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],
- have_tls, [
+ gcc_cv_have_tls, [
AC_RUN_IFELSE([__thread int a; int b; int main() { return a = b; }],
[dnl If the test case passed with dynamic linking, try again with
dnl static linking, but only if static linking is supported (not
chktls_save_LDFLAGS="$LDFLAGS"
LDFLAGS="-static $LDFLAGS"
AC_LINK_IFELSE([int main() { return 0; }],
- AC_RUN_IFELSE([__thread int a; int b; int main() { return a = b; }],
- [have_tls=yes], [have_tls=no],[]),
- [have_tls=yes])
+ [AC_RUN_IFELSE([__thread int a; int b; int main() { return a = b; }],
+ [gcc_cv_have_tls=yes], [gcc_cv_have_tls=no],[])],
+ [gcc_cv_have_tls=yes])
LDFLAGS="$chktls_save_LDFLAGS"
- if test $have_tls = yes; then
+ if test $gcc_cv_have_tls = yes; then
dnl So far, the binutils and the compiler support TLS.
dnl Also check whether the libc supports TLS, i.e. whether a variable
dnl with __thread linkage has a different address in different threads.
CFLAGS="$chktls_save_CFLAGS"
if test "X$thread_CFLAGS" != Xfailed; then
CFLAGS="$thread_CFLAGS $chktls_save_CFLAGS"
+ dnl Test for an old glibc bug that violated the __thread property.
+ dnl Use volatile to ensure the compiler won't optimize away pointer
+ dnl accesses it might otherwise assume to be redundant, or reorder
+ dnl them and reuse storage, which might lead to them pointing to
+ dnl the same location.
AC_RUN_IFELSE(
[AC_LANG_PROGRAM(
[#include <pthread.h>
__thread int a;
- static int *a_in_other_thread;
+ static int *volatile a_in_other_thread;
static void *
thread_func (void *arg)
{
}],
[pthread_t thread;
void *thread_retval;
- int *a_in_main_thread;
+ int *volatile a_in_main_thread;
+ a_in_main_thread = &a;
if (pthread_create (&thread, (pthread_attr_t *)0,
thread_func, (void *)0))
return 0;
- a_in_main_thread = &a;
if (pthread_join (thread, &thread_retval))
return 0;
return (a_in_other_thread == a_in_main_thread);])],
- [have_tls=yes], [have_tls=no], [])
+ [gcc_cv_have_tls=yes], [gcc_cv_have_tls=no], [])
CFLAGS="$chktls_save_CFLAGS"
fi
fi],
- [have_tls=no],
+ [gcc_cv_have_tls=no],
[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; }],
- [have_tls=yes], [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 $have_tls" = "yes yes"; then
+ if test "$enable_tls $gcc_cv_have_tls" = "yes yes"; then
AC_DEFINE(HAVE_TLS, 1,
[Define to 1 if the target supports thread-local storage.])
fi])
+
+dnl Check whether the target assembler supports TLS.
+AC_DEFUN([GCC_CHECK_CC_TLS], [
+ GCC_ENABLE(tls, yes, [], [Use thread-local storage])
+ AC_CACHE_CHECK([whether the target assembler supports thread-local storage],
+ gcc_cv_have_cc_tls, [
+ AC_COMPILE_IFELSE([__thread int a; int b; int main() { return a = b; }],
+ [gcc_cv_have_cc_tls=yes], [gcc_cv_have_cc_tls=no])]
+ )])
+ if test "$enable_tls $gcc_cv_have_cc_tls" = "yes yes"; then
+ AC_DEFINE(HAVE_CC_TLS, 1,
+ [Define to 1 if the target assembler supports thread-local storage.])
+ fi])
+
+dnl Check whether TLS is emulated.
+AC_DEFUN([GCC_CHECK_EMUTLS], [
+ AC_CACHE_CHECK([whether the thread-local storage support is from emutls],
+ gcc_cv_use_emutls, [
+ gcc_cv_use_emutls=no
+ echo '__thread int a; int b; int main() { return a = b; }' > conftest.c
+ if AC_TRY_COMMAND(${CC-cc} -Werror -S -o conftest.s conftest.c 1>&AS_MESSAGE_LOG_FD); then
+ if grep __emutls_get_address conftest.s > /dev/null; then
+ gcc_cv_use_emutls=yes
+ fi
+ fi
+ rm -f conftest.*
+ ])
+ if test "$gcc_cv_use_emutls" = "yes" ; then
+ AC_DEFINE(USE_EMUTLS, 1,
+ [Define to 1 if the target use emutls for thread-local storage.])
+ fi])