From 090d8ad81ef04585d7cf0985f6fa9557f2fc6831 Mon Sep 17 00:00:00 2001
From: CHatingPython <chatingpython@kpgpmc.org>
Date: Tue, 18 Aug 2026 13:55:39 +0200
Subject: [PATCH] feat(furc/SSA): compute dominance frontiers

---
 furc/src/middle/ssa.cpp | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/furc/src/middle/ssa.cpp b/furc/src/middle/ssa.cpp
index 497aac9..96dc994 100644
--- a/furc/src/middle/ssa.cpp
+++ b/furc/src/middle/ssa.cpp
@@ -26,6 +26,9 @@ struct block_info {
     std::unordered_set<std::size_t> preds;
     std::unordered_set<std::size_t> sucs;
     std::size_t                     idom = 0;
+
+    // Dominance Frontiers
+    std::unordered_set<std::size_t> df;
 };
 
 void rpo_dfs(std::unordered_set<std::size_t>& visited,
@@ -116,6 +119,18 @@ void process_function(ir_function& func) {
             }
         }
     }
+
+    // 3. Computing Dominance Frontiers
+    for (std::size_t j = 0; j < blocks.size(); ++j) {
+        const auto& join = blocks[j];
+        if (join.preds.size() < 2) continue;
+        for (std::size_t runner : join.preds) {
+            while (runner != join.idom) {
+                blocks[runner].df.insert(j);
+                runner = blocks[runner].idom;
+            }
+        }
+    }
 }
 
 } // namespace