[turbofan] Fix bogus covering of Word64Equal w/ zero.

test/cctest/compiler/test-run-machops.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 <cmath>
 #include <functional>
 #include <limits>
 
 #include "src/base/bits.h"
 #include "src/codegen.h"
@@ skipping 4418 matching lines @@
   FOR_INT32_INPUTS(i) {
     FOR_INT32_INPUTS(j) {
       int32_t expected;
       if (bits::SignedSubOverflow32(*i, *j, &expected)) expected = constant;
       CHECK_EQ(expected, bt.call(*i, *j));
     }
   }
 }
 
 
+TEST(RunWord64EqualInBranchP) {
+  int64_t input;
+  MLabel blocka, blockb;
+  RawMachineAssemblerTester<int64_t> m;
+  if (!m.machine()->Is64()) return;
+  Node* value = m.LoadFromPointer(&input, kMachInt64);
+  m.Branch(m.Word64Equal(value, m.Int64Constant(0)), &blocka, &blockb);
+  m.Bind(&blocka);
+  m.Return(m.Int32Constant(1));
+  m.Bind(&blockb);
+  m.Return(m.Int32Constant(2));
+  input = V8_INT64_C(0);
+  CHECK_EQ(1, m.Call());
+  input = V8_INT64_C(1);
+  CHECK_EQ(2, m.Call());
+  input = V8_INT64_C(0x100000000);
+  CHECK_EQ(2, m.Call());
+}
+
+
 TEST(RunChangeInt32ToInt64P) {
   if (kPointerSize < 8) return;
   int64_t actual = -1;
   RawMachineAssemblerTester<int32_t> m(kMachInt32);
   m.StoreToPointer(&actual, kMachInt64, m.ChangeInt32ToInt64(m.Parameter(0)));
   m.Return(m.Int32Constant(0));
   FOR_INT32_INPUTS(i) {
     int64_t expected = *i;
     CHECK_EQ(0, m.Call(*i));
     CHECK_EQ(expected, actual);
@@ skipping 337 matching lines @@
       &result, kMachFloat64,
       m.Float64RoundTiesAway(m.LoadFromPointer(&input, kMachFloat64)));
   m.Return(m.Int32Constant(0));
   for (size_t i = 0; i < arraysize(kValues); ++i) {
     input = kValues[i];
     CHECK_EQ(0, m.Call());
     double expected = round(kValues[i]);
     CHECK_EQ(expected, result);
   }
 }
+
 #endif  // V8_TURBOFAN_TARGET