Make control reducer revisit newly introduced merges.

src/compiler/control-reducer.cc

Index: src/compiler/control-reducer.cc
diff --git a/src/compiler/control-reducer.cc b/src/compiler/control-reducer.cc
index acb2f06b04ea116e9c1ccbbf08978e72ae49d532..eef8a49fb12c8cfdf1486d28ec3039223ba80548 100644
--- a/src/compiler/control-reducer.cc
+++ b/src/compiler/control-reducer.cc
@@ -196,6 +196,9 @@ class ControlReducerImpl {
       merge = graph()->NewNode(common_->Merge(2), merge, loop);
       end->ReplaceInput(0, merge);
       to_add = merge;
+      // Mark the node as visited so that we can revisit later.
+      EnsureStateSize(merge->id());
+      state_[merge->id()] = kVisited;
     } else {
       // Append a new input to the final merge at the end.
       merge->AppendInput(graph()->zone(), loop);
@@ -293,14 +296,17 @@ class ControlReducerImpl {
     if (replacement != node) Recurse(replacement);
   }
 
+  void EnsureStateSize(size_t id) {
+    if (id >= state_.size()) {
+      state_.resize((3 * id) / 2, kUnvisited);
+    }
+  }
+
   // Push a node onto the stack if its state is {kUnvisited} or {kRevisit}.
   bool Recurse(Node* node) {
     size_t id = static_cast<size_t>(node->id());
-    if (id < state_.size()) {
-      if (state_[id] != kRevisit && state_[id] != kUnvisited) return false;
-    } else {
-      state_.resize((3 * id) / 2, kUnvisited);
-    }
+    EnsureStateSize(id);
+    if (state_[id] != kRevisit && state_[id] != kUnvisited) return false;
     Push(node);
     return true;
   }