From a8d6f8bf30c07edb775e56889f568ca20240bedf Mon Sep 17 00:00:00 2001
From: lemon <lsof@mailbox.org>
Date: Tue, 17 Mar 2026 13:22:00 +0100
Subject: REFACTOR: move sources to src/

---
 src/ir_cfg.c | 130 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 130 insertions(+)
 create mode 100644 src/ir_cfg.c

(limited to 'src/ir_cfg.c')

diff --git a/src/ir_cfg.c b/src/ir_cfg.c
new file mode 100644
index 0000000..86af3f3
--- /dev/null
+++ b/src/ir_cfg.c
@@ -0,0 +1,130 @@
+#include "ir.h"
+
+static void
+porec(int *nblk, struct block ***rpo, struct block *b)
+{
+   if (wasvisited(b)) return;
+   assert(*nblk > 0 && "nblk bad");
+   --*nblk;
+   markvisited(b);
+   if (b->s2) porec(nblk, rpo, b->s2);
+   if (b->s1) porec(nblk, rpo, b->s1);
+   *--*rpo = b;
+}
+
+/* also blkid */
+void
+sortrpo(struct function *fn)
+{
+   static struct block **rpobuf;
+   struct block **rpoend, **rpo, *blk, *next;
+   int i, ndead;
+
+   xbgrow(&rpobuf, fn->nblk);
+   rpo = rpoend = rpobuf + fn->nblk,
+
+   startbbvisit();
+   fn->entry->id = 0;
+   int nblk = fn->nblk;
+   porec(&nblk, &rpo, fn->entry);
+   ndead = rpo - rpobuf;
+   if (ndead > 0) for (blk = fn->entry->lprev; blk != fn->entry; blk = next) {
+      next = blk->lprev;
+      if (!wasvisited(blk)) {
+         for (int i = 0; i < blk->ins.n; ++i) {
+            /* if unreachable block has alloca pseudo-instrs, move them to the entry
+             * to be able to delete it */
+            if (oisalloca(instrtab[blk->ins.p[i]].op)) {
+               vpush(&fn->entry->ins, blk->ins.p[i]);
+            }
+         }
+         for (int i = 0; i < blk->npred; ++i)
+            assert(!wasvisited(blkpred(blk, i)));
+         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;
+
+   fn->prop |= FNBLKID | FNRPO;
+}
+
+/* also blkid */
+void
+filldom(struct function *fn)
+{
+   struct block *blk = fn->entry;
+   int i = 0;
+
+   FREQUIRE(FNRPO);
+
+   /* Implements 'A Simple, Fast Dominance Algorithm' by K. Cooper, T. Harvey, and K. Kennedy */
+   do blk->id = i++, blk->idom = NULL; while ((blk = blk->lnext) != fn->entry);
+   fn->entry->idom = fn->entry;
+   for (bool changed = 1; changed;) {
+      changed = 0;
+      do {
+         int j;
+         struct block *new = NULL;
+         if (blk->npred == 0) continue;
+         for (j = 0; j < blk->npred; ++j)
+            if ((new = blkpred(blk, j))->id < blk->id) break;
+         assert(new);
+         for (int i = 0; i < blk->npred; ++i) {
+            if (i == j) continue;
+            struct block *p = blkpred(blk, i);
+            if (p->idom) { /* new = intersect(p, new) */
+               while (p != new) {
+                  while (p->id > new->id) p = p->idom;
+                  while (p->id < new->id) new = new->idom;
+               }
+            }
+         }
+         if (blk->idom != new) {
+            blk->idom = new;
+            changed = 1;
+         }
+      } while ((blk = blk->lnext) != fn->entry);
+   }
+   fn->prop |= FNBLKID | FNDOM;
+}
+
+static void
+loopmark(struct block *head, struct block *blk)
+{
+   if (blk->id < head->id || blk->visit == head->id) return;
+   blk->visit = head->id;
+   ++blk->loop;
+   for (int i = 0; i < blk->npred; ++i)
+      loopmark(head, blkpred(blk, i));
+}
+
+void
+fillloop(struct function *fn)
+{
+   struct block *b = fn->entry;
+   int id = 0;
+   FREQUIRE(FNRPO);
+   do {
+      b->id = id++;
+      b->visit = -1u;
+      b->loop = 0;
+   } while ((b = b->lnext) != fn->entry);
+   do {
+      for (int i = 0; i < b->npred; ++i) {
+         struct block *p = blkpred(b, i);
+         if (p->id > b->id) { /* b is loop header */
+            loopmark(b, p);
+         }
+      }
+   } while ((b = b->lnext) != fn->entry);
+   fn->prop |= FNBLKID;
+}
+
+/* vim:set ts=3 sw=3 expandtab: */
-- 
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