libcxx/test/std/utilities/memory/ptr.align/assume_aligned.pass.cpp

   1 //===----------------------------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8
   9 // UNSUPPORTED: c++03, c++11, c++14, c++17
  10
  11 // #include <memory>
  12
  13 // template<size_t N, class T>
  14 // [[nodiscard]] constexpr T* assume_aligned(T* ptr);
  15
  16 #include <memory>
  17 #include <cassert>
  18 #include <cstddef>
  19
  20 #include "test_macros.h"
  21
  22 template <typename T>
  23 constexpr void check(T* p) {
  24   ASSERT_SAME_TYPE(T*, decltype(std::assume_aligned<1>(p)));
  25   constexpr std::size_t alignment = alignof(T);
  26
  27   if constexpr (alignment >= 1)
  28     assert(p == std::assume_aligned<1>(p));
  29   if constexpr (alignment >= 2)
  30     assert(p == std::assume_aligned<2>(p));
  31   if constexpr (alignment >= 4)
  32     assert(p == std::assume_aligned<4>(p));
  33   if constexpr (alignment >= 8)
  34     assert(p == std::assume_aligned<8>(p));
  35   if constexpr (alignment >= 16)
  36     assert(p == std::assume_aligned<16>(p));
  37   if constexpr (alignment >= 32)
  38     assert(p == std::assume_aligned<32>(p));
  39   if constexpr (alignment >= 64)
  40     assert(p == std::assume_aligned<64>(p));
  41   if constexpr (alignment >= 128)
  42     assert(p == std::assume_aligned<128>(p));
  43 }
  44
  45 struct              S    { };
  46 struct alignas(  4) S4   { };
  47 struct alignas(  8) S8   { };
  48 struct alignas( 16) S16  { };
  49 struct alignas( 32) S32  { };
  50 struct alignas( 64) S64  { };
  51 struct alignas(128) S128 { };
  52
  53 constexpr bool tests() {
  54   char        c;
  55   int         i;
  56   long        l;
  57   double      d;
  58   long double ld;
  59   check( &c);
  60   check( &i);
  61   check( &l);
  62   check( &d);
  63   check(&ld);
  64
  65   S    s;
  66   S4   s4;
  67   S8   s8;
  68   S16  s16;
  69   S32  s32;
  70   S64  s64;
  71   S128 s128;
  72   check(&s);
  73   check(&s4);
  74   check(&s8);
  75   check(&s16);
  76   check(&s32);
  77   check(&s64);
  78   check(&s128);
  79
  80   return true;
  81 }
  82
  83 int main(int, char**) {
  84   tests();
  85   static_assert(tests());
  86
  87   return 0;
  88 }