[wasm] Int64Lowering of Word64Ctz.

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 572 matching lines @@
                 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:
+TEST_F(Int64LoweringTest, I64Ctz) {
+  LowerGraph(graph()->NewNode(machine()->Word64CtzPlaceholder(),
+                              Int64Constant(value(0))),
+             MachineRepresentation::kWord64);
+  Capture<Node*> branch_capture;
+  Matcher<Node*> branch_matcher = IsBranch(
+      IsWord32Equal(IsInt32Constant(low_word_value(0)), IsInt32Constant(0)),
+      start());
+  EXPECT_THAT(
+      graph()->end()->InputAt(1),
+      IsReturn2(
+          IsPhi(MachineRepresentation::kWord32,
+                IsInt32Add(IsWord32Ctz(IsInt32Constant(high_word_value(0))),
+                           IsInt32Constant(32)),
+                IsWord32Ctz(IsInt32Constant(low_word_value(0))),
+                IsMerge(
+                    IsIfTrue(AllOf(CaptureEq(&branch_capture), branch_matcher)),
+                    IsIfFalse(
+                        AllOf(CaptureEq(&branch_capture), branch_matcher)))),
+          IsInt32Constant(0), start(), start()));
+}
 // 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(
@@ skipping 14 matching lines @@
 
   EXPECT_THAT(
       graph()->end()->InputAt(1),
       IsReturn2(IsInt32Add(IsWord32Popcnt(IsInt32Constant(low_word_value(0))),
                            IsWord32Popcnt(IsInt32Constant(high_word_value(0)))),
                 IsInt32Constant(0), start(), start()));
 }
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8