daily update
[binutils.git] / config / tls.m4
blobacb123f6986d499a37d24816065cb53c57e34436
1 dnl Check whether the target supports TLS.
2 AC_DEFUN([GCC_CHECK_TLS], [
3   GCC_ENABLE(tls, yes, [], [Use thread-local storage])
4   AC_CACHE_CHECK([whether the target supports thread-local storage],
5                  gcc_cv_have_tls, [
6     AC_RUN_IFELSE([__thread int a; int b; int main() { return a = b; }],
7       [dnl If the test case passed with dynamic linking, try again with
8        dnl static linking, but only if static linking is supported (not
9        dnl on Solaris 10).  This fails with some older Red Hat releases.
10       chktls_save_LDFLAGS="$LDFLAGS"
11       LDFLAGS="-static $LDFLAGS"
12       AC_LINK_IFELSE([int main() { return 0; }],
13         AC_RUN_IFELSE([__thread int a; int b; int main() { return a = b; }],
14                       [gcc_cv_have_tls=yes], [gcc_cv_have_tls=no],[]),
15         [gcc_cv_have_tls=yes])
16       LDFLAGS="$chktls_save_LDFLAGS"
17       if test $gcc_cv_have_tls = yes; then
18         dnl So far, the binutils and the compiler support TLS.
19         dnl Also check whether the libc supports TLS, i.e. whether a variable
20         dnl with __thread linkage has a different address in different threads.
21         dnl First, find the thread_CFLAGS necessary for linking a program that
22         dnl calls pthread_create.
23         chktls_save_CFLAGS="$CFLAGS"
24         thread_CFLAGS=failed
25         for flag in '' '-pthread' '-lpthread'; do
26           CFLAGS="$flag $chktls_save_CFLAGS"
27           AC_LINK_IFELSE(
28             [AC_LANG_PROGRAM(
29                [#include <pthread.h>
30                 void *g(void *d) { return NULL; }],
31                [pthread_t t; pthread_create(&t,NULL,g,NULL);])],
32             [thread_CFLAGS="$flag"])
33           if test "X$thread_CFLAGS" != Xfailed; then
34             break
35           fi
36         done
37         CFLAGS="$chktls_save_CFLAGS"
38         if test "X$thread_CFLAGS" != Xfailed; then
39           CFLAGS="$thread_CFLAGS $chktls_save_CFLAGS"
40           AC_RUN_IFELSE(
41             [AC_LANG_PROGRAM(
42                [#include <pthread.h>
43                 __thread int a;
44                 static int *a_in_other_thread;
45                 static void *
46                 thread_func (void *arg)
47                 {
48                   a_in_other_thread = &a;
49                   return (void *)0;
50                 }],
51                [pthread_t thread;
52                 void *thread_retval;
53                 int *a_in_main_thread;
54                 if (pthread_create (&thread, (pthread_attr_t *)0,
55                                     thread_func, (void *)0))
56                   return 0;
57                 a_in_main_thread = &a;
58                 if (pthread_join (thread, &thread_retval))
59                   return 0;
60                 return (a_in_other_thread == a_in_main_thread);])],
61              [gcc_cv_have_tls=yes], [gcc_cv_have_tls=no], [])
62           CFLAGS="$chktls_save_CFLAGS"
63         fi
64       fi],
65       [gcc_cv_have_tls=no],
66       [dnl This is the cross-compiling case. Assume libc supports TLS if the
67        dnl binutils and the compiler do.
68        AC_LINK_IFELSE([__thread int a; int b; int main() { return a = b; }],
69                       [gcc_cv_have_tls=yes], [gcc_cv_have_tls=no])
70       ]
71     )])
72   if test "$enable_tls $gcc_cv_have_tls" = "yes yes"; then
73     AC_DEFINE(HAVE_TLS, 1,
74               [Define to 1 if the target supports thread-local storage.])
75   fi])
77 dnl Check whether the target assembler supports TLS.
78 AC_DEFUN([GCC_CHECK_CC_TLS], [
79   GCC_ENABLE(tls, yes, [], [Use thread-local storage])
80   AC_CACHE_CHECK([whether the target assembler supports thread-local storage],
81                  gcc_cv_have_cc_tls, [
82     AC_COMPILE_IFELSE([__thread int a; int b; int main() { return a = b; }],
83       [gcc_cv_have_cc_tls=yes], [gcc_cv_have_cc_tls=no])]
84     )])
85   if test "$enable_tls $gcc_cv_have_cc_tls" = "yes yes"; then
86     AC_DEFINE(HAVE_CC_TLS, 1,
87               [Define to 1 if the target assembler supports thread-local storage.])
88   fi])