From: Jonathan Wakely <jwakely@redhat.com>
To: Jakub Jelinek <jakub@redhat.com>
Cc: gcc-patches@gcc.gnu.org, libstdc++@gcc.gnu.org
Subject: Re: [PATCH] libstdc++: Small extended float support tweaks
Date: Mon, 31 Oct 2022 10:16:54 +0000 [thread overview]
Message-ID: <CACb0b4nfx0myG4RSpPB2mKF3biH7cibdYc9zOvLsu5jhYuDEcA@mail.gmail.com> (raw)
In-Reply-To: <Y1JKSqMSPD9xR8qk@tucnak>
On Fri, 21 Oct 2022 at 08:29, Jakub Jelinek <jakub@redhat.com> wrote:
>
> Hi!
>
> The following patch isn't for immediate commit, as it has several
> dependencies, in particular:
> https://gcc.gnu.org/pipermail/gcc-patches/2022-October/603665.html
> https://gcc.gnu.org/pipermail/gcc-patches/2022-October/604080.html
> https://gcc.gnu.org/pipermail/libstdc++/2022-October/054849.html
> On top of those, this patch
> 1) enables the std::float128_t overloads for x86 with glibc 2.26+
> 2) makes std::nextafter(std::float16_t, std::float16_t) and
> std::nextafter(std::bfloat16_t, std::bfloat16_t) constexpr
> 3) adds (small) testsuite coverage for that
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk
> if/when the above dependencies are in?
Yes, thanks.
>
> 2022-10-21 Jakub Jelinek <jakub@redhat.com>
>
> * config/os/gnu-linux/os_defines.h (_GLIBCXX_HAVE_FLOAT128_MATH):
> Uncomment.
> * include/c_global/cmath (nextafter(_Float16, _Float16)): Make it constexpr.
> If std::__is_constant_evaluated() call __builtin_nextafterf16.
> (nextafter(__gnu_cxx::__bfloat16_t, __gnu_cxx::__bfloat16_t): Similarly
> but call __builtin_nextafterf16b.
> * testsuite/26_numerics/headers/cmath/nextafter_c++23.cc (test): Add
> static assertions to test constexpr nextafter.
>
> --- libstdc++-v3/config/os/gnu-linux/os_defines.h.jj 2022-10-18 11:35:55.514865483 +0200
> +++ libstdc++-v3/config/os/gnu-linux/os_defines.h 2022-10-20 16:57:59.715681664 +0200
> @@ -57,7 +57,7 @@
> || (defined(__powerpc__) && defined(_ARCH_PWR8) \
> && defined(__LITTLE_ENDIAN__) && (_CALL_ELF == 2) \
> && defined(__FLOAT128__)))
> -//# define _GLIBCXX_HAVE_FLOAT128_MATH 1
> +# define _GLIBCXX_HAVE_FLOAT128_MATH 1
> #endif
>
> #if __GLIBC_PREREQ(2, 27)
> --- libstdc++-v3/include/c_global/cmath.jj 2022-10-19 11:23:51.484488161 +0200
> +++ libstdc++-v3/include/c_global/cmath 2022-10-20 17:03:56.760805581 +0200
> @@ -2755,9 +2755,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> nearbyint(_Float16 __x)
> { return _Float16(__builtin_nearbyintf(__x)); }
>
> - inline _Float16
> + constexpr _Float16
> nextafter(_Float16 __x, _Float16 __y)
> {
> + if (std::__is_constant_evaluated())
> + return __builtin_nextafterf16(__x, __y);
> #ifdef __INT16_TYPE__
> using __float16_int_type = __INT16_TYPE__;
> #else
> @@ -3471,9 +3473,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
> nearbyint(__gnu_cxx::__bfloat16_t __x)
> { return __gnu_cxx::__bfloat16_t(__builtin_nearbyintf(__x)); }
>
> - inline __gnu_cxx::__bfloat16_t
> + constexpr __gnu_cxx::__bfloat16_t
> nextafter(__gnu_cxx::__bfloat16_t __x, __gnu_cxx::__bfloat16_t __y)
> {
> + if (std::__is_constant_evaluated())
> + return __builtin_nextafterf16b(__x, __y);
> #ifdef __INT16_TYPE__
> using __bfloat16_int_type = __INT16_TYPE__;
> #else
> --- libstdc++-v3/testsuite/26_numerics/headers/cmath/nextafter_c++23.cc.jj 2022-10-20 16:57:29.940088318 +0200
> +++ libstdc++-v3/testsuite/26_numerics/headers/cmath/nextafter_c++23.cc 2022-10-20 17:19:40.141923257 +0200
> @@ -100,6 +100,8 @@ test ()
> VERIFY( std::fpclassify(t36) == FP_NAN );
> T t37 = std::nextafter(T(-0.0), T());
> VERIFY( t37 == T() && !std::signbit(t37) );
> + static_assert(std::nextafter(T(1.0), T(2.0)) > T(1.0));
> + static_assert(std::nextafter(std::nextafter(T(1.0), T(5.0)), T(0.0)) == T(1.0));
> }
>
> int
>
> Jakub
>
prev parent reply other threads:[~2022-10-31 10:17 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-21 7:29 Jakub Jelinek
2022-10-31 10:16 ` Jonathan Wakely [this message]
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