Add compiler directive to mark code paths that log as cold

This causes compiler to naturally favor faster path through code.
Anything that logs a message is not fast path.

2 files changed, 26 insertions, 18 deletions

diff --git a/lib/log.h b/lib/log.h
index b08ae4c2..5411fa6b 100644
--- a/lib/log.h
+++ b/lib/log.h
@@ -105,33 +105,48 @@ extern void closezlog (struct zlog *zl);
 
 /* GCC have printf type attribute check.  */
 #ifdef __GNUC__
-#define PRINTF_ATTRIBUTE(a,b) __attribute__ ((__format__ (__printf__, a, b)))
+#define PRINTF_ATTRIBUTE(a,b) __attribute__ ((format (printf, a, b)))
 #else
 #define PRINTF_ATTRIBUTE(a,b)
 #endif /* __GNUC__ */
 
+#if !(__GNUC__ == 4)
+/* Mark functions as cold. gcc will assume any path leading to a call
+   to them will be unlikely.  This means a lot of paths leading up
+   to log messages are easily marked as not likely.
+*/
+#define COLD_ATTRIBUTE		__attribute__((__cold__))
+#else
+#define COLD_ATTRIBUTE
+#endif
+
 /* Generic function for zlog. */
 extern void zlog (struct zlog *zl, int priority, const char *format, ...)
   PRINTF_ATTRIBUTE(3, 4);
 
 /* Handy zlog functions. */
-extern void zlog_err (const char *format, ...) PRINTF_ATTRIBUTE(1, 2);
-extern void zlog_warn (const char *format, ...) PRINTF_ATTRIBUTE(1, 2);
-extern void zlog_info (const char *format, ...) PRINTF_ATTRIBUTE(1, 2);
-extern void zlog_notice (const char *format, ...) PRINTF_ATTRIBUTE(1, 2);
-extern void zlog_debug (const char *format, ...) PRINTF_ATTRIBUTE(1, 2);
+extern void zlog_err (const char *format, ...)
+  PRINTF_ATTRIBUTE(1, 2) COLD_ATTRIBUTE;
+extern void zlog_warn (const char *format, ...)
+  PRINTF_ATTRIBUTE(1, 2) COLD_ATTRIBUTE;
+extern void zlog_info (const char *format, ...)
+  PRINTF_ATTRIBUTE(1, 2) COLD_ATTRIBUTE;
+extern void zlog_notice (const char *format, ...)
+  PRINTF_ATTRIBUTE(1, 2) COLD_ATTRIBUTE;
+extern void zlog_debug (const char *format, ...)
+  PRINTF_ATTRIBUTE(1, 2) COLD_ATTRIBUTE;
 
 /* For bgpd's peer oriented log. */
 extern void plog_err (struct zlog *, const char *format, ...)
-  PRINTF_ATTRIBUTE(2, 3);
+  PRINTF_ATTRIBUTE(2, 3) COLD_ATTRIBUTE;
 extern void plog_warn (struct zlog *, const char *format, ...)
-  PRINTF_ATTRIBUTE(2, 3);
+  PRINTF_ATTRIBUTE(2, 3) COLD_ATTRIBUTE;
 extern void plog_info (struct zlog *, const char *format, ...)
-  PRINTF_ATTRIBUTE(2, 3);
+  PRINTF_ATTRIBUTE(2, 3) COLD_ATTRIBUTE;
 extern void plog_notice (struct zlog *, const char *format, ...)
-  PRINTF_ATTRIBUTE(2, 3);
+  PRINTF_ATTRIBUTE(2, 3) COLD_ATTRIBUTE;
 extern void plog_debug (struct zlog *, const char *format, ...)
-  PRINTF_ATTRIBUTE(2, 3);
+  PRINTF_ATTRIBUTE(2, 3) COLD_ATTRIBUTE;
 
 /* Set logging level for the given destination.  If the log_level
    argument is ZLOG_DISABLED, then the destination is disabled.
diff --git a/lib/vty.h b/lib/vty.h
index 65ae6201..31cbd498 100644
--- a/lib/vty.h
+++ b/lib/vty.h
@@ -141,13 +141,6 @@ struct vty
 #define IS_DIRECTORY_SEP(c) ((c) == DIRECTORY_SEP)
 #endif
 
-/* GCC have printf type attribute check.  */
-#ifdef __GNUC__
-#define PRINTF_ATTRIBUTE(a,b) __attribute__ ((__format__ (__printf__, a, b)))
-#else
-#define PRINTF_ATTRIBUTE(a,b)
-#endif /* __GNUC__ */
-
 /* Utility macros to convert VTY argument to unsigned long or integer. */
 #define VTY_GET_LONG(NAME,V,STR) \
 do { \