Implemented the Word64Popcnt TurboFan operator for x64.

test/cctest/compiler/test-run-machops.cc

Index: test/cctest/compiler/test-run-machops.cc
diff --git a/test/cctest/compiler/test-run-machops.cc b/test/cctest/compiler/test-run-machops.cc
index b7c978a747d76e8c6639b502e31f64a5164be84d..96bcc86953d79bc41abf2b058d06fbe28791eca1 100644
--- a/test/cctest/compiler/test-run-machops.cc
+++ b/test/cctest/compiler/test-run-machops.cc
@@ -284,6 +284,25 @@ TEST(RunWord64Ctz) {
   CHECK_EQ(1, m.Call(uint64_t(0x000000009afdbc82)));
   CHECK_EQ(0, m.Call(uint64_t(0x000000009afdbc81)));
 }
+
+
+TEST(RunWord64Popcnt) {
+  BufferedRawMachineAssemblerTester<int32_t> m(kMachUint64);
+  if (!m.machine()->Word64Popcnt().IsSupported()) {
+    return;
+  }
+
+  m.Return(m.AddNode(m.machine()->Word64Popcnt().op(), m.Parameter(0)));
+
+  CHECK_EQ(0, m.Call(uint64_t(0x0000000000000000)));
+  CHECK_EQ(1, m.Call(uint64_t(0x0000000000000001)));
+  CHECK_EQ(1, m.Call(uint64_t(0x8000000000000000)));
+  CHECK_EQ(64, m.Call(uint64_t(0xffffffffffffffff)));
+  CHECK_EQ(12, m.Call(uint64_t(0x000dc100000dc100)));
+  CHECK_EQ(18, m.Call(uint64_t(0xe00dc100e00dc100)));
+  CHECK_EQ(22, m.Call(uint64_t(0xe00dc103e00dc103)));
+  CHECK_EQ(18, m.Call(uint64_t(0x000dc107000dc107)));
+}
 #endif  // V8_TARGET_ARCH_64_BIT