[PATCH 5/5] glx: Silence warnings when building with clang

[Jeremy Huddleston]

In file included from glapi.c:46:
In file included from ./glapi.h:51:
./glthread.h:237:20: error: unknown attribute 'tls_model' ignored [-Werror,-Wunknown-attributes]
    __attribute__((tls_model("initial-exec")));
                   ^
In file included from glapi.c:46:
./glapi.h:92:20: error: unknown attribute 'tls_model' ignored [-Werror,-Wunknown-attributes]
    __attribute__((tls_model("initial-exec")));
                   ^
glapi.c:82:20: error: unknown attribute 'tls_model' ignored [-Werror,-Wunknown-attributes]
    __attribute__((tls_model("initial-exec"))) = NULL;
                   ^
glapi.c:85:20: error: unknown attribute 'tls_model' ignored [-Werror,-Wunknown-attributes]
    __attribute__((tls_model("initial-exec")));
                   ^
4 errors generated.

Signed-off-by: Jeremy Huddleston <jeremyhu at freedesktop.org>
---
 glx/glapi.c             |   12 ++++++++----
 glx/glapi.h             |    6 ++++--
 glx/glthread.h          |    6 ++++--
 include/dix-config.h.in |    3 +++
 m4/ax_tls.m4            |   13 ++++++++++++-
 5 files changed, 31 insertions(+), 9 deletions(-)

diff --git a/glx/glapi.c b/glx/glapi.c
index 7cb8495..0a166ce 100644
--- a/glx/glapi.c
+++ b/glx/glapi.c
@@ -78,11 +78,15 @@ static void init_glapi_relocs(void);
 /*@{*/
 #if defined(GLX_USE_TLS)
 
-PUBLIC TLS struct _glapi_table * _glapi_tls_Dispatch
-    __attribute__((tls_model("initial-exec"))) = NULL;
+#ifdef HAVE_TLS_MODEL
+__attribute__((tls_model("initial-exec")))
+#endif
+PUBLIC TLS struct _glapi_table * _glapi_tls_Dispatch = NULL;
 
-PUBLIC TLS void * _glapi_tls_Context
-    __attribute__((tls_model("initial-exec")));
+#ifdef HAVE_TLS_MODEL
+__attribute__((tls_model("initial-exec")))
+#endif
+PUBLIC TLS void * _glapi_tls_Context;
 
 PUBLIC const struct _glapi_table *_glapi_Dispatch = NULL;
 PUBLIC const void *_glapi_Context = NULL;
diff --git a/glx/glapi.h b/glx/glapi.h
index 6521f31..85c5ab7 100644
--- a/glx/glapi.h
+++ b/glx/glapi.h
@@ -83,8 +83,10 @@ typedef void (*_glapi_warning_func)(void *ctx, const char *str, ...);
 const extern void *_glapi_Context;
 const extern struct _glapi_table *_glapi_Dispatch;
 
-extern TLS void * _glapi_tls_Context
-    __attribute__((tls_model("initial-exec")));
+#ifdef HAVE_TLS_MODEL
+__attribute__((tls_model("initial-exec")))
+#endif
+extern TLS void * _glapi_tls_Context;
 
 # define GET_CURRENT_CONTEXT(C)  GLcontext *C = (GLcontext *) _glapi_tls_Context
 
diff --git a/glx/glthread.h b/glx/glthread.h
index 140e2aa..0375443 100644
--- a/glx/glthread.h
+++ b/glx/glthread.h
@@ -233,8 +233,10 @@ _glthread_SetTSD(_glthread_TSD *, void *);
 
 #if defined(GLX_USE_TLS)
 
-extern TLS struct _glapi_table * _glapi_tls_Dispatch
-    __attribute__((tls_model("initial-exec")));
+#ifdef HAVE_TLS_MODEL
+__attribute__((tls_model("initial-exec")))
+#endif
+extern TLS struct _glapi_table * _glapi_tls_Dispatch;
 
 #define GET_DISPATCH() _glapi_tls_Dispatch
 
diff --git a/include/dix-config.h.in b/include/dix-config.h.in
index 14229b4..4fd49ef 100644
--- a/include/dix-config.h.in
+++ b/include/dix-config.h.in
@@ -450,6 +450,9 @@
 /* If the compiler supports a TLS storage class define it to that here */
 #undef TLS
 
+/* Is the __attribute((tls_model(...))) extension supported? */
+#undef HAVE_TLS_MODEL
+
 /* Correctly set _XSERVER64 for OSX fat binaries */
 #ifdef __APPLE__
 #include "dix-config-apple-verbatim.h"
diff --git a/m4/ax_tls.m4 b/m4/ax_tls.m4
index 481c3d0..87c6f3c 100644
--- a/m4/ax_tls.m4
+++ b/m4/ax_tls.m4
@@ -16,6 +16,7 @@
 # LICENSE
 #
 #   Copyright (c) 2008 Alan Woodland <ajw05 at aber.ac.uk>
+#   Copyright (c) 2011 Jeremy Huddleston <jeremyhu at freedesktop.org>
 #
 #   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
@@ -64,11 +65,21 @@ AC_DEFUN([AX_TLS], [
              )
        esac
     done
-])
+  ])
 
   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], $ac_cv_tls, [If the compiler supports a TLS storage class define it to that here])
+
+    save_CFLAGS="$CFLAGS"
+    CFLAGS="$CFLAGS -Werror=unknown-attributes"
+    AC_TRY_COMPILE([], [TLS int bar __attribute__((tls_model("initial-exec")));],
+                   ac_cv_tls_model=yes, ac_cv_tls_model=no)
+    CFLAGS="$save_CFLAGS"
+
+    if test "x$ac_cv_tls_model" = "xyes" ; then
+      AC_DEFINE([HAVE_TLS_MODEL], 1, [Is the __attribute((tls_model(...))) extension supported? ])
+    fi
   fi
   AC_MSG_RESULT($ac_cv_tls)
 ])
-- 
1.7.4.1