1 files changed, 43 insertions, 0 deletions
diff --git a/ir/cfg.c b/ir/cfg.c
new file mode 100644
index 0000000..d9aa409
--- /dev/null
+++ b/ir/cfg.c
@@ -0,0 +1,43 @@
+#include "ir.h"
+
+static void
+porec(struct block ***rpo, struct block *b)
+{
+   if (wasvisited(b)) return;
+   markvisited(b);
+   if (b->s2) porec(rpo, b->s2);
+   if (b->s1) porec(rpo, b->s1);
+   *--*rpo = b;
+}
+
+void
+sortrpo(struct function *fn)
+{
+   static struct block **rpobuf;
+   struct block **rpoend, **rpo;
+   int i, ndead;
+
+   xbgrow(&rpobuf, fn->nblk);
+   rpo = rpoend = rpobuf + fn->nblk,
+
+   startbbvisit();
+   fn->entry->id = 0;
+   porec(&rpo, fn->entry);
+   ndead = rpo - rpobuf;
+   for (struct block *blk = fn->entry; ndead > 0; blk = blk->lnext) {
+      if (!wasvisited(blk)) {
+         blk->lnext = blk->lprev = NULL;
+         freeblk(fn, blk);
+         --ndead;
+      }
+   }
+   for (i = 1, ++rpo; rpo < rpoend; ++rpo, ++i) {
+      rpo[-1]->lnext = rpo[0];
+      rpo[0]->lprev = rpo[-1];
+      rpo[0]->id = i;
+   }
+   fn->entry->lprev = rpo[-1];
+   rpo[-1]->lnext = fn->entry;
+}
+
+/* vim:set ts=3 sw=3 expandtab: */