libstdc++-v3/testsuite/experimental/simd/tests/bits/conversions.h

// Copyright (C) 2020-2025 Free Software Foundation, Inc.
//
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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#ifndef SIMD_TESTS_BITS_CONVERSIONS_H_
#define SIMD_TESTS_BITS_CONVERSIONS_H_
#include <array>

// is_conversion_undefined
/* implementation-defined
 * ======================
 * §4.7 p3 (integral conversions)
 *  If the destination type is signed, the value is unchanged if it can be
 *  represented in the destination type (and bit-field width); otherwise, the
 *  value is implementation-defined.
 *
 * undefined
 * =========
 * §4.9/1  (floating-point conversions)
 *  If the source value is neither exactly represented in the destination type
 *  nor between two adjacent destination values the result is undefined.
 *
 * §4.10/1 (floating-integral conversions)
 *  floating point type can be converted to integer type.
 *  The behavior is undefined if the truncated value cannot be
 *  represented in the destination type.
 *
 * §4.10/2
 *  integer can be converted to floating point type.
 *  If the value being converted is outside the range of values that can be
 *  represented, the behavior is undefined.
 */
template <typename To, typename From>
  constexpr bool
  is_conversion_undefined_impl(From x, std::true_type)
  {
    return x > static_cast<long double>(std::__finite_max_v<To>)
	     || x < static_cast<long double>(std::__finite_min_v<To>);
  }

template <typename To, typename From>
  constexpr bool
  is_conversion_undefined_impl(From, std::false_type)
  { return false; }

template <typename To, typename From>
  constexpr bool
  is_conversion_undefined(From x)
  {
    static_assert(std::is_arithmetic<From>::value,
		  "this overload is only meant for builtin arithmetic types");
    return is_conversion_undefined_impl<To, From>(
	     x, std::integral_constant<
		  bool, std::is_floating_point<From>::value
			  && (std::is_integral<To>::value
				|| (std::is_floating_point<To>::value
				      && sizeof(From) > sizeof(To)))>());
  }

static_assert(is_conversion_undefined<uint>(float(0x100000000LL)),
	      "testing my expectations of is_conversion_undefined");
static_assert(!is_conversion_undefined<float>(0x100000000LL),
	      "testing my expectations of is_conversion_undefined");

template <typename To, typename T, typename A>
  inline std::experimental::simd_mask<T, A>
  is_conversion_undefined(const std::experimental::simd<T, A>& x)
  {
    std::experimental::simd_mask<T, A> k = false;
    for (std::size_t i = 0; i < x.size(); ++i)
      k[i] = is_conversion_undefined(x[i]);
    return k;
  }

template <class T>
  constexpr T
  genHalfBits()
  {
    if constexpr (std::is_floating_point_v<T>)
      return 0;
    else
      return std::__finite_max_v<T> >> (std::__digits_v<T> / 2);
  }

template <class U, class T, class UU>
  constexpr U
  avoid_ub(UU x)
  { return is_conversion_undefined<T>(U(x)) ? U(0) : U(x); }

template <class U, class T, class UU>
  constexpr U
  avoid_ub2(UU x)
  { return is_conversion_undefined<U>(x) ? U(0) : avoid_ub<U, T>(x); }

// conversion test input data
template <class U, class T>
  static const std::array<U, 53> cvt_input_data = {{
    avoid_ub<U, T>(0xc0000080U),
    avoid_ub<U, T>(0xc0000081U),
    avoid_ub<U, T>(0xc0000082U),
    avoid_ub<U, T>(0xc0000084U),
    avoid_ub<U, T>(0xc0000088U),
    avoid_ub<U, T>(0xc0000090U),
    avoid_ub<U, T>(0xc00000A0U),
    avoid_ub<U, T>(0xc00000C0U),
    avoid_ub<U, T>(0xc000017fU),
    avoid_ub<U, T>(0xc0000180U),
    avoid_ub<U, T>(0x100000001LL),
    avoid_ub<U, T>(0x100000011LL),
    avoid_ub<U, T>(0x100000111LL),
    avoid_ub<U, T>(0x100001111LL),
    avoid_ub<U, T>(0x100011111LL),
    avoid_ub<U, T>(0x100111111LL),
    avoid_ub<U, T>(0x101111111LL),
    avoid_ub<U, T>(-0x100000001LL),
    avoid_ub<U, T>(-0x100000011LL),
    avoid_ub<U, T>(-0x100000111LL),
    avoid_ub<U, T>(-0x100001111LL),
    avoid_ub<U, T>(-0x100011111LL),
    avoid_ub<U, T>(-0x100111111LL),
    avoid_ub<U, T>(-0x101111111LL),
    avoid_ub<U, T>(std::__norm_min_v<U>),
    avoid_ub<U, T>(std::__norm_min_v<U> + 1),
    avoid_ub<U, T>(std::__finite_min_v<U>),
    avoid_ub<U, T>(std::__finite_min_v<U> + 1),
    avoid_ub<U, T>(-1),
    avoid_ub<U, T>(-10),
    avoid_ub<U, T>(-100),
    avoid_ub<U, T>(-1000),
    avoid_ub<U, T>(-10000),
    avoid_ub<U, T>(0),
    avoid_ub<U, T>(1),
    avoid_ub<U, T>(genHalfBits<U>() - 1),
    avoid_ub<U, T>(genHalfBits<U>()),
    avoid_ub<U, T>(genHalfBits<U>() + 1),
    avoid_ub<U, T>(std::__finite_max_v<U> - 1),
    avoid_ub<U, T>(std::__finite_max_v<U>),
    avoid_ub<U, T>(std::__finite_max_v<U> - 0xff),
    avoid_ub<U, T>(std::__finite_max_v<U> - 0xff),
    avoid_ub<U, T>(std::__finite_max_v<U> - 0x55),
    avoid_ub<U, T>(-(std::__finite_min_v<U> + 1)),
    avoid_ub<U, T>(-std::__finite_max_v<U>),
    avoid_ub<U, T>(std::__finite_max_v<U> / std::pow(2., sizeof(T) * 6 - 1)),
    avoid_ub2<U, T>(-std::__finite_max_v<U> / std::pow(2., sizeof(T) * 6 - 1)),
    avoid_ub<U, T>(std::__finite_max_v<U> / std::pow(2., sizeof(T) * 4 - 1)),
    avoid_ub2<U, T>(-std::__finite_max_v<U> / std::pow(2., sizeof(T) * 4 - 1)),
    avoid_ub<U, T>(std::__finite_max_v<U> / std::pow(2., sizeof(T) * 2 - 1)),
    avoid_ub2<U, T>(-std::__finite_max_v<U> / std::pow(2., sizeof(T) * 2 - 1)),
    avoid_ub<U, T>(std::__finite_max_v<T> - 1),
    avoid_ub<U, T>(std::__finite_max_v<T> * 0.75),
  }};

template <class T, class U>
  struct cvt_inputs
  {
    static constexpr size_t
    size()
    { return cvt_input_data<U, T>.size(); }

    U
    operator[](size_t i) const
    { return cvt_input_data<U, T>[i]; }
  };
#endif  // SIMD_TESTS_BITS_CONVERSIONS_H_