Undo port to hypothetical nonzero Qnil case

This mostly undoes the previous change in this area.  See:
http://lists.gnu.org/archive/html/emacs-devel/2015-01/msg00570.html
* alloc.c (allocate_pseudovector):
* callint.c (Fcall_interactively):
* dispnew.c (realloc_glyph_pool):
* fringe.c (init_fringe):
* lisp.h (memsetnil):
* xdisp.c (init_iterator):
Simplify by assuming that Qnil is zero, but verify the assumption.
* lisp.h (NIL_IS_ZERO): Revert back to this symbol, removing
NIL_IS_NONZERO.  All uses changed.

1 files changed, 2 insertions, 3 deletions

diff --git a/src/alloc.c b/src/alloc.c
index d758ca18a7b..bf0456c6862 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -3175,10 +3175,9 @@ allocate_pseudovector (int memlen, int lisplen,
   eassert (lisplen <= (1 << PSEUDOVECTOR_SIZE_BITS) - 1);
 
   /* Only the first LISPLEN slots will be traced normally by the GC.
-     If Qnil is nonzero, clear the non-Lisp data separately.  */
+     Since Qnil == 0, we can memset Lisp and non-Lisp data at one go.  */
+  verify (NIL_IS_ZERO);
   memsetnil (v->contents, zerolen);
-  if (NIL_IS_NONZERO)
-    memset (v->contents + lisplen, 0, (zerolen - lisplen) * word_size);
 
   XSETPVECTYPESIZE (v, tag, lisplen, memlen - lisplen);
   return v;