Fix 23563: double unary- operator unstable for NANs

runtime/platform/globals.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef PLATFORM_GLOBALS_H_
 #define PLATFORM_GLOBALS_H_
 
 // __STDC_FORMAT_MACROS has to be defined before including <inttypes.h> to
 // enable platform independent printf format specifiers.
 #ifndef __STDC_FORMAT_MACROS
@@ skipping 316 matching lines @@
 #define DART_2PART_UINT64_C(a, b)                                              \
                  (((static_cast<uint64_t>(a) << 32) + 0x##b##u))
 
 // Integer constants.
 const int32_t kMinInt32 = 0x80000000;
 const int32_t kMaxInt32 = 0x7FFFFFFF;
 const uint32_t kMaxUint32 = 0xFFFFFFFF;
 const int64_t kMinInt64 = DART_INT64_C(0x8000000000000000);
 const int64_t kMaxInt64 = DART_INT64_C(0x7FFFFFFFFFFFFFFF);
 const uint64_t kMaxUint64 = DART_2PART_UINT64_C(0xFFFFFFFF, FFFFFFFF);
+const int64_t kSignBitDouble = DART_INT64_C(0x8000000000000000);
 
 // Types for native machine words. Guaranteed to be able to hold pointers and
 // integers.
 typedef intptr_t word;
 typedef uintptr_t uword;
 
 // Byte sizes.
 const int kWordSize = sizeof(word);
 const int kDoubleSize = sizeof(double);  // NOLINT
 const int kFloatSize = sizeof(float);  // NOLINT
@@ skipping 231 matching lines @@
 // should be counted from two, not one."
 #define PRINTF_ATTRIBUTE(string_index, first_to_check) \
   __attribute__((__format__(__printf__, string_index, first_to_check)))
 #else
 #define PRINTF_ATTRIBUTE(string_index, first_to_check)
 #endif
 
 }  // namespace dart
 
 #endif  // PLATFORM_GLOBALS_H_