Use signaling NaN for holes in fixed double arrays.

src/objects-inl.h

 // Copyright 2012 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.
 //
 // Review notes:
 //
 // - The use of macros in these inline functions may seem superfluous
 // but it is absolutely needed to make sure gcc generates optimal
 // code. gcc is not happy when attempting to inline too deep.
 //
@@ skipping 2271 matching lines @@
   DCHECK_NE(GetHeap()->fixed_cow_array_map(), map());
   DCHECK_EQ(FIXED_ARRAY_TYPE, map()->instance_type());
   DCHECK(index >= 0 && index < this->length());
   int offset = kHeaderSize + index * kPointerSize;
   WRITE_FIELD(this, offset, value);
   WRITE_BARRIER(GetHeap(), this, offset, value);
 }
 
 
 inline bool FixedDoubleArray::is_the_hole_nan(double value) {
-  return bit_cast<uint64_t, double>(value) == kHoleNanInt64;
+  return bit_cast<uint64_t>(value) == kHoleNanInt64;
 }
 
 
 inline double FixedDoubleArray::hole_nan_as_double() {
-  return bit_cast<double, uint64_t>(kHoleNanInt64);
+  return bit_cast<double>(kHoleNanInt64);
 }
 
 
-inline double FixedDoubleArray::canonical_not_the_hole_nan_as_double() {
-  DCHECK(bit_cast<uint64_t>(base::OS::nan_value()) != kHoleNanInt64);
-  DCHECK((bit_cast<uint64_t>(base::OS::nan_value()) >> 32) != kHoleNanUpper32);
-  return base::OS::nan_value();
-}
-
-
 double FixedDoubleArray::get_scalar(int index) {
   DCHECK(map() != GetHeap()->fixed_cow_array_map() &&
          map() != GetHeap()->fixed_array_map());
   DCHECK(index >= 0 && index < this->length());
   double result = READ_DOUBLE_FIELD(this, kHeaderSize + index * kDoubleSize);
   DCHECK(!is_the_hole_nan(result));
   return result;
 }
 
 int64_t FixedDoubleArray::get_representation(int index) {
@@ skipping 11 matching lines @@
   } else {
     return array->GetIsolate()->factory()->NewNumber(array->get_scalar(index));
   }
 }
 
 
 void FixedDoubleArray::set(int index, double value) {
   DCHECK(map() != GetHeap()->fixed_cow_array_map() &&
          map() != GetHeap()->fixed_array_map());
   int offset = kHeaderSize + index * kDoubleSize;
-  if (std::isnan(value)) value = canonical_not_the_hole_nan_as_double();
+  if (std::isnan(value)) {
+    value = std::numeric_limits<double>::quiet_NaN();
+  }
   WRITE_DOUBLE_FIELD(this, offset, value);
 }
 
 
 void FixedDoubleArray::set_the_hole(int index) {
   DCHECK(map() != GetHeap()->fixed_cow_array_map() &&
          map() != GetHeap()->fixed_array_map());
   int offset = kHeaderSize + index * kDoubleSize;
   WRITE_DOUBLE_FIELD(this, offset, hole_nan_as_double());
 }
@@ skipping 5157 matching lines @@
 #undef READ_SHORT_FIELD
 #undef WRITE_SHORT_FIELD
 #undef READ_BYTE_FIELD
 #undef WRITE_BYTE_FIELD
 #undef NOBARRIER_READ_BYTE_FIELD
 #undef NOBARRIER_WRITE_BYTE_FIELD
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_INL_H_