| 1 | dnl Check whether the target supports TLS. |
| 2 | AC_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. This fails at least with some older Red Hat |
| 9 | dnl releases. |
| 10 | save_LDFLAGS="$LDFLAGS" |
| 11 | LDFLAGS="-static $LDFLAGS" |
| 12 | AC_RUN_IFELSE([__thread int a; int b; int main() { return a = b; }], |
| 13 | [have_tls=yes], [have_tls=no], []) |
| 14 | LDFLAGS="$save_LDFLAGS"], |
| 15 | [have_tls=no], |
| 16 | [AC_COMPILE_IFELSE([__thread int foo;], [have_tls=yes], [have_tls=no])] |
| 17 | )]) |
| 18 | if test "$enable_tls $have_tls" = "yes yes"; then |
| 19 | AC_DEFINE(HAVE_TLS, 1, |
| 20 | [Define to 1 if the target supports thread-local storage.]) |
| 21 | fi]) |