libstdc++: Make std::numeric_limits<__float128> more portable [PR104772]
This redefines std::numeric_limits<__float128> so that it works with non-GCC compilers. The previous definition didn't work with Clang, due to it not supporting __builtin_high_valq, __builtin_nanq, and __builtin_nansq. It also didn't work in strict modes, due to using Q literal suffixes. The new definition uses the Q suffixes when supported, or calculates the correct values using __float128 arithmetic from double values. Ideally the values would be defined as hexadecimal-floating-point-literals, but that won't work for C++14 and older. The only member that can't be defined this way is signaling_NaN() which still requires a built-in. If __builtin_nansq is not supported, try to use __builtin_nansf128 (with a possibly-redundant bit_cast) and if that isn't supported, return a quiet NaN and define has_signaling_NaN and is_iec754 to be false. libstdc++-v3/ChangeLog: PR libstdc++/104772 * include/std/limits: (numeric_limits<__float128>): Define for __STRICT_ANSI__ as well. * testsuite/18_support/numeric_limits/128bit.cc: Remove check for __STRICT_ANSI__. Co-authored-by: Jakub Jelinek <jakub@redhat.com>
This commit is contained in:
Jonathan Wakely
parent
97a5e8a2a4
commit
6261d10521
2 changed files with 80 additions and 17 deletions
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@ -2071,9 +2071,11 @@ __glibcxx_float_n(128)
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};
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#endif
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#endif
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#endif // C++23
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#if defined(_GLIBCXX_USE_FLOAT128) && !defined(__STRICT_ANSI__)
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#if defined(_GLIBCXX_USE_FLOAT128)
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// We either need Q literal suffixes, or IEEE double.
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#if ! defined(__STRICT_ANSI__) || defined(_GLIBCXX_DOUBLE_IS_IEEE_BINARY64)
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__extension__
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template<>
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struct numeric_limits<__float128>
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@ -2082,11 +2084,28 @@ __glibcxx_float_n(128)
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static _GLIBCXX_CONSTEXPR __float128
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min() _GLIBCXX_USE_NOEXCEPT
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{ return __extension__ 3.36210314311209350626267781732175260e-4932Q; }
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{
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#ifdef __STRICT_ANSI__
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// 0x1.0p-30 * 0x1.0p-16352
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return double(9.3132257461547852e-10) * _S_1pm16352();
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#else
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return __extension__ 0x1.0p-16382Q;
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#endif
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}
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static _GLIBCXX_CONSTEXPR __float128
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max() _GLIBCXX_USE_NOEXCEPT
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{ return __extension__ 1.18973149535723176508575932662800702e+4932Q; }
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{
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#ifdef __STRICT_ANSI__
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// (0x1.fffffffffffffp+127 + 0x0.fffffffffffffp+75 + 0x0.ffp+23)
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// * 0x1.0p16256
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return (__float128(double(3.4028236692093843e+38))
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+ double(3.7778931862957153e+22) + double(8.35584e+6))
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* _S_1p16256();
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#else
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return __extension__ 0x1.ffffffffffffffffffffffffffffp+16383Q;
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#endif
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}
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static _GLIBCXX_CONSTEXPR __float128
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lowest() _GLIBCXX_USE_NOEXCEPT
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@ -2094,8 +2113,9 @@ __glibcxx_float_n(128)
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static _GLIBCXX_USE_CONSTEXPR int digits = 113;
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static _GLIBCXX_USE_CONSTEXPR int digits10 = 33;
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static _GLIBCXX_USE_CONSTEXPR int max_digits10
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= __glibcxx_max_digits10 (112);
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#if __cplusplus >= 201103L
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static constexpr int max_digits10 = 35;
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#endif
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static _GLIBCXX_USE_CONSTEXPR bool is_signed = true;
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static _GLIBCXX_USE_CONSTEXPR bool is_integer = false;
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static _GLIBCXX_USE_CONSTEXPR bool is_exact = false;
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@ -2103,10 +2123,10 @@ __glibcxx_float_n(128)
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static _GLIBCXX_CONSTEXPR __float128
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epsilon() _GLIBCXX_USE_NOEXCEPT
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{ return __extension__ 1.92592994438723585305597794258492732e-34Q; }
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{ return double(1.9259299443872359e-34); }
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static _GLIBCXX_CONSTEXPR __float128
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round_error() _GLIBCXX_USE_NOEXCEPT { return __extension__ 0.5Q; }
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round_error() _GLIBCXX_USE_NOEXCEPT { return 0.5; }
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static _GLIBCXX_USE_CONSTEXPR int min_exponent = -16381;
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static _GLIBCXX_USE_CONSTEXPR int min_exponent10 = -4931;
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@ -2115,29 +2135,48 @@ __glibcxx_float_n(128)
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static _GLIBCXX_USE_CONSTEXPR bool has_infinity = 1;
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static _GLIBCXX_USE_CONSTEXPR bool has_quiet_NaN = 1;
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static _GLIBCXX_USE_CONSTEXPR bool has_signaling_NaN = has_quiet_NaN;
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#if __has_builtin(__builtin_nansq) \
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|| (__has_builtin(__builtin_bit_cast) && __has_builtin(__builtin_nansf128))
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static _GLIBCXX_USE_CONSTEXPR bool has_signaling_NaN = true;
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#else
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static _GLIBCXX_USE_CONSTEXPR bool has_signaling_NaN = false;
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#endif
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static _GLIBCXX_USE_CONSTEXPR float_denorm_style has_denorm
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= denorm_present;
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static _GLIBCXX_USE_CONSTEXPR bool has_denorm_loss = false;
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static _GLIBCXX_CONSTEXPR __float128
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infinity() _GLIBCXX_USE_NOEXCEPT
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{ return __builtin_huge_valq(); }
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{ return __builtin_huge_val(); }
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static _GLIBCXX_CONSTEXPR __float128
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quiet_NaN() _GLIBCXX_USE_NOEXCEPT
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{ return __builtin_nanq(""); }
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{ return __builtin_nan(""); }
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static _GLIBCXX_CONSTEXPR __float128
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signaling_NaN() _GLIBCXX_USE_NOEXCEPT
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{ return __builtin_nansq(""); }
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{
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#if __has_builtin(__builtin_nansq)
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return __builtin_nansq("");
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#elif __has_builtin(__builtin_bit_cast) && __has_builtin(__builtin_nansf128)
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return __builtin_bit_cast(__float128, __builtin_nansf128(""));
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#else
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return quiet_NaN();
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#endif
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}
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static _GLIBCXX_CONSTEXPR __float128
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denorm_min() _GLIBCXX_USE_NOEXCEPT
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{ return __extension__ 6.47517511943802511092443895822764655e-4966Q; }
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{
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#if defined(__STRICT_ANSI__) || defined(__INTEL_COMPILER)
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// 0x1.0p-142 * 0x1.0p-16352
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return double(1.7936620343357659e-43) * _S_1pm16352();
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#else
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return __extension__ 0x1.0p-16494Q;
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#endif
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}
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static _GLIBCXX_USE_CONSTEXPR bool is_iec559
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= has_infinity && has_quiet_NaN && has_denorm == denorm_present;
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static _GLIBCXX_USE_CONSTEXPR bool is_iec559 = has_signaling_NaN;
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static _GLIBCXX_USE_CONSTEXPR bool is_bounded = true;
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static _GLIBCXX_USE_CONSTEXPR bool is_modulo = false;
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@ -2145,8 +2184,32 @@ __glibcxx_float_n(128)
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static _GLIBCXX_USE_CONSTEXPR bool tinyness_before = false;
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static _GLIBCXX_USE_CONSTEXPR float_round_style round_style
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= round_to_nearest;
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#if defined(__STRICT_ANSI__) || defined(__INTEL_COMPILER)
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private:
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static _GLIBCXX_CONSTEXPR __float128
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_S_4p(__float128 __v) _GLIBCXX_USE_NOEXCEPT
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{ return __v * __v * __v * __v; }
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static _GLIBCXX_CONSTEXPR __float128
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_S_1pm4088() _GLIBCXX_USE_NOEXCEPT
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{ return _S_4p(/* 0x1.0p-1022 */ double(2.2250738585072014e-308)); }
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static _GLIBCXX_CONSTEXPR __float128
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_S_1pm16352() _GLIBCXX_USE_NOEXCEPT
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{ return _S_4p(_S_1pm4088()); }
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static _GLIBCXX_CONSTEXPR __float128
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_S_1p4064() _GLIBCXX_USE_NOEXCEPT
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{ return _S_4p(/* 0x1.0p+1016 */ double(7.0222388080559215e+305)); }
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static _GLIBCXX_CONSTEXPR __float128
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_S_1p16256() _GLIBCXX_USE_NOEXCEPT
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{ return _S_4p(_S_1p4064()); }
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#endif
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};
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#endif // _GLIBCXX_USE_FLOAT128 && ! __STRICT_ANSI__
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#endif // !__STRICT_ANSI__ || DOUBLE_IS_IEEE_BINARY64
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#endif // _GLIBCXX_USE_FLOAT128
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_GLIBCXX_END_NAMESPACE_VERSION
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} // namespace
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@ -2,7 +2,7 @@
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#include <limits>
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#if __SIZEOF_FLOAT128__ && !defined __STRICT_ANSI__
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#if __SIZEOF_FLOAT128__
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__extension__ template class std::numeric_limits<__float128>;
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#endif
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