On Thu, 1 Jun 2023 at 12:05, Jonathan Wakely wrote: > On Thu, 1 Jun 2023 at 10:30, Christophe Lyon via Libstdc++ > wrote: > > > > Hi, > > > > > > On Wed, 31 May 2023 at 14:25, Jonathan Wakely via Gcc-patches < > > gcc-patches@gcc.gnu.org> wrote: > > > > > Tested powerpc64le-linux. Pushed to trunk. > > > > > > -- >8 -- > > > > > > We use the from_chars_strtod function with __strtof128 to read a > > > _Float128 value, but from_chars_strtod is not defined unless uselocale > > > is available. This can lead to compilation failures for some targets, > > > because we try to define the _Flaot128 overload in terms of a > > > non-existing from_chars_strtod function. > > > > > > Only try to use __strtof128 if uselocale is available, otherwise > > > fallback to the long double overload of std::from_chars (which might > > > fallback to the double overload, which should use fast_float). > > > > > > This ensures we always define the full set of overloads, even if they > > > are not always accurate for all values of the wider types. > > > > > > libstdc++-v3/ChangeLog: > > > > > > PR libstdc++/109921 > > > * src/c++17/floating_from_chars.cc > (USE_STRTOF128_FOR_FROM_CHARS): > > > Only define when USE_STRTOD_FOR_FROM_CHARS is also defined. > > > (USE_STRTOD_FOR_FROM_CHARS): Do not undefine when long double > is > > > binary64. > > > (from_chars(const char*, const char*, double&, chars_format)): > > > Check __LDBL_MANT_DIG__ == __DBL_MANT_DIG__ here. > > > (from_chars(const char*, const char*, _Float128&, > chars_format)) > > > Only use from_chars_strtod when USE_STRTOD_FOR_FROM_CHARS is > > > defined, otherwise parse a long double and convert to > _Float128. > > > > > > > > > This is causing a regression on aarch64: > > FAIL: libstdc++-abi/abi_check > > This is now PR 110077. > Hi Christophe, Is this fixed for aarch64 now? I think it should be. > > > > > > The log says: > > > > 3 added symbols > > 0 > > _ZNSt7__cxx1112basic_stringIwSt11char_traitsIwESaIwEE11_S_allocateERS3_m > > std::__cxx11::basic_string, > > std::allocator >::_S_allocate(std::allocator&, unsigned > > long) > > version status: compatible > > GLIBCXX_3.4.32 > > type: function > > status: added > > > > 1 > > _ZNSt7__cxx1112basic_stringIcSt11char_traitsIcESaIcEE11_S_allocateERS3_m > > std::__cxx11::basic_string, > > std::allocator >::_S_allocate(std::allocator&, unsigned long) > > version status: compatible > > GLIBCXX_3.4.32 > > type: function > > status: added > > > > 2 > > _ZSt10from_charsPKcS0_RDF128_St12chars_format > > std::from_chars(char const*, char const*, _Float128&, std::chars_format) > > version status: incompatible > > GLIBCXX_3.4.31 > > type: function > > status: added > > > > > > 2 undesignated symbols > > 0 > > _ZSt11__once_call > > std::__once_call > > version status: compatible > > GLIBCXX_3.4.11 > > type: tls > > type size: 8 > > status: undesignated > > > > 1 > > _ZSt15__once_callable > > std::__once_callable > > version status: compatible > > GLIBCXX_3.4.11 > > type: tls > > type size: 8 > > status: undesignated > > > > > > 1 incompatible symbols > > 0 > > _ZSt10from_charsPKcS0_RDF128_St12chars_format > > std::from_chars(char const*, char const*, _Float128&, std::chars_format) > > version status: incompatible > > GLIBCXX_3.4.31 > > type: function > > status: added > > > > > > > > ==== libstdc++-v3 check-abi Summary ==== > > > > # of added symbols: 3 > > # of missing symbols: 0 > > # of undesignated symbols: 2 > > # of incompatible symbols: 1 > > > > > > Can you have a look? > > > > Thanks, > > Christophe > > > > --- > > > libstdc++-v3/src/c++17/floating_from_chars.cc | 20 ++++++++++++------- > > > 1 file changed, 13 insertions(+), 7 deletions(-) > > > > > > diff --git a/libstdc++-v3/src/c++17/floating_from_chars.cc > > > b/libstdc++-v3/src/c++17/floating_from_chars.cc > > > index ebd428d5be3..eea878072b0 100644 > > > --- a/libstdc++-v3/src/c++17/floating_from_chars.cc > > > +++ b/libstdc++-v3/src/c++17/floating_from_chars.cc > > > @@ -64,7 +64,7 @@ > > > // strtold for __ieee128 > > > extern "C" __ieee128 __strtoieee128(const char*, char**); > > > #elif __FLT128_MANT_DIG__ == 113 && __LDBL_MANT_DIG__ != 113 \ > > > - && defined(__GLIBC_PREREQ) > > > + && defined(__GLIBC_PREREQ) && defined(USE_STRTOD_FOR_FROM_CHARS) > > > #define USE_STRTOF128_FOR_FROM_CHARS 1 > > > extern "C" _Float128 __strtof128(const char*, char**) > > > __asm ("strtof128") > > > @@ -77,10 +77,6 @@ extern "C" _Float128 __strtof128(const char*, > char**) > > > #if _GLIBCXX_FLOAT_IS_IEEE_BINARY32 && > _GLIBCXX_DOUBLE_IS_IEEE_BINARY64 \ > > > && __SIZE_WIDTH__ >= 32 > > > # define USE_LIB_FAST_FLOAT 1 > > > -# if __LDBL_MANT_DIG__ == __DBL_MANT_DIG__ > > > -// No need to use strtold. > > > -# undef USE_STRTOD_FOR_FROM_CHARS > > > -# endif > > > #endif > > > > > > #if USE_LIB_FAST_FLOAT > > > @@ -1261,7 +1257,7 @@ from_chars_result > > > from_chars(const char* first, const char* last, long double& value, > > > chars_format fmt) noexcept > > > { > > > -#if ! USE_STRTOD_FOR_FROM_CHARS > > > +#if __LDBL_MANT_DIG__ == __DBL_MANT_DIG__ || !defined > > > USE_STRTOD_FOR_FROM_CHARS > > > // Either long double is the same as double, or we can't use > strtold. > > > // In the latter case, this might give an incorrect result (e.g. > values > > > // out of range of double give an error, even if they fit in long > > > double). > > > @@ -1329,13 +1325,23 @@ > > > _ZSt10from_charsPKcS0_RDF128_St12chars_format(const char* first, > > > __ieee128& value, > > > chars_format fmt) > noexcept > > > __attribute__((alias > > > ("_ZSt10from_charsPKcS0_Ru9__ieee128St12chars_format"))); > > > -#elif defined(USE_STRTOF128_FOR_FROM_CHARS) > > > +#else > > > from_chars_result > > > from_chars(const char* first, const char* last, _Float128& value, > > > chars_format fmt) noexcept > > > { > > > +#ifdef USE_STRTOF128_FOR_FROM_CHARS > > > // fast_float doesn't support IEEE binary128 format, but we can use > > > strtold. > > > return from_chars_strtod(first, last, value, fmt); > > > +#else > > > + // Read a long double. This might give an incorrect result (e.g. > values > > > + // out of range of long double give an error, even if they fit in > > > _Float128). > > > + long double ldbl_val; > > > + auto res = std::from_chars(first, last, ldbl_val, fmt); > > > + if (res.ec == errc{}) > > > + value = ldbl_val; > > > + return res; > > > +#endif > > > } > > > #endif > > > > > > -- > > > 2.40.1 > > > > > > > >