From d7a01582424ff0119493cb7d41d382849328a118 Mon Sep 17 00:00:00 2001 From: Karel Zak Date: Fri, 4 Dec 2009 15:45:19 +0100 Subject: [PATCH] build-sys: rewrite TLS detection * use more robust tls.m4 from gcc project The old version (from util-linux-ng) used AC_TRY_COMPILE. That's wrong. We need to use AC_RUN_IFELSE to check that the result is link-able and executable. The new version also test it TLS really works in multi-thread applications. * we need to detect TLS usability for cross-compiling * this new version supports __thread keyword only, it seems that we needn't to care about anything other Signed-off-by: Karel Zak --- configure.ac | 9 +-- m4/tls.m4 | 145 ++++++++++++++++++++++++++----------- shlibs/uuid/src/gen_uuid.c | 6 +- 3 files changed, 108 insertions(+), 52 deletions(-) diff --git a/configure.ac b/configure.ac index 886700d3..fd692abc 100644 --- a/configure.ac +++ b/configure.ac @@ -242,14 +242,7 @@ AC_DEFUN([UTIL_RESTORE_FLAGS], [ ]) -AC_ARG_ENABLE([tls], - AS_HELP_STRING([--disable-tls], [disable use of thread local support]), - [], enable_tls=yes -) -if test "x$enable_tls" = xyes; then - AX_TLS -fi - +AX_CHECK_TLS AC_ARG_ENABLE([mount], AS_HELP_STRING([--disable-mount], [do not build mount utilities]), diff --git a/m4/tls.m4 b/m4/tls.m4 index 5644ba70..7adb09ac 100644 --- a/m4/tls.m4 +++ b/m4/tls.m4 @@ -1,48 +1,111 @@ -# from http://autoconf-archive.cryp.to/ax_tls.html # -# This was licensed under the GPL with the following exception: +# AX_CHECK_TLS -- check whether the target supports TLS (thread-local storage) # -# As a special exception, the respective Autoconf Macro's copyright -# owner gives unlimited permission to copy, distribute and modify the -# configure scripts that are the output of Autoconf when processing -# the Macro. You need not follow the terms of the GNU General Public -# License when using or distributing such scripts, even though -# portions of the text of the Macro appear in them. The GNU General -# Public License (GPL) does govern all other use of the material that -# constitutes the Autoconf Macro. +# Based on tls.m4 from gcc and extended by TLS link test for cross-compiling +# support from http://old.nabble.com/Improve-TLS-link-test-for-cross-compiling-td24312975.html # -# This special exception to the GPL applies to versions of the -# Autoconf Macro released by the Autoconf Macro Archive. When you make -# and distribute a modified version of the Autoconf Macro, you may -# extend this special exception to the GPL to apply to your modified -# version as well. +# Note that AX_TLS from http://autoconf-archive.cryp.to/ax_tls.html supports +# more keywords for TLS. We are happy with the "__thread" only. # -AC_DEFUN([AX_TLS], [ - AC_MSG_CHECKING(for thread local storage (TLS) class) - AC_CACHE_VAL(ac_cv_tls, [ - ax_tls_keywords="__thread __declspec(thread) none" - for ax_tls_keyword in $ax_tls_keywords; do - case $ax_tls_keyword in - none) ac_cv_tls=none ; break ;; - *) - AC_TRY_COMPILE( - [#include - static void - foo(void) { - static ] $ax_tls_keyword [ int bar; - exit(1); - }], - [], - [ac_cv_tls=$ax_tls_keyword ; break], - ac_cv_tls=none - ) - esac - done -]) +# -- Karel Zak (04-Dec-2009) +# +dnl Check whether the target supports TLS. +AC_DEFUN([AX_CHECK_TLS], [ + + AC_REQUIRE([AC_CANONICAL_HOST]) + + AC_ARG_ENABLE([tls], + AS_HELP_STRING([--disable-tls], [disable use of thread local support]), + [], enable_tls=yes) + + AC_CACHE_CHECK([whether the target supports thread-local storage], + ax_cv_have_tls, [ + AC_RUN_IFELSE([__thread int a; int b; int main() { return a = b; }], + [dnl If the test case passed with dynamic linking, try again with + dnl static linking, but only if static linking is supported (not + dnl on Solaris 10). This fails with some older Red Hat releases. + chktls_save_LDFLAGS="$LDFLAGS" + LDFLAGS="-static $LDFLAGS" + AC_LINK_IFELSE([int main() { return 0; }], + AC_RUN_IFELSE([__thread int a; int b; int main() { return a = b; }], + [ax_cv_have_tls=yes], [ax_cv_have_tls=no],[]), + [ax_cv_have_tls=yes]) + LDFLAGS="$chktls_save_LDFLAGS" + if test $ax_cv_have_tls = yes; then + dnl So far, the binutils and the compiler support TLS. + dnl Also check whether the libc supports TLS, i.e. whether a variable + dnl with __thread linkage has a different address in different threads. + dnl First, find the thread_CFLAGS necessary for linking a program that + dnl calls pthread_create. + chktls_save_CFLAGS="$CFLAGS" + thread_CFLAGS=failed + for flag in '' '-pthread' '-lpthread'; do + CFLAGS="$flag $chktls_save_CFLAGS" + AC_LINK_IFELSE( + [AC_LANG_PROGRAM( + [#include + void *g(void *d) { return NULL; }], + [pthread_t t; pthread_create(&t,NULL,g,NULL);])], + [thread_CFLAGS="$flag"]) + if test "X$thread_CFLAGS" != Xfailed; then + break + fi + done + CFLAGS="$chktls_save_CFLAGS" + if test "X$thread_CFLAGS" != Xfailed; then + CFLAGS="$thread_CFLAGS $chktls_save_CFLAGS" + AC_RUN_IFELSE( + [AC_LANG_PROGRAM( + [#include + __thread int a; + static int *a_in_other_thread; + static void * + thread_func (void *arg) + { + a_in_other_thread = &a; + return (void *)0; + }], + [pthread_t thread; + void *thread_retval; + int *a_in_main_thread; + if (pthread_create (&thread, (pthread_attr_t *)0, + thread_func, (void *)0)) + return 0; + a_in_main_thread = &a; + if (pthread_join (thread, &thread_retval)) + return 0; + return (a_in_other_thread == a_in_main_thread);])], + [ax_cv_have_tls=yes], [ax_cv_have_tls=no], []) + CFLAGS="$chktls_save_CFLAGS" + fi + fi], + [ax_cv_have_tls=no], + [dnl This is the cross-compiling case. Assume libc supports TLS if the + dnl binutils and the compiler do. + AC_LINK_IFELSE([__thread int a; int b; int main() { return a = b; }], + [chktls_save_LDFLAGS="$LDFLAGS" + dnl Shared library options may depend on the host; this check + dnl is only known to be needed for GNU/Linux. + case $host in + *-*-linux*) + LDFLAGS="-shared -Wl,--no-undefined $LDFLAGS" + ;; + esac + chktls_save_CFLAGS="$CFLAGS" + CFLAGS="-fPIC $CFLAGS" + dnl If -shared works, test if TLS works in a shared library. + AC_LINK_IFELSE([int f() { return 0; }], + [AC_LINK_IFELSE([__thread int a; int b; int f() { return a = b; }], + [ax_cv_have_tls=yes], + [ax_cv_have_tls=no])], + [ax_cv_have_tls=yes]) + CFLAGS="$chktls_save_CFLAGS" + LDFLAGS="$chktls_save_LDFLAGS"], [ax_cv_have_tls=no]) + ] + )]) - if test "$ac_cv_tls" != "none"; then - dnl AC_DEFINE([TLS], [], [If the compiler supports a TLS storage class define it to that here]) - AC_DEFINE_UNQUOTED([TLS], $ac_cv_tls, [If the compiler supports a TLS storage class define it to that here]) + if test "$enable_tls $ax_cv_have_tls" = "yes yes"; then + AC_DEFINE(HAVE_TLS, 1, + [Define to 1 if the target supports thread-local storage.]) fi - AC_MSG_RESULT($ac_cv_tls) ]) diff --git a/shlibs/uuid/src/gen_uuid.c b/shlibs/uuid/src/gen_uuid.c index 8bb29f38..5434b523 100644 --- a/shlibs/uuid/src/gen_uuid.c +++ b/shlibs/uuid/src/gen_uuid.c @@ -98,8 +98,8 @@ #define rand() random() #endif -#ifdef TLS -#define THREAD_LOCAL static TLS +#ifdef HAVE_TLS +#define THREAD_LOCAL static __thread #else #define THREAD_LOCAL static #endif @@ -589,7 +589,7 @@ void uuid__generate_time(uuid_t out, int *num) void uuid_generate_time(uuid_t out) { -#ifdef TLS +#ifdef HAVE_TLS THREAD_LOCAL int num = 0; THREAD_LOCAL struct uuid uu; THREAD_LOCAL time_t last_time = 0; -- 2.39.5