From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ej1-x633.google.com (mail-ej1-x633.google.com [IPv6:2a00:1450:4864:20::633]) by sourceware.org (Postfix) with ESMTPS id A851C3858C41; Thu, 1 Jun 2023 11:05:47 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org A851C3858C41 Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=gmail.com Received: by mail-ej1-x633.google.com with SMTP id a640c23a62f3a-96f683e8855so91128766b.2; Thu, 01 Jun 2023 04:05:47 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1685617546; x=1688209546; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=9/xXI4Q12Wp+0euBZ0K7OVzdCW6W6vFvgUDeJujMvOc=; b=cFtpV2P+ELxnhYIyC9kvtBTL+ZV/gDBVfC5jFi1CL3gLjkszJiHYFJ93oBR8n23wA2 ZNDAOBB0syRIB1asj6fWLtJnN4BMdgVk3aORNCnTwoZz+5f5QAApVfDHkQDK2xUjhsgP Mhp6kOxk8JoKGdi0klT13uJ/ne5e+EqjUhPY0nlaVrnJ3+gqtk80ZkOx0dQ2MOKCmVc6 7Hh5hm2UtmsQlF1XLoaDDLUYbq3jjqF2Z2PFmTYIULXHAtOp6UbBpo7JVuhqoZLCsNBf JVCoL6dxRPlkGox6hJYPkCIYb3BZN9E9iGDWkEgwwds14r/WKwIRJQ4HkUEkiPy9ICah AGIg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1685617546; x=1688209546; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=9/xXI4Q12Wp+0euBZ0K7OVzdCW6W6vFvgUDeJujMvOc=; b=J2uHuC+/Ia0eHorqjrdAFBx8tZgPTWxUoFnUm/uivY0VFQSvdirwxXrGOZY9Bh5rgI tDGRZZ2VCFI6FGqkXtD43d+QXqinRhNI4YrhuC727is//EGgaJSy0vsQKFmRnUuAJG6D 8gNpjyFY/tPGIvXjwi2h35cfSfGrMosXLTWCIf1kwwdEtr7qDHoWpQEkgQCJc4ZoZVSy n2QxCsu7Y6vqnKuewoQai/zVxLEZzUASBtLmgPleHIVAEfz6jQGUhOeu0ViyfPnuFEh0 Dzflp26sa8hMpGbVHfGyIlpeMsSvGTNBeU1C0Q7j/HtcWMpP/Qhd7FtNPvEy8ZJM62s4 IzXQ== X-Gm-Message-State: AC+VfDz0ucLIaa5jdy9X6hXwzMVxbGuyi6cpnY2Ak3nN0dKOspvKYzDs iyk4FpbSQDWs1Sr4JknekQw4x7dgFyaK03O9WH4GWfxm X-Google-Smtp-Source: ACHHUZ6drsaqQ9m7Qb6udjX9NkZQvD3FaNgKDbikTfCoijdvT4fpkw6ZBsuE2/SbeJpxNEKqKpL30UQBgcaVH6I7f5Q= X-Received: by 2002:a17:906:da8e:b0:96a:3119:ac0 with SMTP id xh14-20020a170906da8e00b0096a31190ac0mr7097971ejb.69.1685617546060; Thu, 01 Jun 2023 04:05:46 -0700 (PDT) MIME-Version: 1.0 References: <20230531122222.4116868-1-jwakely@redhat.com> In-Reply-To: From: Jonathan Wakely Date: Thu, 1 Jun 2023 12:05:34 +0100 Message-ID: Subject: Re: [committed] libstdc++: Fix preprocessor conditions for std::from_chars [PR109921] To: Christophe Lyon Cc: Jonathan Wakely , libstdc++@gcc.gnu.org, gcc-patches@gcc.gnu.org Content-Type: text/plain; charset="UTF-8" X-Spam-Status: No, score=-6.7 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM,GIT_PATCH_0,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS,TXREP,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: 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. > > 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 > > > >