* bootstrap-lto.mk: New.

[deliverable/binutils-gdb.git] / config / tls.m4

diff --git a/config/tls.m4 b/config/tls.m4
index 0ae60460bab540ed302bfa63b41df32158d40a2d..4e170c8d6aec3194bc1124b7726ae478b0fcdbff 100644 (file)
--- a/config/tls.m4
+++ b/config/tls.m4
@@ -11,8 +11,8 @@ AC_DEFUN([GCC_CHECK_TLS], [
       chktls_save_LDFLAGS="$LDFLAGS"
       LDFLAGS="-static $LDFLAGS"
       AC_LINK_IFELSE([int main() { return 0; }],
-       AC_RUN_IFELSE([__thread int a; int b; int main() { return a = b; }],
-                     [gcc_cv_have_tls=yes], [gcc_cv_have_tls=no],[]),
+       [AC_RUN_IFELSE([__thread int a; int b; int main() { return a = b; }],
+                      [gcc_cv_have_tls=yes], [gcc_cv_have_tls=no],[])],
        [gcc_cv_have_tls=yes])
       LDFLAGS="$chktls_save_LDFLAGS"
       if test $gcc_cv_have_tls = yes; then
@@ -38,11 +38,16 @@ AC_DEFUN([GCC_CHECK_TLS], [
        CFLAGS="$chktls_save_CFLAGS"
        if test "X$thread_CFLAGS" != Xfailed; then
          CFLAGS="$thread_CFLAGS $chktls_save_CFLAGS"
+         dnl Test for an old glibc bug that violated the __thread property.
+         dnl Use volatile to ensure the compiler won't optimize away pointer
+         dnl accesses it might otherwise assume to be redundant, or reorder 
+         dnl them and reuse storage, which might lead to them pointing to
+         dnl the same location.
          AC_RUN_IFELSE(
            [AC_LANG_PROGRAM(
               [#include <pthread.h>
                __thread int a;
-               static int *a_in_other_thread;
+               static int *volatile a_in_other_thread;
                static void *
                thread_func (void *arg)
                {
@@ -51,11 +56,11 @@ AC_DEFUN([GCC_CHECK_TLS], [
                }],
               [pthread_t thread;
                void *thread_retval;
-               int *a_in_main_thread;
+               int *volatile a_in_main_thread;
+               a_in_main_thread = &a;
                if (pthread_create (&thread, (pthread_attr_t *)0,
                                    thread_func, (void *)0))
                  return 0;
-               a_in_main_thread = &a;
                if (pthread_join (thread, &thread_retval))
                  return 0;
                return (a_in_other_thread == a_in_main_thread);])],
@@ -104,3 +109,21 @@ AC_DEFUN([GCC_CHECK_CC_TLS], [
     AC_DEFINE(HAVE_CC_TLS, 1,
              [Define to 1 if the target assembler supports thread-local storage.])
   fi])
+
+dnl Check whether TLS is emulated.
+AC_DEFUN([GCC_CHECK_EMUTLS], [
+  AC_CACHE_CHECK([whether the thread-local storage support is from emutls],
+                gcc_cv_use_emutls, [
+    gcc_cv_use_emutls=no
+    echo '__thread int a; int b; int main() { return a = b; }' > conftest.c
+    if AC_TRY_COMMAND(${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])