diff options
Diffstat (limited to 'src/alloc.c')
| -rw-r--r-- | src/alloc.c | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/src/alloc.c b/src/alloc.c index d4e24b6244b..ccb955a547b 100644 --- a/src/alloc.c +++ b/src/alloc.c @@ -2647,18 +2647,24 @@ DEFUN ("make-list", Fmake_list, Smake_list, 2, 2, 0, ***********************************************************************/ /* Sometimes a vector's contents are merely a pointer internally used - in vector allocation code. Usually you don't want to touch this. */ + in vector allocation code. On the rare platforms where a null + pointer cannot be tagged, represent it with a Lisp 0. + Usually you don't want to touch this. */ + +enum { TAGGABLE_NULL = (DATA_SEG_BITS & ~VALMASK) == 0 }; static struct Lisp_Vector * next_vector (struct Lisp_Vector *v) { + if (! TAGGABLE_NULL && EQ (v->contents[0], make_number (0))) + return 0; return XUNTAG (v->contents[0], 0); } static void set_next_vector (struct Lisp_Vector *v, struct Lisp_Vector *p) { - v->contents[0] = make_lisp_ptr (p, 0); + v->contents[0] = TAGGABLE_NULL || p ? make_lisp_ptr (p, 0) : make_number (0); } /* This value is balanced well enough to avoid too much internal overhead |