fix comment


git-svn-id: svn://svn.valgrind.org/valgrind/trunk@2157 a5019735-40e9-0310-863c-91ae7b9d1cf9
diff --git a/memcheck/mc_translate.c b/memcheck/mc_translate.c
index 249076c..58bc4a8 100644
--- a/memcheck/mc_translate.c
+++ b/memcheck/mc_translate.c
@@ -1491,7 +1491,7 @@
                case Tag_ImproveAND1_TQ:
                   sz = 1; goto do_ImproveAND;
                do_ImproveAND:
-                  /* Implements Q = T OR Q.  So if Q is entirely defined,
+                  /* Implements Q = T AND Q.  So if Q is entirely defined,
                      ie all 0s, we get MOV T, Q. */
 		  if (def[u->val2] <= 4) {
                      sk_assert(def[u->val2] == sz);