[turbofan] Correctify TruncateFloat64ToInt32 reduction in MachineOperatorReducer.

test/unittests/compiler/machine-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/base/bits.h"
 #include "src/base/division-by-constant.h"
 #include "src/compiler/js-graph.h"
 #include "src/compiler/machine-operator-reducer.h"
 #include "src/compiler/typer.h"
 #include "test/unittests/compiler/graph-unittest.h"
@@ skipping 451 matching lines @@
   Reduction reduction = Reduce(graph()->NewNode(
       machine()->TruncateFloat64ToInt32(),
       graph()->NewNode(common()->Phi(kMachFloat64, 2), p0, p1, merge)));
   ASSERT_TRUE(reduction.Changed());
   EXPECT_THAT(reduction.replacement(),
               IsPhi(kMachInt32, IsTruncateFloat64ToInt32(p0),
                     IsTruncateFloat64ToInt32(p1), merge));
 }
 
 
+TEST_F(MachineOperatorReducerTest,
+       TruncateFloat64ToInt32WithPhiAndChangeInt32ToFloat64) {
+  Node* const p0 = Parameter(0);
+  Node* const merge = graph()->start();
+  Node* const truncate = graph()->NewNode(
+      machine()->TruncateFloat64ToInt32(),
+      graph()->NewNode(common()->Phi(kMachFloat64, 2), p0, p0, merge));
+  truncate->InputAt(0)->ReplaceInput(
+      1, graph()->NewNode(machine()->ChangeInt32ToFloat64(), truncate));
+  Reduction reduction = Reduce(truncate);
+  ASSERT_TRUE(reduction.Changed());
+  Capture<Node*> phi;
+  EXPECT_THAT(
+      reduction.replacement(),
+      AllOf(CaptureEq(&phi), IsPhi(kMachInt32, IsTruncateFloat64ToInt32(p0),
+                                   CaptureEq(&phi), merge)));
+}
+
+
 // -----------------------------------------------------------------------------
 // TruncateInt64ToInt32
 
 
 TEST_F(MachineOperatorReducerTest, TruncateInt64ToInt32WithChangeInt32ToInt64) {
   Node* value = Parameter(0);
   Reduction reduction = Reduce(graph()->NewNode(
       machine()->TruncateInt64ToInt32(),
       graph()->NewNode(machine()->ChangeInt32ToInt64(), value)));
   ASSERT_TRUE(reduction.Changed());
@@ skipping 849 matching lines @@
     Reduction r = Reduce(node);
     ASSERT_TRUE(r.Changed());
     EXPECT_THAT(r.replacement(),
                 IsStore(rep, base, index, value, effect, control));
   }
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8