[turbofan] Turn Math.clz32 into an inlinable builtin.

test/unittests/compiler/x64/instruction-selector-x64-unittest.cc

Index: test/unittests/compiler/x64/instruction-selector-x64-unittest.cc
diff --git a/test/unittests/compiler/x64/instruction-selector-x64-unittest.cc b/test/unittests/compiler/x64/instruction-selector-x64-unittest.cc
index 13899c5c3ce89221e1ada0d98520f254f0353ed0..a83deafe7d9a7e257dd8ab36347744d4a01c0985 100644
--- a/test/unittests/compiler/x64/instruction-selector-x64-unittest.cc
+++ b/test/unittests/compiler/x64/instruction-selector-x64-unittest.cc
@@ -1146,6 +1146,21 @@ TEST_F(InstructionSelectorTest, Word32AndWith0xffff) {
   }
 }
 
+
+TEST_F(InstructionSelectorTest, Word32Clz) {
+  StreamBuilder m(this, kMachUint32, kMachUint32);
+  Node* const p0 = m.Parameter(0);
+  Node* const n = m.Word32Clz(p0);
+  m.Return(n);
+  Stream s = m.Build();
+  ASSERT_EQ(1U, s.size());
+  EXPECT_EQ(kX64Lzcnt32, 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()));
+}
+
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8