[turbofan] Clean up cached nodes in JSGraph.

test/cctest/compiler/test-control-reducer.cc

 // Copyright 2014 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/v8.h"
 #include "test/cctest/cctest.h"
 
 #include "src/base/bits.h"
 #include "src/compiler/common-operator.h"
 #include "src/compiler/control-reducer.h"
@@ skipping 382 matching lines @@
       T.jsgraph.NullConstant(),      T.jsgraph.ZeroConstant(),
       T.jsgraph.OneConstant(),       T.jsgraph.NaNConstant(),
       T.jsgraph.Constant(21),        T.jsgraph.Constant(22.2)};
 
   for (size_t i = 0; i < arraysize(other_constants); i++) {
     CheckTrimConstant(&T, other_constants[i]);
   }
 }
 
 
+TEST(Trim_EmptyFrameState1) {
+  ControlReducerTester T;
+
+  Node* node = T.jsgraph.EmptyFrameState();
+  T.Trim();
+
+  for (Node* input : node->inputs()) {
+    CHECK_NOT_NULL(input);
+  }
+}
+
+
+TEST(Trim_EmptyFrameState2) {
+  ControlReducerTester T;
+  CheckTrimConstant(&T, T.jsgraph.EmptyFrameState());
+}
+
+
 TEST(CReducePhi1) {
   ControlReducerTester R;
 
   R.ReducePhi(R.leaf[0], R.Phi(R.leaf[0]));
   R.ReducePhi(R.leaf[1], R.Phi(R.leaf[1]));
   R.ReducePhi(R.leaf[2], R.Phi(R.leaf[2]));
   R.ReducePhi(R.leaf[3], R.Phi(R.leaf[3]));
 }
 
 
@@ skipping 1108 matching lines @@
 
   Node* ret = R.Return(d1.phi, R.start, d1.merge);
 
   R.ReduceGraph();  // d1 gets folded true.
 
   CheckInputs(ret, y2, R.start, R.start);
   CheckDeadDiamond(d1);
   CheckDeadDiamond(d2);
   CheckDeadDiamond(d3);
 }