altos/lisp: Deal with memory compation in the middle of operations

Handle memory compaction in places where we've got pointers into the
heap across an allocation operation. Either re-compute the values from
managed global references or add new roots across the allocation.

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

1 files changed, 7 insertions, 1 deletions

diff --git a/src/lisp/ao_lisp_cons.c b/src/lisp/ao_lisp_cons.c
index 855079b8..cd8a8d1d 100644
--- a/src/lisp/ao_lisp_cons.c
+++ b/src/lisp/ao_lisp_cons.c
@@ -67,7 +67,13 @@ const struct ao_lisp_type ao_lisp_cons_type = {
 struct ao_lisp_cons *
 ao_lisp_cons_cons(ao_poly car, struct ao_lisp_cons *cdr)
 {
-	struct ao_lisp_cons	*cons = ao_lisp_alloc(sizeof (struct ao_lisp_cons));
+	struct ao_lisp_cons	*cons;
+
+	ao_lisp_root_add(&ao_lisp_cons_type, &cdr);
+	ao_lisp_root_poly_add(&car);
+	cons = ao_lisp_alloc(sizeof (struct ao_lisp_cons));
+	ao_lisp_root_clear(&car);
+	ao_lisp_root_clear(&cdr);
 	if (!cons)
 		return NULL;
 	cons->car = car;