GLX: Support TLS with better portability

AX_TLS detects when toolchains support __thread or __declspec(thread),
but existing code assumed __thread.

This also adds a check to configure.ac to error out if TLS is requested
but unsupported.

Found-by: Tinderbox
http://tinderbox.x.org/builds/2011-03-22-0007

Regression-from: 82b1eaa6ca

Signed-off-by: Jeremy Huddleston <jeremyhu@apple.com>
Reviewed-by: Tom Fogal <tfogal@alumni.unh.edu>
Reviewed-by: Dan Nicholson <dbn.lists@gmail.com>
(cherry picked from commit c55baebf4e)

configure.ac

@@ -599,7 +599,10 @@ AC_ARG_ENABLE(aiglx,          AS_HELP_STRING([--enable-aiglx], [Build accelerate
                                 [AIGLX=yes])
 AX_TLS
 AC_ARG_ENABLE(glx-tls,        AS_HELP_STRING([--enable-glx-tls], [Build GLX with TLS support (default: auto)]),
-                                [GLX_USE_TLS=$enableval],
+                                [GLX_USE_TLS=$enableval
+                                 if test "x$GLX_USE_TLS" = "xyes" && test "${ac_cv_tls}" = "none" ; then
+                                   AC_MSG_ERROR([GLX with TLS support requested, but the compiler does not support it.])
+                                 fi],
                                 [GLX_USE_TLS=no
                                  if test "${ac_cv_tls}" != "none" ; then
                                    GLX_USE_TLS=yes

glx/glapi.c

@@ -190,11 +190,11 @@ static GLint NoOpUnused(void)
 /*@{*/
 #if defined(GLX_USE_TLS)
 
-PUBLIC __thread struct _glapi_table * _glapi_tls_Dispatch
+PUBLIC TLS struct _glapi_table * _glapi_tls_Dispatch
     __attribute__((tls_model("initial-exec")))
     = (struct _glapi_table *) __glapi_noop_table;
 
-PUBLIC __thread void * _glapi_tls_Context
+PUBLIC TLS void * _glapi_tls_Context
     __attribute__((tls_model("initial-exec")));
 
 PUBLIC const struct _glapi_table *_glapi_Dispatch = NULL;

glx/glapi.h

@@ -83,7 +83,7 @@ typedef void (*_glapi_warning_func)(void *ctx, const char *str, ...);
 const extern void *_glapi_Context;
 const extern struct _glapi_table *_glapi_Dispatch;
 
-extern __thread void * _glapi_tls_Context
+extern TLS void * _glapi_tls_Context
     __attribute__((tls_model("initial-exec")));
 
 # define GET_CURRENT_CONTEXT(C)  GLcontext *C = (GLcontext *) _glapi_tls_Context

glx/glthread.h

@@ -300,7 +300,7 @@ _glthread_SetTSD(_glthread_TSD *, void *);
 
 #if defined(GLX_USE_TLS)
 
-extern __thread struct _glapi_table * _glapi_tls_Dispatch
+extern TLS struct _glapi_table * _glapi_tls_Dispatch
     __attribute__((tls_model("initial-exec")));
 
 #define GET_DISPATCH() _glapi_tls_Dispatch

include/dix-config.h.in

@@ -441,6 +441,9 @@
 /* Define to 1 if you have the `ffs' function. */
 #undef HAVE_FFS
 
+/* If the compiler supports a TLS storage class define it to that here */
+#undef TLS
+
 /* Correctly set _XSERVER64 for OSX fat binaries */
 #ifdef __APPLE__
 #include "dix-config-apple-verbatim.h"