Make sure floating phi nodes are coupled to their control.

src/compiler/scheduler.h

Index: src/compiler/scheduler.h
diff --git a/src/compiler/scheduler.h b/src/compiler/scheduler.h
index a5207128beb62d77e9049f3e38941a82ec521016..88f7be75a8a02b9e8905ad314a1a4276a1a73887 100644
--- a/src/compiler/scheduler.h
+++ b/src/compiler/scheduler.h
@@ -27,7 +27,7 @@ class Scheduler {
   static BasicBlockVector* ComputeSpecialRPO(Schedule* schedule);
 
  private:
-  enum Placement { kUnknown, kSchedulable, kFixed };
+  enum Placement { kUnknown, kSchedulable, kFixed, kCoupled };
 
   // Per-node data tracked during scheduling.
   struct SchedulerData {
@@ -36,8 +36,8 @@ class Scheduler {
     bool is_connected_control_;  // {true} if control-connected to the end node.
     bool is_floating_control_;   // {true} if control, but not control-connected
                                  // to the end node.
-    Placement placement_ : 3;    // Whether the node is fixed, schedulable,
-                                 // or not yet known.
+    Placement placement_ : 2;    // Whether the node is fixed, schedulable,
+                                 // coupled to another node, or not yet known.
   };
 
   Zone* zone_;
@@ -50,23 +50,15 @@ class Scheduler {
 
   Scheduler(Zone* zone, Graph* graph, Schedule* schedule);
 
-  SchedulerData DefaultSchedulerData();
-
-  SchedulerData* GetData(Node* node) {
-    DCHECK(node->id() < static_cast<int>(node_data_.size()));
-    return &node_data_[node->id()];
-  }
+  inline SchedulerData DefaultSchedulerData();
+  inline SchedulerData* GetData(Node* node);
 
   Placement GetPlacement(Node* node);
 
-  int GetRPONumber(BasicBlock* block) {
-    DCHECK(block->rpo_number() >= 0 &&
-           block->rpo_number() <
-               static_cast<int>(schedule_->rpo_order_.size()));
-    DCHECK(schedule_->rpo_order_[block->rpo_number()] == block);
-    return block->rpo_number();
-  }
+  void IncrementUnscheduledUseCount(Node* node, Node* from);
+  void DecrementUnscheduledUseCount(Node* node, Node* from);
 
+  inline int GetRPONumber(BasicBlock* block);
   BasicBlock* GetCommonDominator(BasicBlock* b1, BasicBlock* b2);
 
   // Phase 1: Build control-flow graph and dominator tree.