[turbofan] Fix tail call optimization.

src/compiler/node.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/compiler/node.h"
 
 #include <algorithm>
 
 namespace v8 {
 namespace internal {
@@ skipping 120 matching lines @@
   if (last_use) {
     // Concat the use list of {this} and {that}.
     last_use->next = that->first_use_;
     if (that->first_use_) that->first_use_->prev = last_use;
     that->first_use_ = this->first_use_;
   }
   first_use_ = nullptr;
 }
 
 
+bool Node::OwnedBy(Node const* owner1, Node const* owner2) const {
+  unsigned mask = 0;
+  for (Use* use = first_use_; use; use = use->next) {
+    if (use->from == owner1) {
+      mask |= 1;
+    } else if (use->from == owner2) {
+      mask |= 2;
+    } else {
+      return false;
+    }
+  }
+  return mask == 3;
+}
+
+
 void Node::Input::Update(Node* new_to) {
   Node* old_to = this->to;
   if (new_to == old_to) return;  // Nothing to do.
   // Snip out the use from where it used to be
   if (old_to) {
     old_to->RemoveUse(use);
   }
   to = new_to;
   // And put it into the new node's use list.
   if (new_to) {
@@ skipping 102 matching lines @@
   ++(*this);
   return result;
 }
 
 
 bool Node::Uses::empty() const { return begin() == end(); }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8