* tls.m4 (GCC_CHECK_TLS): Also test TLS in a shared library when

	cross-compiling.

diff --git a/config/ChangeLog b/config/ChangeLog
index d6ff565..9b8cd93 100644 (file)
--- a/config/ChangeLog
+++ b/config/ChangeLog
@@ -1,3 +1,8 @@
+2009-07-16  Joseph Myers  <joseph@codesourcery.com>
+
+       * tls.m4 (GCC_CHECK_TLS): Also test TLS in a shared library when
+       cross-compiling.
+
 2009-05-26  Rafael Avila de Espindola  <espindola@google.com>
 
        * plugins.m4: New.

diff --git a/config/tls.m4 b/config/tls.m4
index acb123f..4648a90 100644 (file)
--- a/config/tls.m4
+++ b/config/tls.m4
@@ -1,5 +1,6 @@
 dnl Check whether the target supports TLS.
 AC_DEFUN([GCC_CHECK_TLS], [
+  AC_REQUIRE([AC_CANONICAL_HOST])
   GCC_ENABLE(tls, yes, [], [Use thread-local storage])
   AC_CACHE_CHECK([whether the target supports thread-local storage],
                 gcc_cv_have_tls, [
@@ -66,7 +67,24 @@ AC_DEFUN([GCC_CHECK_TLS], [
       [dnl This is the cross-compiling case. Assume libc supports TLS if the
        dnl binutils and the compiler do.
        AC_LINK_IFELSE([__thread int a; int b; int main() { return a = b; }],
-                     [gcc_cv_have_tls=yes], [gcc_cv_have_tls=no])
+        [chktls_save_LDFLAGS="$LDFLAGS"
+         dnl Shared library options may depend on the host; this check
+         dnl is only known to be needed for GNU/Linux.
+         case $host in
+           *-*-linux*)
+             LDFLAGS="-shared -Wl,--no-undefined $LDFLAGS"
+             ;;
+         esac
+         chktls_save_CFLAGS="$CFLAGS"
+         CFLAGS="-fPIC $CFLAGS"
+         dnl If -shared works, test if TLS works in a shared library.
+         AC_LINK_IFELSE([int f() { return 0; }],
+           AC_LINK_IFELSE([__thread int a; int b; int f() { return a = b; }],
+             [gcc_cv_have_tls=yes],
+             [gcc_cv_have_tls=no]),
+           [gcc_cv_have_tls=yes])
+         CFLAGS="$chktls_save_CFLAGS"
+         LDFLAGS="$chktls_save_LDFLAGS"], [gcc_cv_have_tls=no])
       ]
     )])
   if test "$enable_tls $gcc_cv_have_tls" = "yes yes"; then