| 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, [ |
| 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 |
| dnl on Solaris 10). This fails with some older Red Hat releases. |
| chktls_save_LDFLAGS="$LDFLAGS" |
| LDFLAGS="-static $LDFLAGS" |
| AC_LINK_IFELSE([int main() { return 0; }], |
| [AC_RUN_IFELSE([__thread int a; int b; int main() { return a = b; }], |
| [gcc_cv_have_tls=yes], [gcc_cv_have_tls=no],[])], |
| [gcc_cv_have_tls=yes]) |
| LDFLAGS="$chktls_save_LDFLAGS" |
| if test $gcc_cv_have_tls = yes; then |
| dnl So far, the binutils and the compiler support TLS. |
| dnl Also check whether the libc supports TLS, i.e. whether a variable |
| dnl with __thread linkage has a different address in different threads. |
| dnl First, find the thread_CFLAGS necessary for linking a program that |
| dnl calls pthread_create. |
| chktls_save_CFLAGS="$CFLAGS" |
| thread_CFLAGS=failed |
| for flag in '' '-pthread' '-lpthread'; do |
| CFLAGS="$flag $chktls_save_CFLAGS" |
| AC_LINK_IFELSE( |
| [AC_LANG_PROGRAM( |
| [#include <pthread.h> |
| void *g(void *d) { return NULL; }], |
| [pthread_t t; pthread_create(&t,NULL,g,NULL);])], |
| [thread_CFLAGS="$flag"]) |
| if test "X$thread_CFLAGS" != Xfailed; then |
| break |
| fi |
| done |
| CFLAGS="$chktls_save_CFLAGS" |
| if test "X$thread_CFLAGS" != Xfailed; then |
| CFLAGS="$thread_CFLAGS $chktls_save_CFLAGS" |
| dnl Test for an old glibc bug that violated the __thread property. |
| dnl Use volatile to ensure the compiler won't optimize away pointer |
| dnl accesses it might otherwise assume to be redundant, or reorder |
| dnl them and reuse storage, which might lead to them pointing to |
| dnl the same location. |
| AC_RUN_IFELSE( |
| [AC_LANG_PROGRAM( |
| [#include <pthread.h> |
| __thread int a; |
| static int *volatile a_in_other_thread; |
| static void * |
| thread_func (void *arg) |
| { |
| a_in_other_thread = &a; |
| return (void *)0; |
| }], |
| [pthread_t thread; |
| void *thread_retval; |
| int *volatile a_in_main_thread; |
| a_in_main_thread = &a; |
| if (pthread_create (&thread, (pthread_attr_t *)0, |
| thread_func, (void *)0)) |
| return 0; |
| if (pthread_join (thread, &thread_retval)) |
| return 0; |
| return (a_in_other_thread == a_in_main_thread);])], |
| [gcc_cv_have_tls=yes], [gcc_cv_have_tls=no], []) |
| CFLAGS="$chktls_save_CFLAGS" |
| fi |
| fi], |
| [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; }], |
| [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 $gcc_cv_have_tls" = "yes yes"; then |
| AC_DEFINE(HAVE_TLS, 1, |
| [Define to 1 if the target supports thread-local storage.]) |
| fi]) |
| |
| dnl Check whether the target assembler supports TLS. |
| AC_DEFUN([GCC_CHECK_CC_TLS], [ |
| GCC_ENABLE(tls, yes, [], [Use thread-local storage]) |
| AC_CACHE_CHECK([whether the target assembler supports thread-local storage], |
| gcc_cv_have_cc_tls, [ |
| AC_COMPILE_IFELSE([__thread int a; int b; int main() { return a = b; }], |
| [gcc_cv_have_cc_tls=yes], [gcc_cv_have_cc_tls=no])] |
| )]) |
| if test "$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]) |