[compiler] [wasm] Introduce Word32/64ReverseBytes as TF Optional Opcode

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

Index: test/unittests/compiler/int64-lowering-unittest.cc
diff --git a/test/unittests/compiler/int64-lowering-unittest.cc b/test/unittests/compiler/int64-lowering-unittest.cc
index 934756bf600aaf4569c6c2f84e7827dcf34ebf8a..8331b0ebd19ca4530808bf2ad93b70da9ac38dbf 100644
--- a/test/unittests/compiler/int64-lowering-unittest.cc
+++ b/test/unittests/compiler/int64-lowering-unittest.cc
@@ -819,6 +819,17 @@ TEST_F(Int64LoweringTest, I64PhiWord32) {
   TestPhi(this, MachineRepresentation::kWord32, Float32Constant(1),
           Float32Constant(2));
 }
+
+TEST_F(Int64LoweringTest, I64ReverseBytes) {
+  LowerGraph(graph()->NewNode(machine()->Word64ReverseBytes().placeholder(),
+                              Int64Constant(value(0))),
+             MachineRepresentation::kWord64);
+  EXPECT_THAT(
+      graph()->end()->InputAt(1),
+      IsReturn2(IsWord32ReverseBytes(IsInt32Constant(high_word_value(0))),
+                IsWord32ReverseBytes(IsInt32Constant(low_word_value(0))),
+                start(), start()));
+}
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8