [AC_COMPILE_IFELSE([__thread int foo;], [have_tls=yes], [have_tls=no])] 19 )]) 20 if test "$enable_tls $have_tls" = "yes yes"; then 21 AC_DEFINE(HAVE_TLS, 1, 22 [Define to 1 if the target supports thread-local storage.]) 23 fi]) 24