Port to hypothetical case where Qnil is nonzero

* alloc.c (allocate_pseudovector):
* callint.c (Fcall_interactively):
* coding.c (syms_of_coding):
* dispnew.c (realloc_glyph_pool):
* fringe.c (init_fringe):
* lisp.h (memsetnil):
* xdisp.c (init_iterator):
Port to the currently-hypothetical case where Qnil is nonzero.
* dispnew.c (adjust_glyph_matrix): Remove unnecessary verification,
as there are no Lisp_Object values in the data here.
* lisp.h (NIL_IS_NONZERO): New symbol, replacing NIL_IS_ZERO.
All uses changed.  Define only if not already defined, so that one
can debug with -DNIL_IS_NONZERO.
* xdisp.c (init_iterator): Remove unnecessary initializations to 0.

1 files changed, 4 insertions, 3 deletions

diff --git a/src/alloc.c b/src/alloc.c
index 2c7b02f1158..d758ca18a7b 100644
--- a/src/alloc.c
+++ b/src/alloc.c
@@ -3175,9 +3175,10 @@ 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.
-     But since Qnil == 0, we can memset Lisp_Object slots as well.  */
-  verify (NIL_IS_ZERO);
-  memset (v->contents, 0, zerolen * word_size);
+     If Qnil is nonzero, clear the non-Lisp data separately.  */
+  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;