altos/lisp: Simplify GC a bit by only marking the head of each object

We don't need to mark the whole object now as we're getting
information about where objects are by walking the tree each time
around the loop; ao_lisp_busy is only useful for terminating the walk
now.

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

1 files changed, 19 insertions, 75 deletions

diff --git a/src/lisp/ao_lisp_mem.c b/src/lisp/ao_lisp_mem.c
index 60f4bbee..08b5bac0 100644
--- a/src/lisp/ao_lisp_mem.c
+++ b/src/lisp/ao_lisp_mem.c
@@ -282,62 +282,11 @@ static inline int limit(int offset) {
 
 static int total_marked;
 
-/*
- * Mark a range of addresses
- */
-static int
-mark_object(uint8_t *tag, void *addr, int size) {
-	int	base;
-	int	bound;
-
-	MDBG_DO(if (!AO_LISP_IS_POOL((uint8_t *) addr + size - 1))
-			ao_lisp_abort());
-
-	base = pool_offset(addr);
-	bound = base + size;
-
-	MDBG_DO(if (bound > ao_lisp_top) ao_lisp_abort());
-
-	if (busy(tag, base))
-		return 1;
-	if (tag == ao_lisp_busy)
-		total_marked += size;
-	while (base < bound) {
-		mark(tag, base);
-		base += 4;
-	}
-	return 0;
-}
-
-MDBG_DO(
-static int
-clear_object(uint8_t *tag, void *addr, int size) {
-	int	base;
-	int	bound;
-
-	MDBG_DO(if (!AO_LISP_IS_POOL((uint8_t *) addr + size - 1))
-			ao_lisp_abort());
-
-	base = (uint8_t *) addr - ao_lisp_pool;
-	bound = base + size;
-
-	base = limit(base);
-	bound = limit(bound);
-	if (!busy(tag, base))
-		return 1;
-	total_marked -= size;
-	while (base < bound) {
-		clear(tag, base);
-		base += 4;
-	}
-	return 0;
-})
-
 static void
 note_cons(void *addr)
 {
 	if (AO_LISP_IS_POOL(addr)) {
-		int	offset = (uint8_t *) addr - ao_lisp_pool;
+		int	offset = pool_offset(addr);
 		MDBG_MOVE("note cons %d\n", MDBG_OFFSET(addr));
 		ao_lisp_cons_noted = 1;
 		mark(ao_lisp_cons_note, offset);
@@ -539,14 +488,10 @@ ao_lisp_collect(void)
 			memmove(&ao_lisp_pool[top],
 				&ao_lisp_pool[ao_lisp_chunk[i].old_addr],
 				size);
-			MDBG_DO(clear_object(ao_lisp_busy, &ao_lisp_pool[ao_lisp_chunk[i].old_addr], size));
-			MDBG_DO(mark_object(ao_lisp_busy, &ao_lisp_pool[top], size));
 			top += size;
 			chunk_low = ao_lisp_chunk[i].old_addr + size;
 		}
 
-		MDBG_MOVE("after moving objects, busy is now:\n");
-		DUMP_BUSY();
 		chunk_last = i;
 
 		if (chunk_first < chunk_last) {
@@ -587,19 +532,19 @@ ao_lisp_collect(void)
 int
 ao_lisp_mark_memory(const struct ao_lisp_type *type, void *addr)
 {
-	int size;
+	int offset;
 	if (!AO_LISP_IS_POOL(addr))
 		return 1;
 
-	size = ao_lisp_size(type, addr);
+	offset = pool_offset(addr);
 	MDBG_MOVE("mark memory %d\n", MDBG_OFFSET(addr));
-	if (!mark_object(ao_lisp_busy, addr, size)) {
-		note_chunk(pool_offset(addr), size);
-		MDBG_DO(ao_lisp_record(type, addr, size));
-		return 0;
+	if (busy(ao_lisp_busy, offset)) {
+		MDBG_MOVE("already marked\n");
+		return 1;
 	}
-	MDBG_MOVE("already marked\n");
-	return 1;
+	mark(ao_lisp_busy, offset);
+	note_chunk(offset, ao_lisp_size(type, addr));
+	return 0;
 }
 
 int
@@ -672,26 +617,27 @@ int
 ao_lisp_move_memory(const struct ao_lisp_type *type, void **ref)
 {
 	void		*addr = *ref;
-	int		size;
+	int		offset;
 
 	if (!AO_LISP_IS_POOL(addr))
 		return 1;
 
 	MDBG_MOVE("move memory %d\n", MDBG_OFFSET(addr));
 	addr = move_map(addr);
-	size = ao_lisp_size(type, addr);
 	if (addr != *ref) {
 		MDBG_MOVE("update ref %d %d -> %d\n",
 			  AO_LISP_IS_POOL(ref) ? MDBG_OFFSET(ref) : -1,
 			  MDBG_OFFSET(*ref), MDBG_OFFSET(addr));
 		*ref = addr;
 	}
-	if (!mark_object(ao_lisp_busy, addr, size)) {
-		MDBG_DO(ao_lisp_record(type, addr, size));
-		return 0;
+	offset = pool_offset(addr);
+	if (busy(ao_lisp_busy, offset)) {
+		MDBG_MOVE("already moved\n");
+		return 1;
 	}
-	MDBG_MOVE("already moved\n");
-	return 1;
+	mark(ao_lisp_busy, offset);
+	MDBG_DO(ao_lisp_record(type, addr, ao_lisp_size(type, addr)));
+	return 0;
 }
 
 int
@@ -720,16 +666,14 @@ ao_lisp_poly_move(ao_poly *ref, uint8_t do_note_cons)
 	if (!p)
 		return 1;
 
-	type = ao_lisp_poly_base_type(p);
 	addr = ao_lisp_ref(p);
 
 	if (!AO_LISP_IS_POOL(addr))
 		return 1;
 
-	if (type == AO_LISP_CONS && do_note_cons) {
-//		addr = move_map(addr);
-		MDBG_DO(if (addr != move_map(addr)) MDBG_MOVE("noting cons at old addr %d instead of new addr %d\n", MDBG_OFFSET(addr), MDBG_OFFSET(move_map(addr))););
+	type = ao_lisp_poly_base_type(p);
 
+	if (type == AO_LISP_CONS && do_note_cons) {
 		note_cons(addr);
 		addr = move_map(addr);
 		ret = 1;