Implemented the Word64Clz TurboFan operator for x64, arm64, and mips64.

test/unittests/compiler/mips64/instruction-selector-mips64-unittest.cc

 // Copyright 2014 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 "test/unittests/compiler/instruction-selector-unittest.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
@@ skipping 823 matching lines @@
   Stream s = m.Build();
   ASSERT_EQ(1U, s.size());
   EXPECT_EQ(kMips64Clz, s[0]->arch_opcode());
   ASSERT_EQ(1U, s[0]->InputCount());
   EXPECT_EQ(s.ToVreg(p0), s.ToVreg(s[0]->InputAt(0)));
   ASSERT_EQ(1U, s[0]->OutputCount());
   EXPECT_EQ(s.ToVreg(n), s.ToVreg(s[0]->Output()));
 }
 
 
+TEST_F(InstructionSelectorTest, Word64Clz) {
+  StreamBuilder m(this, kMachUint64, kMachUint64);
+  Node* const p0 = m.Parameter(0);
+  Node* const n = m.Word64Clz(p0);
+  m.Return(n);
+  Stream s = m.Build();
+  ASSERT_EQ(1U, s.size());
+  EXPECT_EQ(kMips64Dclz, s[0]->arch_opcode());
+  ASSERT_EQ(1U, s[0]->InputCount());
+  EXPECT_EQ(s.ToVreg(p0), s.ToVreg(s[0]->InputAt(0)));
+  ASSERT_EQ(1U, s[0]->OutputCount());
+  EXPECT_EQ(s.ToVreg(n), s.ToVreg(s[0]->Output()));
+}
+
+
 TEST_F(InstructionSelectorTest, Float32Abs) {
   StreamBuilder m(this, kMachFloat32, kMachFloat32);
   Node* const p0 = m.Parameter(0);
   Node* const n = m.Float32Abs(p0);
   m.Return(n);
   Stream s = m.Build();
   ASSERT_EQ(1U, s.size());
   EXPECT_EQ(kMips64AbsS, s[0]->arch_opcode());
   ASSERT_EQ(1U, s[0]->InputCount());
   EXPECT_EQ(s.ToVreg(p0), s.ToVreg(s[0]->InputAt(0)));
@@ skipping 76 matching lines @@
   ASSERT_EQ(1U, s.size());
   EXPECT_EQ(kMips64Float64Min, s[0]->arch_opcode());
   ASSERT_EQ(2U, s[0]->InputCount());
   ASSERT_EQ(1U, s[0]->OutputCount());
   EXPECT_EQ(s.ToVreg(n), s.ToVreg(s[0]->Output()));
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8