[wasm] Int64Lowering of Word64Clz.

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 874488b476ab0b1409d4b8f72f83cdb92b54e668..002775c57207a05e92f925c475fb60a75ab03954 100644
--- a/test/unittests/compiler/int64-lowering-unittest.cc
+++ b/test/unittests/compiler/int64-lowering-unittest.cc
@@ -551,6 +551,28 @@ TEST_F(Int64LoweringTest, I64ReinterpretF64) {
                 start(), start()));
 }
 // kExprI64Clz:
+TEST_F(Int64LoweringTest, I64Clz) {
+  LowerGraph(graph()->NewNode(machine()->Word64Clz(), Int64Constant(value(0))),
+             MachineRepresentation::kWord64);
+
+  Capture<Node*> branch_capture;
+  Matcher<Node*> branch_matcher = IsBranch(
+      IsWord32Equal(IsInt32Constant(high_word_value(0)), IsInt32Constant(0)),
+      start());
+
+  EXPECT_THAT(
+      graph()->end()->InputAt(1),
+      IsReturn2(
+          IsPhi(MachineRepresentation::kWord32,
+                IsInt32Add(IsWord32Clz(IsInt32Constant(low_word_value(0))),
+                           IsInt32Constant(32)),
+                IsWord32Clz(IsInt32Constant(high_word_value(0))),
+                IsMerge(
+                    IsIfTrue(AllOf(CaptureEq(&branch_capture), branch_matcher)),
+                    IsIfFalse(
+                        AllOf(CaptureEq(&branch_capture), branch_matcher)))),
+          IsInt32Constant(0), start(), start()));
+}
 // kExprI64Ctz:
 // kExprI64Popcnt: