| 1 | dnl Check whether the target supports TLS. |
| 2 | AC_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([AC_LANG_SOURCE([__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 $LDFLAGS" |
| 13 | AC_LINK_IFELSE([AC_LANG_SOURCE([int main() { return 0; }])], |
| 14 | [AC_RUN_IFELSE([AC_LANG_SOURCE([__thread int a; int b; int main() { return a = b; }])], |
| 15 | [gcc_cv_have_tls=yes], [gcc_cv_have_tls=no],[])], |
| 16 | [gcc_cv_have_tls=yes]) |
| 17 | LDFLAGS="$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([AC_LANG_SOURCE([__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 $CFLAGS" |
| 85 | dnl If -shared works, test if TLS works in a shared library. |
| 86 | AC_LINK_IFELSE([AC_LANG_SOURCE([int f() { return 0; }])], |
| 87 | [AC_LINK_IFELSE([AC_LANG_SOURCE([__thread int a; int b; int f() { return a = b; }])], |
| 88 | [gcc_cv_have_tls=yes], |
| 89 | [gcc_cv_have_tls=no])], |
| 90 | [gcc_cv_have_tls=yes]) |
| 91 | CFLAGS="$chktls_save_CFLAGS" |
| 92 | LDFLAGS="$chktls_save_LDFLAGS"], [gcc_cv_have_tls=no]) |
| 93 | ] |
| 94 | )]) |
| 95 | if test "$enable_tls $gcc_cv_have_tls" = "yes yes"; then |
| 96 | AC_DEFINE(HAVE_TLS, 1, |
| 97 | [Define to 1 if the target supports thread-local storage.]) |
| 98 | fi]) |
| 99 | |
| 100 | dnl Check whether the target assembler supports TLS. |
| 101 | AC_DEFUN([GCC_CHECK_CC_TLS], [ |
| 102 | GCC_ENABLE(tls, yes, [], [Use thread-local storage]) |
| 103 | AC_CACHE_CHECK([whether the target assembler supports thread-local storage], |
| 104 | gcc_cv_have_cc_tls, [ |
| 105 | AC_COMPILE_IFELSE([AC_LANG_SOURCE([__thread int a; int b; int main() { return a = b; }])], |
| 106 | [gcc_cv_have_cc_tls=yes], [gcc_cv_have_cc_tls=no])] |
| 107 | )]) |
| 108 | if test "$enable_tls $gcc_cv_have_cc_tls" = "yes yes"; then |
| 109 | AC_DEFINE(HAVE_CC_TLS, 1, |
| 110 | [Define to 1 if the target assembler supports thread-local storage.]) |
| 111 | fi]) |
| 112 | |
| 113 | dnl Check whether TLS is emulated. |
| 114 | AC_DEFUN([GCC_CHECK_EMUTLS], [ |
| 115 | AC_CACHE_CHECK([whether the thread-local storage support is from emutls], |
| 116 | gcc_cv_use_emutls, [ |
| 117 | gcc_cv_use_emutls=no |
| 118 | echo '__thread int a; int b; int main() { return a = b; }' > conftest.c |
| 119 | if AC_TRY_COMMAND(${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]) |