[turbofan] Fix tail call optimization.

test/unittests/compiler/scheduler-unittest.cc

Index: test/unittests/compiler/scheduler-unittest.cc
diff --git a/test/unittests/compiler/scheduler-unittest.cc b/test/unittests/compiler/scheduler-unittest.cc
index 5ebe270677dfe26880364e1de93745639554aea0..22b04ef9ec17d4e8ff01ce66191626a61443eea4 100644
--- a/test/unittests/compiler/scheduler-unittest.cc
+++ b/test/unittests/compiler/scheduler-unittest.cc
@@ -138,6 +138,8 @@ const Operator kIntAdd(IrOpcode::kInt32Add, Operator::kPure, "Int32Add", 2, 0,
                        0, 1, 0, 0);
 const Operator kMockCall(IrOpcode::kCall, Operator::kNoProperties, "MockCall",
                          0, 0, 1, 1, 0, 2);
+const Operator kMockTailCall(IrOpcode::kTailCall, Operator::kNoProperties,
+                             "MockTailCall", 1, 1, 1, 0, 0, 1);
 
 }  // namespace
 
@@ -2406,6 +2408,20 @@ TARGET_TEST_F(SchedulerTest, CallException) {
 }
 
 
+TARGET_TEST_F(SchedulerTest, TailCall) {
+  Node* start = graph()->NewNode(common()->Start(1));
+  graph()->SetStart(start);
+
+  Node* p0 = graph()->NewNode(common()->Parameter(0), start);
+  Node* call = graph()->NewNode(&kMockTailCall, p0, start, start);
+  Node* end = graph()->NewNode(common()->End(), call);
+
+  graph()->SetEnd(end);
+
+  ComputeAndVerifySchedule(4);
+}
+
+
 TARGET_TEST_F(SchedulerTest, Switch) {
   Node* start = graph()->NewNode(common()->Start(1));
   graph()->SetStart(start);