* lisp.h (eassert): Don't use 'assume'.

Sometimes 'assume' wins in performance, and sometimes it loses,
so it shouldn't be used all the time.  Perhaps we need two
flavors of 'eassert', one for where 'assume' is far more likely
to help or to hurt; but that can be done later.
Problem reported by Dmitry Andipov in
<http://lists.gnu.org/archive/html/emacs-devel/2013-10/msg00276.html>.
Also, don't include <verify.h>; no longer needed.

diff --git a/src/ChangeLog b/src/ChangeLog
index 3ae42ea..7800959 100644 (file)
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,14 @@
+2013-10-09  Paul Eggert  <eggert@cs.ucla.edu>
+
+       * lisp.h (eassert): Don't use 'assume'.
+       Sometimes 'assume' wins in performance, and sometimes it loses,
+       so it shouldn't be used all the time.  Perhaps we need two
+       flavors of 'eassert', one for where 'assume' is far more likely
+       to help or to hurt; but that can be done later.
+       Problem reported by Dmitry Andipov in
+       <http://lists.gnu.org/archive/html/emacs-devel/2013-10/msg00276.html>.
+       Also, don't include <verify.h>; no longer needed.
+
 2013-10-09  Glenn Morris  <rgm@gnu.org>
 
        * eval.c (Fcond): Doc tweak.

diff --git a/src/lisp.h b/src/lisp.h
index 3773398..6638cc6 100644 (file)
--- a/src/lisp.h
+++ b/src/lisp.h
@@ -31,7 +31,6 @@ along with GNU Emacs.  If not, see <http://www.gnu.org/licenses/>.  */
 #include <limits.h>
 
 #include <intprops.h>
-#include <verify.h>
 
 INLINE_HEADER_BEGIN
 
@@ -115,11 +114,9 @@ typedef EMACS_UINT uprintmax_t;
 /* Extra internal type checking?  */
 
 /* Define an Emacs version of 'assert (COND)'.  COND should be free of
-   side effects; it may be evaluated zero or more times.  If COND is false,
-   Emacs reliably crashes if ENABLE_CHECKING is defined and behavior
-   is undefined if not.  The compiler may assume COND while optimizing.  */
+   side effects; it may be evaluated zero or more times.  */
 #ifndef ENABLE_CHECKING
-# define eassert(cond) assume (cond)
+# define eassert(cond) ((void) (0 && (cond))) /* Check that COND compiles.  */
 #else /* ENABLE_CHECKING */
 
 extern _Noreturn void die (const char *, const char *, int);
@@ -136,7 +133,7 @@ extern bool suppress_checking EXTERNALLY_VISIBLE;
 
 # define eassert(cond)                                         \
    (suppress_checking || (cond)                                \
-    ? assume (cond)                                            \
+    ? (void) 0                                                 \
     : die (# cond, __FILE__, __LINE__))
 #endif /* ENABLE_CHECKING */