[PATCH:x11proto] Add _X_COLD attribute for branch prediction hints

[Alan Coopersmith]

Unfortunately the Solaris Studio equivalent is a pragma taking the
function names as arguments, so doesn't translate cleanly into a
common macro form.

Signed-off-by: Alan Coopersmith <alan.coopersmith at oracle.com>
---

To be used in code we pretty much only call in error paths, such as in Xlib:
  extern void _XEatData(....) _X_COLD;

or in the xserver now:
  extern void c2p_unsupported(void) _X_COLD;

 Xfuncproto.h.in |    9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/Xfuncproto.h.in b/Xfuncproto.h.in
index 8256fec..dac9229 100644
--- a/Xfuncproto.h.in
+++ b/Xfuncproto.h.in
@@ -97,6 +97,7 @@ in this Software without prior written authorization from The Open Group.
 # define _X_INTERNAL
 #endif /* GNUC >= 4 */
 
+/* Branch prediction hints for individual conditionals */
 /* requires xproto >= 7.0.9 */
 #if defined(__GNUC__) && ((__GNUC__ * 100 + __GNUC_MINOR__) >= 303)
 # define _X_LIKELY(x)   __builtin_expect(!!(x), 1)
@@ -106,6 +107,14 @@ in this Software without prior written authorization from The Open Group.
 # define _X_UNLIKELY(x) (x)
 #endif
 
+/* Bulk branch prediction hints via marking error path functions as "cold" */
+/* requires xproto >= 7.0.25 */
+#if defined(__GNUC__) && ((__GNUC__ * 100 + __GNUC_MINOR__) >= 403) /* 4.3+ */
+# define _X_COLD __attribute__((__cold__))
+#else
+# define _X_COLD /* nothing */
+#endif
+
 /* Added in X11R6.9, so available in any version of modular xproto */
 #if defined(__GNUC__) && ((__GNUC__ * 100 + __GNUC_MINOR__) >= 301)
 # define _X_DEPRECATED  __attribute__((deprecated))
-- 
1.7.9.2