ceph/src/boost/boost/type_traits/type_with_alignment.hpp

   1 //  (C) Copyright John Maddock 2000.
   2 //  Use, modification and distribution are subject to the Boost Software License,
   3 //  Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
   4 //  http://www.boost.org/LICENSE_1_0.txt).
   5 //
   6 //  See http://www.boost.org/libs/type_traits for most recent version including documentation.
   7
   8 #ifndef BOOST_TT_TYPE_WITH_ALIGNMENT_INCLUDED
   9 #define BOOST_TT_TYPE_WITH_ALIGNMENT_INCLUDED
  10
  11 #include <boost/type_traits/alignment_of.hpp>
  12 #include <boost/type_traits/is_pod.hpp>
  13 #include <boost/static_assert.hpp>
  14 #include <boost/config.hpp>
  15 #include <cstddef> // size_t
  16 #include <boost/detail/workaround.hpp>
  17
  18 #ifdef BOOST_MSVC
  19 #   pragma warning(push)
  20 #   pragma warning(disable: 4121) // alignment is sensitive to packing
  21 #endif
  22
  23 #ifdef _MSC_VER
  24 #include <boost/type_traits/conditional.hpp>
  25 #endif
  26
  27 namespace boost {
  28 #ifndef BOOST_BORLANDC
  29    namespace detail{
  30
  31       union max_align
  32       {
  33          char c;
  34          short s;
  35          int i;
  36          long l;
  37 #ifndef BOOST_NO_LONG_LONG
  38          boost::long_long_type ll;
  39 #endif
  40 #ifdef BOOST_HAS_INT128
  41          boost::int128_type i128;
  42 #endif
  43          float f;
  44          double d;
  45          long double ld;
  46 #ifdef BOOST_HAS_FLOAT128
  47          __float128 f128;
  48 #endif
  49       };
  50
  51 template <std::size_t Target, bool check> struct long_double_alignment{ typedef long double type; };
  52 template <std::size_t Target> struct long_double_alignment<Target, false>{ typedef boost::detail::max_align type; };
  53
  54 template <std::size_t Target, bool check> struct double_alignment{ typedef double type; };
  55 template <std::size_t Target> struct double_alignment<Target, false>{ typedef typename long_double_alignment<Target, boost::alignment_of<long double>::value >= Target>::type type; };
  56
  57 #ifndef BOOST_NO_LONG_LONG
  58 template <std::size_t Target, bool check> struct long_long_alignment{ typedef boost::long_long_type type; };
  59 template <std::size_t Target> struct long_long_alignment<Target, false>{ typedef typename double_alignment<Target, boost::alignment_of<double>::value >= Target>::type type; };
  60 #endif
  61
  62 template <std::size_t Target, bool check> struct long_alignment{ typedef long type; };
  63 #ifndef BOOST_NO_LONG_LONG
  64 template <std::size_t Target> struct long_alignment<Target, false>{ typedef typename long_long_alignment<Target, boost::alignment_of<boost::long_long_type>::value >= Target>::type type; };
  65 #else
  66 template <std::size_t Target> struct long_alignment<Target, false>{ typedef typename double_alignment<Target, boost::alignment_of<double>::value >= Target>::type type; };
  67 #endif
  68
  69 template <std::size_t Target, bool check> struct int_alignment{ typedef int type; };
  70 template <std::size_t Target> struct int_alignment<Target, false>{ typedef typename long_alignment<Target, boost::alignment_of<long>::value >= Target>::type type; };
  71
  72 template <std::size_t Target, bool check> struct short_alignment{ typedef short type; };
  73 template <std::size_t Target> struct short_alignment<Target, false>{ typedef typename int_alignment<Target, boost::alignment_of<int>::value >= Target>::type type; };
  74
  75 template <std::size_t Target, bool check> struct char_alignment{ typedef char type; };
  76 template <std::size_t Target> struct char_alignment<Target, false>{ typedef typename short_alignment<Target, boost::alignment_of<short>::value >= Target>::type type; };
  77
  78 } // namespace detail
  79
  80 template <std::size_t Align>
  81 struct type_with_alignment
  82 {
  83    typedef typename boost::detail::char_alignment<Align, boost::alignment_of<char>::value >= Align>::type type;
  84 };
  85
  86 #if (defined(__GNUC__) || (defined (__SUNPRO_CC) &&  (__SUNPRO_CC >= 0x5130)) || defined(__clang__)) && !defined(BOOST_TT_DISABLE_INTRINSICS)
  87 namespace tt_align_ns {
  88 struct __attribute__((__aligned__(2))) a2 {};
  89 struct __attribute__((__aligned__(4))) a4 {};
  90 struct __attribute__((__aligned__(8))) a8 {};
  91 struct __attribute__((__aligned__(16))) a16 {};
  92 struct __attribute__((__aligned__(32))) a32 {};
  93 struct __attribute__((__aligned__(64))) a64 {};
  94 struct __attribute__((__aligned__(128))) a128 {};
  95 }
  96
  97 template<> struct type_with_alignment<1>  { public: typedef char type; };
  98 template<> struct type_with_alignment<2>  { public: typedef tt_align_ns::a2 type; };
  99 template<> struct type_with_alignment<4>  { public: typedef tt_align_ns::a4 type; };
 100 template<> struct type_with_alignment<8>  { public: typedef tt_align_ns::a8 type; };
 101 template<> struct type_with_alignment<16> { public: typedef tt_align_ns::a16 type; };
 102 template<> struct type_with_alignment<32> { public: typedef tt_align_ns::a32 type; };
 103 template<> struct type_with_alignment<64> { public: typedef tt_align_ns::a64 type; };
 104 template<> struct type_with_alignment<128> { public: typedef tt_align_ns::a128 type; };
 105
 106 template<> struct is_pod< ::boost::tt_align_ns::a2> : public true_type{};
 107 template<> struct is_pod< ::boost::tt_align_ns::a4> : public true_type{};
 108 template<> struct is_pod< ::boost::tt_align_ns::a8> : public true_type{};
 109 template<> struct is_pod< ::boost::tt_align_ns::a16> : public true_type{};
 110 template<> struct is_pod< ::boost::tt_align_ns::a32> : public true_type{};
 111 template<> struct is_pod< ::boost::tt_align_ns::a64> : public true_type{};
 112 template<> struct is_pod< ::boost::tt_align_ns::a128> : public true_type{};
 113
 114 #endif
 115 #if (defined(BOOST_MSVC) || (defined(BOOST_INTEL) && defined(_MSC_VER))) && !defined(BOOST_TT_DISABLE_INTRINSICS)
 116 //
 117 // MSVC supports types which have alignments greater than the normal
 118 // maximum: these are used for example in the types __m64 and __m128
 119 // to provide types with alignment requirements which match the SSE
 120 // registers.  Therefore we extend type_with_alignment<> to support
 121 // such types, however, we have to be careful to use a builtin type
 122 // whenever possible otherwise we break previously working code:
 123 // see https://lists.boost.org/Archives/boost/2014/03/212391.php
 124 // for an example and test case.  Thus types like a8 below will
 125 // be used *only* if the existing implementation can't provide a type
 126 // with suitable alignment.  This does mean however, that type_with_alignment<>
 127 // may return a type which cannot be passed through a function call
 128 // by value (and neither can any type containing such a type like
 129 // Boost.Optional).  However, this only happens when we have no choice
 130 // in the matter because no other "ordinary" type is available.
 131 //
 132 namespace tt_align_ns {
 133 struct __declspec(align(8)) a8 {
 134    char m[8];
 135    typedef a8 type;
 136 };
 137 struct __declspec(align(16)) a16 {
 138    char m[16];
 139    typedef a16 type;
 140 };
 141 struct __declspec(align(32)) a32 {
 142    char m[32];
 143    typedef a32 type;
 144 };
 145 struct __declspec(align(64)) a64
 146 {
 147    char m[64];
 148    typedef a64 type;
 149 };
 150 struct __declspec(align(128)) a128 {
 151    char m[128];
 152    typedef a128 type;
 153 };
 154 }
 155
 156 template<> struct type_with_alignment<8>
 157 {
 158    typedef boost::conditional<
 159       ::boost::alignment_of<boost::detail::max_align>::value < 8,
 160       tt_align_ns::a8,
 161       boost::detail::char_alignment<8, false> >::type t1;
 162 public:
 163    typedef t1::type type;
 164 };
 165 template<> struct type_with_alignment<16>
 166 {
 167    typedef boost::conditional<
 168       ::boost::alignment_of<boost::detail::max_align>::value < 16,
 169       tt_align_ns::a16,
 170       boost::detail::char_alignment<16, false> >::type t1;
 171 public:
 172    typedef t1::type type;
 173 };
 174 template<> struct type_with_alignment<32>
 175 {
 176    typedef boost::conditional<
 177       ::boost::alignment_of<boost::detail::max_align>::value < 32,
 178       tt_align_ns::a32,
 179       boost::detail::char_alignment<32, false> >::type t1;
 180 public:
 181    typedef t1::type type;
 182 };
 183 template<> struct type_with_alignment<64> {
 184    typedef boost::conditional<
 185       ::boost::alignment_of<boost::detail::max_align>::value < 64,
 186       tt_align_ns::a64,
 187       boost::detail::char_alignment<64, false> >::type t1;
 188 public:
 189    typedef t1::type type;
 190 };
 191 template<> struct type_with_alignment<128> {
 192    typedef boost::conditional<
 193       ::boost::alignment_of<boost::detail::max_align>::value < 128,
 194       tt_align_ns::a128,
 195       boost::detail::char_alignment<128, false> >::type t1;
 196 public:
 197    typedef t1::type type;
 198 };
 199
 200 template<> struct is_pod< ::boost::tt_align_ns::a8> : public true_type{};
 201 template<> struct is_pod< ::boost::tt_align_ns::a16> : public true_type{};
 202 template<> struct is_pod< ::boost::tt_align_ns::a32> : public true_type{};
 203 template<> struct is_pod< ::boost::tt_align_ns::a64> : public true_type{};
 204 template<> struct is_pod< ::boost::tt_align_ns::a128> : public true_type{};
 205
 206 #endif
 207
 208 #else
 209
 210 //
 211 // Borland specific version, we have this for two reasons:
 212 // 1) The version above doesn't always compile (with the new test cases for example)
 213 // 2) Because of Borlands #pragma option we can create types with alignments that are
 214 //    greater that the largest aligned builtin type.
 215
 216 namespace tt_align_ns{
 217 #pragma option push -a16
 218 struct a2{ short s; };
 219 struct a4{ int s; };
 220 struct a8{ double s; };
 221 struct a16{ long double s; };
 222 #pragma option pop
 223 }
 224
 225 namespace detail {
 226
 227 typedef ::boost::tt_align_ns::a16 max_align;
 228
 229 }
 230 //#if ! BOOST_WORKAROUND(BOOST_CODEGEARC, BOOST_TESTED_AT(0x610))
 231 template <> struct is_pod< ::boost::tt_align_ns::a2> : public true_type{};
 232 template <> struct is_pod< ::boost::tt_align_ns::a4> : public true_type{};
 233 template <> struct is_pod< ::boost::tt_align_ns::a8> : public true_type{};
 234 template <> struct is_pod< ::boost::tt_align_ns::a16> : public true_type{};
 235 //#endif
 236
 237 template <std::size_t N> struct type_with_alignment
 238 {
 239    // We should never get to here, but if we do use the maximally
 240    // aligned type:
 241    // BOOST_STATIC_ASSERT(0);
 242    typedef tt_align_ns::a16 type;
 243 };
 244 template <> struct type_with_alignment<1>{ typedef char type; };
 245 template <> struct type_with_alignment<2>{ typedef tt_align_ns::a2 type; };
 246 template <> struct type_with_alignment<4>{ typedef tt_align_ns::a4 type; };
 247 template <> struct type_with_alignment<8>{ typedef tt_align_ns::a8 type; };
 248 template <> struct type_with_alignment<16>{ typedef tt_align_ns::a16 type; };
 249
 250 #endif
 251
 252 } // namespace boost
 253
 254 #ifdef BOOST_MSVC
 255 #   pragma warning(pop)
 256 #endif
 257
 258 #endif // BOOST_TT_TYPE_WITH_ALIGNMENT_INCLUDED
 259
 260