[lttng-dev] [RFC PATCH urcu] Add TLS detection m4 macro

Mathieu Desnoyers mathieu.desnoyers at efficios.com
Wed May 16 09:56:01 EDT 2012


Will allow urcu to support OSes that require to use pthread TLS (and do
not provide __thread TLS support).
    
Suggested-by: Marek Vavruša <marek.vavrusa at nic.cz>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers at efficios.com>
---
diff --git a/.gitignore b/.gitignore
index 1112e43..15e9fc3 100644
--- a/.gitignore
+++ b/.gitignore
@@ -78,7 +78,6 @@ tests/*.log
 .libs/
 Makefile.in
 Makefile
-*.m4
 *.la
 *.bz2
 *.o
@@ -86,7 +85,18 @@ Makefile
 *.loT
 /config.log
 /configure
-/config/
+/config/compile
+/config/config.guess
+/config/config.sub
+/config/depcomp
+/config/install-sh
+/config/libtool.m4
+/config/ltmain.sh
+/config/lt~obsolete.m4
+/config/ltoptions.m4
+/config/ltsugar.m4
+/config/ltversion.m4
+/config/missing
 /libtool
 /stamp-h1
 /config.h.in
diff --git a/LICENSE b/LICENSE
index ad13f78..eb696b2 100644
--- a/LICENSE
+++ b/LICENSE
@@ -1,6 +1,6 @@
 Userspace RCU library licensing
 Mathieu Desnoyers
-May 10, 2009
+May 15, 2012
 
 
 * LGPLv2.1
@@ -57,3 +57,9 @@ test_urcu.c
 test_urcu_yield.c
 test_rwlock_timing.c
 urcu-asm.c
+
+* GPLv3 (or later)
+
+The following build-related macro is under GPLv3 (or later):
+
+m4/ax_tls.m4
diff --git a/config/ax_tls.m4 b/config/ax_tls.m4
new file mode 100644
index 0000000..033e3b1
--- /dev/null
+++ b/config/ax_tls.m4
@@ -0,0 +1,76 @@
+# ===========================================================================
+#          http://www.gnu.org/software/autoconf-archive/ax_tls.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_TLS([action-if-found], [action-if-not-found])
+#
+# DESCRIPTION
+#
+#   Provides a test for the compiler support of thread local storage (TLS)
+#   extensions. Defines TLS if it is found. Currently knows about GCC/ICC
+#   and MSVC. I think SunPro uses the same as GCC, and Borland apparently
+#   supports either.
+#
+# LICENSE
+#
+#   Copyright (c) 2008 Alan Woodland <ajw05 at aber.ac.uk>
+#   Copyright (c) 2010 Diego Elio Petteno` <flameeyes at gmail.com>
+#
+#   This program is free software: you can redistribute it and/or modify it
+#   under the terms of the GNU General Public License as published by the
+#   Free Software Foundation, either version 3 of the License, or (at your
+#   option) any later version.
+#
+#   This program is distributed in the hope that it will be useful, but
+#   WITHOUT ANY WARRANTY; without even the implied warranty of
+#   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General
+#   Public License for more details.
+#
+#   You should have received a copy of the GNU General Public License along
+#   with this program. If not, see <http://www.gnu.org/licenses/>.
+#
+#   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.
+#
+#   This special exception to the GPL applies to versions of the Autoconf
+#   Macro released by the Autoconf 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.
+
+#serial 10
+
+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 $ax_tls_keywords; do
+       AS_CASE([$ax_tls_keyword],
+          [none], [ac_cv_tls=none ; break],
+          [AC_TRY_COMPILE(
+              [#include <stdlib.h>
+               static void
+               foo(void) {
+               static ] $ax_tls_keyword [ int bar;
+               exit(1);
+               }],
+               [],
+               [ac_cv_tls=$ax_tls_keyword ; break],
+               ac_cv_tls=none
+           )])
+    done
+  ])
+  AC_MSG_RESULT($ac_cv_tls)
+
+  AS_IF([test "$ac_cv_tls" != "none"],
+    AC_DEFINE_UNQUOTED([TLS], $ac_cv_tls, [If the compiler supports a TLS storage class define it to that here])
+      m4_ifnblank([$1], [$1]),
+    m4_ifnblank([$2], [$2])
+  )
+])
diff --git a/configure.ac b/configure.ac
index 6bf1cb9..1790bb8 100644
--- a/configure.ac
+++ b/configure.ac
@@ -15,6 +15,8 @@ AC_CANONICAL_HOST
 AM_INIT_AUTOMAKE([foreign dist-bzip2 no-dist-gzip])
 m4_ifdef([AM_SILENT_RULES], [AM_SILENT_RULES([yes])])
 
+m4_include([config/ax_tls.m4])
+
 AC_CONFIG_SRCDIR([urcu.h])
 
 AC_CONFIG_HEADERS([config.h urcu/config.h])
@@ -24,6 +26,9 @@ AH_TEMPLATE([CONFIG_RCU_HAVE_FENCE], [Defined when on a system that has memory f
 AH_TEMPLATE([CONFIG_RCU_HAVE_FUTEX], [Defined when on a system with futex support.])
 AH_TEMPLATE([CONFIG_RCU_COMPAT_ARCH], [Compatibility mode for i386 which lacks cmpxchg instruction.])
 AH_TEMPLATE([CONFIG_RCU_ARM_HAVE_DMB], [Use the dmb instruction if available for use on ARM.])
+AH_TEMPLATE([CONFIG_RCU_TLS], [TLS provided by the compiler.])
+
+AX_TLS([AC_DEFINE_UNQUOTED([CONFIG_RCU_TLS], $ac_cv_tls)], [])
 
 # Checks for programs.
 AC_PROG_CC
diff --git a/urcu/config.h.in b/urcu/config.h.in
index 02c7b2e..de1d1d0 100644
--- a/urcu/config.h.in
+++ b/urcu/config.h.in
@@ -16,3 +16,6 @@
 
 /* Use the dmb instruction is available for use on ARM. */
 #undef CONFIG_RCU_ARM_HAVE_DMB
+
+/* TLS provided by the compiler. */
+#define CONFIG_RCU_TLS TLS

-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com



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