[wasm] New attempt to implement the Int64Lowering of phis.

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 624 matching lines @@
   LowerGraph(graph()->NewNode(machine()->Word64PopcntPlaceholder(),
                               Int64Constant(value(0))),
              MachineRepresentation::kWord64);
 
   EXPECT_THAT(
       graph()->end()->InputAt(1),
       IsReturn2(IsInt32Add(IsWord32Popcnt(IsInt32Constant(low_word_value(0))),
                            IsWord32Popcnt(IsInt32Constant(high_word_value(0)))),
                 IsInt32Constant(0), start(), start()));
 }
+
+TEST_F(Int64LoweringTest, I64PhiWord64) {
+  LowerGraph(graph()->NewNode(common()->Phi(MachineRepresentation::kWord64, 2),
+                              Int64Constant(value(0)), Int64Constant(value(1)),
+                              start()),
+             MachineRepresentation::kWord64);
+
+  EXPECT_THAT(graph()->end()->InputAt(1),
+              IsReturn2(IsPhi(MachineRepresentation::kWord32,
+                              IsInt32Constant(low_word_value(0)),
+                              IsInt32Constant(low_word_value(1)), start()),
+                        IsPhi(MachineRepresentation::kWord32,
+                              IsInt32Constant(high_word_value(0)),
+                              IsInt32Constant(high_word_value(1)), start()),
+                        start(), start()));
+}
+
+void TestPhi(Int64LoweringTest* test, MachineRepresentation rep, Node* v1,
+             Node* v2) {
+  test->LowerGraph(test->graph()->NewNode(test->common()->Phi(rep, 2), v1, v2,
+                                          test->start()),
+                   rep);
+
+  EXPECT_THAT(test->graph()->end()->InputAt(1),
+              IsReturn(IsPhi(rep, v1, v2, test->start()), test->start(),
+                       test->start()));
+}
+
+TEST_F(Int64LoweringTest, I64PhiFloat32) {
+  TestPhi(this, MachineRepresentation::kFloat32, Float32Constant(1.5),
+          Float32Constant(2.5));
+}
+
+TEST_F(Int64LoweringTest, I64PhiFloat64) {
+  TestPhi(this, MachineRepresentation::kFloat64, Float32Constant(1.5),
+          Float32Constant(2.5));
+}
+
+TEST_F(Int64LoweringTest, I64PhiWord32) {
+  TestPhi(this, MachineRepresentation::kWord32, Float32Constant(1),
+          Float32Constant(2));
+}
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8