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author | Matthias Kretz <m.kretz@gsi.de> | 2022-01-18 17:04:06 +0100 |
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committer | Matthias Kretz <m.kretz@gsi.de> | 2022-01-19 13:45:58 +0100 |
commit | 39f581028c76ebfc94a5c2714f43c9e56089a9b0 (patch) | |
tree | 3a06c8127a051a0b74024a05dc4234f9d95ae3d3 /libstdc++-v3 | |
parent | 2cef99175af1ad95283d4b35bced73c3a510f6d6 (diff) | |
download | gcc-39f581028c76ebfc94a5c2714f43c9e56089a9b0.zip gcc-39f581028c76ebfc94a5c2714f43c9e56089a9b0.tar.gz gcc-39f581028c76ebfc94a5c2714f43c9e56089a9b0.tar.bz2 |
libstdc++: Fix for non-constexpr math_errhandling
Use SFINAE magic to support: "It is unspecified whether math_errhandling
is a macro or an identifier with external linkage." [C Standard]
Signed-off-by: Matthias Kretz <m.kretz@gsi.de>
libstdc++-v3/ChangeLog:
* include/experimental/bits/simd.h (__floating_point_flags): Do
not rely on math_errhandling to expand to a constant expression.
Diffstat (limited to 'libstdc++-v3')
-rw-r--r-- | libstdc++-v3/include/experimental/bits/simd.h | 26 |
1 files changed, 20 insertions, 6 deletions
diff --git a/libstdc++-v3/include/experimental/bits/simd.h b/libstdc++-v3/include/experimental/bits/simd.h index c991e3f..82e9841 100644 --- a/libstdc++-v3/include/experimental/bits/simd.h +++ b/libstdc++-v3/include/experimental/bits/simd.h @@ -283,20 +283,34 @@ constexpr inline bool __have_power_vmx = __have_power_vsx; namespace __detail { - constexpr bool __handle_fpexcept = #ifdef math_errhandling - math_errhandling & MATH_ERREXCEPT; -#elif defined __FAST_MATH__ - false; + // Determines _S_handle_fpexcept from math_errhandling if it is defined and expands to a constant + // expression. math_errhandling may expand to an extern symbol, in which case a constexpr value + // must be guessed. + template <int = math_errhandling> + constexpr bool __handle_fpexcept_impl(int) + { return math_errhandling & MATH_ERREXCEPT; } +#endif + + // Fallback if math_errhandling doesn't work: with fast-math assume floating-point exceptions are + // ignored, otherwise implement correct exception behavior. + constexpr bool __handle_fpexcept_impl(float) + { +#if defined __FAST_MATH__ + return false; #else - true; + return true; #endif + } + + /// True if math functions must raise floating-point exceptions as specified by C17. + static constexpr bool _S_handle_fpexcept = __handle_fpexcept_impl(0); constexpr std::uint_least64_t __floating_point_flags() { std::uint_least64_t __flags = 0; - if constexpr (__handle_fpexcept) + if constexpr (_S_handle_fpexcept) __flags |= 1; #ifdef __FAST_MATH__ __flags |= 1 << 1; |