libstdc++-v3/testsuite/20_util/assume_aligned/1.cc

   1 // Copyright (C) 2018-2021 Free Software Foundation, Inc.
   2 //
   3 // This file is part of the GNU ISO C++ Library.  This library is free
   4 // software; you can redistribute it and/or modify it under the
   5 // terms of the GNU General Public License as published by the
   6 // Free Software Foundation; either version 3, or (at your option)
   7 // any later version.
   8
   9 // This library is distributed in the hope that it will be useful,
  10 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 // GNU General Public License for more details.
  13
  14 // You should have received a copy of the GNU General Public License along
  15 // with this library; see the file COPYING3.  If not see
  16 // <http://www.gnu.org/licenses/>.
  17
  18 // { dg-options "-std=gnu++2a -O2" }
  19 // { dg-do run { target c++2a } }
  20
  21 #include <memory>
  22 #include <testsuite_hooks.h>
  23
  24 void
  25 test01()
  26 {
  27   int i = 0;
  28   int* p = std::assume_aligned<alignof(int)>(&i);
  29   VERIFY( p == &i );
  30 }
  31
  32 [[gnu::noipa,gnu::noinline]]
  33 int*
  34 create_aligned(std::size_t alignment, void* p, std::size_t n)
  35 {
  36   return ::new(std::align(alignment, sizeof(int), p, n)) int(42);
  37 }
  38
  39 extern "C" void undefined(); // call to this should be optimized away
  40
  41 void
  42 test02()
  43 {
  44   unsigned char buf[sizeof(int) * 128];
  45   int* p = create_aligned(64, buf + 1, sizeof(buf) - 1);
  46   int* q = std::assume_aligned<64>(p);
  47   if ((std::uintptr_t)q % 64)
  48     undefined();
  49   VERIFY( p == q );
  50 }
  51
  52 int main()
  53 {
  54   test01();
  55   test02();
  56 }