[gcc r12-7231] libstdc++: Fix stream extraction of IEEE128 long double [PR100912]

[gcc r12-7231] libstdc++: Fix stream extraction of IEEE128 long double [PR100912]

[Jonathan Wakely]

https://gcc.gnu.org/g:3d50dede07de0923f0f320d385162e546445e640

commit r12-7231-g3d50dede07de0923f0f320d385162e546445e640
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Mon Feb 14 16:46:55 2022 +0000

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

Diff:
---
 libstdc++-v3/config/locale/gnu/c_locale.h          | 10 ++++++++++
 .../config/os/gnu-linux/ldbl-ieee128-extra.ver     |  7 ++++++-
 libstdc++-v3/include/bits/locale_facets_nonio.tcc  | 23 ++++++++++------------
 libstdc++-v3/testsuite/util/testsuite_abi.cc       |  8 +++-----
 4 files changed, 29 insertions(+), 19 deletions(-)

diff --git a/libstdc++-v3/config/locale/gnu/c_locale.h b/libstdc++-v3/config/locale/gnu/c_locale.h
index 176e022b85c..526b62215e1 100644
--- a/libstdc++-v3/config/locale/gnu/c_locale.h
+++ b/libstdc++-v3/config/locale/gnu/c_locale.h
@@ -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
 
diff --git a/libstdc++-v3/config/os/gnu-linux/ldbl-ieee128-extra.ver b/libstdc++-v3/config/os/gnu-linux/ldbl-ieee128-extra.ver
index 9b421b6f1f9..830cb8c40f4 100644
--- a/libstdc++-v3/config/os/gnu-linux/ldbl-ieee128-extra.ver
+++ b/libstdc++-v3/config/os/gnu-linux/ldbl-ieee128-extra.ver
@@ -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;
diff --git a/libstdc++-v3/include/bits/locale_facets_nonio.tcc b/libstdc++-v3/include/bits/locale_facets_nonio.tcc
index 64737823374..98442418f51 100644
--- a/libstdc++-v3/include/bits/locale_facets_nonio.tcc
+++ b/libstdc++-v3/include/bits/locale_facets_nonio.tcc
@@ -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)
diff --git a/libstdc++-v3/testsuite/util/testsuite_abi.cc b/libstdc++-v3/testsuite/util/testsuite_abi.cc
index 0ac0ea3fa90..3dee737b2e5 100644
--- a/libstdc++-v3/testsuite/util/testsuite_abi.cc
+++ b/libstdc++-v3/testsuite/util/testsuite_abi.cc
@@ -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");