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1 dnl Check whether the target supports TLS.
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2 AC_DEFUN([GCC_CHECK_TLS], [
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3 GCC_ENABLE(tls, yes, [], [Use thread-local storage])
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4 AC_CACHE_CHECK([whether the target supports thread-local storage],
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5 gcc_cv_have_tls, [
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6 AC_RUN_IFELSE([__thread int a; int b; int main() { return a = b; }],
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7 [dnl If the test case passed with dynamic linking, try again with
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8 dnl static linking, but only if static linking is supported (not
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9 dnl on Solaris 10). This fails with some older Red Hat releases.
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10 chktls_save_LDFLAGS="$LDFLAGS"
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11 LDFLAGS="-static $LDFLAGS"
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12 AC_LINK_IFELSE([int main() { return 0; }],
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13 AC_RUN_IFELSE([__thread int a; int b; int main() { return a = b; }],
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14 [gcc_cv_have_tls=yes], [gcc_cv_have_tls=no],[]),
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15 [gcc_cv_have_tls=yes])
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16 LDFLAGS="$chktls_save_LDFLAGS"
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17 if test $gcc_cv_have_tls = yes; then
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18 dnl So far, the binutils and the compiler support TLS.
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19 dnl Also check whether the libc supports TLS, i.e. whether a variable
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20 dnl with __thread linkage has a different address in different threads.
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21 dnl First, find the thread_CFLAGS necessary for linking a program that
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22 dnl calls pthread_create.
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23 chktls_save_CFLAGS="$CFLAGS"
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24 thread_CFLAGS=failed
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25 for flag in '' '-pthread' '-lpthread'; do
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26 CFLAGS="$flag $chktls_save_CFLAGS"
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27 AC_LINK_IFELSE(
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28 [AC_LANG_PROGRAM(
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29 [#include <pthread.h>
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30 void *g(void *d) { return NULL; }],
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31 [pthread_t t; pthread_create(&t,NULL,g,NULL);])],
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32 [thread_CFLAGS="$flag"])
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33 if test "X$thread_CFLAGS" != Xfailed; then
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34 break
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35 fi
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36 done
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37 CFLAGS="$chktls_save_CFLAGS"
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38 if test "X$thread_CFLAGS" != Xfailed; then
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39 CFLAGS="$thread_CFLAGS $chktls_save_CFLAGS"
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40 AC_RUN_IFELSE(
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41 [AC_LANG_PROGRAM(
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42 [#include <pthread.h>
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43 __thread int a;
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44 static int *a_in_other_thread;
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45 static void *
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46 thread_func (void *arg)
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47 {
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48 a_in_other_thread = &a;
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49 return (void *)0;
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50 }],
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51 [pthread_t thread;
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52 void *thread_retval;
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53 int *a_in_main_thread;
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54 if (pthread_create (&thread, (pthread_attr_t *)0,
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55 thread_func, (void *)0))
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56 return 0;
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57 a_in_main_thread = &a;
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58 if (pthread_join (thread, &thread_retval))
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59 return 0;
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60 return (a_in_other_thread == a_in_main_thread);])],
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61 [gcc_cv_have_tls=yes], [gcc_cv_have_tls=no], [])
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62 CFLAGS="$chktls_save_CFLAGS"
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63 fi
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64 fi],
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65 [gcc_cv_have_tls=no],
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66 [dnl This is the cross-compiling case. Assume libc supports TLS if the
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67 dnl binutils and the compiler do.
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68 AC_LINK_IFELSE([__thread int a; int b; int main() { return a = b; }],
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69 [gcc_cv_have_tls=yes], [gcc_cv_have_tls=no])
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70 ]
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71 )])
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72 if test "$enable_tls $gcc_cv_have_tls" = "yes yes"; then
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73 AC_DEFINE(HAVE_TLS, 1,
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74 [Define to 1 if the target supports thread-local storage.])
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75 fi])
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76
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77 dnl Check whether the target assembler supports TLS.
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78 AC_DEFUN([GCC_CHECK_CC_TLS], [
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79 GCC_ENABLE(tls, yes, [], [Use thread-local storage])
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80 AC_CACHE_CHECK([whether the target assembler supports thread-local storage],
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81 gcc_cv_have_cc_tls, [
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82 AC_COMPILE_IFELSE([__thread int a; int b; int main() { return a = b; }],
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83 [gcc_cv_have_cc_tls=yes], [gcc_cv_have_cc_tls=no])]
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84 )])
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85 if test "$enable_tls $gcc_cv_have_cc_tls" = "yes yes"; then
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86 AC_DEFINE(HAVE_CC_TLS, 1,
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87 [Define to 1 if the target assembler supports thread-local storage.])
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88 fi])
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89
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90 dnl Check whether TLS is emulated.
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91 AC_DEFUN([GCC_CHECK_EMUTLS], [
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92 AC_CACHE_CHECK([whether the thread-local storage support is from emutls],
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93 gcc_cv_use_emutls, [
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94 gcc_cv_use_emutls=no
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95 echo '__thread int a; int b; int main() { return a = b; }' > conftest.c
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96 if AC_TRY_COMMAND(${CC-cc} -Werror -S -o conftest.s conftest.c 1>&AS_MESSAGE_LOG_FD); then
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97 if grep __emutls_get_address conftest.s > /dev/null; then
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98 gcc_cv_use_emutls=yes
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99 fi
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100 fi
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101 rm -f conftest.*
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102 ])
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103 if test "$gcc_cv_use_emutls" = "yes" ; then
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104 AC_DEFINE(USE_EMUTLS, 1,
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105 [Define to 1 if the target use emutls for thread-local storage.])
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106 fi])
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