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    namespace detail{
29 
30 #ifndef __BORLANDC__
31 
32       union max_align
33       {
34          char c;
35          short s;
36          int i;
37          long l;
38 #ifndef BOOST_NO_LONG_LONG
39          boost::long_long_type ll;
40 #endif
41 #ifdef BOOST_HAS_INT128
42          boost::int128_type i128;
43 #endif
44          float f;
45          double d;
46          long double ld;
47 #ifdef BOOST_HAS_FLOAT128
48          __float128 f128;
49 #endif
50       };
51 
52 template <std::size_t Target, bool check> struct long_double_alignment{ typedef long double type; };
53 template <std::size_t Target> struct long_double_alignment<Target, false>{ typedef boost::detail::max_align type; };
54 
55 template <std::size_t Target, bool check> struct double_alignment{ typedef double type; };
56 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; };
57 
58 #ifndef BOOST_NO_LONG_LONG
59 template <std::size_t Target, bool check> struct long_long_alignment{ typedef boost::long_long_type type; };
60 template <std::size_t Target> struct long_long_alignment<Target, false>{ typedef typename double_alignment<Target, boost::alignment_of<double>::value >= Target>::type type; };
61 #endif
62 
63 template <std::size_t Target, bool check> struct long_alignment{ typedef long type; };
64 #ifndef BOOST_NO_LONG_LONG
65 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; };
66 #else
67 template <std::size_t Target> struct long_alignment<Target, false>{ typedef typename double_alignment<Target, boost::alignment_of<double>::value >= Target>::type type; };
68 #endif
69 
70 template <std::size_t Target, bool check> struct int_alignment{ typedef int type; };
71 template <std::size_t Target> struct int_alignment<Target, false>{ typedef typename long_alignment<Target, boost::alignment_of<long>::value >= Target>::type type; };
72 
73 template <std::size_t Target, bool check> struct short_alignment{ typedef short type; };
74 template <std::size_t Target> struct short_alignment<Target, false>{ typedef typename int_alignment<Target, boost::alignment_of<int>::value >= Target>::type type; };
75 
76 template <std::size_t Target, bool check> struct char_alignment{ typedef char type; };
77 template <std::size_t Target> struct char_alignment<Target, false>{ typedef typename short_alignment<Target, boost::alignment_of<short>::value >= Target>::type type; };
78 
79 }
80 
81 template <std::size_t Align>
82 struct type_with_alignment
83 {
84    typedef typename boost::detail::char_alignment<Align, boost::alignment_of<char>::value >= Align>::type type;
85 };
86 
87 #if (defined(__GNUC__) || (defined (__SUNPRO_CC) &&  (__SUNPRO_CC >= 0x5130)) || defined(__clang__)) && !defined(BOOST_TT_DISABLE_INTRINSICS)
88 namespace tt_align_ns {
89 struct __attribute__((__aligned__(2))) a2 {};
90 struct __attribute__((__aligned__(4))) a4 {};
91 struct __attribute__((__aligned__(8))) a8 {};
92 struct __attribute__((__aligned__(16))) a16 {};
93 struct __attribute__((__aligned__(32))) a32 {};
94 struct __attribute__((__aligned__(64))) a64 {};
95 struct __attribute__((__aligned__(128))) a128 {};
96 }
97 
98 template<> struct type_with_alignment<1>  { public: typedef char type; };
99 template<> struct type_with_alignment<2>  { public: typedef tt_align_ns::a2 type; };
100 template<> struct type_with_alignment<4>  { public: typedef tt_align_ns::a4 type; };
101 template<> struct type_with_alignment<8>  { public: typedef tt_align_ns::a8 type; };
102 template<> struct type_with_alignment<16> { public: typedef tt_align_ns::a16 type; };
103 template<> struct type_with_alignment<32> { public: typedef tt_align_ns::a32 type; };
104 template<> struct type_with_alignment<64> { public: typedef tt_align_ns::a64 type; };
105 template<> struct type_with_alignment<128> { public: typedef tt_align_ns::a128 type; };
106 
107 template<> struct is_pod< ::boost::tt_align_ns::a2> : public true_type{};
108 template<> struct is_pod< ::boost::tt_align_ns::a4> : public true_type{};
109 template<> struct is_pod< ::boost::tt_align_ns::a8> : public true_type{};
110 template<> struct is_pod< ::boost::tt_align_ns::a16> : public true_type{};
111 template<> struct is_pod< ::boost::tt_align_ns::a32> : public true_type{};
112 template<> struct is_pod< ::boost::tt_align_ns::a64> : public true_type{};
113 template<> struct is_pod< ::boost::tt_align_ns::a128> : public true_type{};
114 
115 #endif
116 #if (defined(BOOST_MSVC) || (defined(BOOST_INTEL) && defined(_MSC_VER))) && !defined(BOOST_TT_DISABLE_INTRINSICS)
117 //
118 // MSVC supports types which have alignments greater than the normal
119 // maximum: these are used for example in the types __m64 and __m128
120 // to provide types with alignment requirements which match the SSE
121 // registers.  Therefore we extend type_with_alignment<> to support
122 // such types, however, we have to be careful to use a builtin type
123 // whenever possible otherwise we break previously working code:
124 // see http://article.gmane.org/gmane.comp.lib.boost.devel/173011
125 // for an example and test case.  Thus types like a8 below will
126 // be used *only* if the existing implementation can't provide a type
127 // with suitable alignment.  This does mean however, that type_with_alignment<>
128 // may return a type which cannot be passed through a function call
129 // by value (and neither can any type containing such a type like
130 // Boost.Optional).  However, this only happens when we have no choice
131 // in the matter because no other "ordinary" type is available.
132 //
133 namespace tt_align_ns {
134 struct __declspec(align(8)) a8 {
135    char m[8];
136    typedef a8 type;
137 };
138 struct __declspec(align(16)) a16 {
139    char m[16];
140    typedef a16 type;
141 };
142 struct __declspec(align(32)) a32 {
143    char m[32];
144    typedef a32 type;
145 };
146 struct __declspec(align(64)) a64
147 {
148    char m[64];
149    typedef a64 type;
150 };
151 struct __declspec(align(128)) a128 {
152    char m[128];
153    typedef a128 type;
154 };
155 }
156 
157 template<> struct type_with_alignment<8>
158 {
159    typedef boost::conditional<
160       ::boost::alignment_of<boost::detail::max_align>::value < 8,
161       tt_align_ns::a8,
162       boost::detail::char_alignment<8, false> >::type t1;
163 public:
164    typedef t1::type type;
165 };
166 template<> struct type_with_alignment<16>
167 {
168    typedef boost::conditional<
169       ::boost::alignment_of<boost::detail::max_align>::value < 16,
170       tt_align_ns::a16,
171       boost::detail::char_alignment<16, false> >::type t1;
172 public:
173    typedef t1::type type;
174 };
175 template<> struct type_with_alignment<32>
176 {
177    typedef boost::conditional<
178       ::boost::alignment_of<boost::detail::max_align>::value < 32,
179       tt_align_ns::a32,
180       boost::detail::char_alignment<32, false> >::type t1;
181 public:
182    typedef t1::type type;
183 };
184 template<> struct type_with_alignment<64> {
185    typedef boost::conditional<
186       ::boost::alignment_of<boost::detail::max_align>::value < 64,
187       tt_align_ns::a64,
188       boost::detail::char_alignment<64, false> >::type t1;
189 public:
190    typedef t1::type type;
191 };
192 template<> struct type_with_alignment<128> {
193    typedef boost::conditional<
194       ::boost::alignment_of<boost::detail::max_align>::value < 128,
195       tt_align_ns::a128,
196       boost::detail::char_alignment<128, false> >::type t1;
197 public:
198    typedef t1::type type;
199 };
200 
201 template<> struct is_pod< ::boost::tt_align_ns::a8> : public true_type{};
202 template<> struct is_pod< ::boost::tt_align_ns::a16> : public true_type{};
203 template<> struct is_pod< ::boost::tt_align_ns::a32> : public true_type{};
204 template<> struct is_pod< ::boost::tt_align_ns::a64> : public true_type{};
205 template<> struct is_pod< ::boost::tt_align_ns::a128> : public true_type{};
206 
207 #endif
208 
209 #else
210 
211 //
212 // Borland specific version, we have this for two reasons:
213 // 1) The version above doesn't always compile (with the new test cases for example)
214 // 2) Because of Borlands #pragma option we can create types with alignments that are
215 //    greater that the largest aligned builtin type.
216 
217 namespace tt_align_ns{
218 #pragma option push -a16
219 struct a2{ short s; };
220 struct a4{ int s; };
221 struct a8{ double s; };
222 struct a16{ long double s; };
223 #pragma option pop
224 }
225 
226 namespace detail {
227 
228 typedef ::boost::tt_align_ns::a16 max_align;
229 
230 }
231 //#if ! BOOST_WORKAROUND(__CODEGEARC__, BOOST_TESTED_AT(0x610))
232 template <> struct is_pod< ::boost::tt_align_ns::a2> : public true_type{};
233 template <> struct is_pod< ::boost::tt_align_ns::a4> : public true_type{};
234 template <> struct is_pod< ::boost::tt_align_ns::a8> : public true_type{};
235 template <> struct is_pod< ::boost::tt_align_ns::a16> : public true_type{};
236 //#endif
237 
238 template <std::size_t N> struct type_with_alignment
239 {
240    // We should never get to here, but if we do use the maximally
241    // aligned type:
242    // BOOST_STATIC_ASSERT(0);
243    typedef tt_align_ns::a16 type;
244 };
245 template <> struct type_with_alignment<1>{ typedef char type; };
246 template <> struct type_with_alignment<2>{ typedef tt_align_ns::a2 type; };
247 template <> struct type_with_alignment<4>{ typedef tt_align_ns::a4 type; };
248 template <> struct type_with_alignment<8>{ typedef tt_align_ns::a8 type; };
249 template <> struct type_with_alignment<16>{ typedef tt_align_ns::a16 type; };
250 
251 #endif
252 
253 } // namespace boost
254 
255 #ifdef BOOST_MSVC
256 #   pragma warning(pop)
257 #endif
258 
259 #endif // BOOST_TT_TYPE_WITH_ALIGNMENT_INCLUDED
260 
261 
262