+if test "x$TARGET" = "xAMD64" -o "x$TARGET" = "xX86"; then
+ if test "x$with_tls" = "x__thread"; then
+ #
+ # On some linux distributions, TLS works in executables, but linking
+ # against a shared library containing TLS fails with:
+ # undefined reference to `__tls_get_addr'
+ #
+ rm -f conftest.c conftest.so conftest
+ echo "static __thread int foo; void main () { foo = 5; }" > conftest.c
+ gcc -fPIC --shared -o conftest.so conftest.c > /dev/null 2>&1
+ gcc -o conftest conftest.so > /dev/null 2>&1
+ if test ! -f conftest; then
+ AC_MSG_WARN([Disabling usage of __thread.]);
+ with_tls=pthread
+ fi
+ rm -f conftest.c conftest.so conftest
+ fi
+fi
+
+if test "x$with_tls" = "x__thread"; then
+ AC_DEFINE(HAVE_KW_THREAD)
+ # Pass the information to libgc
+ CPPFLAGS="$CPPFLAGS -DUSE_COMPILER_TLS"
+ export CPPFLAGS
+fi
+