From: Keith Packard <keithp@keithp.com>
Date: Mon, 4 Dec 2017 03:49:20 +0000 (-0800)
Subject: altos/lisp: Check only cdr base type when moving cons cells
X-Git-Tag: 1.8.3~1^2~22^2~7
X-Git-Url: https://git.gag.com/?p=fw%2Faltos;a=commitdiff_plain;h=32ab76c3049b913283caafbaef873754d76dc9d4

altos/lisp: Check only cdr base type when moving cons cells

The cdr may have moved, so we can't look at the target object
type. Fortunately, the base type encoded in the reference itself is
sufficient to check for a non-cons cdr.

Signed-off-by: Keith Packard <keithp@keithp.com>
---

diff --git a/src/lisp/ao_lisp_cons.c b/src/lisp/ao_lisp_cons.c
index 06e9d361..d3b97383 100644
--- a/src/lisp/ao_lisp_cons.c
+++ b/src/lisp/ao_lisp_cons.c
@@ -58,8 +58,8 @@ static void cons_move(void *addr)
 		cdr = cons->cdr;
 		if (!cdr)
 			break;
-		if (ao_lisp_poly_type(cdr) != AO_LISP_CONS) {
-			(void) ao_lisp_poly_move(&cons->cdr, 1);
+		if (ao_lisp_poly_base_type(cdr) != AO_LISP_CONS) {
+			(void) ao_lisp_poly_move(&cons->cdr, 0);
 			break;
 		}
 		c = ao_lisp_poly_cons(cdr);
@@ -95,8 +95,8 @@ ao_lisp_cons_cons(ao_poly car, ao_poly cdr)
 		ao_lisp_poly_stash(0, car);
 		ao_lisp_poly_stash(1, cdr);
 		cons = ao_lisp_alloc(sizeof (struct ao_lisp_cons));
-		car = ao_lisp_poly_fetch(0);
 		cdr = ao_lisp_poly_fetch(1);
+		car = ao_lisp_poly_fetch(0);
 		if (!cons)
 			return NULL;
 	}