altos/lisp: convert GC to non-recursive

Use a boolean array to note cons cells which would otherwise recurse,
then loop until that array is empty.

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

7 files changed, 170 insertions, 79 deletions

diff --git a/src/lisp/ao_lisp.h b/src/lisp/ao_lisp.h
index 0d179942..17f1e0f5 100644
--- a/src/lisp/ao_lisp.h
+++ b/src/lisp/ao_lisp.h
@@ -221,6 +221,10 @@ ao_lisp_mem_round(int size)
 
 #define AO_LISP_OTHER_POLY(other) ((ao_poly)(other) + AO_LISP_OTHER)
 
+static inline int ao_lisp_poly_base_type(ao_poly poly) {
+	return poly & AO_LISP_TYPE_MASK;
+}
+
 static inline int ao_lisp_poly_type(ao_poly poly) {
 	int	type = poly & AO_LISP_TYPE_MASK;
 	if (type == AO_LISP_OTHER)
@@ -384,11 +388,11 @@ void
 ao_lisp_poly_patom(ao_poly p);
 
 int
-ao_lisp_poly_mark(ao_poly p);
+ao_lisp_poly_mark(ao_poly p, uint8_t note_cons);
 
 /* returns 1 if the object has already been moved */
 int
-ao_lisp_poly_move(ao_poly *p);
+ao_lisp_poly_move(ao_poly *p, uint8_t note_cons);
 
 /* eval */
 
diff --git a/src/lisp/ao_lisp_atom.c b/src/lisp/ao_lisp_atom.c
index 5f1bcda0..41ba97f5 100644
--- a/src/lisp/ao_lisp_atom.c
+++ b/src/lisp/ao_lisp_atom.c
@@ -48,7 +48,7 @@ static void atom_move(void *addr)
 	struct ao_lisp_atom	*atom = addr;
 
 	for (;;) {
-		if (ao_lisp_poly_move(&atom->next))
+		if (ao_lisp_poly_move(&atom->next, 0))
 			break;
 		atom = ao_lisp_poly_atom(atom->next);
 	}
diff --git a/src/lisp/ao_lisp_cons.c b/src/lisp/ao_lisp_cons.c
index 7d3ca68d..855079b8 100644
--- a/src/lisp/ao_lisp_cons.c
+++ b/src/lisp/ao_lisp_cons.c
@@ -21,7 +21,7 @@ static void cons_mark(void *addr)
 	struct ao_lisp_cons	*cons = addr;
 
 	for (;;) {
-		ao_lisp_poly_mark(cons->car);
+		ao_lisp_poly_mark(cons->car, 1);
 		cons = ao_lisp_poly_cons(cons->cdr);
 		if (!cons)
 			break;
@@ -44,10 +44,17 @@ static void cons_move(void *addr)
 		return;
 
 	for (;;) {
-		(void) ao_lisp_poly_move(&cons->car);
-		if (ao_lisp_poly_move(&cons->cdr))
+		struct ao_lisp_cons	*cdr;
+		int			ret;
+
+		(void) ao_lisp_poly_move(&cons->car, 1);
+		cdr = ao_lisp_poly_cons(cons->cdr);
+		ret = ao_lisp_move_memory((void **) &cdr, sizeof (struct ao_lisp_cons));
+		if (cdr != ao_lisp_poly_cons(cons->cdr))
+			cons->cdr = ao_lisp_cons_poly(cdr);
+		if (ret)
 			break;
-		cons = ao_lisp_poly_cons(cons->cdr);
+		cons = cdr;
 	}
 }
 
diff --git a/src/lisp/ao_lisp_eval.c b/src/lisp/ao_lisp_eval.c
index e3d653b9..a5c74250 100644
--- a/src/lisp/ao_lisp_eval.c
+++ b/src/lisp/ao_lisp_eval.c
@@ -79,10 +79,10 @@ stack_mark(void *addr)
 {
 	struct ao_lisp_stack	*stack = addr;
 	for (;;) {
-		ao_lisp_poly_mark(stack->actuals);
-		ao_lisp_poly_mark(stack->formals);
+		ao_lisp_poly_mark(stack->actuals, 0);
+		ao_lisp_poly_mark(stack->formals, 0);
 		/* no need to mark formals_tail */
-		ao_lisp_poly_mark(stack->frame);
+		ao_lisp_poly_mark(stack->frame, 0);
 		stack = ao_lisp_poly_stack(stack->prev);
 		if (ao_lisp_mark_memory(stack, sizeof (struct ao_lisp_stack)))
 			break;
@@ -122,10 +122,10 @@ stack_move(void *addr)
 	while (stack) {
 		void	*prev;
 		int	ret;
-		(void) ao_lisp_poly_move(&stack->actuals);
-		(void) ao_lisp_poly_move(&stack->formals);
-		(void) ao_lisp_poly_move(&stack->formals_tail);
-		(void) ao_lisp_poly_move(&stack->frame);
+		(void) ao_lisp_poly_move(&stack->actuals, 0);
+		(void) ao_lisp_poly_move(&stack->formals, 0);
+		(void) ao_lisp_poly_move(&stack->formals_tail, 0);
+		(void) ao_lisp_poly_move(&stack->frame, 0);
 		prev = ao_lisp_poly_stack(stack->prev);
 		ret = ao_lisp_move(&ao_lisp_stack_type, &prev);
 		if (prev != ao_lisp_poly_stack(stack->prev))
diff --git a/src/lisp/ao_lisp_frame.c b/src/lisp/ao_lisp_frame.c
index 8bf98571..8791c4de 100644
--- a/src/lisp/ao_lisp_frame.c
+++ b/src/lisp/ao_lisp_frame.c
@@ -48,7 +48,7 @@ frame_mark(void *addr)
 		for (f = 0; f < frame->num; f++) {
 			struct ao_lisp_val	*v = &frame->vals[f];
 
-			ao_lisp_poly_mark(v->val);
+			ao_lisp_poly_mark(v->val, 0);
 			DBG ("\tframe mark atom %s %d val %d at %d\n",
 			     ao_lisp_poly_atom(v->atom)->name,
 			     OFFSET(v->atom), OFFSET(v->val), f);
@@ -69,19 +69,28 @@ frame_move(void *addr)
 	int			f;
 
 	for (;;) {
+		struct ao_lisp_frame	*next;
+		int			ret;
+
 		DBG("frame move %p\n", frame);
 		if (!AO_LISP_IS_POOL(frame))
 			break;
 		for (f = 0; f < frame->num; f++) {
 			struct ao_lisp_val	*v = &frame->vals[f];
 
-			ao_lisp_poly_move(&v->atom);
+			ao_lisp_poly_move(&v->atom, 0);
 			DBG("moved atom %s\n", ao_lisp_poly_atom(v->atom)->name);
-			ao_lisp_poly_move(&v->val);
+			ao_lisp_poly_move(&v->val, 0);
 		}
-		if (ao_lisp_poly_move(&frame->next))
+		next = ao_lisp_poly_frame(frame->next);
+		ret = 1;
+		if (next)
+			ret = ao_lisp_move_memory((void **) &next, frame_size(next));
+		if (next != ao_lisp_poly_frame(frame->next))
+			frame->next = ao_lisp_frame_poly(next);
+		if (ret)
 			break;
-		frame = ao_lisp_poly_frame(frame->next);
+		frame = next;
 	}
 }
 
diff --git a/src/lisp/ao_lisp_mem.c b/src/lisp/ao_lisp_mem.c
index 6e656454..c11ec25d 100644
--- a/src/lisp/ao_lisp_mem.c
+++ b/src/lisp/ao_lisp_mem.c
@@ -41,7 +41,7 @@ uint8_t	ao_lisp_pool[AO_LISP_POOL] __attribute__((aligned(4)));
 #define DBG_OFFSET(a)	((int) ((uint8_t *) (a) - ao_lisp_pool))
 #define DBG(...) printf(__VA_ARGS__)
 #define DBG_DO(a)	a
-static int move_dump;
+static int move_dump = 1;
 static int move_depth;
 #define DBG_RESET() (move_depth = 0)
 #define DBG_MOVE(...) do { if(move_dump) { int d; for (d = 0; d < move_depth; d++) printf ("  "); printf(__VA_ARGS__); } } while (0)
@@ -68,8 +68,10 @@ struct ao_lisp_root {
 static struct ao_lisp_root	ao_lisp_root[AO_LISP_ROOT];
 
 static uint8_t	ao_lisp_busy[AO_LISP_POOL / 32];
-
 static uint8_t	ao_lisp_moving[AO_LISP_POOL / 32];
+static uint8_t	ao_lisp_cons[AO_LISP_POOL / 32];
+static uint8_t	ao_lisp_cons_last[AO_LISP_POOL / 32];
+static uint8_t	ao_lisp_cons_noted;
 
 uint16_t	ao_lisp_top;
 
@@ -161,6 +163,17 @@ busy_object(uint8_t *tag, void *addr) {
 	return 0;
 }
 
+static void
+note_cons(void *addr)
+{
+	DBG_MOVE("note cons %d\n", DBG_OFFSET(addr));
+	if (AO_LISP_IS_POOL(addr)) {
+		ao_lisp_cons_noted = 1;
+		mark(ao_lisp_cons, (uint8_t *) addr - ao_lisp_pool);
+	}
+}
+
+
 static void	*move_old, *move_new;
 static int	move_size;
 
@@ -173,11 +186,15 @@ move_object(void)
 	DBG_MOVE("move %d -> %d\n", DBG_OFFSET(move_old), DBG_OFFSET(move_new));
 	DBG_MOVE_IN();
 	memset(ao_lisp_moving, '\0', sizeof (ao_lisp_moving));
+	memset(ao_lisp_cons, '\0', sizeof (ao_lisp_cons));
+	ao_lisp_cons_noted = 0;
 	for (i = 0; i < AO_LISP_ROOT; i++) {
 		if (!ao_lisp_root[i].addr)
 			continue;
 		if (ao_lisp_root[i].type) {
-			DBG_DO(void *addr = *ao_lisp_root[i].addr);
+			void *addr = *ao_lisp_root[i].addr;
+			if (!addr)
+				continue;
 			DBG_MOVE("root %d\n", DBG_OFFSET(addr));
 			if (!ao_lisp_move(ao_lisp_root[i].type,
 					  ao_lisp_root[i].addr)) {
@@ -186,13 +203,30 @@ move_object(void)
 					 *ao_lisp_root[i].addr);
 			}
 		} else {
-			DBG_DO(ao_poly p = *(ao_poly *) ao_lisp_root[i].addr);
-			if (!ao_lisp_poly_move((ao_poly *) ao_lisp_root[i].addr)) {
+			ao_poly p = *(ao_poly *) ao_lisp_root[i].addr;
+			if (!p)
+				continue;
+			if (!ao_lisp_poly_move((ao_poly *) ao_lisp_root[i].addr, 0)) {
 				DBG_MOVE("root poly move from %04x to %04x\n",
 					 p, *(ao_poly *) ao_lisp_root[i].addr);
 			}
 		}
 	}
+	while (ao_lisp_cons_noted) {
+		memcpy(ao_lisp_cons_last, ao_lisp_cons, sizeof (ao_lisp_cons));
+		memset(ao_lisp_cons, '\0', sizeof (ao_lisp_cons));
+		ao_lisp_cons_noted = 0;
+		for (i = 0; i < AO_LISP_POOL; i += 4) {
+			if (busy(ao_lisp_cons_last, i)) {
+				void *addr = ao_lisp_pool + i;
+				DBG_MOVE("cons %d\n", DBG_OFFSET(addr));
+				if (!ao_lisp_move(&ao_lisp_cons_type, &addr)) {
+					DBG_MOVE("cons moves from %p to %p\n",
+						 ao_lisp_pool + i, addr);
+				}
+			}
+		}
+	}
 	DBG_MOVE_OUT();
 	DBG_MOVE("move done\n");
 }
@@ -220,25 +254,50 @@ dump_busy(void)
 #define DUMP_BUSY()
 #endif
 
+static const struct ao_lisp_type const *ao_lisp_types[AO_LISP_NUM_TYPE] = {
+	[AO_LISP_CONS] = &ao_lisp_cons_type,
+	[AO_LISP_INT] = NULL,
+	[AO_LISP_STRING] = &ao_lisp_string_type,
+	[AO_LISP_OTHER] = (void *) 0x1,
+	[AO_LISP_ATOM] = &ao_lisp_atom_type,
+	[AO_LISP_BUILTIN] = &ao_lisp_builtin_type,
+	[AO_LISP_FRAME] = &ao_lisp_frame_type,
+};
+
+
 static void
 ao_lisp_mark_busy(void)
 {
 	int i;
 
 	memset(ao_lisp_busy, '\0', sizeof (ao_lisp_busy));
+	memset(ao_lisp_cons, '\0', sizeof (ao_lisp_cons));
+	ao_lisp_cons_noted = 0;
 	DBG("mark\n");
 	for (i = 0; i < AO_LISP_ROOT; i++) {
 		if (ao_lisp_root[i].type) {
 			void **a = ao_lisp_root[i].addr, *v;
 			if (a && (v = *a)) {
-				DBG("root %p\n", v);
+				DBG("root %d\n", DBG_OFFSET(v));
 				ao_lisp_mark(ao_lisp_root[i].type, v);
 			}
 		} else {
 			ao_poly *a = (ao_poly *) ao_lisp_root[i].addr, p;
 			if (a && (p = *a)) {
-				DBG("root %04x\n", p);
-				ao_lisp_poly_mark(p);
+				DBG("root 0x%04x\n", p);
+				ao_lisp_poly_mark(p, 0);
+			}
+		}
+	}
+	while (ao_lisp_cons_noted) {
+		memcpy(ao_lisp_cons_last, ao_lisp_cons, sizeof (ao_lisp_cons));
+		memset(ao_lisp_cons, '\0', sizeof (ao_lisp_cons));
+		ao_lisp_cons_noted = 0;
+		for (i = 0; i < AO_LISP_POOL; i += 4) {
+			if (busy(ao_lisp_cons_last, i)) {
+				void *v = ao_lisp_pool + i;
+				DBG("cons %d\n", DBG_OFFSET(v));
+				ao_lisp_mark(&ao_lisp_cons_type, v);
 			}
 		}
 	}
@@ -274,6 +333,10 @@ ao_lisp_collect(void)
 				abort();
 			clear_object(ao_lisp_busy, move_old, move_size);
 			mark_object(ao_lisp_busy, move_new, move_size);
+			if (busy_object(ao_lisp_cons, move_old)) {
+				clear_object(ao_lisp_cons, move_old, move_size);
+				mark_object(ao_lisp_cons, move_new, move_size);
+			}
 			i += move_size;
 			top += move_size;
 			DUMP_BUSY();
@@ -297,6 +360,24 @@ ao_lisp_mark(const struct ao_lisp_type *type, void *addr)
 }
 
 int
+ao_lisp_poly_mark(ao_poly p, uint8_t do_note_cons)
+{
+	uint8_t type = ao_lisp_poly_type(p);
+
+	if (!p)
+		return 1;
+	if (type == AO_LISP_CONS && do_note_cons) {
+		note_cons(ao_lisp_ref(p));
+		return 0;
+	} else {
+		const struct ao_lisp_type *lisp_type = ao_lisp_types[ao_lisp_poly_type(p)];
+		if (lisp_type)
+			return ao_lisp_mark(lisp_type, ao_lisp_ref(p));
+		return 1;
+	}
+}
+
+int
 ao_lisp_mark_memory(void *addr, int size)
 {
 	return mark_object(ao_lisp_busy, addr, size);
@@ -348,7 +429,7 @@ ao_lisp_move(const struct ao_lisp_type *type, void **ref)
 		return 1;
 #endif
 	DBG_MOVE("object %d\n", DBG_OFFSET(addr));
-	if (a < ao_lisp_pool || ao_lisp_pool + AO_LISP_POOL <= a)
+	if (!AO_LISP_IS_POOL(a))
 		abort();
 	DBG_MOVE_IN();
 	addr = check_move(addr, size);
@@ -389,6 +470,47 @@ ao_lisp_move_memory(void **ref, int size)
 	return 0;
 }
 
+int
+ao_lisp_poly_move(ao_poly *ref, uint8_t do_note_cons)
+{
+	uint8_t				type;
+	ao_poly				p = *ref;
+	const struct ao_lisp_type	*lisp_type;
+	int				ret;
+	void				*addr;
+
+	if (!p)
+		return 1;
+
+	type = ao_lisp_poly_base_type(p);
+	addr = ao_lisp_ref(p);
+	if (type == AO_LISP_CONS && do_note_cons) {
+		note_cons(addr);
+		addr = check_move(addr, sizeof (struct ao_lisp_cons));
+		ret = 1;
+	} else {
+
+		if (type == AO_LISP_OTHER)
+			type = ao_lisp_other_type(ao_lisp_move_map(ao_lisp_poly_other(p)));
+
+		if (type >= AO_LISP_NUM_TYPE)
+			abort();
+
+		lisp_type = ao_lisp_types[type];
+		if (!lisp_type)
+			return 1;
+		ret = ao_lisp_move(lisp_type, &addr);
+	}
+
+	if (addr != ao_lisp_ref(p)) {
+		ao_poly np = ao_lisp_poly(addr, p & AO_LISP_TYPE_MASK);
+		DBG("poly %d moved %04x -> %04x\n",
+		    type, p, np);
+		*ref = np;
+	}
+	return ret;
+}
+
 #ifdef DBG_POOL
 static int AO_LISP_POOL_CUR = AO_LISP_POOL / 8;
 
diff --git a/src/lisp/ao_lisp_prim.c b/src/lisp/ao_lisp_prim.c
index 82386a83..3c081ee8 100644
--- a/src/lisp/ao_lisp_prim.c
+++ b/src/lisp/ao_lisp_prim.c
@@ -76,54 +76,3 @@ ao_lisp_poly_patom(ao_poly p)
 		f->patom(p);
 }
 
-static const struct ao_lisp_type const *ao_lisp_types[AO_LISP_NUM_TYPE] = {
-	[AO_LISP_CONS] = &ao_lisp_cons_type,
-	[AO_LISP_INT] = NULL,
-	[AO_LISP_STRING] = &ao_lisp_string_type,
-	[AO_LISP_OTHER] = (void *) 0x1,
-	[AO_LISP_ATOM] = &ao_lisp_atom_type,
-	[AO_LISP_BUILTIN] = &ao_lisp_builtin_type,
-	[AO_LISP_FRAME] = &ao_lisp_frame_type,
-};
-
-int
-ao_lisp_poly_mark(ao_poly p)
-{
-	const struct ao_lisp_type *lisp_type = ao_lisp_types[ao_lisp_poly_type(p)];
-	if (lisp_type)
-		return ao_lisp_mark(lisp_type, ao_lisp_ref(p));
-	return 1;
-}
-
-int
-ao_lisp_poly_move(ao_poly *ref)
-{
-	uint8_t				type;
-	ao_poly				p = *ref;
-	const struct ao_lisp_type	*lisp_type;
-	int				ret;
-	void				*addr;
-
-	if (!p)
-		return 1;
-
-	type = p & AO_LISP_TYPE_MASK;
-	if (type == AO_LISP_OTHER)
-		type = ao_lisp_other_type(ao_lisp_move_map(ao_lisp_poly_other(p)));
-
-	if (type >= AO_LISP_NUM_TYPE)
-		abort();
-
-	lisp_type = ao_lisp_types[type];
-	if (!lisp_type)
-		return 1;
-	addr = ao_lisp_ref(p);
-	ret = ao_lisp_move(lisp_type, &addr);
-	if (addr != ao_lisp_ref(p)) {
-		ao_poly np = ao_lisp_poly(addr, p & AO_LISP_TYPE_MASK);
-		DBG("poly %d moved %04x -> %04x\n",
-		    type, p, np);
-		*ref = np;
-	}
-	return ret;
-}