st/mesa: add comment to explain _min(), _maxf(), etc. functions

Reviewed-by: Marek Olšák <marek.olsak@amd.com>

diff --git a/src/mesa/state_tracker/st_extensions.c b/src/mesa/state_tracker/st_extensions.c
index d053efbb20f513d574b2647087e9c6053d156548..18ddd4e471a1574cd259ba36cf84224bbaa5bdbe 100644 (file)
--- a/src/mesa/state_tracker/st_extensions.c
+++ b/src/mesa/state_tracker/st_extensions.c
@@ -39,6 +39,12 @@
 #include "st_extensions.h"
 #include "st_format.h"
 
+
+/*
+ * Note: we use these function rather than the MIN2, MAX2, CLAMP macros to
+ * avoid evaluating arguments (which are often function calls) more than once.
+ */
+
 static unsigned _min(unsigned a, unsigned b)
 {
    return (a < b) ? a : b;