[wasm] Int64Lowering: changing to DFS.

test/unittests/compiler/int64-lowering-unittest.cc

 // Copyright 2016 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/int64-lowering.h"
 #include "src/compiler/common-operator.h"
 #include "src/compiler/linkage.h"
 #include "src/compiler/machine-operator.h"
 #include "src/compiler/node.h"
 
@@ skipping 476 matching lines @@
   EXPECT_THAT(graph()->end()->InputAt(1),
               IsReturn2(IsInt32Constant(low_word_value(0)), IsInt32Constant(0),
                         start(), start()));
 }
 // kExprF64ReinterpretI64:
 // kExprI64ReinterpretF64:
 
 // kExprI64Clz:
 // kExprI64Ctz:
 // kExprI64Popcnt:
+
+TEST_F(Int64LoweringTest, Dfs) {
+  Node* common = Int64Constant(value(0));
+  LowerGraph(graph()->NewNode(machine()->Word64And(), common,
+                              graph()->NewNode(machine()->Word64And(), common,
+                                               Int64Constant(value(1)))),
+             MachineRepresentation::kWord64);
+
+  EXPECT_THAT(
+      graph()->end()->InputAt(1),
+      IsReturn2(IsWord32And(IsInt32Constant(low_word_value(0)),
+                            IsWord32And(IsInt32Constant(low_word_value(0)),
+                                        IsInt32Constant(low_word_value(1)))),
+                IsWord32And(IsInt32Constant(high_word_value(0)),
+                            IsWord32And(IsInt32Constant(high_word_value(0)),
+                                        IsInt32Constant(high_word_value(1)))),
+                start(), start()));
+}
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8