[turbofan] Support variable size argument popping in TF-generated functions

test/unittests/compiler/common-operator-reducer-unittest.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/compiler/common-operator.h"
 #include "src/compiler/common-operator-reducer.h"
 #include "src/compiler/machine-operator.h"
 #include "src/compiler/operator.h"
 #include "src/compiler/simplified-operator.h"
 #include "src/machine-type.h"
@@ skipping 343 matching lines @@
   Node* if_true = graph()->NewNode(common()->IfTrue(), branch);
   Node* etrue = graph()->start();
   Node* vtrue = Parameter(0);
   Node* if_false = graph()->NewNode(common()->IfFalse(), branch);
   Node* efalse = graph()->start();
   Node* vfalse = Parameter(1);
   Node* merge = graph()->NewNode(common()->Merge(2), if_true, if_false);
   Node* ephi = graph()->NewNode(common()->EffectPhi(2), etrue, efalse, merge);
   Node* phi = graph()->NewNode(common()->Phi(MachineRepresentation::kTagged, 2),
                                vtrue, vfalse, merge);
-  Node* ret = graph()->NewNode(common()->Return(), phi, ephi, merge);
+
+  Node* zero = graph()->NewNode(common()->Int32Constant(0));
+  Node* ret = graph()->NewNode(common()->Return(), zero, phi, ephi, merge);
   graph()->SetEnd(graph()->NewNode(common()->End(1), ret));
   StrictMock<MockAdvancedReducerEditor> editor;
   EXPECT_CALL(editor, Replace(merge, IsDead()));
   Reduction const r = Reduce(&editor, ret);
   ASSERT_TRUE(r.Changed());
   EXPECT_THAT(r.replacement(), IsDead());
   EXPECT_THAT(graph()->end(), IsEnd(ret, IsReturn(vtrue, etrue, if_true),
                                     IsReturn(vfalse, efalse, if_false)));
 }
 
@@ skipping 83 matching lines @@
       graph()->NewNode(common()->Select(MachineRepresentation::kFloat64), check,
                        p0, graph()->NewNode(machine()->Float64Sub(), c0, p0));
   Reduction r = Reduce(select);
   ASSERT_TRUE(r.Changed());
   EXPECT_THAT(r.replacement(), IsFloat64Abs(p0));
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8