libstdc++-v3/testsuite/26_numerics/bit/bitops.count/countl_zero.cc

   1 // Copyright (C) 2018 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-do run { target c++11 } }
  19
  20 // { dg-options "-std=gnu++2a" }
  21 // { dg-do compile { target c++2a } }
  22
  23 #include <bit>
  24
  25 template<typename UInt>
  26 constexpr auto
  27 test(UInt x)
  28 -> decltype(std::countl_zero(x))
  29 {
  30   static_assert( noexcept(std::countl_zero(x)) );
  31
  32   constexpr unsigned digits = std::numeric_limits<UInt>::digits;
  33
  34   static_assert( std::countl_zero((UInt)0) == digits );
  35   static_assert( std::countl_zero((UInt)-1) == 0 );
  36
  37   static_assert( std::countl_zero((UInt)1) == digits - 1 );
  38   static_assert( std::countl_zero((UInt)3) == digits - 2 );
  39   static_assert( std::countl_zero((UInt)0b0101'1010) == digits - 7 );
  40
  41   if constexpr (std::numeric_limits<UInt>::digits > 8)
  42   {
  43     static_assert( std::countl_zero((UInt)(1u << 8)) == digits - 9 );
  44     static_assert( std::countl_zero((UInt)(3u << 9)) == digits - 11 );
  45   }
  46
  47   if constexpr (std::numeric_limits<UInt>::digits > 64)
  48   {
  49     static_assert( std::countl_zero((UInt)3 << 70) == digits - 72 );
  50   }
  51
  52   return true;
  53 }
  54
  55 static_assert( test( (unsigned char)0 ) );
  56 static_assert( test( (unsigned short)0 ) );
  57 static_assert( test( (unsigned int)0 ) );
  58 static_assert( test( (unsigned long)0 ) );
  59 static_assert( test( (unsigned long long)0 ) );
  60
  61 // std::countl_zero(T) shall not participate in overload resolution
  62 // unless T is an unsigned integer type.
  63 struct X { constexpr bool did_not_match() { return true; } };
  64 constexpr X test(...) { return X{}; }
  65 static_assert( test( (bool)0 ).did_not_match() );
  66 static_assert( test( (char)0 ).did_not_match() );
  67 static_assert( test( (int)0 ).did_not_match() );
  68 static_assert( test( (char16_t)0 ).did_not_match() );
  69 static_assert( test( (float)0 ).did_not_match() );
  70 static_assert( test( (void*)0 ).did_not_match() );
  71 static_assert( test( X{} ).did_not_match() );
  72 enum E : unsigned { e };
  73 static_assert( test( e ).did_not_match() );
  74
  75 #ifndef __STRICT_ANSI__
  76 #include <cstddef>
  77 constexpr int bits = std::numeric_limits<unsigned char>::digits;
  78 static_assert( std::countl_zero(std::byte{0}) == bits );
  79 static_assert( std::countl_zero(std::byte{0x01}) == bits - 1 );
  80 static_assert( std::countl_zero(std::byte{0x02}) == bits - 2 );
  81 static_assert( std::countl_zero(std::byte{0x03}) == bits - 2 );
  82 static_assert( std::countl_zero(std::byte{0x30}) == 2 );
  83 static_assert( std::countl_zero(std::byte{0x40}) == 1 );
  84 static_assert( std::countl_zero(std::byte{0x41}) == 1 );
  85 #else
  86 static_assert( test( (std::byte)0 ).did_not_match() );
  87 #endif
  88
  89 #if !defined(__STRICT_ANSI__) && defined _GLIBCXX_USE_INT128
  90 static_assert( test( (unsigned __int128)0 ) );
  91 static_assert( test( (__int128)0 ).did_not_match() );
  92 #endif
  93 #if defined(__GLIBCXX_TYPE_INT_N_0)
  94 static_assert( test( (unsigned __GLIBCXX_TYPE_INT_N_0)0 ) );
  95 static_assert( test( (__GLIBCXX_TYPE_INT_N_0)0 ).did_not_match() );
  96 #endif
  97 #if defined(__GLIBCXX_TYPE_INT_N_1)
  98 static_assert( test( (unsigned __GLIBCXX_TYPE_INT_N_1)0 ) );
  99 static_assert( test( (__GLIBCXX_TYPE_INT_N_1)0 ).did_not_match() );
 100 #endif
 101 #if defined(__GLIBCXX_TYPE_INT_N_2)
 102 static_assert( test( (unsigned __GLIBCXX_TYPE_INT_N_2)0 ) );
 103 static_assert( test( (__GLIBCXX_TYPE_INT_N_2)0 ).did_not_match() );
 104 #endif