X64: Convert smis to holding 32 bits of payload.

src/objects-inl.h

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 726 matching lines @@
 }
 
 
 int Smi::value() {
   return Internals::SmiValue(this);
 }
 
 
 Smi* Smi::FromInt(int value) {
   ASSERT(Smi::IsValid(value));
+  int smi_shift_bits = kSmiTagSize + kSmiShiftSize;
   intptr_t tagged_value =
-      (static_cast<intptr_t>(value) << kSmiTagSize) | kSmiTag;
+      (static_cast<intptr_t>(value) << smi_shift_bits) | kSmiTag;
   return reinterpret_cast<Smi*>(tagged_value);
 }
 
 
 Smi* Smi::FromIntptr(intptr_t value) {
   ASSERT(Smi::IsValid(value));
-  return reinterpret_cast<Smi*>((value << kSmiTagSize) | kSmiTag);
+  int smi_shift_bits = kSmiTagSize + kSmiShiftSize;
+  return reinterpret_cast<Smi*>((value << smi_shift_bits) | kSmiTag);
 }
 
 
 Failure::Type Failure::type() const {
   return static_cast<Type>(value() & kFailureTypeTagMask);
 }
 
 
 bool Failure::IsInternalError() const {
   return type() == INTERNAL_ERROR;
@@ skipping 59 matching lines @@
   ASSERT(((info << kFailureTagSize) >> kFailureTagSize) == info);
   return reinterpret_cast<Failure*>(
       (static_cast<intptr_t>(info) << kFailureTagSize) | kFailureTag);
 }
 
 
 bool Smi::IsValid(intptr_t value) {
 #ifdef DEBUG
   bool in_range = (value >= kMinValue) && (value <= kMaxValue);
 #endif
+
+#ifdef V8_LONG_SMI
+  // To be representable as a long smi, the value must be a 32-bit integer.
+  bool result = (value == static_cast<int32_t>(value));
+#else
   // To be representable as an tagged small integer, the two
   // most-significant bits of 'value' must be either 00 or 11 due to
   // sign-extension. To check this we add 01 to the two
   // most-significant bits, and check if the most-significant bit is 0
   //
   // CAUTION: The original code below:
   // bool result = ((value + 0x40000000) & 0x80000000) == 0;
   // may lead to incorrect results according to the C language spec, and
   // in fact doesn't work correctly with gcc4.1.1 in some cases: The
   // compiler may produce undefined results in case of signed integer
   // overflow. The computation must be done w/ unsigned ints.
-  bool result =
-      ((static_cast<unsigned int>(value) + 0x40000000U) & 0x80000000U) == 0;
+  bool result = (static_cast<uintptr_t>(value + 0x40000000U) < 0x80000000U);
+#endif
   ASSERT(result == in_range);
   return result;
 }
-
-
-bool Smi::IsIntptrValid(intptr_t value) {
-#ifdef DEBUG
-  bool in_range = (value >= kMinValue) && (value <= kMaxValue);
-#endif
-  // See Smi::IsValid(int) for description.
-  bool result =
-      ((static_cast<uintptr_t>(value) + 0x40000000U) < 0x80000000U);
-  ASSERT(result == in_range);
-  return result;
-}
 
 
 MapWord MapWord::FromMap(Map* map) {
   return MapWord(reinterpret_cast<uintptr_t>(map));
 }
 
 
 Map* MapWord::ToMap() {
   return reinterpret_cast<Map*>(value_);
 }
@@ skipping 2019 matching lines @@
 #undef WRITE_INT_FIELD
 #undef READ_SHORT_FIELD
 #undef WRITE_SHORT_FIELD
 #undef READ_BYTE_FIELD
 #undef WRITE_BYTE_FIELD
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_INL_H_