add simple unreachability

1 files changed, 38 insertions, 0 deletions

diff --git a/src/unreachable.c b/src/unreachable.c
new file mode 100644
index 0000000..90a65bd
--- /dev/null
+++ b/src/unreachable.c
@@ -0,0 +1,38 @@
+#include <qbt/unreachable.h>
+
+void build_reachable_vec(struct vec *reachable, struct blk *cur)
+{
+	if (cur->reachable)
+		return;
+
+	cur->reachable = true;
+	vec_append(reachable, &cur);
+
+	if (cur->btype == RET)
+		return;
+
+	if (cur->btype == J)
+		cur->s1 = cur->s2;
+
+	if (cur->s1)
+		build_reachable_vec(reachable, cur->s1);
+
+	if (cur->s2)
+		build_reachable_vec(reachable, cur->s2);
+}
+
+void unreachable(struct fn *f)
+{
+	struct vec reachable = vec_create(sizeof(struct blk *));
+	struct blk *b = blk_at(f->blks, 0);
+	build_reachable_vec(&reachable, b);
+	foreach_blk(bi, f->blks) {
+		struct blk *b = blk_at(f->blks, bi);
+		if (!b->reachable)
+			destroy_block(b);
+
+	}
+
+	vec_destroy(&f->blks);
+	f->blks = reachable;
+}