[turbofan] Fix control reducer for dead loops.

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 7f97254b372bf0c4c9a16fbddefd9a0938ca7acd..df302dd8ed838f37c6d7045cdea78d2be6b1c3b5 100644
--- a/src/compiler/control-reducer.cc
+++ b/src/compiler/control-reducer.cc
@@ -384,7 +384,8 @@ class ControlReducerImpl {
   // Reducer implementation: perform reductions on a node.
   //===========================================================================
   Node* ReduceNode(Node* node) {
-    if (node->op()->ControlInputCount() == 1) {
+    if (node->op()->ControlInputCount() == 1 ||
+        node->opcode() == IrOpcode::kLoop) {
       // If a node has only one control input and it is dead, replace with dead.
       Node* control = NodeProperties::GetControlInput(node);
       if (control->opcode() == IrOpcode::kDead) {
@@ -611,21 +612,20 @@ void ControlReducer::TrimGraph(Zone* zone, JSGraph* jsgraph) {
 }
 
 
-Node* ControlReducer::ReducePhiForTesting(JSGraph* jsgraph,
-                                          CommonOperatorBuilder* common,
-                                          Node* node) {
+Node* ControlReducer::ReduceMerge(JSGraph* jsgraph,
+                                  CommonOperatorBuilder* common, Node* node) {
   Zone zone;
   ControlReducerImpl impl(&zone, jsgraph, common);
-  return impl.ReducePhi(node);
+  return impl.ReduceMerge(node);
 }
 
 
-Node* ControlReducer::ReduceMergeForTesting(JSGraph* jsgraph,
-                                            CommonOperatorBuilder* common,
-                                            Node* node) {
+Node* ControlReducer::ReducePhiForTesting(JSGraph* jsgraph,
+                                          CommonOperatorBuilder* common,
+                                          Node* node) {
   Zone zone;
   ControlReducerImpl impl(&zone, jsgraph, common);
-  return impl.ReduceMerge(node);
+  return impl.ReducePhi(node);
 }