Apply previous change even if valgrind is not in use, since it avoids undefined behavior. This is simpler.

src/ChangeLog

@@ -1,12 +1,9 @@
 2014-01-20  Paul Eggert  <eggert@cs.ucla.edu>
 
-	Pacify valgrind by initializing buffer redisplay bit.
+	Avoid undefined behavior by initializing buffer redisplay bit.
 	Problem reported by Dmitry Antipov in
 	<http://lists.gnu.org/archive/html/emacs-devel/2014-01/msg01756.html>.
-	* alloc.c (USE_VALGRIND): Move this to ...
-	* conf_post.h (USE_VALGRIND): ... here.  Use booleans.
-	* buffer.c (Fget_buffer_create): Initialize redisplay bit
-	to pacify valgrind.
+	* buffer.c (Fget_buffer_create): Initialize redisplay bit.
 
 	Revert some of the CANNOT_DUMP fix (Bug#16494).
 	* lread.c (init_lread): Fix typo: NILP, not !NILP.

src/alloc.c

@@ -48,6 +48,12 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 
 #include <verify.h>
 
+#if (defined ENABLE_CHECKING			\
+     && defined HAVE_VALGRIND_VALGRIND_H	\
+     && !defined USE_VALGRIND)
+# define USE_VALGRIND 1
+#endif
+
 #if USE_VALGRIND
 #include <valgrind/valgrind.h>
 #include <valgrind/memcheck.h>

src/buffer.c

@@ -574,8 +574,7 @@ even if it is dead.  The return value is never nil.  */)
   BUF_BEG_UNCHANGED (b) = 0;
   *(BUF_GPT_ADDR (b)) = *(BUF_Z_ADDR (b)) = 0; /* Put an anchor '\0'.  */
   b->text->inhibit_shrinking = false;
-  if (USE_VALGRIND)
-    b->text->redisplay = false;
+  b->text->redisplay = false;
 
   b->newline_cache = 0;
   b->width_run_cache = 0;

src/conf_post.h

@@ -65,15 +65,6 @@ typedef bool bool_bf;
 # define ADDRESS_SANITIZER false
 #endif
 
-/* True if Emacs might be run under valgrind.  */
-#ifndef USE_VALGRIND
-# if defined ENABLE_CHECKING && defined HAVE_VALGRIND_VALGRIND_H
-#  define USE_VALGRIND true
-# else
-#  define USE_VALGRIND false
-# endif
-#endif
-
 #ifdef DARWIN_OS
 #ifdef emacs
 #define malloc unexec_malloc