76 lines
2.6 KiB
Plaintext
76 lines
2.6 KiB
Plaintext
dnl Check whether the target supports TLS.
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AC_DEFUN([GCC_CHECK_TLS], [
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GCC_ENABLE(tls, yes, [], [Use thread-local storage])
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AC_CACHE_CHECK([whether the target supports thread-local storage],
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have_tls, [
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AC_RUN_IFELSE([__thread int a; int b; int main() { return a = b; }],
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[dnl If the test case passed with dynamic linking, try again with
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dnl static linking, but only if static linking is supported (not
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dnl on Solaris 10). This fails with some older Red Hat releases.
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chktls_save_LDFLAGS="$LDFLAGS"
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LDFLAGS="-static $LDFLAGS"
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AC_LINK_IFELSE([int main() { return 0; }],
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AC_RUN_IFELSE([__thread int a; int b; int main() { return a = b; }],
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[have_tls=yes], [have_tls=no],[]),
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[have_tls=yes])
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LDFLAGS="$chktls_save_LDFLAGS"
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if test $have_tls = yes; then
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dnl So far, the binutils and the compiler support TLS.
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dnl Also check whether the libc supports TLS, i.e. whether a variable
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dnl with __thread linkage has a different address in different threads.
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dnl First, find the thread_CFLAGS necessary for linking a program that
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dnl calls pthread_create.
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chktls_save_CFLAGS="$CFLAGS"
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thread_CFLAGS=failed
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for flag in '' '-pthread' '-lpthread'; do
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CFLAGS="$flag $chktls_save_CFLAGS"
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AC_LINK_IFELSE(
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[AC_LANG_PROGRAM(
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[#include <pthread.h>
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void *g(void *d) { return NULL; }],
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[pthread_t t; pthread_create(&t,NULL,g,NULL);])],
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[thread_CFLAGS="$flag"])
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if test "X$thread_CFLAGS" != Xfailed; then
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break
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fi
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done
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CFLAGS="$chktls_save_CFLAGS"
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if test "X$thread_CFLAGS" != Xfailed; then
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CFLAGS="$thread_CFLAGS $chktls_save_CFLAGS"
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AC_RUN_IFELSE(
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[AC_LANG_PROGRAM(
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[#include <pthread.h>
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__thread int a;
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static int *a_in_other_thread;
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static void *
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thread_func (void *arg)
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{
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a_in_other_thread = &a;
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return (void *)0;
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}],
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[pthread_t thread;
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void *thread_retval;
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int *a_in_main_thread;
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if (pthread_create (&thread, (pthread_attr_t *)0,
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thread_func, (void *)0))
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return 0;
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a_in_main_thread = &a;
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if (pthread_join (thread, &thread_retval))
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return 0;
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return (a_in_other_thread == a_in_main_thread);])],
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[have_tls=yes], [have_tls=no], [])
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CFLAGS="$chktls_save_CFLAGS"
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fi
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fi],
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[have_tls=no],
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[dnl This is the cross-compiling case. Assume libc supports TLS if the
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dnl binutils and the compiler do.
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AC_LINK_IFELSE([__thread int a; int b; int main() { return a = b; }],
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[have_tls=yes], [have_tls=no])
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]
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)])
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if test "$enable_tls $have_tls" = "yes yes"; then
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AC_DEFINE(HAVE_TLS, 1,
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[Define to 1 if the target supports thread-local storage.])
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fi])
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