1dnl Check whether the target supports TLS.
2AC_DEFUN([GCC_CHECK_TLS], [
3  AC_REQUIRE([AC_CANONICAL_HOST])
4  GCC_ENABLE(tls, yes, [], [Use thread-local storage])
5  AC_CACHE_CHECK([whether the target supports thread-local storage],
6		 gcc_cv_have_tls, [
7    AC_RUN_IFELSE([__thread int a; int b; int main() { return a = b; }],
8      [dnl If the test case passed with dynamic linking, try again with
9       dnl static linking, but only if static linking is supported (not
10       dnl on Solaris 10).  This fails with some older Red Hat releases.
11      chktls_save_LDFLAGS="$LDFLAGS"
12      LDFLAGS="-static $LDFLAGS"
13      AC_LINK_IFELSE([int main() { return 0; }],
14	[AC_RUN_IFELSE([__thread int a; int b; int main() { return a = b; }],
15		       [gcc_cv_have_tls=yes], [gcc_cv_have_tls=no],[])],
16	[gcc_cv_have_tls=yes])
17      LDFLAGS="$chktls_save_LDFLAGS"
18      if test $gcc_cv_have_tls = yes; then
19	dnl So far, the binutils and the compiler support TLS.
20	dnl Also check whether the libc supports TLS, i.e. whether a variable
21	dnl with __thread linkage has a different address in different threads.
22	dnl First, find the thread_CFLAGS necessary for linking a program that
23	dnl calls pthread_create.
24	chktls_save_CFLAGS="$CFLAGS"
25	thread_CFLAGS=failed
26	for flag in '' '-pthread' '-lpthread'; do
27	  CFLAGS="$flag $chktls_save_CFLAGS"
28	  AC_LINK_IFELSE(
29	    [AC_LANG_PROGRAM(
30	       [#include <pthread.h>
31		void *g(void *d) { return NULL; }],
32	       [pthread_t t; pthread_create(&t,NULL,g,NULL);])],
33	    [thread_CFLAGS="$flag"])
34	  if test "X$thread_CFLAGS" != Xfailed; then
35	    break
36	  fi
37	done
38	CFLAGS="$chktls_save_CFLAGS"
39	if test "X$thread_CFLAGS" != Xfailed; then
40	  CFLAGS="$thread_CFLAGS $chktls_save_CFLAGS"
41 	  dnl Test for an old glibc bug that violated the __thread property.
42	  dnl Use volatile to ensure the compiler won't optimize away pointer
43	  dnl accesses it might otherwise assume to be redundant, or reorder 
44	  dnl them and reuse storage, which might lead to them pointing to
45	  dnl the same location.
46	  AC_RUN_IFELSE(
47	    [AC_LANG_PROGRAM(
48	       [#include <pthread.h>
49		__thread int a;
50		static int *volatile a_in_other_thread;
51		static void *
52		thread_func (void *arg)
53		{
54		  a_in_other_thread = &a;
55		  return (void *)0;
56		}],
57	       [pthread_t thread;
58		void *thread_retval;
59		int *volatile a_in_main_thread;
60		a_in_main_thread = &a;
61		if (pthread_create (&thread, (pthread_attr_t *)0,
62				    thread_func, (void *)0))
63		  return 0;
64		if (pthread_join (thread, &thread_retval))
65		  return 0;
66		return (a_in_other_thread == a_in_main_thread);])],
67	     [gcc_cv_have_tls=yes], [gcc_cv_have_tls=no], [])
68	  CFLAGS="$chktls_save_CFLAGS"
69	fi
70      fi],
71      [gcc_cv_have_tls=no],
72      [dnl This is the cross-compiling case. Assume libc supports TLS if the
73       dnl binutils and the compiler do.
74       AC_LINK_IFELSE([__thread int a; int b; int main() { return a = b; }],
75	 [chktls_save_LDFLAGS="$LDFLAGS"
76	  dnl Shared library options may depend on the host; this check
77	  dnl is only known to be needed for GNU/Linux.
78	  case $host in
79	    *-*-linux*)
80	      LDFLAGS="-shared -Wl,--no-undefined $LDFLAGS"
81	      ;;
82	  esac
83	  chktls_save_CFLAGS="$CFLAGS"
84	  CFLAGS="-fPIC $CFLAGS"
85	  dnl If -shared works, test if TLS works in a shared library.
86	  AC_LINK_IFELSE([int f() { return 0; }],
87	    [AC_LINK_IFELSE([__thread int a; int b; int f() { return a = b; }],
88	      [gcc_cv_have_tls=yes],
89	      [gcc_cv_have_tls=no])],
90	    [gcc_cv_have_tls=yes])
91	  CFLAGS="$chktls_save_CFLAGS"
92	  LDFLAGS="$chktls_save_LDFLAGS"], [gcc_cv_have_tls=no])
93      ]
94    )])
95  if test "$enable_tls $gcc_cv_have_tls" = "yes yes"; then
96    AC_DEFINE(HAVE_TLS, 1,
97	      [Define to 1 if the target supports thread-local storage.])
98  fi])
99
100dnl Check whether the target assembler supports TLS.
101AC_DEFUN([GCC_CHECK_CC_TLS], [
102  GCC_ENABLE(tls, yes, [], [Use thread-local storage])
103  AC_CACHE_CHECK([whether the target assembler supports thread-local storage],
104		 gcc_cv_have_cc_tls, [
105    AC_COMPILE_IFELSE([__thread int a; int b; int main() { return a = b; }],
106      [gcc_cv_have_cc_tls=yes], [gcc_cv_have_cc_tls=no])]
107    )])
108  if test "$enable_tls $gcc_cv_have_cc_tls" = "yes yes"; then
109    AC_DEFINE(HAVE_CC_TLS, 1,
110	      [Define to 1 if the target assembler supports thread-local storage.])
111  fi])
112
113dnl Check whether TLS is emulated.
114AC_DEFUN([GCC_CHECK_EMUTLS], [
115  AC_CACHE_CHECK([whether the thread-local storage support is from emutls],
116  		 gcc_cv_use_emutls, [
117    gcc_cv_use_emutls=no
118    echo '__thread int a; int b; int main() { return a = b; }' > conftest.c
119    if AC_TRY_COMMAND(${CC-cc} -Werror -S -o conftest.s conftest.c 1>&AS_MESSAGE_LOG_FD); then
120      if grep __emutls_get_address conftest.s > /dev/null; then
121	gcc_cv_use_emutls=yes
122      fi
123    fi
124    rm -f conftest.*
125    ])
126  if test "$gcc_cv_use_emutls" = "yes" ; then
127    AC_DEFINE(USE_EMUTLS, 1,
128      	      [Define to 1 if the target use emutls for thread-local storage.])
129  fi])
130