Unify ULL ctor for C++03 and C++11

Author: winner245

libcxx/include/bitset

@@ -229,10 +229,6 @@ protected:
   _LIBCPP_HIDE_FROM_ABI size_t __hash_code() const _NOEXCEPT;
 
 private:
-#  ifdef _LIBCPP_CXX03_LANG
-  void __init(unsigned long long __v, false_type) _NOEXCEPT;
-  _LIBCPP_HIDE_FROM_ABI void __init(unsigned long long __v, true_type) _NOEXCEPT;
-#  endif // _LIBCPP_CXX03_LANG
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 unsigned long to_ulong(false_type) const;
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 unsigned long to_ulong(true_type) const;
   _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 unsigned long long to_ullong(false_type) const;
@@ -242,53 +238,20 @@ private:
 };
 
 template <size_t _N_words, size_t _Size>
-inline _LIBCPP_CONSTEXPR __bitset<_N_words, _Size>::__bitset() _NOEXCEPT
-#  ifndef _LIBCPP_CXX03_LANG
-    : __first_{0}
-#  endif
-{
-#  ifdef _LIBCPP_CXX03_LANG
-  std::fill_n(__first_, _N_words, __storage_type(0));
-#  endif
-}
-
-#  ifdef _LIBCPP_CXX03_LANG
+inline _LIBCPP_CONSTEXPR __bitset<_N_words, _Size>::__bitset() _NOEXCEPT : __first_() {}
 
 template <size_t _N_words, size_t _Size>
-void __bitset<_N_words, _Size>::__init(unsigned long long __v, false_type) _NOEXCEPT {
-  const size_t __n_words = std::min((sizeof(unsigned long long) - 1) / sizeof(__storage_type) + 1, _N_words);
-  for (size_t __i = 0; __i < __n_words; ++__i, __v >>= __bits_per_word)
-    __first_[__i] = static_cast<__storage_type>(__v);
-  std::fill(__first_ + __n_words, __first_ + _N_words, __storage_type(0));
-}
+inline _LIBCPP_CONSTEXPR __bitset<_N_words, _Size>::__bitset(unsigned long long __v) _NOEXCEPT : __first_() {
+  _LIBCPP_CONSTEXPR size_t __ull_words = (sizeof(unsigned long long) - 1) / sizeof(__storage_type) + 1;
+  static_assert(__ull_words <= 4, "This constructor has not been ported to this platform");
 
-template <size_t _N_words, size_t _Size>
-inline _LIBCPP_HIDE_FROM_ABI void __bitset<_N_words, _Size>::__init(unsigned long long __v, true_type) _NOEXCEPT {
   __first_[0] = __v;
-  std::fill(__first_ + 1, __first_ + _N_words, __storage_type(0));
-}
-
-#  endif // _LIBCPP_CXX03_LANG
-
-template <size_t _N_words, size_t _Size>
-inline _LIBCPP_CONSTEXPR __bitset<_N_words, _Size>::__bitset(unsigned long long __v) _NOEXCEPT
-#  ifndef _LIBCPP_CXX03_LANG
-#    if __SIZEOF_SIZE_T__ == 8
-    : __first_{__v}
-#    elif __SIZEOF_SIZE_T__ == 4
-    : __first_{static_cast<__storage_type>(__v),
-               _Size >= 2 * __bits_per_word
-                   ? static_cast<__storage_type>(__v >> __bits_per_word)
-                   : static_cast<__storage_type>((__v >> __bits_per_word) &
-                                                 (__storage_type(1) << (_Size - __bits_per_word)) - 1)}
-#    else
-#      error This constructor has not been ported to this platform
-#    endif
-#  endif
-{
-#  ifdef _LIBCPP_CXX03_LANG
-  __init(__v, integral_constant<bool, sizeof(unsigned long long) == sizeof(__storage_type)>());
-#  endif
+  if _LIBCPP_CONSTEXPR (__ull_words >= 2)
+    __first_[1] = __v >> __bits_per_word;
+  if _LIBCPP_CONSTEXPR (__ull_words >= 3 && _N_words >= 3)
+    __first_[2] = __v >> (2 * __bits_per_word);
+  if _LIBCPP_CONSTEXPR (__ull_words >= 4 && _N_words >= 4)
+    __first_[3] = __v >> (3 * __bits_per_word);
 }
 
 template <size_t _N_words, size_t _Size>
@@ -480,8 +443,7 @@ inline _LIBCPP_CONSTEXPR __bitset<1, _Size>::__bitset() _NOEXCEPT : __first_(0)
 
 template <size_t _Size>
 inline _LIBCPP_CONSTEXPR __bitset<1, _Size>::__bitset(unsigned long long __v) _NOEXCEPT
-    : __first_(_Size == __bits_per_word ? static_cast<__storage_type>(__v)
-                                        : static_cast<__storage_type>(__v) & ((__storage_type(1) << _Size) - 1)) {}
+    : __first_(static_cast<__storage_type>(__v)) {}
 
 template <size_t _Size>
 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX23 void