os,llvmpipe: Set rasterizer thread names on Linux.

To help identify llvmpipe rasterizer threads -- especially when there
can be so many.

We can eventually generalize this to other OSes, but for that we must
restrict the function to be called from the current thread.  See also
http://stackoverflow.com/a/7989973

Reviewed-by: Roland Scheidegger <sroland@vmware.com>

src/gallium/auxiliary/os/os_thread.h

@@ -85,6 +85,17 @@ static INLINE int pipe_thread_destroy( pipe_thread thread )
    return thrd_detach( thread );
 }
 
+static INLINE void pipe_thread_setname( const char *name )
+{
+#if defined(HAVE_PTHREAD)
+#  if defined(__GNU_LIBRARY__) && defined(__GLIBC__) && defined(__GLIBC_MINOR__) && \
+      (__GLIBC__ >= 3 || (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 12))
+   pthread_setname_np(pthread_self(), name);
+#  endif
+#endif
+   (void)name;
+}
+
 
 /* pipe_mutex
  */

src/gallium/drivers/llvmpipe/lp_rast.c

@@ -31,6 +31,7 @@
 #include "util/u_rect.h"
 #include "util/u_surface.h"
 #include "util/u_pack_color.h"
+#include "util/u_string.h"
 
 #include "os/os_time.h"
 
@@ -747,11 +748,16 @@ static PIPE_THREAD_ROUTINE( thread_function, init_data )
    struct lp_rasterizer_task *task = (struct lp_rasterizer_task *) init_data;
    struct lp_rasterizer *rast = task->rast;
    boolean debug = false;
-   unsigned fpstate = util_fpstate_get();
+   char thread_name[16];
+   unsigned fpstate;
+
+   util_snprintf(thread_name, sizeof thread_name, "llvmpipe-%u", task->thread_index);
+   pipe_thread_setname(thread_name);
 
    /* Make sure that denorms are treated like zeros. This is 
     * the behavior required by D3D10. OpenGL doesn't care.
     */
+   fpstate = util_fpstate_get();
    util_fpstate_set_denorms_to_zero(fpstate);
 
    while (1) {