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libstdc++: Fix stream extraction of IEEE128 long double [PR100912]

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The std::__convert_from_v helper that formats double and long double
values into a char buffer was not being duplicated for the two long
double ABIs. This resulted in an ODR violation inside the library, where
some callers needed it to use snprintf to format __ibm128 values and
other callers needed it to use __snprintfieee128 to format __ieee128
values. The linker discarded one of the definitions, leaving one set of
callers using the wrong code.

This puts __convert_from_v in the __gnu_cxx_ieee128 inline namespace
when long double is __ieee128, so that there are two different
definitions of the function.

The std::money_put::__do_put overload for __ibm128 values needs a
different fix, because that is defined when long double is __ieee128 and
so would call the one in the inline namespace. That can be fixed by just
inlining the code directly into the function and using an asm alias to
call the right version of snprintf for the __ibm128 format. The code to
do that can be simpler than __convert_from_v because if we're defining
the ALT128_COMPAT symbols we know that we have a recent glibc and so we
can assume that uselocale and snprintf are supported.

libstdc++-v3/ChangeLog:

	PR libstdc++/100912
	* config/locale/gnu/c_locale.h (__convert_from_v): Use inline
	namespace for IEEE128 long double mode.
	* config/os/gnu-linux/ldbl-ieee128-extra.ver: Add new symbol
	version and export __gnu_cxx_ieee128::__convert_from_v.
	* include/bits/locale_facets_nonio.tcc (money_put::__do_put):
	Make __ibm128 overload use snprintf directly
	* testsuite/util/testsuite_abi.cc: Add new symbol version.
	Remove stable IEEE128/LDBL versions.
This commit is contained in:
Jonathan Wakely 2022-02-14 16:46:55 +00:00
parent 02a981a8e5
commit 3d50dede07
4 changed files with 29 additions and 19 deletions
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10
libstdc++-v3/config/locale/gnu/c_locale.h
View File

@ -61,6 +61,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
typedef __locale_t __c_locale;
#if defined _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT \
&& defined __LONG_DOUBLE_IEEE128__
namespace __gnu_cxx_ieee128 {
#endif
// Convert numeric value of type double and long double to string and
// return length of string. If vsnprintf is available use it, otherwise
// fall back to the unsafe vsprintf which, in general, can be dangerous
@ -108,6 +113,11 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
return __ret;
}
#if defined _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT \
&& defined __LONG_DOUBLE_IEEE128__
} // namespace __gnu_cxx_ieee128
#endif
_GLIBCXX_END_NAMESPACE_VERSION
} // namespace

7
libstdc++-v3/config/os/gnu-linux/ldbl-ieee128-extra.ver
View File

@ -2,7 +2,8 @@
GLIBCXX_IEEE128_3.4.29 {
*__gnu_cxx_ieee128*;
_Z*St17__gnu_cxx_ieee1287num_get*;
_Z*St17__gnu_cxx_ieee1287num_put*;
_ZNSt14numeric_limitsIu9__ieee128E*;
_ZNSirsERu9__ieee128;
@ -45,6 +46,10 @@ GLIBCXX_IEEE128_3.4.29 {
} GLIBCXX_3.4.29;
GLIBCXX_IEEE128_3.4.30 {
_ZNSt17__gnu_cxx_ieee12816__convert_from_vERKP15__locale_structPciPKcz;
} GLIBCXX_3.4.30;
CXXABI_IEEE128_1.3.13 {
_ZT[IS]u9__ieee128;

23
libstdc++-v3/include/bits/locale_facets_nonio.tcc
View File

@ -635,6 +635,9 @@ _GLIBCXX_BEGIN_NAMESPACE_LDBL_OR_CXX11
#if defined _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT \
&& defined __LONG_DOUBLE_IEEE128__
extern "C"
__typeof__(__builtin_snprintf) __glibcxx_snprintfibm128 __asm__("snprintf");
template<typename _CharT, typename _OutIter>
_OutIter
money_put<_CharT, _OutIter>::
@ -643,30 +646,24 @@ _GLIBCXX_BEGIN_NAMESPACE_LDBL_OR_CXX11
{
const locale __loc = __io.getloc();
const ctype<_CharT>& __ctype = use_facet<ctype<_CharT> >(__loc);
#if _GLIBCXX_USE_C99_STDIO
// First try a buffer perhaps big enough.
int __cs_size = 64;
char* __cs = static_cast<char*>(__builtin_alloca(__cs_size));
const __c_locale __old = __gnu_cxx::__uselocale(_S_get_c_locale());
// _GLIBCXX_RESOLVE_LIB_DEFECTS
// 328. Bad sprintf format modifier in money_put<>::do_put()
int __len = std::__convert_from_v(_S_get_c_locale(), __cs, __cs_size,
"%.*Lf", 0, __units);
int __len = __glibcxx_snprintfibm128(__cs, __cs_size, "%.*Lf", 0,
__units);
// If the buffer was not large enough, try again with the correct size.
if (__len >= __cs_size)
{
__cs_size = __len + 1;
__cs = static_cast<char*>(__builtin_alloca(__cs_size));
__len = std::__convert_from_v(_S_get_c_locale(), __cs, __cs_size,
"%.*Lf", 0, __units);
__len = __glibcxx_snprintfibm128(__cs, __cs_size, "%.*Lf", 0,
__units);
}
#else
// max_exponent10 + 1 for the integer part, + 2 for sign and '\0'.
const int __cs_size =
__gnu_cxx::__numeric_traits<long double>::__max_exponent10 + 3;
char* __cs = static_cast<char*>(__builtin_alloca(__cs_size));
int __len = std::__convert_from_v(_S_get_c_locale(), __cs, 0, "%.*Lf",
0, __units);
#endif
__gnu_cxx::__uselocale(__old);
string_type __digits(__len, char_type());
__ctype.widen(__cs, __cs + __len, &__digits[0]);
return __intl ? _M_insert<true>(__s, __io, __fill, __digits)

8
libstdc++-v3/testsuite/util/testsuite_abi.cc
View File

@ -213,6 +213,7 @@ check_version(symbol& test, bool added)
known_versions.push_back("GLIBCXX_3.4.30");
known_versions.push_back("GLIBCXX_LDBL_3.4.29");
known_versions.push_back("GLIBCXX_IEEE128_3.4.29");
known_versions.push_back("GLIBCXX_IEEE128_3.4.30");
known_versions.push_back("CXXABI_1.3");
known_versions.push_back("CXXABI_LDBL_1.3");
known_versions.push_back("CXXABI_1.3.1");
@ -247,11 +248,8 @@ check_version(symbol& test, bool added)
// Check that added symbols are added in the latest pre-release version.
bool latestp = (test.version_name == "GLIBCXX_3.4.30"
// XXX remove next 3 lines when baselines have been regenerated
// to include {IEEE128,LDBL} symbols:
|| test.version_name == "GLIBCXX_LDBL_3.4.29"
|| test.version_name == "GLIBCXX_IEEE128_3.4.29"
|| test.version_name == "CXXABI_IEEE128_1.3.13"
// XXX remove next line when baselines have been regenerated.
|| test.version_name == "GLIBCXX_IEEE128_3.4.30"
|| test.version_name == "CXXABI_1.3.13"
|| test.version_name == "CXXABI_FLOAT128"
|| test.version_name == "CXXABI_TM_1");