From: Jonathan Wakely <jwakely@redhat.com>
Date: Wed, 16 Dec 2020 23:25:01 +0000 (+0000)
Subject: libstdc++: Add C++ runtime support for new 128-bit long double format
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=7c1e7eed891a7b8fd8bbe6a13e6435cfbe7e9055;p=gcc.git

libstdc++: Add C++ runtime support for new 128-bit long double format

This adds support for the new __ieee128 long double format on
powerpc64le targets.

Most of the complexity comes from wanting a single libstdc++.so library
that contains the symbols needed by code compiled with both
-mabi=ibmlongdouble and -mabi=ieeelongdouble (and not forgetting
-mlong-double-64 as well!)

In a few places this just requires an extra overload, for example
std::from_chars has to be overloaded for both forms of long double.
That can be done in a single translation unit that defines overloads
for 'long double' and also '__ieee128', so that user code including
<charconv> will be able to link to a definition for either type of long
double. Those are the easy cases.

The difficult parts are (as for the std::string ABI transition) the I/O
and locale facets. In order to be able to write either form of long
double to an ostream such as std::cout we need the locale to contain a
std::num_put facet that can handle both forms. The same approach is
taken as was already done for supporting 64-bit long double and 128-bit
long double: adding extra overloads of do_put to the facet class. On
targets where the new long double code is enabled, the facets that are
registered in the locale at program startup have additional overloads so
that they can work with any long double type. Where this fails to work
is if user code installs its own facet, which will probably not have the
additional overloads and so will only be able to output one or the other
type. In practice the number of users expecting to be able to use their
own locale facets in code using a mix of -mabi=ibmlongdouble and
-mabi=ieeelongdouble is probably close to zero.

libstdc++-v3/ChangeLog:

	* Makefile.in: Regenerate.
	* config.h.in: Regenerate.
	* config/abi/pre/gnu.ver: Make patterns less greedy.
	* config/os/gnu-linux/ldbl-ieee128-extra.ver: New file with patterns
	for IEEE128 long double symbols.
	* configure: Regenerate.
	* configure.ac: Enable alternative 128-bit long double format on
	powerpc64*-*-linux*.
	* doc/Makefile.in: Regenerate.
	* fragment.am: Regenerate.
	* include/Makefile.am: Set _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT.
	* include/Makefile.in: Regenerate.
	* include/bits/c++config: Define inline namespace for new long
	double symbols. Don't define _GLIBCXX_USE_FLOAT128 when it's the
	same type as long double.
	* include/bits/locale_classes.h [_GLIBCXX_LONG_DOUBLE_ALT128_COMPAT]
	(locale::_Impl::_M_init_extra_ldbl128): Declare new member function.
	* include/bits/locale_facets.h (_GLIBCXX_NUM_FACETS): Simplify by
	only counting narrow character facets.
	(_GLIBCXX_NUM_CXX11_FACETS): Likewise.
	(_GLIBCXX_NUM_LBDL_ALT128_FACETS): New.
	[_GLIBCXX_LONG_DOUBLE_ALT128_COMPAT] (num_get::__do_get): Define
	vtable placeholder for __ibm128 long double type.
	[_GLIBCXX_LONG_DOUBLE_ALT128_COMPAT && __LONG_DOUBLE_IEEE128__]
	(num_get::__do_get): Declare vtable placeholder for __ibm128 long
	double type.
	[_GLIBCXX_LONG_DOUBLE_ALT128_COMPAT && __LONG_DOUBLE_IEEE128__]
	(num_put::__do_put): Likewise.
	* include/bits/locale_facets.tcc
	[_GLIBCXX_LONG_DOUBLE_ALT128_COMPAT && __LONG_DOUBLE_IEEE128__]
	(num_get::__do_get, num_put::__do_put): Define.
	* include/bits/locale_facets_nonio.h
	[_GLIBCXX_LONG_DOUBLE_ALT128_COMPAT && __LONG_DOUBLE_IEEE128__]
	(money_get::__do_get): Declare vtable placeholder for __ibm128 long
	double type.
	[_GLIBCXX_LONG_DOUBLE_ALT128_COMPAT && __LONG_DOUBLE_IEEE128__]
	(money_put::__do_put): Likewise.
	* include/bits/locale_facets_nonio.tcc
	[_GLIBCXX_LONG_DOUBLE_ALT128_COMPAT && __LONG_DOUBLE_IEEE128__]
	(money_get::__do_get, money_put::__do_put): Define.
	* include/ext/numeric_traits.h [_GLIBCXX_LONG_DOUBLE_ALT128_COMPAT]
	(__numeric_traits<__ibm128>, __numeric_traits<__ieee128>): Define.
	* libsupc++/Makefile.in: Regenerate.
	* po/Makefile.in: Regenerate.
	* python/Makefile.in: Regenerate.
	* src/Makefile.am: Add compatibility-ldbl-alt128.cc and
	compatibility-ldbl-alt128-cxx11.cc sources and recipes for objects.
	* src/Makefile.in: Regenerate.
	* src/c++11/Makefile.in: Regenerate.
	* src/c++11/compatibility-ldbl-alt128-cxx11.cc: New file defining
	symbols using the old 128-bit long double format, for the cxx11 ABI.
	* src/c++11/compatibility-ldbl-alt128.cc: Likewise, for the
	gcc4-compatible ABI.
	* src/c++11/compatibility-ldbl-facets-aliases.h: New header for long
	double compat aliases.
	* src/c++11/cow-locale_init.cc: Add comment.
	* src/c++11/cxx11-locale-inst.cc: Define C and C_is_char
	unconditionally.
	* src/c++11/cxx11-wlocale-inst.cc: Add sanity check. Include
	locale-inst.cc directly, not via cxx11-locale-inst.cc.
	* src/c++11/locale-inst-monetary.h: New header for monetary
	category instantiations.
	* src/c++11/locale-inst-numeric.h: New header for numeric category
	instantiations.
	* src/c++11/locale-inst.cc: Include new headers for monetary,
	numeric, and long double definitions.
	* src/c++11/wlocale-inst.cc: Remove long double compat aliases that
	are defined in new header now.
	* src/c++17/Makefile.am: Use -mabi=ibmlongdouble for
	floating_from_chars.cc.
	* src/c++17/Makefile.in: Regenerate.
	* src/c++17/floating_from_chars.cc (from_chars_impl): Add
	if-constexpr branch for __ieee128.
	(from_chars): Overload for __ieee128.
	* src/c++20/Makefile.in: Regenerate.
	* src/c++98/Makefile.in: Regenerate.
	* src/c++98/locale_init.cc (num_facets): Adjust calculation.
	(locale::_Impl::_Impl(size_t)): Call _M_init_extra_ldbl128.
	* src/c++98/localename.cc (num_facets): Adjust calculation.
	(locale::_Impl::_Impl(const char*, size_t)): Call
	_M_init_extra_ldbl128.
	* src/filesystem/Makefile.in: Regenerate.
	* testsuite/Makefile.in: Regenerate.
	* testsuite/util/testsuite_abi.cc: Add new symbol versions.
	Allow new symbols to be added to GLIBCXX_IEEE128_3.4.29 and
	CXXABI_IEEE128_1.3.13 too.
	* testsuite/26_numerics/complex/abi_tag.cc: Add u9__ieee128 to
	regex matching expected symbols.
---

diff --git a/libstdc++-v3/Makefile.in b/libstdc++-v3/Makefile.in
index f5287248770..a1955dddd15 100644
--- a/libstdc++-v3/Makefile.in
+++ b/libstdc++-v3/Makefile.in
@@ -257,6 +257,8 @@ LIBS = @LIBS@
 LIBTOOL = @LIBTOOL@
 LIPO = @LIPO@
 LN_S = @LN_S@
+LONG_DOUBLE_128_FLAGS = @LONG_DOUBLE_128_FLAGS@
+LONG_DOUBLE_ALT128_COMPAT_FLAGS = @LONG_DOUBLE_ALT128_COMPAT_FLAGS@
 LONG_DOUBLE_COMPAT_FLAGS = @LONG_DOUBLE_COMPAT_FLAGS@
 LTLIBICONV = @LTLIBICONV@
 LTLIBOBJS = @LTLIBOBJS@
@@ -396,11 +398,13 @@ toolexeclibdir = $(glibcxx_toolexeclibdir)
 @ENABLE_WERROR_TRUE@WERROR_FLAG = -Werror
 @ENABLE_EXTERN_TEMPLATE_FALSE@XTEMPLATE_FLAGS = 
 @ENABLE_EXTERN_TEMPLATE_TRUE@XTEMPLATE_FLAGS = -fno-implicit-templates
+@GLIBCXX_LDBL_ALT128_COMPAT_FALSE@LDBL_128_FLAGS = 
+@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@LDBL_128_FLAGS = $(LONG_DOUBLE_128_FLAGS)
 
 # These bits are all figured out from configure.  Look in acinclude.m4
 # or configure.ac to see how they are set.  See GLIBCXX_EXPORT_FLAGS.
 CONFIG_CXXFLAGS = \
-	$(SECTION_FLAGS) $(HWCAP_CFLAGS) -frandom-seed=$@
+	$(SECTION_FLAGS) $(HWCAP_CFLAGS) -frandom-seed=$@ $(LDBL_128_FLAGS)
 
 WARN_CXXFLAGS = \
 	$(WARN_FLAGS) $(WERROR_FLAG) -fdiagnostics-show-location=once 
diff --git a/libstdc++-v3/config.h.in b/libstdc++-v3/config.h.in
index 5889f32922e..937c19c3075 100644
--- a/libstdc++-v3/config.h.in
+++ b/libstdc++-v3/config.h.in
@@ -882,6 +882,10 @@
 /* Define to 1 if a full hosted library is built, or 0 if freestanding. */
 #undef _GLIBCXX_HOSTED
 
+/* Define if compatibility should be provided for alternative 128-bit long
+   double formats. */
+#undef _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT
+
 /* Define if compatibility should be provided for -mlong-double-64. */
 #undef _GLIBCXX_LONG_DOUBLE_COMPAT
 
diff --git a/libstdc++-v3/config/abi/pre/gnu.ver b/libstdc++-v3/config/abi/pre/gnu.ver
index 46769db1530..4b4bd8ab6da 100644
--- a/libstdc++-v3/config/abi/pre/gnu.ver
+++ b/libstdc++-v3/config/abi/pre/gnu.ver
@@ -682,7 +682,7 @@ GLIBCXX_3.4 {
     _ZNSt12__basic_fileIcED*;
 
     # std::__convert_to_v
-    _ZSt14__convert_to_vI[^g]*;
+    _ZSt14__convert_to_vI[^gU]*;
 
     # __gnu_cxx::stdio_sync_filebuf
     _ZTVN9__gnu_cxx18stdio_sync_filebufI[cw]St11char_traitsI[cw]EEE;
@@ -931,7 +931,7 @@ GLIBCXX_3.4 {
     _ZGVNSt8time_putI[cw]*;
     _ZGVNSt9money_getI[cw]*;
     _ZGVNSt9money_putI[cw]*;
-    _ZGVNSt1[^07]*;
+    _ZGVNSt1[^079]*;
     _ZGVNSt10moneypunctI[cw]Lb[01]*;
 
     # exception constructors taking std::string
diff --git a/libstdc++-v3/config/os/gnu-linux/ldbl-ieee128-extra.ver b/libstdc++-v3/config/os/gnu-linux/ldbl-ieee128-extra.ver
new file mode 100644
index 00000000000..3c3395e4d4e
--- /dev/null
+++ b/libstdc++-v3/config/os/gnu-linux/ldbl-ieee128-extra.ver
@@ -0,0 +1,53 @@
+# Appended to version file.
+
+GLIBCXX_IEEE128_3.4.29 {
+
+  *__gnu_cxx_ieee128*;
+
+  _ZNSt14numeric_limitsIu9__ieee128E*;
+  _ZNSirsERu9__ieee128;
+  _ZNSolsEu9__ieee128;
+  _ZNSt13basic_istreamIwSt11char_traitsIwEErsERu9__ieee128;
+  _ZNSt13basic_ostreamIwSt11char_traitsIwEElsEu9__ieee128;
+  _ZSt14__convert_to_vIu9__ieee128EvPKcRT_RSt12_Ios_IostateRKP*;
+  _ZStlsIu9__ieee128[cw]St11char_traitsI[cw]EERSt13basic_ostreamIT0_T1_ES6_RKSt7complexIT_E;
+  _ZStrsIu9__ieee128[cw]St11char_traitsI[cw]EERSt13basic_istreamIT0_T1_ES6_RSt7complexIT_E;
+
+  _ZNSi10_M_extractIu9__ieee128EERSiRT_;
+  _ZNSt13basic_istreamIwSt11char_traitsIwEE10_M_extractIu9__ieee128EERS2_RT_;
+  _ZNSo9_M_insertIu9__ieee128EERSoT_;
+  _ZNSt13basic_ostreamIwSt11char_traitsIwEE9_M_insertIu9__ieee128EERS2_T_;
+
+  _ZNKSt3tr14hashIu9__ieee128EclEu9__ieee128;
+  _ZNKSt4hashIu9__ieee128EclEu9__ieee128;
+
+  _ZNKSt19__gnu_cxx11_ieee1289money_getIcSt19istreambuf_iteratorIcSt11char_traitsIcEEE6do_getES4_S4_bRSt8ios_baseRSt12_Ios_IostateRNSt7__cxx1112basic_stringIcS3_SaIcEEE;
+  _ZNKSt19__gnu_cxx11_ieee1289money_getIcSt19istreambuf_iteratorIcSt11char_traitsIcEEE6do_getES4_S4_bRSt8ios_baseRSt12_Ios_IostateRu9__ieee128;
+  _ZNKSt19__gnu_cxx11_ieee1289money_getIcSt19istreambuf_iteratorIcSt11char_traitsIcEEE8__do_getES4_S4_bRSt8ios_baseRSt12_Ios_IostateRd;
+  _ZNKSt19__gnu_cxx11_ieee1289money_getIcSt19istreambuf_iteratorIcSt11char_traitsIcEEE8__do_getES4_S4_bRSt8ios_baseRSt12_Ios_IostateRg;
+  _ZNKSt19__gnu_cxx11_ieee1289money_putIcSt19ostreambuf_iteratorIcSt11char_traitsIcEEE6do_putES4_bRSt8ios_basecRKNSt7__cxx1112basic_stringIcS3_SaIcEEE;
+  _ZNKSt19__gnu_cxx11_ieee1289money_putIcSt19ostreambuf_iteratorIcSt11char_traitsIcEEE6do_putES4_bRSt8ios_basecu9__ieee128;
+  _ZNKSt19__gnu_cxx11_ieee1289money_putIcSt19ostreambuf_iteratorIcSt11char_traitsIcEEE8__do_putES4_bRSt8ios_basecd;
+  _ZNKSt19__gnu_cxx11_ieee1289money_putIcSt19ostreambuf_iteratorIcSt11char_traitsIcEEE8__do_putES4_bRSt8ios_basecg;
+  _ZSt9has_facetINSt19__gnu_cxx11_ieee1289money_getI[cw]St19istreambuf_iteratorI[cw]St11char_traitsI[cw]EEEEEbRKSt6locale;
+  _ZSt9has_facetINSt19__gnu_cxx11_ieee1289money_putI[cw]St19ostreambuf_iteratorI[cw]St11char_traitsI[cw]EEEEEbRKSt6locale;
+  _ZSt9use_facetINSt19__gnu_cxx11_ieee1289money_getI[cw]St19istreambuf_iteratorI[cw]St11char_traitsI[cw]EEEEERKT_RKSt6locale;
+  _ZSt9use_facetINSt19__gnu_cxx11_ieee1289money_putI[cw]St19ostreambuf_iteratorI[cw]St11char_traitsI[cw]EEEEERKT_RKSt6locale;
+  _ZTINSt19__gnu_cxx11_ieee1289money_getI[cw]St19istreambuf_iteratorI[cw]St11char_traitsI[cw]EEEE;
+  _ZTVNSt19__gnu_cxx11_ieee1289money_getI[cw]St19istreambuf_iteratorI[cw]St11char_traitsI[cw]EEEE;
+  _ZTINSt19__gnu_cxx11_ieee1289money_putI[cw]St19ostreambuf_iteratorI[cw]St11char_traitsI[cw]EEEE;
+  _ZTVNSt19__gnu_cxx11_ieee1289money_putI[cw]St19ostreambuf_iteratorI[cw]St11char_traitsI[cw]EEEE;
+
+  _ZNKSt19__gnu_cxx11_ieee1289money_putI[cw]St19ostreambuf_iteratorI[cw]St11char_traitsI[cw]EEE3putES4_bRSt8ios_base[cw]u9__ieee128;
+
+  _ZSt10from_charsPKcS0_Ru9__ieee128St12chars_format;
+
+} GLIBCXX_3.4.29;
+
+CXXABI_IEEE128_1.3.13 {
+
+  _ZT[IS]u9__ieee128;
+  _ZT[IS]Pu9__ieee128;
+  _ZT[IS]PKu9__ieee128;
+
+} CXXABI_1.3.13;
diff --git a/libstdc++-v3/configure b/libstdc++-v3/configure
index 7647a182161..5249453b6c8 100755
--- a/libstdc++-v3/configure
+++ b/libstdc++-v3/configure
@@ -680,8 +680,12 @@ ENABLE_FILESYSTEM_TS_TRUE
 baseline_subdir_switch
 baseline_dir
 HWCAP_CFLAGS
+GLIBCXX_LDBL_ALT128_COMPAT_FALSE
+GLIBCXX_LDBL_ALT128_COMPAT_TRUE
 GLIBCXX_LDBL_COMPAT_FALSE
 GLIBCXX_LDBL_COMPAT_TRUE
+LONG_DOUBLE_ALT128_COMPAT_FLAGS
+LONG_DOUBLE_128_FLAGS
 LONG_DOUBLE_COMPAT_FLAGS
 ENABLE_CXX11_ABI_FALSE
 ENABLE_CXX11_ABI_TRUE
@@ -12136,7 +12140,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 12139 "configure"
+#line 12143 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -12242,7 +12246,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<_LT_EOF
-#line 12245 "configure"
+#line 12249 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -15934,7 +15938,7 @@ $as_echo "$glibcxx_cv_atomic_long_long" >&6; }
   # Fake what AC_TRY_COMPILE does.
 
     cat > conftest.$ac_ext << EOF
-#line 15937 "configure"
+#line 15941 "configure"
 int main()
 {
   typedef bool atomic_type;
@@ -15969,7 +15973,7 @@ $as_echo "$glibcxx_cv_atomic_bool" >&6; }
     rm -f conftest*
 
     cat > conftest.$ac_ext << EOF
-#line 15972 "configure"
+#line 15976 "configure"
 int main()
 {
   typedef short atomic_type;
@@ -16004,7 +16008,7 @@ $as_echo "$glibcxx_cv_atomic_short" >&6; }
     rm -f conftest*
 
     cat > conftest.$ac_ext << EOF
-#line 16007 "configure"
+#line 16011 "configure"
 int main()
 {
   // NB: _Atomic_word not necessarily int.
@@ -16040,7 +16044,7 @@ $as_echo "$glibcxx_cv_atomic_int" >&6; }
     rm -f conftest*
 
     cat > conftest.$ac_ext << EOF
-#line 16043 "configure"
+#line 16047 "configure"
 int main()
 {
   typedef long long atomic_type;
@@ -16193,7 +16197,7 @@ $as_echo "mutex" >&6; }
   # unnecessary for this test.
 
     cat > conftest.$ac_ext << EOF
-#line 16196 "configure"
+#line 16200 "configure"
 int main()
 {
   _Decimal32 d1;
@@ -16235,7 +16239,7 @@ ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
   # unnecessary for this test.
 
     cat > conftest.$ac_ext << EOF
-#line 16238 "configure"
+#line 16242 "configure"
 template<typename T1, typename T2>
   struct same
   { typedef T2 type; };
@@ -16269,7 +16273,7 @@ $as_echo "$enable_int128" >&6; }
     rm -f conftest*
 
     cat > conftest.$ac_ext << EOF
-#line 16272 "configure"
+#line 16276 "configure"
 template<typename T1, typename T2>
   struct same
   { typedef T2 type; };
@@ -75695,7 +75699,11 @@ $as_echo "${default_libstdcxx_abi}" >&6; }
 
 
 ac_ldbl_compat=no
+ac_ldbl_alt128_compat=no
+ac_ldbl_ieee128_default=no
 LONG_DOUBLE_COMPAT_FLAGS="-mlong-double-64"
+LONG_DOUBLE_128_FLAGS=
+LONG_DOUBLE_ALT128_COMPAT_FLAGS=
 case "$target" in
   powerpc*-*-linux* | \
   sparc*-*-linux* | \
@@ -75729,13 +75737,103 @@ $as_echo "#define _GLIBCXX_LONG_DOUBLE_COMPAT 1" >>confdefs.h
     port_specific_symbol_files="\$(top_srcdir)/config/os/gnu-linux/ldbl-extra.ver"
     case "$target" in
       powerpc*-*-linux*)
-	LONG_DOUBLE_COMPAT_FLAGS="$LONG_DOUBLE_COMPAT_FLAGS -mno-gnu-attribute" ;;
+	LONG_DOUBLE_COMPAT_FLAGS="$LONG_DOUBLE_COMPAT_FLAGS -mno-gnu-attribute"
+        # Check for IEEE128 support in libm:
+        { $as_echo "$as_me:${as_lineno-$LINENO}: checking for __frexpieee128 in -lm" >&5
+$as_echo_n "checking for __frexpieee128 in -lm... " >&6; }
+if ${ac_cv_lib_m___frexpieee128+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  ac_check_lib_save_LIBS=$LIBS
+LIBS="-lm  $LIBS"
+if test x$gcc_no_link = xyes; then
+  as_fn_error $? "Link tests are not allowed after GCC_NO_EXECUTABLES." "$LINENO" 5
+fi
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+/* Override any GCC internal prototype to avoid an error.
+   Use char because int might match the return type of a GCC
+   builtin and then its argument prototype would still apply.  */
+#ifdef __cplusplus
+extern "C"
+#endif
+char __frexpieee128 ();
+int
+main ()
+{
+return __frexpieee128 ();
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_link "$LINENO"; then :
+  ac_cv_lib_m___frexpieee128=yes
+else
+  ac_cv_lib_m___frexpieee128=no
+fi
+rm -f core conftest.err conftest.$ac_objext \
+    conftest$ac_exeext conftest.$ac_ext
+LIBS=$ac_check_lib_save_LIBS
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $ac_cv_lib_m___frexpieee128" >&5
+$as_echo "$ac_cv_lib_m___frexpieee128" >&6; }
+if test "x$ac_cv_lib_m___frexpieee128" = xyes; then :
+  ac_ldbl_ieee128_in_libc=yes
+else
+  ac_ldbl_ieee128_in_libc=no
+fi
+
+        if test $ac_ldbl_ieee128_in_libc = yes; then
+          # Determine which long double format is the compiler's default:
+          cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+
+            #ifndef __LONG_DOUBLE_IEEE128__
+            #error compiler defaults to ibm128
+            #endif
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  ac_ldbl_ieee128_default=yes
+else
+  ac_ldbl_ieee128_default=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+          # Library objects should use default long double format.
+          if test "$ac_ldbl_ieee128_default" = yes; then
+            LONG_DOUBLE_128_FLAGS="-mno-gnu-attribute"
+            # Except for the ones that explicitly use these flags:
+            LONG_DOUBLE_ALT128_COMPAT_FLAGS="-mabi=ibmlongdouble -mno-gnu-attribute -Wno-psabi"
+          else
+            LONG_DOUBLE_128_FLAGS="-mno-gnu-attribute"
+            LONG_DOUBLE_ALT128_COMPAT_FLAGS="-mabi=ieeelongdouble -mno-gnu-attribute -Wno-psabi"
+          fi
+
+$as_echo "#define _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT 1" >>confdefs.h
+
+          port_specific_symbol_files="$port_specific_symbol_files \$(top_srcdir)/config/os/gnu-linux/ldbl-ieee128-extra.ver"
+          ac_ldbl_alt128_compat=yes
+        else
+          ac_ldbl_alt128_compat=no
+        fi
+	;;
     esac
   fi
 esac
 
 
 
+
+
+
 # Check if assembler supports disabling hardware capability support.
 
   test -z "$HWCAP_CFLAGS" && HWCAP_CFLAGS=''
@@ -78268,6 +78366,15 @@ else
 fi
 
 
+    if test $ac_ldbl_alt128_compat = yes; then
+  GLIBCXX_LDBL_ALT128_COMPAT_TRUE=
+  GLIBCXX_LDBL_ALT128_COMPAT_FALSE='#'
+else
+  GLIBCXX_LDBL_ALT128_COMPAT_TRUE='#'
+  GLIBCXX_LDBL_ALT128_COMPAT_FALSE=
+fi
+
+
     if test $enable_libstdcxx_filesystem_ts = yes; then
   ENABLE_FILESYSTEM_TS_TRUE=
   ENABLE_FILESYSTEM_TS_FALSE='#'
@@ -78778,6 +78885,10 @@ if test -z "${GLIBCXX_LDBL_COMPAT_TRUE}" && test -z "${GLIBCXX_LDBL_COMPAT_FALSE
   as_fn_error $? "conditional \"GLIBCXX_LDBL_COMPAT\" was never defined.
 Usually this means the macro was only invoked conditionally." "$LINENO" 5
 fi
+if test -z "${GLIBCXX_LDBL_ALT128_COMPAT_TRUE}" && test -z "${GLIBCXX_LDBL_ALT128_COMPAT_FALSE}"; then
+  as_fn_error $? "conditional \"GLIBCXX_LDBL_ALT128_COMPAT\" was never defined.
+Usually this means the macro was only invoked conditionally." "$LINENO" 5
+fi
 if test -z "${ENABLE_FILESYSTEM_TS_TRUE}" && test -z "${ENABLE_FILESYSTEM_TS_FALSE}"; then
   as_fn_error $? "conditional \"ENABLE_FILESYSTEM_TS\" was never defined.
 Usually this means the macro was only invoked conditionally." "$LINENO" 5
diff --git a/libstdc++-v3/configure.ac b/libstdc++-v3/configure.ac
index 9138ba22588..3c799be82b1 100644
--- a/libstdc++-v3/configure.ac
+++ b/libstdc++-v3/configure.ac
@@ -403,7 +403,11 @@ GLIBCXX_ENABLE_LIBSTDCXX_DUAL_ABI([yes])
 GLIBCXX_DEFAULT_ABI
 
 ac_ldbl_compat=no
+ac_ldbl_alt128_compat=no
+ac_ldbl_ieee128_default=no
 LONG_DOUBLE_COMPAT_FLAGS="-mlong-double-64"
+LONG_DOUBLE_128_FLAGS=
+LONG_DOUBLE_ALT128_COMPAT_FLAGS=
 case "$target" in
   powerpc*-*-linux* | \
   sparc*-*-linux* | \
@@ -420,12 +424,43 @@ case "$target" in
     port_specific_symbol_files="\$(top_srcdir)/config/os/gnu-linux/ldbl-extra.ver"
     case "$target" in
       powerpc*-*-linux*)
-	LONG_DOUBLE_COMPAT_FLAGS="$LONG_DOUBLE_COMPAT_FLAGS -mno-gnu-attribute" ;;
+	LONG_DOUBLE_COMPAT_FLAGS="$LONG_DOUBLE_COMPAT_FLAGS -mno-gnu-attribute"
+        # Check for IEEE128 support in libm:
+        AC_CHECK_LIB(m, __frexpieee128,
+                     [ac_ldbl_ieee128_in_libc=yes],
+                     [ac_ldbl_ieee128_in_libc=no])
+        if test $ac_ldbl_ieee128_in_libc = yes; then
+          # Determine which long double format is the compiler's default:
+          AC_TRY_COMPILE(, [
+            #ifndef __LONG_DOUBLE_IEEE128__
+            #error compiler defaults to ibm128
+            #endif
+          ], [ac_ldbl_ieee128_default=yes], [ac_ldbl_ieee128_default=no])
+          # Library objects should use default long double format.
+          if test "$ac_ldbl_ieee128_default" = yes; then
+            LONG_DOUBLE_128_FLAGS="-mno-gnu-attribute"
+            # Except for the ones that explicitly use these flags:
+            LONG_DOUBLE_ALT128_COMPAT_FLAGS="-mabi=ibmlongdouble -mno-gnu-attribute -Wno-psabi"
+          else
+            LONG_DOUBLE_128_FLAGS="-mno-gnu-attribute"
+            LONG_DOUBLE_ALT128_COMPAT_FLAGS="-mabi=ieeelongdouble -mno-gnu-attribute -Wno-psabi"
+          fi
+          AC_DEFINE([_GLIBCXX_LONG_DOUBLE_ALT128_COMPAT],1,
+                [Define if compatibility should be provided for alternative 128-bit long double formats.])
+          port_specific_symbol_files="$port_specific_symbol_files \$(top_srcdir)/config/os/gnu-linux/ldbl-ieee128-extra.ver"
+          ac_ldbl_alt128_compat=yes
+        else
+          ac_ldbl_alt128_compat=no
+        fi
+	;;
     esac
   fi
 esac
 AC_SUBST(LONG_DOUBLE_COMPAT_FLAGS)
+AC_SUBST(LONG_DOUBLE_128_FLAGS)
+AC_SUBST(LONG_DOUBLE_ALT128_COMPAT_FLAGS)
 GLIBCXX_CONDITIONAL(GLIBCXX_LDBL_COMPAT, test $ac_ldbl_compat = yes)
+GLIBCXX_CONDITIONAL(GLIBCXX_LDBL_ALT128_COMPAT, test $ac_ldbl_alt128_compat = yes)
 
 # Check if assembler supports disabling hardware capability support.
 GCC_CHECK_ASSEMBLER_HWCAP
diff --git a/libstdc++-v3/doc/Makefile.in b/libstdc++-v3/doc/Makefile.in
index bb994287f80..7681908103a 100644
--- a/libstdc++-v3/doc/Makefile.in
+++ b/libstdc++-v3/doc/Makefile.in
@@ -216,6 +216,8 @@ LIBS = @LIBS@
 LIBTOOL = @LIBTOOL@
 LIPO = @LIPO@
 LN_S = @LN_S@
+LONG_DOUBLE_128_FLAGS = @LONG_DOUBLE_128_FLAGS@
+LONG_DOUBLE_ALT128_COMPAT_FLAGS = @LONG_DOUBLE_ALT128_COMPAT_FLAGS@
 LONG_DOUBLE_COMPAT_FLAGS = @LONG_DOUBLE_COMPAT_FLAGS@
 LTLIBICONV = @LTLIBICONV@
 LTLIBOBJS = @LTLIBOBJS@
@@ -365,11 +367,13 @@ toolexeclibdir = $(glibcxx_toolexeclibdir)
 @ENABLE_WERROR_TRUE@WERROR_FLAG = -Werror
 @ENABLE_EXTERN_TEMPLATE_FALSE@XTEMPLATE_FLAGS = 
 @ENABLE_EXTERN_TEMPLATE_TRUE@XTEMPLATE_FLAGS = -fno-implicit-templates
+@GLIBCXX_LDBL_ALT128_COMPAT_FALSE@LDBL_128_FLAGS = 
+@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@LDBL_128_FLAGS = $(LONG_DOUBLE_128_FLAGS)
 
 # These bits are all figured out from configure.  Look in acinclude.m4
 # or configure.ac to see how they are set.  See GLIBCXX_EXPORT_FLAGS.
 CONFIG_CXXFLAGS = \
-	$(SECTION_FLAGS) $(HWCAP_CFLAGS) -frandom-seed=$@
+	$(SECTION_FLAGS) $(HWCAP_CFLAGS) -frandom-seed=$@ $(LDBL_128_FLAGS)
 
 WARN_CXXFLAGS = \
 	$(WARN_FLAGS) $(WERROR_FLAG) -fdiagnostics-show-location=once 
diff --git a/libstdc++-v3/fragment.am b/libstdc++-v3/fragment.am
index 216c572fc60..54645739e5c 100644
--- a/libstdc++-v3/fragment.am
+++ b/libstdc++-v3/fragment.am
@@ -25,10 +25,16 @@ else
 XTEMPLATE_FLAGS =
 endif
 
+if GLIBCXX_LDBL_ALT128_COMPAT
+LDBL_128_FLAGS = $(LONG_DOUBLE_128_FLAGS)
+else
+LDBL_128_FLAGS =
+endif
+
 # These bits are all figured out from configure.  Look in acinclude.m4
 # or configure.ac to see how they are set.  See GLIBCXX_EXPORT_FLAGS.
 CONFIG_CXXFLAGS = \
-	$(SECTION_FLAGS) $(HWCAP_CFLAGS) -frandom-seed=$@
+	$(SECTION_FLAGS) $(HWCAP_CFLAGS) -frandom-seed=$@ $(LDBL_128_FLAGS)
 
 WARN_CXXFLAGS = \
 	$(WARN_FLAGS) $(WERROR_FLAG) -fdiagnostics-show-location=once 
diff --git a/libstdc++-v3/include/Makefile.am b/libstdc++-v3/include/Makefile.am
index 9dbc7dcb32d..958dfea5a98 100644
--- a/libstdc++-v3/include/Makefile.am
+++ b/libstdc++-v3/include/Makefile.am
@@ -1294,6 +1294,10 @@ ${host_builddir}/c++config.h: ${CONFIG_HEADER} \
 	grep "^[	 ]*#[	 ]*define[	 ][	 ]*_GLIBCXX_LONG_DOUBLE_COMPAT[	 ][	 ]*1[	 ]*$$" \
 	${CONFIG_HEADER} > /dev/null 2>&1 \
 	&& ldbl_compat='s,^#undef _GLIBCXX_LONG_DOUBLE_COMPAT$$,#define _GLIBCXX_LONG_DOUBLE_COMPAT 1,' ;\
+	ldbl_alt128_compat='s,g,g,' ;\
+	grep "^[	 ]*#[	 ]*define[	 ][	 ]*_GLIBCXX_LONG_DOUBLE_ALT128_COMPAT[	 ][	 ]*1[	 ]*$$" \
+	${CONFIG_HEADER} > /dev/null 2>&1 \
+	&& ldbl_alt128_compat='s,^#undef _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT$$,#define _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT 1,' ;\
 	sed -e "s,define __GLIBCXX__,define __GLIBCXX__ $$date," \
 	-e "s,define _GLIBCXX_RELEASE,define _GLIBCXX_RELEASE $$release," \
 	-e "s,define _GLIBCXX_INLINE_VERSION, define _GLIBCXX_INLINE_VERSION $$ns_version," \
@@ -1304,6 +1308,7 @@ ${host_builddir}/c++config.h: ${CONFIG_HEADER} \
 	-e "s,define _GLIBCXX_USE_ALLOCATOR_NEW, define _GLIBCXX_USE_ALLOCATOR_NEW $$allocatornew," \
 	-e "s,define _GLIBCXX_USE_FLOAT128,$$float128," \
 	-e "$$ldbl_compat" \
+	-e "$$ldbl_alt128_compat" \
 	    < ${glibcxx_srcdir}/include/bits/c++config > $@ ;\
 	sed -e 's/HAVE_/_GLIBCXX_HAVE_/g' \
 	    -e 's/PACKAGE/_GLIBCXX_PACKAGE/g' \
@@ -1314,6 +1319,7 @@ ${host_builddir}/c++config.h: ${CONFIG_HEADER} \
 	    -e 's/_LARGE_FILES/_GLIBCXX_LARGE_FILES/g' \
 	    -e 's/ICONV_CONST/_GLIBCXX_ICONV_CONST/g' \
 	    -e '/[	 ]_GLIBCXX_LONG_DOUBLE_COMPAT[	 ]/d' \
+	    -e '/[	 ]_GLIBCXX_LONG_DOUBLE_ALT128_COMPAT[	 ]/d' \
 	    < ${CONFIG_HEADER} >> $@ ;\
 	echo "" >> $@ ;\
 	echo "#endif // _GLIBCXX_CXX_CONFIG_H" >> $@
diff --git a/libstdc++-v3/include/Makefile.in b/libstdc++-v3/include/Makefile.in
index 0cb0fdf5ef1..b3256a7835e 100644
--- a/libstdc++-v3/include/Makefile.in
+++ b/libstdc++-v3/include/Makefile.in
@@ -216,6 +216,8 @@ LIBS = @LIBS@
 LIBTOOL = @LIBTOOL@
 LIPO = @LIPO@
 LN_S = @LN_S@
+LONG_DOUBLE_128_FLAGS = @LONG_DOUBLE_128_FLAGS@
+LONG_DOUBLE_ALT128_COMPAT_FLAGS = @LONG_DOUBLE_ALT128_COMPAT_FLAGS@
 LONG_DOUBLE_COMPAT_FLAGS = @LONG_DOUBLE_COMPAT_FLAGS@
 LTLIBICONV = @LTLIBICONV@
 LTLIBOBJS = @LTLIBOBJS@
@@ -355,11 +357,13 @@ toolexeclibdir = $(glibcxx_toolexeclibdir)
 @ENABLE_WERROR_TRUE@WERROR_FLAG = -Werror
 @ENABLE_EXTERN_TEMPLATE_FALSE@XTEMPLATE_FLAGS = 
 @ENABLE_EXTERN_TEMPLATE_TRUE@XTEMPLATE_FLAGS = -fno-implicit-templates
+@GLIBCXX_LDBL_ALT128_COMPAT_FALSE@LDBL_128_FLAGS = 
+@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@LDBL_128_FLAGS = $(LONG_DOUBLE_128_FLAGS)
 
 # These bits are all figured out from configure.  Look in acinclude.m4
 # or configure.ac to see how they are set.  See GLIBCXX_EXPORT_FLAGS.
 CONFIG_CXXFLAGS = \
-	$(SECTION_FLAGS) $(HWCAP_CFLAGS) -frandom-seed=$@
+	$(SECTION_FLAGS) $(HWCAP_CFLAGS) -frandom-seed=$@ $(LDBL_128_FLAGS)
 
 WARN_CXXFLAGS = \
 	$(WARN_FLAGS) $(WERROR_FLAG) -fdiagnostics-show-location=once 
@@ -1776,6 +1780,10 @@ ${host_builddir}/c++config.h: ${CONFIG_HEADER} \
 	grep "^[	 ]*#[	 ]*define[	 ][	 ]*_GLIBCXX_LONG_DOUBLE_COMPAT[	 ][	 ]*1[	 ]*$$" \
 	${CONFIG_HEADER} > /dev/null 2>&1 \
 	&& ldbl_compat='s,^#undef _GLIBCXX_LONG_DOUBLE_COMPAT$$,#define _GLIBCXX_LONG_DOUBLE_COMPAT 1,' ;\
+	ldbl_alt128_compat='s,g,g,' ;\
+	grep "^[	 ]*#[	 ]*define[	 ][	 ]*_GLIBCXX_LONG_DOUBLE_ALT128_COMPAT[	 ][	 ]*1[	 ]*$$" \
+	${CONFIG_HEADER} > /dev/null 2>&1 \
+	&& ldbl_alt128_compat='s,^#undef _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT$$,#define _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT 1,' ;\
 	sed -e "s,define __GLIBCXX__,define __GLIBCXX__ $$date," \
 	-e "s,define _GLIBCXX_RELEASE,define _GLIBCXX_RELEASE $$release," \
 	-e "s,define _GLIBCXX_INLINE_VERSION, define _GLIBCXX_INLINE_VERSION $$ns_version," \
@@ -1786,6 +1794,7 @@ ${host_builddir}/c++config.h: ${CONFIG_HEADER} \
 	-e "s,define _GLIBCXX_USE_ALLOCATOR_NEW, define _GLIBCXX_USE_ALLOCATOR_NEW $$allocatornew," \
 	-e "s,define _GLIBCXX_USE_FLOAT128,$$float128," \
 	-e "$$ldbl_compat" \
+	-e "$$ldbl_alt128_compat" \
 	    < ${glibcxx_srcdir}/include/bits/c++config > $@ ;\
 	sed -e 's/HAVE_/_GLIBCXX_HAVE_/g' \
 	    -e 's/PACKAGE/_GLIBCXX_PACKAGE/g' \
@@ -1796,6 +1805,7 @@ ${host_builddir}/c++config.h: ${CONFIG_HEADER} \
 	    -e 's/_LARGE_FILES/_GLIBCXX_LARGE_FILES/g' \
 	    -e 's/ICONV_CONST/_GLIBCXX_ICONV_CONST/g' \
 	    -e '/[	 ]_GLIBCXX_LONG_DOUBLE_COMPAT[	 ]/d' \
+	    -e '/[	 ]_GLIBCXX_LONG_DOUBLE_ALT128_COMPAT[	 ]/d' \
 	    < ${CONFIG_HEADER} >> $@ ;\
 	echo "" >> $@ ;\
 	echo "#endif // _GLIBCXX_CXX_CONFIG_H" >> $@
diff --git a/libstdc++-v3/include/bits/c++config b/libstdc++-v3/include/bits/c++config
index cd7678eb16d..8cce88aa87b 100644
--- a/libstdc++-v3/include/bits/c++config
+++ b/libstdc++-v3/include/bits/c++config
@@ -425,8 +425,28 @@ _GLIBCXX_END_NAMESPACE_VERSION
 // GLIBCXX_ABI Deprecated
 // Define if compatibility should be provided for -mlong-double-64.
 #undef _GLIBCXX_LONG_DOUBLE_COMPAT
+// Define if compatibility should be provided for alternative 128-bit long
+// double formats.
+#undef _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT
+
+// Inline namespaces for long double 128 modes.
+#if defined _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT \
+  && defined __LONG_DOUBLE_IEEE128__
+namespace std
+{
+  // Namespaces for 128-bit IEEE long double format on 64-bit POWER LE.
+  inline namespace __gnu_cxx_ieee128 { }
+  inline namespace __gnu_cxx11_ieee128 { }
+}
+# define _GLIBCXX_NAMESPACE_LDBL __gnu_cxx_ieee128::
+# define _GLIBCXX_BEGIN_NAMESPACE_LDBL namespace __gnu_cxx_ieee128 {
+# define _GLIBCXX_END_NAMESPACE_LDBL }
+# define _GLIBCXX_NAMESPACE_LDBL_OR_CXX11 __gnu_cxx11_ieee128::
+# define _GLIBCXX_BEGIN_NAMESPACE_LDBL_OR_CXX11 namespace __gnu_cxx11_ieee128 {
+# define _GLIBCXX_END_NAMESPACE_LDBL_OR_CXX11 }
+
+#else // _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT && IEEE128
 
-// Inline namespace for long double 128 mode.
 #if defined _GLIBCXX_LONG_DOUBLE_COMPAT && defined __LONG_DOUBLE_128__
 namespace std
 {
@@ -440,6 +460,7 @@ namespace std
 # define _GLIBCXX_BEGIN_NAMESPACE_LDBL
 # define _GLIBCXX_END_NAMESPACE_LDBL
 #endif
+
 #if _GLIBCXX_USE_CXX11_ABI
 # define _GLIBCXX_NAMESPACE_LDBL_OR_CXX11 _GLIBCXX_NAMESPACE_CXX11
 # define _GLIBCXX_BEGIN_NAMESPACE_LDBL_OR_CXX11 _GLIBCXX_BEGIN_NAMESPACE_CXX11
@@ -450,6 +471,8 @@ namespace std
 # define _GLIBCXX_END_NAMESPACE_LDBL_OR_CXX11 _GLIBCXX_END_NAMESPACE_LDBL
 #endif
 
+#endif // _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT && IEEE128
+
 // Debug Mode implies checking assertions.
 #if defined(_GLIBCXX_DEBUG) && !defined(_GLIBCXX_ASSERTIONS)
 # define _GLIBCXX_ASSERTIONS 1
@@ -657,9 +680,12 @@ namespace std
 # define __cpp_lib_char8_t 201907L
 #endif
 
-/* Define if __float128 is supported on this host. */
+/* Define if __float128 is supported on this host.  */
 #if defined(__FLOAT128__) || defined(__SIZEOF_FLOAT128__)
-#define _GLIBCXX_USE_FLOAT128
+/* For powerpc64 don't use __float128 when it's the same type as long double. */
+# if !(defined(_GLIBCXX_LONG_DOUBLE_ALT128_COMPAT) && defined(__LONG_DOUBLE_IEEE128__))
+#  define _GLIBCXX_USE_FLOAT128
+# endif
 #endif
 
 #ifdef __has_builtin
diff --git a/libstdc++-v3/include/bits/locale_classes.h b/libstdc++-v3/include/bits/locale_classes.h
index ab90682cde2..ed7764e06e7 100644
--- a/libstdc++-v3/include/bits/locale_classes.h
+++ b/libstdc++-v3/include/bits/locale_classes.h
@@ -625,6 +625,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
     void _M_init_extra(facet**);
     void _M_init_extra(void*, void*, const char*, const char*);
+
+#ifdef _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT
+    void _M_init_extra_ldbl128(bool);
+#endif
   };
 
 
diff --git a/libstdc++-v3/include/bits/locale_facets.h b/libstdc++-v3/include/bits/locale_facets.h
index 3e0ae8776c9..07be38fc92f 100644
--- a/libstdc++-v3/include/bits/locale_facets.h
+++ b/libstdc++-v3/include/bits/locale_facets.h
@@ -51,20 +51,23 @@ namespace std _GLIBCXX_VISIBILITY(default)
 {
 _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
-  // NB: Don't instantiate required wchar_t facets if no wchar_t support.
-#ifdef _GLIBCXX_USE_WCHAR_T
-# define  _GLIBCXX_NUM_FACETS 28
-# define  _GLIBCXX_NUM_CXX11_FACETS 16
-#else
-# define  _GLIBCXX_NUM_FACETS 14
-# define  _GLIBCXX_NUM_CXX11_FACETS 8
-#endif
+// Number of standard facets (for narrow characters only)
+#define  _GLIBCXX_NUM_FACETS 14
+
+// Number of duplicated facets for cxx11 ABI
+#define  _GLIBCXX_NUM_CXX11_FACETS (_GLIBCXX_USE_DUAL_ABI ? 8 : 0)
+
+// codecvt<char16_t> and codecvt<char32_t>
 #ifdef _GLIBCXX_USE_CHAR8_T
 # define _GLIBCXX_NUM_UNICODE_FACETS 4
 #else
 # define _GLIBCXX_NUM_UNICODE_FACETS 2
 #endif
 
+// Facets duplicated for alt128 long double format
+// num_get, num_put, money_get, money_put (+ cxx11 money_get, money_put)
+#define _GLIBCXX_NUM_LBDL_ALT128_FACETS (4 + (_GLIBCXX_USE_DUAL_ABI ? 2 : 0))
+
   // Convert string to numeric value of type _Tp and store results.
   // NB: This is specialized for all required types, there is no
   // generic definition.
@@ -2252,6 +2255,10 @@ _GLIBCXX_BEGIN_NAMESPACE_LDBL
 
       // XXX GLIBCXX_ABI Deprecated
 #if defined _GLIBCXX_LONG_DOUBLE_COMPAT && defined __LONG_DOUBLE_128__
+      // For __gnu_cxx_ldbl128::num_get and __gnu_cxx_ieee128::num_get
+      // this entry in the vtable is for a 64-bit "long double" with the
+      // same format as double. This keeps the vtable layout consistent
+      // with std::num_get (visible when -mlong-double-64 is used).
       virtual iter_type
       __do_get(iter_type, iter_type, ios_base&, ios_base::iostate&,
 	       double&) const;
@@ -2264,8 +2271,21 @@ _GLIBCXX_BEGIN_NAMESPACE_LDBL
       virtual iter_type
       do_get(iter_type, iter_type, ios_base&, ios_base::iostate&, void*&) const;
 
+      // XXX GLIBCXX_ABI Deprecated
+#if defined _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT \
+      && defined __LONG_DOUBLE_IEEE128__
+      // For __gnu_cxx_ieee128::num_get this entry in the vtable is for
+      // the non-IEEE 128-bit "long double" (aka "double double"). This
+      // is consistent with __gnu_cxx_ldbl128::num_get (-mabi=ibmlongdouble)
+      virtual iter_type
+      __do_get(iter_type, iter_type, ios_base&, ios_base::iostate&,
+	       __ibm128&) const;
+#endif
+
       // XXX GLIBCXX_ABI Deprecated
 #if defined _GLIBCXX_LONG_DOUBLE_COMPAT && defined __LONG_DOUBLE_128__
+      // For __gnu_cxx_ldbl128::num_get and __gnu_cxx_ieee128::num_get
+      // this entry in the vtable is for the 128-bit "long double" type.
       virtual iter_type
       do_get(iter_type, iter_type, ios_base&, ios_base::iostate&,
 	     long double&) const;
@@ -2545,6 +2565,13 @@ _GLIBCXX_BEGIN_NAMESPACE_LDBL
       virtual iter_type
       do_put(iter_type, ios_base&, char_type, const void*) const;
 
+      // XXX GLIBCXX_ABI Deprecated
+#if defined _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT \
+      && defined __LONG_DOUBLE_IEEE128__
+      virtual iter_type
+      __do_put(iter_type, ios_base&, char_type, __ibm128) const;
+#endif
+
       // XXX GLIBCXX_ABI Deprecated
 #if defined _GLIBCXX_LONG_DOUBLE_COMPAT && defined __LONG_DOUBLE_128__
       virtual iter_type
diff --git a/libstdc++-v3/include/bits/locale_facets.tcc b/libstdc++-v3/include/bits/locale_facets.tcc
index ebc993339a6..4fdca180a87 100644
--- a/libstdc++-v3/include/bits/locale_facets.tcc
+++ b/libstdc++-v3/include/bits/locale_facets.tcc
@@ -772,6 +772,24 @@ _GLIBCXX_BEGIN_NAMESPACE_LDBL
       return __beg;
     }
 
+#if defined _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT \
+      && defined __LONG_DOUBLE_IEEE128__
+  template<typename _CharT, typename _InIter>
+    _InIter
+    num_get<_CharT, _InIter>::
+    __do_get(iter_type __beg, iter_type __end, ios_base& __io,
+	     ios_base::iostate& __err, __ibm128& __v) const
+    {
+      string __xtrc;
+      __xtrc.reserve(32);
+      __beg = _M_extract_float(__beg, __end, __io, __err, __xtrc);
+      std::__convert_to_v(__xtrc.c_str(), __v, __err, _S_get_c_locale());
+      if (__beg == __end)
+	__err |= ios_base::eofbit;
+      return __beg;
+    }
+#endif
+
   // For use by integer and floating-point types after they have been
   // converted into a char_type string.
   template<typename _CharT, typename _OutIter>
@@ -1194,6 +1212,15 @@ _GLIBCXX_BEGIN_NAMESPACE_LDBL
       return __s;
     }
 
+#if defined _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT \
+      && defined __LONG_DOUBLE_IEEE128__
+  template<typename _CharT, typename _OutIter>
+    _OutIter
+    num_put<_CharT, _OutIter>::
+    __do_put(iter_type __s, ios_base& __io, char_type __fill,
+	     __ibm128 __v) const
+    { return _M_insert_float(__s, __io, __fill, 'L', __v); }
+#endif
 _GLIBCXX_END_NAMESPACE_LDBL
 
   // Construct correctly padded string, as per 22.2.2.2.2
diff --git a/libstdc++-v3/include/bits/locale_facets_nonio.h b/libstdc++-v3/include/bits/locale_facets_nonio.h
index b76eac435bd..6af68d3fa90 100644
--- a/libstdc++-v3/include/bits/locale_facets_nonio.h
+++ b/libstdc++-v3/include/bits/locale_facets_nonio.h
@@ -1566,7 +1566,7 @@ _GLIBCXX_BEGIN_NAMESPACE_LDBL_OR_CXX11
        */
       // XXX GLIBCXX_ABI Deprecated
 #if defined _GLIBCXX_LONG_DOUBLE_COMPAT && defined __LONG_DOUBLE_128__ \
-      && _GLIBCXX_USE_CXX11_ABI == 0
+      && (_GLIBCXX_USE_CXX11_ABI == 0 || defined __LONG_DOUBLE_IEEE128__)
       virtual iter_type
       __do_get(iter_type __s, iter_type __end, bool __intl, ios_base& __io,
 	       ios_base::iostate& __err, double& __units) const;
@@ -1587,9 +1587,17 @@ _GLIBCXX_BEGIN_NAMESPACE_LDBL_OR_CXX11
       do_get(iter_type __s, iter_type __end, bool __intl, ios_base& __io,
 	     ios_base::iostate& __err, string_type& __digits) const;
 
+      // XXX GLIBCXX_ABI Deprecated
+#if defined _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT \
+      && defined __LONG_DOUBLE_IEEE128__
+      virtual iter_type
+      __do_get(iter_type __s, iter_type __end, bool __intl, ios_base& __io,
+	       ios_base::iostate& __err, __ibm128& __units) const;
+#endif
+
       // XXX GLIBCXX_ABI Deprecated
 #if defined _GLIBCXX_LONG_DOUBLE_COMPAT && defined __LONG_DOUBLE_128__ \
-      && _GLIBCXX_USE_CXX11_ABI == 0
+      && (_GLIBCXX_USE_CXX11_ABI == 0 || defined __LONG_DOUBLE_IEEE128__)
       virtual iter_type
       do_get(iter_type __s, iter_type __end, bool __intl, ios_base& __io,
 	     ios_base::iostate& __err, long double& __units) const;
@@ -1711,7 +1719,7 @@ _GLIBCXX_BEGIN_NAMESPACE_LDBL_OR_CXX11
        */
       // XXX GLIBCXX_ABI Deprecated
 #if defined _GLIBCXX_LONG_DOUBLE_COMPAT && defined __LONG_DOUBLE_128__ \
-      && _GLIBCXX_USE_CXX11_ABI == 0
+      && (_GLIBCXX_USE_CXX11_ABI == 0 || defined __LONG_DOUBLE_IEEE128__)
       virtual iter_type
       __do_put(iter_type __s, bool __intl, ios_base& __io, char_type __fill,
 	       double __units) const;
@@ -1744,9 +1752,17 @@ _GLIBCXX_BEGIN_NAMESPACE_LDBL_OR_CXX11
       do_put(iter_type __s, bool __intl, ios_base& __io, char_type __fill,
 	     const string_type& __digits) const;
 
+      // XXX GLIBCXX_ABI Deprecated
+#if defined _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT \
+      && defined __LONG_DOUBLE_IEEE128__
+      virtual iter_type
+      __do_put(iter_type __s, bool __intl, ios_base& __io, char_type __fill,
+	       __ibm128 __units) const;
+#endif
+
       // XXX GLIBCXX_ABI Deprecated
 #if defined _GLIBCXX_LONG_DOUBLE_COMPAT && defined __LONG_DOUBLE_128__ \
-      && _GLIBCXX_USE_CXX11_ABI == 0
+      && (_GLIBCXX_USE_CXX11_ABI == 0 || defined __LONG_DOUBLE_IEEE128__)
       virtual iter_type
       do_put(iter_type __s, bool __intl, ios_base& __io, char_type __fill,
 	     long double __units) const;
diff --git a/libstdc++-v3/include/bits/locale_facets_nonio.tcc b/libstdc++-v3/include/bits/locale_facets_nonio.tcc
index a8639f6ba28..9e2b6577969 100644
--- a/libstdc++-v3/include/bits/locale_facets_nonio.tcc
+++ b/libstdc++-v3/include/bits/locale_facets_nonio.tcc
@@ -350,7 +350,7 @@ _GLIBCXX_BEGIN_NAMESPACE_LDBL_OR_CXX11
       }
 
 #if defined _GLIBCXX_LONG_DOUBLE_COMPAT && defined __LONG_DOUBLE_128__ \
-      && _GLIBCXX_USE_CXX11_ABI == 0
+      && (_GLIBCXX_USE_CXX11_ABI == 0 || defined __LONG_DOUBLE_IEEE128__)
   template<typename _CharT, typename _InIter>
     _InIter
     money_get<_CharT, _InIter>::
@@ -401,6 +401,22 @@ _GLIBCXX_BEGIN_NAMESPACE_LDBL_OR_CXX11
       return __beg;
     }
 
+#if defined _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT \
+      && defined __LONG_DOUBLE_IEEE128__
+  template<typename _CharT, typename _InIter>
+    _InIter
+    money_get<_CharT, _InIter>::
+    __do_get(iter_type __beg, iter_type __end, bool __intl, ios_base& __io,
+	     ios_base::iostate& __err, __ibm128& __units) const
+    {
+      string __str;
+      __beg = __intl ? _M_extract<true>(__beg, __end, __io, __err, __str)
+	             : _M_extract<false>(__beg, __end, __io, __err, __str);
+      std::__convert_to_v(__str.c_str(), __units, __err, _S_get_c_locale());
+      return __beg;
+    }
+#endif
+
   template<typename _CharT, typename _OutIter>
     template<bool _Intl>
       _OutIter
@@ -562,7 +578,7 @@ _GLIBCXX_BEGIN_NAMESPACE_LDBL_OR_CXX11
       }
 
 #if defined _GLIBCXX_LONG_DOUBLE_COMPAT && defined __LONG_DOUBLE_128__ \
-      && _GLIBCXX_USE_CXX11_ABI == 0
+      && (_GLIBCXX_USE_CXX11_ABI == 0 || defined __LONG_DOUBLE_IEEE128__)
   template<typename _CharT, typename _OutIter>
     _OutIter
     money_put<_CharT, _OutIter>::
@@ -617,6 +633,47 @@ _GLIBCXX_BEGIN_NAMESPACE_LDBL_OR_CXX11
     { return __intl ? _M_insert<true>(__s, __io, __fill, __digits)
 	            : _M_insert<false>(__s, __io, __fill, __digits); }
 
+#if defined _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT \
+      && defined __LONG_DOUBLE_IEEE128__
+  template<typename _CharT, typename _OutIter>
+    _OutIter
+    money_put<_CharT, _OutIter>::
+    __do_put(iter_type __s, bool __intl, ios_base& __io, char_type __fill,
+	     __ibm128 __units) const
+    {
+      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));
+      // _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);
+      // 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);
+	}
+#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
+      string_type __digits(__len, char_type());
+      __ctype.widen(__cs, __cs + __len, &__digits[0]);
+      return __intl ? _M_insert<true>(__s, __io, __fill, __digits)
+	            : _M_insert<false>(__s, __io, __fill, __digits);
+    }
+#endif
+
 _GLIBCXX_END_NAMESPACE_LDBL_OR_CXX11
 
   // NB: Not especially useful. Without an ios_base object or some
diff --git a/libstdc++-v3/include/ext/numeric_traits.h b/libstdc++-v3/include/ext/numeric_traits.h
index 2cac7f1d1ed..78a03e3f00d 100644
--- a/libstdc++-v3/include/ext/numeric_traits.h
+++ b/libstdc++-v3/include/ext/numeric_traits.h
@@ -201,6 +201,38 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
     : public __numeric_traits_floating<long double>
     { };
 
+#ifdef _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT
+# if defined __LONG_DOUBLE_IEEE128__
+  // long double is __ieee128, define traits for __ibm128
+  template<>
+    struct __numeric_traits_floating<__ibm128>
+    {
+      static const int __max_digits10 = 33;
+      static const bool __is_signed = true;
+      static const int __digits10 = 31;
+      static const int __max_exponent10 = 308;
+    };
+  template<>
+    struct __numeric_traits<__ibm128>
+    : public __numeric_traits_floating<__ibm128>
+    { };
+# elif defined __LONG_DOUBLE_IBM128__
+  // long double is __ibm128, define traits for __ieee128
+  template<>
+    struct __numeric_traits_floating<__ieee128>
+    {
+      static const int __max_digits10 = 36;
+      static const bool __is_signed = true;
+      static const int __digits10 = 33;
+      static const int __max_exponent10 = 4932;
+    };
+  template<>
+    struct __numeric_traits<__ieee128>
+    : public __numeric_traits_floating<__ieee128>
+    { };
+# endif
+#endif
+
 _GLIBCXX_END_NAMESPACE_VERSION
 } // namespace
 
diff --git a/libstdc++-v3/libsupc++/Makefile.in b/libstdc++-v3/libsupc++/Makefile.in
index 82056e4693c..831f3ed0ad3 100644
--- a/libstdc++-v3/libsupc++/Makefile.in
+++ b/libstdc++-v3/libsupc++/Makefile.in
@@ -325,6 +325,8 @@ LIBS = @LIBS@
 LIBTOOL = @LIBTOOL@
 LIPO = @LIPO@
 LN_S = @LN_S@
+LONG_DOUBLE_128_FLAGS = @LONG_DOUBLE_128_FLAGS@
+LONG_DOUBLE_ALT128_COMPAT_FLAGS = @LONG_DOUBLE_ALT128_COMPAT_FLAGS@
 LONG_DOUBLE_COMPAT_FLAGS = @LONG_DOUBLE_COMPAT_FLAGS@
 LTLIBICONV = @LTLIBICONV@
 LTLIBOBJS = @LTLIBOBJS@
@@ -464,11 +466,13 @@ toolexeclibdir = $(glibcxx_toolexeclibdir)
 @ENABLE_WERROR_TRUE@WERROR_FLAG = -Werror
 @ENABLE_EXTERN_TEMPLATE_FALSE@XTEMPLATE_FLAGS = 
 @ENABLE_EXTERN_TEMPLATE_TRUE@XTEMPLATE_FLAGS = -fno-implicit-templates
+@GLIBCXX_LDBL_ALT128_COMPAT_FALSE@LDBL_128_FLAGS = 
+@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@LDBL_128_FLAGS = $(LONG_DOUBLE_128_FLAGS)
 
 # These bits are all figured out from configure.  Look in acinclude.m4
 # or configure.ac to see how they are set.  See GLIBCXX_EXPORT_FLAGS.
 CONFIG_CXXFLAGS = \
-	$(SECTION_FLAGS) $(HWCAP_CFLAGS) -frandom-seed=$@
+	$(SECTION_FLAGS) $(HWCAP_CFLAGS) -frandom-seed=$@ $(LDBL_128_FLAGS)
 
 WARN_CXXFLAGS = \
 	$(WARN_FLAGS) $(WERROR_FLAG) -fdiagnostics-show-location=once 
diff --git a/libstdc++-v3/po/Makefile.in b/libstdc++-v3/po/Makefile.in
index 745958a519d..8edd2e05639 100644
--- a/libstdc++-v3/po/Makefile.in
+++ b/libstdc++-v3/po/Makefile.in
@@ -216,6 +216,8 @@ LIBS = @LIBS@
 LIBTOOL = @LIBTOOL@
 LIPO = @LIPO@
 LN_S = @LN_S@
+LONG_DOUBLE_128_FLAGS = @LONG_DOUBLE_128_FLAGS@
+LONG_DOUBLE_ALT128_COMPAT_FLAGS = @LONG_DOUBLE_ALT128_COMPAT_FLAGS@
 LONG_DOUBLE_COMPAT_FLAGS = @LONG_DOUBLE_COMPAT_FLAGS@
 LTLIBICONV = @LTLIBICONV@
 LTLIBOBJS = @LTLIBOBJS@
@@ -355,11 +357,13 @@ toolexeclibdir = $(glibcxx_toolexeclibdir)
 @ENABLE_WERROR_TRUE@WERROR_FLAG = -Werror
 @ENABLE_EXTERN_TEMPLATE_FALSE@XTEMPLATE_FLAGS = 
 @ENABLE_EXTERN_TEMPLATE_TRUE@XTEMPLATE_FLAGS = -fno-implicit-templates
+@GLIBCXX_LDBL_ALT128_COMPAT_FALSE@LDBL_128_FLAGS = 
+@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@LDBL_128_FLAGS = $(LONG_DOUBLE_128_FLAGS)
 
 # These bits are all figured out from configure.  Look in acinclude.m4
 # or configure.ac to see how they are set.  See GLIBCXX_EXPORT_FLAGS.
 CONFIG_CXXFLAGS = \
-	$(SECTION_FLAGS) $(HWCAP_CFLAGS) -frandom-seed=$@
+	$(SECTION_FLAGS) $(HWCAP_CFLAGS) -frandom-seed=$@ $(LDBL_128_FLAGS)
 
 WARN_CXXFLAGS = \
 	$(WARN_FLAGS) $(WERROR_FLAG) -fdiagnostics-show-location=once 
diff --git a/libstdc++-v3/python/Makefile.in b/libstdc++-v3/python/Makefile.in
index eedd7f80f23..c35dbe55961 100644
--- a/libstdc++-v3/python/Makefile.in
+++ b/libstdc++-v3/python/Makefile.in
@@ -246,6 +246,8 @@ LIBS = @LIBS@
 LIBTOOL = @LIBTOOL@
 LIPO = @LIPO@
 LN_S = @LN_S@
+LONG_DOUBLE_128_FLAGS = @LONG_DOUBLE_128_FLAGS@
+LONG_DOUBLE_ALT128_COMPAT_FLAGS = @LONG_DOUBLE_ALT128_COMPAT_FLAGS@
 LONG_DOUBLE_COMPAT_FLAGS = @LONG_DOUBLE_COMPAT_FLAGS@
 LTLIBICONV = @LTLIBICONV@
 LTLIBOBJS = @LTLIBOBJS@
@@ -385,11 +387,13 @@ toolexeclibdir = $(glibcxx_toolexeclibdir)
 @ENABLE_WERROR_TRUE@WERROR_FLAG = -Werror
 @ENABLE_EXTERN_TEMPLATE_FALSE@XTEMPLATE_FLAGS = 
 @ENABLE_EXTERN_TEMPLATE_TRUE@XTEMPLATE_FLAGS = -fno-implicit-templates
+@GLIBCXX_LDBL_ALT128_COMPAT_FALSE@LDBL_128_FLAGS = 
+@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@LDBL_128_FLAGS = $(LONG_DOUBLE_128_FLAGS)
 
 # These bits are all figured out from configure.  Look in acinclude.m4
 # or configure.ac to see how they are set.  See GLIBCXX_EXPORT_FLAGS.
 CONFIG_CXXFLAGS = \
-	$(SECTION_FLAGS) $(HWCAP_CFLAGS) -frandom-seed=$@
+	$(SECTION_FLAGS) $(HWCAP_CFLAGS) -frandom-seed=$@ $(LDBL_128_FLAGS)
 
 WARN_CXXFLAGS = \
 	$(WARN_FLAGS) $(WERROR_FLAG) -fdiagnostics-show-location=once 
diff --git a/libstdc++-v3/src/Makefile.am b/libstdc++-v3/src/Makefile.am
index 21b6db7fb1c..c32c88954f3 100644
--- a/libstdc++-v3/src/Makefile.am
+++ b/libstdc++-v3/src/Makefile.am
@@ -71,6 +71,20 @@ else
 ldbl_compat_sources =
 endif
 
+if GLIBCXX_LDBL_ALT128_COMPAT
+if ENABLE_DUAL_ABI
+ldbl_alt128_compat_cxx11_sources = \
+	compatibility-ldbl-alt128-cxx11.cc
+else
+ldbl_alt128_compat_cxx11_sources =
+endif
+ldbl_alt128_compat_sources = \
+	compatibility-ldbl-alt128.cc \
+	${ldbl_alt128_compat_cxx11_sources}
+else
+ldbl_alt128_compat_sources =
+endif
+
 
 parallel_compat_sources = \
 	compatibility-parallel_list.cc  compatibility-parallel_list-2.cc
@@ -87,7 +101,8 @@ cxx11_sources = \
 	compatibility-atomic-c++0x.cc \
 	compatibility-thread-c++0x.cc \
 	compatibility-chrono.cc \
-	compatibility-condvar.cc
+	compatibility-condvar.cc \
+	${ldbl_alt128_compat_sources}
 
 libstdc___la_SOURCES = $(cxx98_sources) $(cxx11_sources)
 
@@ -113,12 +128,36 @@ libstdc___la_LDFLAGS = \
 libstdc___la_LINK = $(CXXLINK) $(libstdc___la_LDFLAGS) $(lt_host_flags)
 
 # Use special rules for compatibility-ldbl.cc compilation, as we need to
-# pass -mlong-double-64.
+# pass -mlong-double-64, and not use -mabi={ieee,ibm}longdouble.
 if GLIBCXX_LDBL_COMPAT
+if GLIBCXX_LDBL_ALT128_COMPAT
+LTCXXCOMPILE64 = \
+  $(filter-out -mabi=ieeelongdouble -mabi=ibmlongdouble,$(LTCXXCOMPILE))
+CXXCOMPILE64 = \
+  $(filter-out -mabi=ieeelongdouble -mabi=ibmlongdouble,$(CXXCOMPILE))
+else
+LTCXXCOMPILE64 = $(LTCXXCOMPILE)
+CXXCOMPILE64 = $(CXXCOMPILE)
+endif
 compatibility-ldbl.lo: compatibility-ldbl.cc
-	$(LTCXXCOMPILE) $(LONG_DOUBLE_COMPAT_FLAGS) -c $<
+	$(LTCXXCOMPILE64) $(LONG_DOUBLE_COMPAT_FLAGS) -c $<
 compatibility-ldbl.o: compatibility-ldbl.cc
-	$(CXXCOMPILE) $(LONG_DOUBLE_COMPAT_FLAGS) -c $<
+	$(CXXCOMPILE64) $(LONG_DOUBLE_COMPAT_FLAGS) -c $<
+endif
+
+# Use special rules for compatibility-ldbl-alt128.cc compilation, as we need to
+# ensure it is compiled with the correct flag.
+if GLIBCXX_LDBL_ALT128_COMPAT
+compatibility-ldbl-alt128.lo: compatibility-ldbl-alt128.cc
+	$(LTCXXCOMPILE) $(LONG_DOUBLE_ALT128_COMPAT_FLAGS) -std=gnu++11 -c $<
+compatibility-ldbl-alt128.o: compatibility-ldbl-alt128.cc
+	$(CXXCOMPILE) $(LONG_DOUBLE_ALT128_COMPAT_FLAGS) -std=gnu++11 -c $<
+if ENABLE_DUAL_ABI
+compatibility-ldbl-alt128-cxx11.lo: compatibility-ldbl-alt128-cxx11.cc
+	$(LTCXXCOMPILE) $(LONG_DOUBLE_ALT128_COMPAT_FLAGS) -std=gnu++11 -c $<
+compatibility-ldbl-alt128-cxx11.o: compatibility-ldbl-alt128-cxx11.cc
+	$(CXXCOMPILE) $(LONG_DOUBLE_ALT128_COMPAT_FLAGS) -std=gnu++11 -c $<
+endif
 endif
 
 # Use special rules for C++11 files/objects.
diff --git a/libstdc++-v3/src/Makefile.in b/libstdc++-v3/src/Makefile.in
index e7ccdaeceab..684b7aee16b 100644
--- a/libstdc++-v3/src/Makefile.in
+++ b/libstdc++-v3/src/Makefile.in
@@ -153,10 +153,14 @@ am__DEPENDENCIES_1 =
 @GLIBCXX_LDBL_COMPAT_TRUE@am__objects_1 = compatibility-ldbl.lo
 am__objects_2 = compatibility.lo compatibility-debug_list.lo \
 	compatibility-debug_list-2.lo $(am__objects_1)
-am__objects_3 = compatibility-c++0x.lo compatibility-atomic-c++0x.lo \
+@ENABLE_DUAL_ABI_TRUE@@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@am__objects_3 = compatibility-ldbl-alt128-cxx11.lo
+@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@am__objects_4 =  \
+@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@	compatibility-ldbl-alt128.lo \
+@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@	$(am__objects_3)
+am__objects_5 = compatibility-c++0x.lo compatibility-atomic-c++0x.lo \
 	compatibility-thread-c++0x.lo compatibility-chrono.lo \
-	compatibility-condvar.lo
-am_libstdc___la_OBJECTS = $(am__objects_2) $(am__objects_3)
+	compatibility-condvar.lo $(am__objects_4)
+am_libstdc___la_OBJECTS = $(am__objects_2) $(am__objects_5)
 libstdc___la_OBJECTS = $(am_libstdc___la_OBJECTS)
 @VTV_CYGMIN_FALSE@am_libstdc___la_rpath = -rpath $(toolexeclibdir)
 @VTV_CYGMIN_TRUE@am_libstdc___la_rpath = -rpath $(toolexeclibdir)
@@ -311,6 +315,8 @@ LIBS = @LIBS@
 LIBTOOL = @LIBTOOL@
 LIPO = @LIPO@
 LN_S = @LN_S@
+LONG_DOUBLE_128_FLAGS = @LONG_DOUBLE_128_FLAGS@
+LONG_DOUBLE_ALT128_COMPAT_FLAGS = @LONG_DOUBLE_ALT128_COMPAT_FLAGS@
 LONG_DOUBLE_COMPAT_FLAGS = @LONG_DOUBLE_COMPAT_FLAGS@
 LTLIBICONV = @LTLIBICONV@
 LTLIBOBJS = @LTLIBOBJS@
@@ -450,11 +456,13 @@ toolexeclibdir = $(glibcxx_toolexeclibdir)
 @ENABLE_WERROR_TRUE@WERROR_FLAG = -Werror
 @ENABLE_EXTERN_TEMPLATE_FALSE@XTEMPLATE_FLAGS = 
 @ENABLE_EXTERN_TEMPLATE_TRUE@XTEMPLATE_FLAGS = -fno-implicit-templates
+@GLIBCXX_LDBL_ALT128_COMPAT_FALSE@LDBL_128_FLAGS = 
+@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@LDBL_128_FLAGS = $(LONG_DOUBLE_128_FLAGS)
 
 # These bits are all figured out from configure.  Look in acinclude.m4
 # or configure.ac to see how they are set.  See GLIBCXX_EXPORT_FLAGS.
 CONFIG_CXXFLAGS = \
-	$(SECTION_FLAGS) $(HWCAP_CFLAGS) -frandom-seed=$@
+	$(SECTION_FLAGS) $(HWCAP_CFLAGS) -frandom-seed=$@ $(LDBL_128_FLAGS)
 
 WARN_CXXFLAGS = \
 	$(WARN_FLAGS) $(WERROR_FLAG) -fdiagnostics-show-location=once 
@@ -483,6 +491,15 @@ SUBDIRS = c++98 c++11 c++17 c++20 $(filesystem_dir)
 
 @GLIBCXX_LDBL_COMPAT_FALSE@ldbl_compat_sources = 
 @GLIBCXX_LDBL_COMPAT_TRUE@ldbl_compat_sources = compatibility-ldbl.cc
+@ENABLE_DUAL_ABI_FALSE@@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@ldbl_alt128_compat_cxx11_sources = 
+@ENABLE_DUAL_ABI_TRUE@@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@ldbl_alt128_compat_cxx11_sources = \
+@ENABLE_DUAL_ABI_TRUE@@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@	compatibility-ldbl-alt128-cxx11.cc
+
+@GLIBCXX_LDBL_ALT128_COMPAT_FALSE@ldbl_alt128_compat_sources = 
+@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@ldbl_alt128_compat_sources = \
+@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@	compatibility-ldbl-alt128.cc \
+@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@	${ldbl_alt128_compat_cxx11_sources}
+
 parallel_compat_sources = \
 	compatibility-parallel_list.cc  compatibility-parallel_list-2.cc
 
@@ -497,7 +514,8 @@ cxx11_sources = \
 	compatibility-atomic-c++0x.cc \
 	compatibility-thread-c++0x.cc \
 	compatibility-chrono.cc \
-	compatibility-condvar.cc
+	compatibility-condvar.cc \
+	${ldbl_alt128_compat_sources}
 
 libstdc___la_SOURCES = $(cxx98_sources) $(cxx11_sources)
 libstdc___la_LIBADD = \
@@ -520,6 +538,17 @@ libstdc___la_LDFLAGS = \
 	-version-info $(libtool_VERSION) ${version_arg} -lm
 
 libstdc___la_LINK = $(CXXLINK) $(libstdc___la_LDFLAGS) $(lt_host_flags)
+@GLIBCXX_LDBL_ALT128_COMPAT_FALSE@@GLIBCXX_LDBL_COMPAT_TRUE@LTCXXCOMPILE64 = $(LTCXXCOMPILE)
+
+# Use special rules for compatibility-ldbl.cc compilation, as we need to
+# pass -mlong-double-64, and not use -mabi={ieee,ibm}longdouble.
+@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@@GLIBCXX_LDBL_COMPAT_TRUE@LTCXXCOMPILE64 = \
+@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@@GLIBCXX_LDBL_COMPAT_TRUE@  $(filter-out -mabi=ieeelongdouble -mabi=ibmlongdouble,$(LTCXXCOMPILE))
+
+@GLIBCXX_LDBL_ALT128_COMPAT_FALSE@@GLIBCXX_LDBL_COMPAT_TRUE@CXXCOMPILE64 = $(CXXCOMPILE)
+@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@@GLIBCXX_LDBL_COMPAT_TRUE@CXXCOMPILE64 = \
+@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@@GLIBCXX_LDBL_COMPAT_TRUE@  $(filter-out -mabi=ieeelongdouble -mabi=ibmlongdouble,$(CXXCOMPILE))
+
 
 # A note on compatibility and static libraries.
 #
@@ -962,13 +991,21 @@ vpath % $(top_srcdir)/src/c++11
 vpath % $(top_srcdir)/src/c++17
 vpath % $(top_srcdir)/src/c++20
 @ENABLE_FILESYSTEM_TS_TRUE@vpath % $(top_srcdir)/src/filesystem
-
-# Use special rules for compatibility-ldbl.cc compilation, as we need to
-# pass -mlong-double-64.
 @GLIBCXX_LDBL_COMPAT_TRUE@compatibility-ldbl.lo: compatibility-ldbl.cc
-@GLIBCXX_LDBL_COMPAT_TRUE@	$(LTCXXCOMPILE) $(LONG_DOUBLE_COMPAT_FLAGS) -c $<
+@GLIBCXX_LDBL_COMPAT_TRUE@	$(LTCXXCOMPILE64) $(LONG_DOUBLE_COMPAT_FLAGS) -c $<
 @GLIBCXX_LDBL_COMPAT_TRUE@compatibility-ldbl.o: compatibility-ldbl.cc
-@GLIBCXX_LDBL_COMPAT_TRUE@	$(CXXCOMPILE) $(LONG_DOUBLE_COMPAT_FLAGS) -c $<
+@GLIBCXX_LDBL_COMPAT_TRUE@	$(CXXCOMPILE64) $(LONG_DOUBLE_COMPAT_FLAGS) -c $<
+
+# Use special rules for compatibility-ldbl-alt128.cc compilation, as we need to
+# ensure it is compiled with the correct flag.
+@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@compatibility-ldbl-alt128.lo: compatibility-ldbl-alt128.cc
+@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@	$(LTCXXCOMPILE) $(LONG_DOUBLE_ALT128_COMPAT_FLAGS) -std=gnu++11 -c $<
+@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@compatibility-ldbl-alt128.o: compatibility-ldbl-alt128.cc
+@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@	$(CXXCOMPILE) $(LONG_DOUBLE_ALT128_COMPAT_FLAGS) -std=gnu++11 -c $<
+@ENABLE_DUAL_ABI_TRUE@@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@compatibility-ldbl-alt128-cxx11.lo: compatibility-ldbl-alt128-cxx11.cc
+@ENABLE_DUAL_ABI_TRUE@@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@	$(LTCXXCOMPILE) $(LONG_DOUBLE_ALT128_COMPAT_FLAGS) -std=gnu++11 -c $<
+@ENABLE_DUAL_ABI_TRUE@@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@compatibility-ldbl-alt128-cxx11.o: compatibility-ldbl-alt128-cxx11.cc
+@ENABLE_DUAL_ABI_TRUE@@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@	$(CXXCOMPILE) $(LONG_DOUBLE_ALT128_COMPAT_FLAGS) -std=gnu++11 -c $<
 
 # Use special rules for C++11 files/objects.
 compatibility-c++0x.lo: compatibility-c++0x.cc
diff --git a/libstdc++-v3/src/c++11/Makefile.in b/libstdc++-v3/src/c++11/Makefile.in
index dbef02597ac..ae3a2fd5b4e 100644
--- a/libstdc++-v3/src/c++11/Makefile.in
+++ b/libstdc++-v3/src/c++11/Makefile.in
@@ -282,6 +282,8 @@ LIBS = @LIBS@
 LIBTOOL = @LIBTOOL@
 LIPO = @LIPO@
 LN_S = @LN_S@
+LONG_DOUBLE_128_FLAGS = @LONG_DOUBLE_128_FLAGS@
+LONG_DOUBLE_ALT128_COMPAT_FLAGS = @LONG_DOUBLE_ALT128_COMPAT_FLAGS@
 LONG_DOUBLE_COMPAT_FLAGS = @LONG_DOUBLE_COMPAT_FLAGS@
 LTLIBICONV = @LTLIBICONV@
 LTLIBOBJS = @LTLIBOBJS@
@@ -421,11 +423,13 @@ toolexeclibdir = $(glibcxx_toolexeclibdir)
 @ENABLE_WERROR_TRUE@WERROR_FLAG = -Werror
 @ENABLE_EXTERN_TEMPLATE_FALSE@XTEMPLATE_FLAGS = 
 @ENABLE_EXTERN_TEMPLATE_TRUE@XTEMPLATE_FLAGS = -fno-implicit-templates
+@GLIBCXX_LDBL_ALT128_COMPAT_FALSE@LDBL_128_FLAGS = 
+@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@LDBL_128_FLAGS = $(LONG_DOUBLE_128_FLAGS)
 
 # These bits are all figured out from configure.  Look in acinclude.m4
 # or configure.ac to see how they are set.  See GLIBCXX_EXPORT_FLAGS.
 CONFIG_CXXFLAGS = \
-	$(SECTION_FLAGS) $(HWCAP_CFLAGS) -frandom-seed=$@
+	$(SECTION_FLAGS) $(HWCAP_CFLAGS) -frandom-seed=$@ $(LDBL_128_FLAGS)
 
 WARN_CXXFLAGS = \
 	$(WARN_FLAGS) $(WERROR_FLAG) -fdiagnostics-show-location=once 
diff --git a/libstdc++-v3/src/c++11/compatibility-ldbl-alt128-cxx11.cc b/libstdc++-v3/src/c++11/compatibility-ldbl-alt128-cxx11.cc
new file mode 100644
index 00000000000..7c03606bce4
--- /dev/null
+++ b/libstdc++-v3/src/c++11/compatibility-ldbl-alt128-cxx11.cc
@@ -0,0 +1,102 @@
+// Compatibility symbols for alternate 128-bit long-double format -*- C++ -*-
+
+// Copyright (C) 2018 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// Under Section 7 of GPL version 3, you are granted additional
+// permissions described in the GCC Runtime Library Exception, version
+// 3.1, as published by the Free Software Foundation.
+
+// You should have received a copy of the GNU General Public License and
+// a copy of the GCC Runtime Library Exception along with this program;
+// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+// <http://www.gnu.org/licenses/>.
+
+#define _GLIBCXX_USE_CXX11_ABI 1
+#include <locale>
+
+#ifdef _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT
+
+#if !defined(_GLIBCXX_USE_DUAL_ABI)
+#error "compatibility-ldbl-alt128-cxx11.cc must only be compiled when dual ABI is enabled"
+#endif
+
+#if ! defined __LONG_DOUBLE_IBM128__ && ! defined __LONG_DOUBLE_IEEE128__
+#error "compatibility-ldbl-alt128.cc must only be compiled for 128-bit long double"
+#endif
+
+#define C char
+#define C_is_char
+#include "locale-inst-monetary.h"
+
+#ifdef _GLIBCXX_USE_WCHAR_T
+# undef C
+# undef C_is_char
+# define C wchar_t
+# include "locale-inst-monetary.h"
+#endif
+
+#include <functional>
+namespace std _GLIBCXX_VISIBILITY(default)
+{
+_GLIBCXX_BEGIN_NAMESPACE_VERSION
+
+  namespace
+  {
+    alignas(money_get<char>) char money_get_c[sizeof(money_get<char>)];
+    alignas(money_put<char>) char money_put_c[sizeof(money_put<char>)];
+#ifdef _GLIBCXX_USE_WCHAR_T
+    alignas(money_get<wchar_t>) char money_get_w[sizeof(money_get<wchar_t>)];
+    alignas(money_put<wchar_t>) char money_put_w[sizeof(money_put<wchar_t>)];
+#endif
+
+  template<typename Facet>
+    void
+    init_facet(function<void(const locale::id*, const locale::facet*)>& func,
+	       Facet* facet)
+    {
+      func(&Facet::id, facet);
+    }
+
+  } // namespace
+
+  template class function<void(const locale::id*, const locale::facet*)>;
+
+  void
+  __locale_Impl_init_extra_ldbl128(
+      function<void(const locale::id*, const locale::facet*)> f,
+      bool classic)
+  {
+    if (classic)
+      {
+	init_facet(f, new (&money_get_c) money_get<char>(1));
+	init_facet(f, new (&money_put_c) money_put<char>(1));
+#ifdef _GLIBCXX_USE_WCHAR_T
+	init_facet(f, new (&money_get_w) money_get<wchar_t>(1));
+	init_facet(f, new (&money_put_w) money_put<wchar_t>(1));
+#endif
+      }
+    else
+      {
+	init_facet(f, new money_get<char>);
+	init_facet(f, new money_put<char>);
+#ifdef _GLIBCXX_USE_WCHAR_T
+	init_facet(f, new money_get<wchar_t>);
+	init_facet(f, new money_put<wchar_t>);
+#endif
+      }
+  }
+
+_GLIBCXX_END_NAMESPACE_VERSION
+} // namespace
+#endif
diff --git a/libstdc++-v3/src/c++11/compatibility-ldbl-alt128.cc b/libstdc++-v3/src/c++11/compatibility-ldbl-alt128.cc
new file mode 100644
index 00000000000..7fb66917db1
--- /dev/null
+++ b/libstdc++-v3/src/c++11/compatibility-ldbl-alt128.cc
@@ -0,0 +1,244 @@
+// Compatibility symbols for alternate 128-bit long-double format -*- C++ -*-
+
+// Copyright (C) 2018 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// Under Section 7 of GPL version 3, you are granted additional
+// permissions described in the GCC Runtime Library Exception, version
+// 3.1, as published by the Free Software Foundation.
+
+// You should have received a copy of the GNU General Public License and
+// a copy of the GCC Runtime Library Exception along with this program;
+// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+// <http://www.gnu.org/licenses/>.
+
+#define _GLIBCXX_USE_CXX11_ABI 0
+#include <locale>
+
+#ifdef _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT
+
+#if ! defined __LONG_DOUBLE_IBM128__ && ! defined __LONG_DOUBLE_IEEE128__
+#error "compatibility-ldbl-alt128.cc must only be compiled for 128-bit long double"
+#endif
+
+#define C char
+#define C_is_char
+#include "locale-inst-numeric.h"
+#include "locale-inst-monetary.h"
+#include "compatibility-ldbl-facets-aliases.h"
+
+#ifdef _GLIBCXX_USE_WCHAR_T
+# undef C
+# undef C_is_char
+# define C wchar_t
+# include "locale-inst-numeric.h"
+# include "locale-inst-monetary.h"
+# include "compatibility-ldbl-facets-aliases.h"
+# undef C
+#endif
+
+#include <limits>
+#include <functional>
+
+namespace std _GLIBCXX_VISIBILITY(default)
+{
+_GLIBCXX_BEGIN_NAMESPACE_VERSION
+
+  // long double
+  const bool numeric_limits<long double>::is_specialized;
+  const int  numeric_limits<long double>::digits;
+  const int  numeric_limits<long double>::digits10;
+  const int  numeric_limits<long double>::max_digits10;
+  const bool numeric_limits<long double>::is_signed;
+  const bool numeric_limits<long double>::is_integer;
+  const bool numeric_limits<long double>::is_exact;
+  const int  numeric_limits<long double>::radix;
+  const int  numeric_limits<long double>::min_exponent;
+  const int  numeric_limits<long double>::min_exponent10;
+  const int  numeric_limits<long double>::max_exponent;
+  const int  numeric_limits<long double>::max_exponent10;
+  const bool numeric_limits<long double>::has_infinity;
+  const bool numeric_limits<long double>::has_quiet_NaN;
+  const bool numeric_limits<long double>::has_signaling_NaN;
+  const float_denorm_style numeric_limits<long double>::has_denorm;
+  const bool numeric_limits<long double>::has_denorm_loss;
+  const bool numeric_limits<long double>::is_iec559;
+  const bool numeric_limits<long double>::is_bounded;
+  const bool numeric_limits<long double>::is_modulo;
+  const bool numeric_limits<long double>::traps;
+  const bool numeric_limits<long double>::tinyness_before;
+  const float_round_style numeric_limits<long double>::round_style;
+
+  template<>
+    void
+    __convert_to_v(const char* __s, long double& __v, ios_base::iostate& __err,
+		   const __c_locale& __cloc) throw()
+    {
+      char* __sanity;
+#if __GLIBC__ > 2 || (__GLIBC__ == 2 && __GLIBC_MINOR__ > 2)
+      // Prefer strtold_l, as __strtold_l isn't prototyped in more recent
+      // glibc versions.
+      __v = strtold_l(__s, &__sanity, __cloc);
+#else
+      __v = __strtold_l(__s, &__sanity, __cloc);
+#endif
+
+      // _GLIBCXX_RESOLVE_LIB_DEFECTS
+      // 23. Num_get overflow result.
+      if (__sanity == __s || *__sanity != '\0')
+	{
+	  __v = 0.0l;
+	  __err = ios_base::failbit;
+	}
+      else if (__v == numeric_limits<long double>::infinity())
+	{
+	  __v = numeric_limits<long double>::max();
+	  __err = ios_base::failbit;
+	}
+      else if (__v == -numeric_limits<long double>::infinity())
+	{
+	  __v = -numeric_limits<long double>::max();
+	  __err = ios_base::failbit;
+	}
+    }
+
+  namespace
+  {
+    alignas(money_get<char>) char money_get_c[sizeof(money_get<char>)];
+    alignas(money_put<char>) char money_put_c[sizeof(money_put<char>)];
+    alignas(num_get<char>) char num_get_c[sizeof(num_get<char>)];
+    alignas(num_put<char>) char num_put_c[sizeof(num_put<char>)];
+#ifdef _GLIBCXX_USE_WCHAR_T
+    alignas(money_get<wchar_t>) char money_get_w[sizeof(money_get<wchar_t>)];
+    alignas(money_put<wchar_t>) char money_put_w[sizeof(money_put<wchar_t>)];
+    alignas(num_get<wchar_t>) char num_get_w[sizeof(num_get<wchar_t>)];
+    alignas(num_put<wchar_t>) char num_put_w[sizeof(num_put<wchar_t>)];
+#endif
+  }
+
+  extern void
+  __locale_Impl_init_extra_ldbl128(
+      function<void(const locale::id*, const locale::facet*)>,
+      bool);
+
+  void
+  locale::_Impl::_M_init_extra_ldbl128(bool classic)
+  {
+    if (classic)
+      {
+	_M_init_facet(new (&money_get_c) money_get<char>(1));
+	_M_init_facet(new (&money_put_c) money_put<char>(1));
+	_M_init_facet(new (&num_get_c) num_get<char>(1));
+	_M_init_facet(new (&num_put_c) num_put<char>(1));
+#ifdef _GLIBCXX_USE_WCHAR_T
+	_M_init_facet(new (&money_get_w) money_get<wchar_t>(1));
+	_M_init_facet(new (&money_put_w) money_put<wchar_t>(1));
+	_M_init_facet(new (&num_get_w) num_get<wchar_t>(1));
+	_M_init_facet(new (&num_put_w) num_put<wchar_t>(1));
+#endif
+      }
+    else
+      {
+	_M_init_facet(new money_get<char>);
+	_M_init_facet(new money_put<char>);
+	_M_init_facet(new num_get<char>);
+	_M_init_facet(new num_put<char>);
+#ifdef _GLIBCXX_USE_WCHAR_T
+	_M_init_facet(new money_get<wchar_t>);
+	_M_init_facet(new money_put<wchar_t>);
+	_M_init_facet(new num_get<wchar_t>);
+	_M_init_facet(new num_put<wchar_t>);
+#endif
+      }
+
+#if _GLIBCXX_USE_DUAL_ABI
+    __locale_Impl_init_extra_ldbl128(
+	[this](const locale::id* i, const facet* f) {
+	    _M_install_facet(i, f);
+	},
+	classic);
+#endif
+  }
+
+_GLIBCXX_END_NAMESPACE_VERSION
+} // namespace
+
+#include <istream>
+#include <ostream>
+
+namespace std _GLIBCXX_VISIBILITY(default)
+{
+_GLIBCXX_BEGIN_NAMESPACE_VERSION
+  template istream& istream::operator>>(long double&);
+  template istream& istream::_M_extract(long double&);
+  template ostream& ostream::operator<<(long double);
+  template ostream& ostream::_M_insert(long double);
+#ifdef _GLIBCXX_USE_WCHAR_T
+  template wistream& wistream::operator>>(long double&);
+  template wistream& wistream::_M_extract(long double&);
+  template wostream& wostream::operator<<(long double);
+  template wostream& wostream::_M_insert(long double);
+#endif
+_GLIBCXX_END_NAMESPACE_VERSION
+} // namespace
+
+#include <complex>
+
+namespace std _GLIBCXX_VISIBILITY(default)
+{
+_GLIBCXX_BEGIN_NAMESPACE_VERSION
+  template
+    basic_istream<char, char_traits<char> >&
+    operator>>(basic_istream<char, char_traits<char> >&,
+	       complex<long double>&);
+  template
+    basic_ostream<char, char_traits<char> >&
+    operator<<(basic_ostream<char, char_traits<char> >&,
+               const complex<long double>&);
+#ifdef _GLIBCXX_USE_WCHAR_T
+  template
+    basic_istream<wchar_t, char_traits<wchar_t> >&
+    operator>>(basic_istream<wchar_t, char_traits<wchar_t> >&,
+               complex<long double>&);
+  template
+    basic_ostream<wchar_t, char_traits<wchar_t> >&
+    operator<<(basic_ostream<wchar_t, char_traits<wchar_t> >&,
+               const complex<long double>&);
+#endif
+_GLIBCXX_END_NAMESPACE_VERSION
+} // namespace
+
+#include <cmath>
+#include <tr1/functional>
+
+// For std::tr1::hash<long double>::operator()
+#include "../c++98/hash-long-double-tr1-aux.cc"
+
+// std::tr1::hash<long double>::operator()
+// and std::hash<long double>::operator()
+// are the same, no need to duplicate them.
+#ifdef __LONG_DOUBLE_IBM128__
+extern "C" size_t
+_ZNKSt4hashIgEclEg (void)
+  __attribute__((pure))
+  __attribute__((alias ("_ZNKSt3tr14hashIgEclEg")));
+#elif __LONG_DOUBLE_IEEE128__
+extern "C" size_t
+_ZNKSt4hashIu9__ieee128EclEu9__ieee128 (void)
+  __attribute__((pure))
+  __attribute__((alias ("_ZNKSt3tr14hashIu9__ieee128EclEu9__ieee128")));
+#else
+# error "Configuration error"
+#endif
+
+#endif
diff --git a/libstdc++-v3/src/c++11/compatibility-ldbl-facets-aliases.h b/libstdc++-v3/src/c++11/compatibility-ldbl-facets-aliases.h
new file mode 100644
index 00000000000..7bdf9810d0e
--- /dev/null
+++ b/libstdc++-v3/src/c++11/compatibility-ldbl-facets-aliases.h
@@ -0,0 +1,128 @@
+// Compatibility aliases for long double support in locales -*- C++ -*-
+
+// Copyright (C) 1999-2018 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// Under Section 7 of GPL version 3, you are granted additional
+// permissions described in the GCC Runtime Library Exception, version
+// 3.1, as published by the Free Software Foundation.
+
+// You should have received a copy of the GNU General Public License and
+// a copy of the GCC Runtime Library Exception along with this program;
+// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+// <http://www.gnu.org/licenses/>.
+
+#ifndef C
+#define "This file should not be compiled directly, only included"
+#endif
+
+#ifndef _GLIBCXX_LONG_DOUBLE_COMPAT
+#define "This file should only be used for _GLIBCXX_LONG_DOUBLE_COMPAT builds"
+#endif
+
+// XXX GLIBCXX_ABI Deprecated
+#if defined __LONG_DOUBLE_128__ && ! defined __LONG_DOUBLE_IEEE128__
+
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wattribute-alias"
+
+#define _GLIBCXX_LDBL_COMPAT(dbl, ldbl) \
+  extern "C" void ldbl (void) __attribute__ ((alias (#dbl), weak))
+
+// Define members of std::num_get and std::num_put as aliases for
+// members of __gnu_cxx_ldbl128::num_get and __gnu_cxx_ldbl128::num_put
+#ifdef C_is_char
+_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_getIcSt19istreambuf_iteratorIcSt11char_traitsIcEEE14_M_extract_intIjEES4_S4_S4_RSt8ios_baseRSt12_Ios_IostateRT_,
+		     _ZNKSt7num_getIcSt19istreambuf_iteratorIcSt11char_traitsIcEEE14_M_extract_intIjEES3_S3_S3_RSt8ios_baseRSt12_Ios_IostateRT_);
+_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_getIcSt19istreambuf_iteratorIcSt11char_traitsIcEEE14_M_extract_intIlEES4_S4_S4_RSt8ios_baseRSt12_Ios_IostateRT_,
+		     _ZNKSt7num_getIcSt19istreambuf_iteratorIcSt11char_traitsIcEEE14_M_extract_intIlEES3_S3_S3_RSt8ios_baseRSt12_Ios_IostateRT_);
+_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_getIcSt19istreambuf_iteratorIcSt11char_traitsIcEEE14_M_extract_intImEES4_S4_S4_RSt8ios_baseRSt12_Ios_IostateRT_,
+		     _ZNKSt7num_getIcSt19istreambuf_iteratorIcSt11char_traitsIcEEE14_M_extract_intImEES3_S3_S3_RSt8ios_baseRSt12_Ios_IostateRT_);
+_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_getIcSt19istreambuf_iteratorIcSt11char_traitsIcEEE14_M_extract_intItEES4_S4_S4_RSt8ios_baseRSt12_Ios_IostateRT_,
+		     _ZNKSt7num_getIcSt19istreambuf_iteratorIcSt11char_traitsIcEEE14_M_extract_intItEES3_S3_S3_RSt8ios_baseRSt12_Ios_IostateRT_);
+_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_getIcSt19istreambuf_iteratorIcSt11char_traitsIcEEE14_M_extract_intIxEES4_S4_S4_RSt8ios_baseRSt12_Ios_IostateRT_,
+		     _ZNKSt7num_getIcSt19istreambuf_iteratorIcSt11char_traitsIcEEE14_M_extract_intIxEES3_S3_S3_RSt8ios_baseRSt12_Ios_IostateRT_);
+_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_getIcSt19istreambuf_iteratorIcSt11char_traitsIcEEE14_M_extract_intIyEES4_S4_S4_RSt8ios_baseRSt12_Ios_IostateRT_,
+		     _ZNKSt7num_getIcSt19istreambuf_iteratorIcSt11char_traitsIcEEE14_M_extract_intIyEES3_S3_S3_RSt8ios_baseRSt12_Ios_IostateRT_);
+_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_putIcSt19ostreambuf_iteratorIcSt11char_traitsIcEEE13_M_insert_intIlEES4_S4_RSt8ios_basecT_,
+		     _ZNKSt7num_putIcSt19ostreambuf_iteratorIcSt11char_traitsIcEEE13_M_insert_intIlEES3_S3_RSt8ios_basecT_);
+_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_putIcSt19ostreambuf_iteratorIcSt11char_traitsIcEEE13_M_insert_intImEES4_S4_RSt8ios_basecT_,
+		     _ZNKSt7num_putIcSt19ostreambuf_iteratorIcSt11char_traitsIcEEE13_M_insert_intImEES3_S3_RSt8ios_basecT_);
+_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_putIcSt19ostreambuf_iteratorIcSt11char_traitsIcEEE13_M_insert_intIxEES4_S4_RSt8ios_basecT_,
+		     _ZNKSt7num_putIcSt19ostreambuf_iteratorIcSt11char_traitsIcEEE13_M_insert_intIxEES3_S3_RSt8ios_basecT_);
+_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_putIcSt19ostreambuf_iteratorIcSt11char_traitsIcEEE13_M_insert_intIyEES4_S4_RSt8ios_basecT_,
+		     _ZNKSt7num_putIcSt19ostreambuf_iteratorIcSt11char_traitsIcEEE13_M_insert_intIyEES3_S3_RSt8ios_basecT_);
+_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_putIcSt19ostreambuf_iteratorIcSt11char_traitsIcEEE15_M_insert_floatIdEES4_S4_RSt8ios_baseccT_,
+		     _ZNKSt7num_putIcSt19ostreambuf_iteratorIcSt11char_traitsIcEEE15_M_insert_floatIdEES3_S3_RSt8ios_baseccT_);
+_GLIBCXX_LDBL_COMPAT(_ZNKSt7num_putIcSt19ostreambuf_iteratorIcSt11char_traitsIcEEE15_M_insert_floatIdEES3_S3_RSt8ios_baseccT_,
+		     _ZNKSt7num_putIcSt19ostreambuf_iteratorIcSt11char_traitsIcEEE15_M_insert_floatIeEES3_S3_RSt8ios_baseccT_);
+_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1289money_getIcSt19istreambuf_iteratorIcSt11char_traitsIcEEE10_M_extractILb0EEES4_S4_S4_RSt8ios_baseRSt12_Ios_IostateRSs,
+		     _ZNKSt9money_getIcSt19istreambuf_iteratorIcSt11char_traitsIcEEE10_M_extractILb0EEES3_S3_S3_RSt8ios_baseRSt12_Ios_IostateRSs);
+_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1289money_getIcSt19istreambuf_iteratorIcSt11char_traitsIcEEE10_M_extractILb1EEES4_S4_S4_RSt8ios_baseRSt12_Ios_IostateRSs,
+		     _ZNKSt9money_getIcSt19istreambuf_iteratorIcSt11char_traitsIcEEE10_M_extractILb1EEES3_S3_S3_RSt8ios_baseRSt12_Ios_IostateRSs);
+_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1289money_putIcSt19ostreambuf_iteratorIcSt11char_traitsIcEEE9_M_insertILb0EEES4_S4_RSt8ios_basecRKSs,
+		     _ZNKSt9money_putIcSt19ostreambuf_iteratorIcSt11char_traitsIcEEE9_M_insertILb0EEES3_S3_RSt8ios_basecRKSs);
+_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1289money_putIcSt19ostreambuf_iteratorIcSt11char_traitsIcEEE9_M_insertILb1EEES4_S4_RSt8ios_basecRKSs,
+		     _ZNKSt9money_putIcSt19ostreambuf_iteratorIcSt11char_traitsIcEEE9_M_insertILb1EEES3_S3_RSt8ios_basecRKSs);
+#else // ! C_is_char
+_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_getIwSt19istreambuf_iteratorIwSt11char_traitsIwEEE14_M_extract_intIjEES4_S4_S4_RSt8ios_baseRSt12_Ios_IostateRT_,
+		     _ZNKSt7num_getIwSt19istreambuf_iteratorIwSt11char_traitsIwEEE14_M_extract_intIjEES3_S3_S3_RSt8ios_baseRSt12_Ios_IostateRT_);
+_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_getIwSt19istreambuf_iteratorIwSt11char_traitsIwEEE14_M_extract_intIlEES4_S4_S4_RSt8ios_baseRSt12_Ios_IostateRT_,
+		     _ZNKSt7num_getIwSt19istreambuf_iteratorIwSt11char_traitsIwEEE14_M_extract_intIlEES3_S3_S3_RSt8ios_baseRSt12_Ios_IostateRT_);
+_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_getIwSt19istreambuf_iteratorIwSt11char_traitsIwEEE14_M_extract_intImEES4_S4_S4_RSt8ios_baseRSt12_Ios_IostateRT_,
+		     _ZNKSt7num_getIwSt19istreambuf_iteratorIwSt11char_traitsIwEEE14_M_extract_intImEES3_S3_S3_RSt8ios_baseRSt12_Ios_IostateRT_);
+_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_getIwSt19istreambuf_iteratorIwSt11char_traitsIwEEE14_M_extract_intItEES4_S4_S4_RSt8ios_baseRSt12_Ios_IostateRT_,
+		     _ZNKSt7num_getIwSt19istreambuf_iteratorIwSt11char_traitsIwEEE14_M_extract_intItEES3_S3_S3_RSt8ios_baseRSt12_Ios_IostateRT_);
+_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_getIwSt19istreambuf_iteratorIwSt11char_traitsIwEEE14_M_extract_intIxEES4_S4_S4_RSt8ios_baseRSt12_Ios_IostateRT_,
+		     _ZNKSt7num_getIwSt19istreambuf_iteratorIwSt11char_traitsIwEEE14_M_extract_intIxEES3_S3_S3_RSt8ios_baseRSt12_Ios_IostateRT_);
+_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_getIwSt19istreambuf_iteratorIwSt11char_traitsIwEEE14_M_extract_intIyEES4_S4_S4_RSt8ios_baseRSt12_Ios_IostateRT_,
+		     _ZNKSt7num_getIwSt19istreambuf_iteratorIwSt11char_traitsIwEEE14_M_extract_intIyEES3_S3_S3_RSt8ios_baseRSt12_Ios_IostateRT_);
+_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_putIwSt19ostreambuf_iteratorIwSt11char_traitsIwEEE13_M_insert_intIlEES4_S4_RSt8ios_basewT_,
+		     _ZNKSt7num_putIwSt19ostreambuf_iteratorIwSt11char_traitsIwEEE13_M_insert_intIlEES3_S3_RSt8ios_basewT_);
+_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_putIwSt19ostreambuf_iteratorIwSt11char_traitsIwEEE13_M_insert_intImEES4_S4_RSt8ios_basewT_,
+		     _ZNKSt7num_putIwSt19ostreambuf_iteratorIwSt11char_traitsIwEEE13_M_insert_intImEES3_S3_RSt8ios_basewT_);
+_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_putIwSt19ostreambuf_iteratorIwSt11char_traitsIwEEE13_M_insert_intIxEES4_S4_RSt8ios_basewT_,
+		     _ZNKSt7num_putIwSt19ostreambuf_iteratorIwSt11char_traitsIwEEE13_M_insert_intIxEES3_S3_RSt8ios_basewT_);
+_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_putIwSt19ostreambuf_iteratorIwSt11char_traitsIwEEE13_M_insert_intIyEES4_S4_RSt8ios_basewT_,
+		     _ZNKSt7num_putIwSt19ostreambuf_iteratorIwSt11char_traitsIwEEE13_M_insert_intIyEES3_S3_RSt8ios_basewT_);
+_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_putIwSt19ostreambuf_iteratorIwSt11char_traitsIwEEE15_M_insert_floatIdEES4_S4_RSt8ios_basewcT_,
+		     _ZNKSt7num_putIwSt19ostreambuf_iteratorIwSt11char_traitsIwEEE15_M_insert_floatIdEES3_S3_RSt8ios_basewcT_);
+_GLIBCXX_LDBL_COMPAT(_ZNKSt7num_putIwSt19ostreambuf_iteratorIwSt11char_traitsIwEEE15_M_insert_floatIdEES3_S3_RSt8ios_basewcT_,
+		     _ZNKSt7num_putIwSt19ostreambuf_iteratorIwSt11char_traitsIwEEE15_M_insert_floatIeEES3_S3_RSt8ios_basewcT_);
+_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1289money_getIwSt19istreambuf_iteratorIwSt11char_traitsIwEEE10_M_extractILb0EEES4_S4_S4_RSt8ios_baseRSt12_Ios_IostateRSs,
+		     _ZNKSt9money_getIwSt19istreambuf_iteratorIwSt11char_traitsIwEEE10_M_extractILb0EEES3_S3_S3_RSt8ios_baseRSt12_Ios_IostateRSs);
+_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1289money_getIwSt19istreambuf_iteratorIwSt11char_traitsIwEEE10_M_extractILb1EEES4_S4_S4_RSt8ios_baseRSt12_Ios_IostateRSs,
+		     _ZNKSt9money_getIwSt19istreambuf_iteratorIwSt11char_traitsIwEEE10_M_extractILb1EEES3_S3_S3_RSt8ios_baseRSt12_Ios_IostateRSs);
+_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1289money_putIwSt19ostreambuf_iteratorIwSt11char_traitsIwEEE9_M_insertILb0EEES4_S4_RSt8ios_basewRKSbIwS3_SaIwEE,
+		     _ZNKSt9money_putIwSt19ostreambuf_iteratorIwSt11char_traitsIwEEE9_M_insertILb0EEES3_S3_RSt8ios_basewRKSbIwS2_SaIwEE);
+_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1289money_putIwSt19ostreambuf_iteratorIwSt11char_traitsIwEEE9_M_insertILb1EEES4_S4_RSt8ios_basewRKSbIwS3_SaIwEE,
+		     _ZNKSt9money_putIwSt19ostreambuf_iteratorIwSt11char_traitsIwEEE9_M_insertILb1EEES3_S3_RSt8ios_basewRKSbIwS2_SaIwEE);
+#endif // C_is_char
+
+
+#if defined _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT
+// Define __gnu_cxx_ieee128::num_put<>::_M_insert_float(..., __ibm128) as
+// alias of __gnu_cxx_ldbl128::num_put<>::_M_insert_float(..., __ibm128)
+# ifdef C_is_char
+_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_putIcSt19ostreambuf_iteratorIcSt11char_traitsIcEEE15_M_insert_floatIgEES4_S4_RSt8ios_baseccT_,
+		     _ZNKSt17__gnu_cxx_ieee1287num_putIcSt19ostreambuf_iteratorIcSt11char_traitsIcEEE15_M_insert_floatIgEES4_S4_RSt8ios_baseccT_);
+# else
+_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_putIwSt19ostreambuf_iteratorIwSt11char_traitsIwEEE15_M_insert_floatIgEES4_S4_RSt8ios_basewcT_,
+		     _ZNKSt17__gnu_cxx_ieee1287num_putIwSt19ostreambuf_iteratorIwSt11char_traitsIwEEE15_M_insert_floatIgEES4_S4_RSt8ios_basewcT_);
+# endif
+#endif // _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT
+
+#undef _GLIBCXX_LDBL_COMPAT
+#pragma GCC diagnostic pop
+
+#endif  // __LONG_DOUBLE_128__ && ! __LONG_DOUBLE_IEEE128__
diff --git a/libstdc++-v3/src/c++11/cow-locale_init.cc b/libstdc++-v3/src/c++11/cow-locale_init.cc
index 98a2ef41f56..bf270712e47 100644
--- a/libstdc++-v3/src/c++11/cow-locale_init.cc
+++ b/libstdc++-v3/src/c++11/cow-locale_init.cc
@@ -125,6 +125,7 @@ namespace
     _M_init_facet_unchecked(new (&messages_w) std::messages<wchar_t>(1));
 #endif
 
+    // The caches must be populated last, after creating all facets.
     _M_caches[numpunct<char>::id._M_id()] = __npc;
     _M_caches[moneypunct<char, false>::id._M_id()] = __mpcf;
     _M_caches[moneypunct<char, true>::id._M_id()] = __mpct;
diff --git a/libstdc++-v3/src/c++11/cxx11-locale-inst.cc b/libstdc++-v3/src/c++11/cxx11-locale-inst.cc
index 7b132a748bf..9378550124f 100644
--- a/libstdc++-v3/src/c++11/cxx11-locale-inst.cc
+++ b/libstdc++-v3/src/c++11/cxx11-locale-inst.cc
@@ -32,8 +32,6 @@
 # error This file should not be compiled for this configuration.
 #endif
 
-#ifndef C
-# define C char
-# define C_is_char
-#endif
+#define C char
+#define C_is_char
 # include "locale-inst.cc"
diff --git a/libstdc++-v3/src/c++11/cxx11-wlocale-inst.cc b/libstdc++-v3/src/c++11/cxx11-wlocale-inst.cc
index cf3d6dc7e34..07eb6008361 100644
--- a/libstdc++-v3/src/c++11/cxx11-wlocale-inst.cc
+++ b/libstdc++-v3/src/c++11/cxx11-wlocale-inst.cc
@@ -24,9 +24,15 @@
 // ISO C++ 14882: 22.1  Locales
 //
 
+// Facet wchar_t instantiations using new ABI strings.
+
 #define _GLIBCXX_USE_CXX11_ABI 1
 #include <bits/c++config.h>
+#if ! _GLIBCXX_USE_DUAL_ABI
+# error This file should not be compiled for this configuration.
+#endif
+
 #ifdef _GLIBCXX_USE_WCHAR_T
 #define C wchar_t
-#include "cxx11-locale-inst.cc"
+#include "locale-inst.cc"
 #endif
diff --git a/libstdc++-v3/src/c++11/locale-inst-monetary.h b/libstdc++-v3/src/c++11/locale-inst-monetary.h
new file mode 100644
index 00000000000..e9b3e7c4e0c
--- /dev/null
+++ b/libstdc++-v3/src/c++11/locale-inst-monetary.h
@@ -0,0 +1,69 @@
+// Explicit instantantiations for monetary facets -*- C++ -*-
+
+// Copyright (C) 2018 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// Under Section 7 of GPL version 3, you are granted additional
+// permissions described in the GCC Runtime Library Exception, version
+// 3.1, as published by the Free Software Foundation.
+
+// You should have received a copy of the GNU General Public License and
+// a copy of the GCC Runtime Library Exception along with this program;
+// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+// <http://www.gnu.org/licenses/>.
+
+#ifndef C
+#define "This file should not be compiled directly, only included"
+#endif
+
+// This header is included multiple times, to instantiate these symbols
+// for char/wchar_t and for both std::string ABIs,
+// and (depending on the target) for two long double formats.
+
+namespace std _GLIBCXX_VISIBILITY(default)
+{
+  template const money_put<C>& use_facet<money_put<C> >(const locale&);
+  template const money_get<C>& use_facet<money_get<C> >(const locale&);
+
+  template bool has_facet<money_put<C> >(const locale&);
+  template bool has_facet<money_get<C> >(const locale&);
+
+_GLIBCXX_BEGIN_NAMESPACE_LDBL_OR_CXX11
+  template class money_get<C, istreambuf_iterator<C> >;
+  template class money_put<C, ostreambuf_iterator<C> >;
+
+  template
+    istreambuf_iterator<C>
+    money_get<C, istreambuf_iterator<C> >::
+    _M_extract<true>(istreambuf_iterator<C>, istreambuf_iterator<C>,
+		     ios_base&, ios_base::iostate&, string&) const;
+
+  template
+    istreambuf_iterator<C>
+    money_get<C, istreambuf_iterator<C> >::
+    _M_extract<false>(istreambuf_iterator<C>, istreambuf_iterator<C>,
+		      ios_base&, ios_base::iostate&, string&) const;
+
+  template
+    ostreambuf_iterator<C>
+    money_put<C, ostreambuf_iterator<C> >::
+    _M_insert<true>(ostreambuf_iterator<C>, ios_base&, C,
+		    const string_type&) const;
+
+  template
+    ostreambuf_iterator<C>
+    money_put<C, ostreambuf_iterator<C> >::
+    _M_insert<false>(ostreambuf_iterator<C>, ios_base&, C,
+		     const string_type&) const;
+_GLIBCXX_END_NAMESPACE_LDBL_OR_CXX11
+} // namespace std
diff --git a/libstdc++-v3/src/c++11/locale-inst-numeric.h b/libstdc++-v3/src/c++11/locale-inst-numeric.h
new file mode 100644
index 00000000000..0ec93e27937
--- /dev/null
+++ b/libstdc++-v3/src/c++11/locale-inst-numeric.h
@@ -0,0 +1,133 @@
+// Explicit instantantiations for numeric facets -*- C++ -*-
+
+// Copyright (C) 2018 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library.  This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+
+// Under Section 7 of GPL version 3, you are granted additional
+// permissions described in the GCC Runtime Library Exception, version
+// 3.1, as published by the Free Software Foundation.
+
+// You should have received a copy of the GNU General Public License and
+// a copy of the GCC Runtime Library Exception along with this program;
+// see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
+// <http://www.gnu.org/licenses/>.
+
+#ifndef C
+#define "This file should not be compiled directly, only included"
+#endif
+
+namespace std _GLIBCXX_VISIBILITY(default)
+{
+#if ! _GLIBCXX_USE_CXX11_ABI
+  template const num_get<C>& use_facet<num_get<C> >(const locale&);
+  template const num_put<C>& use_facet<num_put<C> >(const locale&);
+
+  template bool has_facet<num_get<C> >(const locale&);
+  template bool has_facet<num_put<C> >(const locale&);
+#endif
+
+_GLIBCXX_BEGIN_NAMESPACE_LDBL
+
+#if ! _GLIBCXX_USE_CXX11_ABI
+  template class num_get<C, istreambuf_iterator<C> >;
+  template class num_put<C, ostreambuf_iterator<C> >;
+#endif
+
+  // num_get member function templates
+  template
+    istreambuf_iterator<C>
+    num_get<C, istreambuf_iterator<C> >::
+    _M_extract_int(istreambuf_iterator<C>, istreambuf_iterator<C>,
+		   ios_base&, ios_base::iostate&,
+		   long&) const;
+
+  template
+    istreambuf_iterator<C>
+    num_get<C, istreambuf_iterator<C> >::
+    _M_extract_int(istreambuf_iterator<C>, istreambuf_iterator<C>,
+		   ios_base&, ios_base::iostate&,
+		   unsigned short&) const;
+
+  template
+    istreambuf_iterator<C>
+    num_get<C, istreambuf_iterator<C> >::
+    _M_extract_int(istreambuf_iterator<C>, istreambuf_iterator<C>,
+		   ios_base&, ios_base::iostate&,
+		   unsigned int&) const;
+
+  template
+    istreambuf_iterator<C>
+    num_get<C, istreambuf_iterator<C> >::
+    _M_extract_int(istreambuf_iterator<C>, istreambuf_iterator<C>,
+		   ios_base&, ios_base::iostate&,
+		   unsigned long&) const;
+
+#ifdef _GLIBCXX_USE_LONG_LONG
+  template
+    istreambuf_iterator<C>
+    num_get<C, istreambuf_iterator<C> >::
+    _M_extract_int(istreambuf_iterator<C>, istreambuf_iterator<C>,
+		   ios_base&, ios_base::iostate&,
+		   long long&) const;
+
+  template
+    istreambuf_iterator<C>
+    num_get<C, istreambuf_iterator<C> >::
+    _M_extract_int(istreambuf_iterator<C>, istreambuf_iterator<C>,
+		   ios_base&, ios_base::iostate&,
+		   unsigned long long&) const;
+#endif
+
+#if ! _GLIBCXX_USE_CXX11_ABI
+  // num_put member function templates
+  template
+    ostreambuf_iterator<C>
+    num_put<C, ostreambuf_iterator<C> >::
+    _M_insert_int(ostreambuf_iterator<C>, ios_base&, C,
+		  long) const;
+
+  template
+    ostreambuf_iterator<C>
+    num_put<C, ostreambuf_iterator<C> >::
+    _M_insert_int(ostreambuf_iterator<C>, ios_base&, C,
+		  unsigned long) const;
+
+#ifdef _GLIBCXX_USE_LONG_LONG
+  template
+    ostreambuf_iterator<C>
+    num_put<C, ostreambuf_iterator<C> >::
+    _M_insert_int(ostreambuf_iterator<C>, ios_base&, C,
+		  long long) const;
+
+  template
+    ostreambuf_iterator<C>
+    num_put<C, ostreambuf_iterator<C> >::
+    _M_insert_int(ostreambuf_iterator<C>, ios_base&, C,
+		  unsigned long long) const;
+#endif
+
+  template
+    ostreambuf_iterator<C>
+    num_put<C, ostreambuf_iterator<C> >::
+    _M_insert_float(ostreambuf_iterator<C>, ios_base&, C, char,
+		    double) const;
+
+  template
+    ostreambuf_iterator<C>
+    num_put<C, ostreambuf_iterator<C> >::
+    _M_insert_float(ostreambuf_iterator<C>, ios_base&, C, char,
+		    long double) const;
+#endif
+
+_GLIBCXX_END_NAMESPACE_LDBL
+} // namespace std
diff --git a/libstdc++-v3/src/c++11/locale-inst.cc b/libstdc++-v3/src/c++11/locale-inst.cc
index 4dc7f5c0780..cd99648e8f6 100644
--- a/libstdc++-v3/src/c++11/locale-inst.cc
+++ b/libstdc++-v3/src/c++11/locale-inst.cc
@@ -43,6 +43,9 @@
 # define C_is_char
 #endif
 
+#include "locale-inst-numeric.h"
+#include "locale-inst-monetary.h"
+
 namespace std _GLIBCXX_VISIBILITY(default)
 {
 _GLIBCXX_BEGIN_NAMESPACE_VERSION
@@ -58,33 +61,6 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
   template class moneypunct_byname<C, false>;
   template class moneypunct_byname<C, true>;
 _GLIBCXX_END_NAMESPACE_CXX11
-_GLIBCXX_BEGIN_NAMESPACE_LDBL_OR_CXX11
-  template class money_get<C, istreambuf_iterator<C> >;
-  template class money_put<C, ostreambuf_iterator<C> >;
-  template
-    istreambuf_iterator<C>
-    money_get<C, istreambuf_iterator<C> >::
-    _M_extract<true>(istreambuf_iterator<C>, istreambuf_iterator<C>,
-		     ios_base&, ios_base::iostate&, string&) const;
-
-  template
-    istreambuf_iterator<C>
-    money_get<C, istreambuf_iterator<C> >::
-    _M_extract<false>(istreambuf_iterator<C>, istreambuf_iterator<C>,
-		      ios_base&, ios_base::iostate&, string&) const;
-
-  template
-    ostreambuf_iterator<C>
-    money_put<C, ostreambuf_iterator<C> >::
-    _M_insert<true>(ostreambuf_iterator<C>, ios_base&, C,
-		    const string_type&) const;
-
-  template
-    ostreambuf_iterator<C>
-    money_put<C, ostreambuf_iterator<C> >::
-    _M_insert<false>(ostreambuf_iterator<C>, ios_base&, C,
-		     const string_type&) const;
-_GLIBCXX_END_NAMESPACE_LDBL_OR_CXX11
 
   // numpunct, numpunct_byname, num_get, and num_put
 #if ! _GLIBCXX_USE_CXX11_ABI
@@ -94,97 +70,6 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11
   template class numpunct<C>;
   template class numpunct_byname<C>;
 _GLIBCXX_END_NAMESPACE_CXX11
-_GLIBCXX_BEGIN_NAMESPACE_LDBL
-#if ! _GLIBCXX_USE_CXX11_ABI
-  template class num_get<C, istreambuf_iterator<C> >;
-#endif
-
-  template
-    istreambuf_iterator<C>
-    num_get<C, istreambuf_iterator<C> >::
-    _M_extract_int(istreambuf_iterator<C>, istreambuf_iterator<C>,
-		   ios_base&, ios_base::iostate&,
-		   long&) const;
-
-  template
-    istreambuf_iterator<C>
-    num_get<C, istreambuf_iterator<C> >::
-    _M_extract_int(istreambuf_iterator<C>, istreambuf_iterator<C>,
-		   ios_base&, ios_base::iostate&,
-		   unsigned short&) const;
-
-  template
-    istreambuf_iterator<C>
-    num_get<C, istreambuf_iterator<C> >::
-    _M_extract_int(istreambuf_iterator<C>, istreambuf_iterator<C>,
-		   ios_base&, ios_base::iostate&,
-		   unsigned int&) const;
-
-  template
-    istreambuf_iterator<C>
-    num_get<C, istreambuf_iterator<C> >::
-    _M_extract_int(istreambuf_iterator<C>, istreambuf_iterator<C>,
-		   ios_base&, ios_base::iostate&,
-		   unsigned long&) const;
-
-#ifdef _GLIBCXX_USE_LONG_LONG
-  template
-    istreambuf_iterator<C>
-    num_get<C, istreambuf_iterator<C> >::
-    _M_extract_int(istreambuf_iterator<C>, istreambuf_iterator<C>,
-		   ios_base&, ios_base::iostate&,
-		   long long&) const;
-
-  template
-    istreambuf_iterator<C>
-    num_get<C, istreambuf_iterator<C> >::
-    _M_extract_int(istreambuf_iterator<C>, istreambuf_iterator<C>,
-		   ios_base&, ios_base::iostate&,
-		   unsigned long long&) const;
-#endif
-
-#if ! _GLIBCXX_USE_CXX11_ABI
-  template class num_put<C, ostreambuf_iterator<C> >;
-
-  template
-    ostreambuf_iterator<C>
-    num_put<C, ostreambuf_iterator<C> >::
-    _M_insert_int(ostreambuf_iterator<C>, ios_base&, C,
-		  long) const;
-
-  template
-    ostreambuf_iterator<C>
-    num_put<C, ostreambuf_iterator<C> >::
-    _M_insert_int(ostreambuf_iterator<C>, ios_base&, C,
-		  unsigned long) const;
-
-#ifdef _GLIBCXX_USE_LONG_LONG
-  template
-    ostreambuf_iterator<C>
-    num_put<C, ostreambuf_iterator<C> >::
-    _M_insert_int(ostreambuf_iterator<C>, ios_base&, C,
-		  long long) const;
-
-  template
-    ostreambuf_iterator<C>
-    num_put<C, ostreambuf_iterator<C> >::
-    _M_insert_int(ostreambuf_iterator<C>, ios_base&, C,
-		  unsigned long long) const;
-#endif
-
-  template
-    ostreambuf_iterator<C>
-    num_put<C, ostreambuf_iterator<C> >::
-    _M_insert_float(ostreambuf_iterator<C>, ios_base&, C, char,
-		    double) const;
-
-  template
-    ostreambuf_iterator<C>
-    num_put<C, ostreambuf_iterator<C> >::
-    _M_insert_float(ostreambuf_iterator<C>, ios_base&, C, char,
-		    long double) const;
-#endif
-_GLIBCXX_END_NAMESPACE_LDBL
 
   // time_get and time_put
 #if ! _GLIBCXX_USE_CXX11_ABI
@@ -250,16 +135,6 @@ _GLIBCXX_END_NAMESPACE_CXX11
     const numpunct<C>&
     use_facet<numpunct<C> >(const locale&);
 
-#if ! _GLIBCXX_USE_CXX11_ABI
-  template
-    const num_put<C>&
-    use_facet<num_put<C> >(const locale&);
-
-  template
-    const num_get<C>&
-    use_facet<num_get<C> >(const locale&);
-#endif
-
   template
     const moneypunct<C, true>&
     use_facet<moneypunct<C, true> >(const locale&);
@@ -268,14 +143,6 @@ _GLIBCXX_END_NAMESPACE_CXX11
     const moneypunct<C, false>&
     use_facet<moneypunct<C, false> >(const locale&);
 
-  template
-    const money_put<C>&
-    use_facet<money_put<C> >(const locale&);
-
-  template
-    const money_get<C>&
-    use_facet<money_get<C> >(const locale&);
-
 #if ! _GLIBCXX_USE_CXX11_ABI
   template
     const __timepunct<C>&
@@ -313,28 +180,10 @@ _GLIBCXX_END_NAMESPACE_CXX11
     bool
     has_facet<numpunct<C> >(const locale&);
 
-#if ! _GLIBCXX_USE_CXX11_ABI
-  template
-    bool
-    has_facet<num_put<C> >(const locale&);
-
-  template
-    bool
-    has_facet<num_get<C> >(const locale&);
-#endif
-
   template
     bool
     has_facet<moneypunct<C> >(const locale&);
 
-  template
-    bool
-    has_facet<money_put<C> >(const locale&);
-
-  template
-    bool
-    has_facet<money_get<C> >(const locale&);
-
 #if ! _GLIBCXX_USE_CXX11_ABI
   template
     bool
@@ -380,45 +229,6 @@ _GLIBCXX_END_NAMESPACE_VERSION
 } // namespace
 
 // XXX GLIBCXX_ABI Deprecated
-#if defined _GLIBCXX_LONG_DOUBLE_COMPAT && defined C_is_char \
-      && _GLIBCXX_USE_CXX11_ABI == 0
-
-#pragma GCC diagnostic ignored "-Wattribute-alias"
-
-#define _GLIBCXX_LDBL_COMPAT(dbl, ldbl) \
-  extern "C" void ldbl (void) __attribute__ ((alias (#dbl), weak))
-
-_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_getIcSt19istreambuf_iteratorIcSt11char_traitsIcEEE14_M_extract_intIjEES4_S4_S4_RSt8ios_baseRSt12_Ios_IostateRT_,
-		     _ZNKSt7num_getIcSt19istreambuf_iteratorIcSt11char_traitsIcEEE14_M_extract_intIjEES3_S3_S3_RSt8ios_baseRSt12_Ios_IostateRT_);
-_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_getIcSt19istreambuf_iteratorIcSt11char_traitsIcEEE14_M_extract_intIlEES4_S4_S4_RSt8ios_baseRSt12_Ios_IostateRT_,
-		     _ZNKSt7num_getIcSt19istreambuf_iteratorIcSt11char_traitsIcEEE14_M_extract_intIlEES3_S3_S3_RSt8ios_baseRSt12_Ios_IostateRT_);
-_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_getIcSt19istreambuf_iteratorIcSt11char_traitsIcEEE14_M_extract_intImEES4_S4_S4_RSt8ios_baseRSt12_Ios_IostateRT_,
-		     _ZNKSt7num_getIcSt19istreambuf_iteratorIcSt11char_traitsIcEEE14_M_extract_intImEES3_S3_S3_RSt8ios_baseRSt12_Ios_IostateRT_);
-_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_getIcSt19istreambuf_iteratorIcSt11char_traitsIcEEE14_M_extract_intItEES4_S4_S4_RSt8ios_baseRSt12_Ios_IostateRT_,
-		     _ZNKSt7num_getIcSt19istreambuf_iteratorIcSt11char_traitsIcEEE14_M_extract_intItEES3_S3_S3_RSt8ios_baseRSt12_Ios_IostateRT_);
-_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_getIcSt19istreambuf_iteratorIcSt11char_traitsIcEEE14_M_extract_intIxEES4_S4_S4_RSt8ios_baseRSt12_Ios_IostateRT_,
-		     _ZNKSt7num_getIcSt19istreambuf_iteratorIcSt11char_traitsIcEEE14_M_extract_intIxEES3_S3_S3_RSt8ios_baseRSt12_Ios_IostateRT_);
-_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_getIcSt19istreambuf_iteratorIcSt11char_traitsIcEEE14_M_extract_intIyEES4_S4_S4_RSt8ios_baseRSt12_Ios_IostateRT_,
-		     _ZNKSt7num_getIcSt19istreambuf_iteratorIcSt11char_traitsIcEEE14_M_extract_intIyEES3_S3_S3_RSt8ios_baseRSt12_Ios_IostateRT_);
-_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_putIcSt19ostreambuf_iteratorIcSt11char_traitsIcEEE13_M_insert_intIlEES4_S4_RSt8ios_basecT_,
-		     _ZNKSt7num_putIcSt19ostreambuf_iteratorIcSt11char_traitsIcEEE13_M_insert_intIlEES3_S3_RSt8ios_basecT_);
-_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_putIcSt19ostreambuf_iteratorIcSt11char_traitsIcEEE13_M_insert_intImEES4_S4_RSt8ios_basecT_,
-		     _ZNKSt7num_putIcSt19ostreambuf_iteratorIcSt11char_traitsIcEEE13_M_insert_intImEES3_S3_RSt8ios_basecT_);
-_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_putIcSt19ostreambuf_iteratorIcSt11char_traitsIcEEE13_M_insert_intIxEES4_S4_RSt8ios_basecT_,
-		     _ZNKSt7num_putIcSt19ostreambuf_iteratorIcSt11char_traitsIcEEE13_M_insert_intIxEES3_S3_RSt8ios_basecT_);
-_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_putIcSt19ostreambuf_iteratorIcSt11char_traitsIcEEE13_M_insert_intIyEES4_S4_RSt8ios_basecT_,
-		     _ZNKSt7num_putIcSt19ostreambuf_iteratorIcSt11char_traitsIcEEE13_M_insert_intIyEES3_S3_RSt8ios_basecT_);
-_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_putIcSt19ostreambuf_iteratorIcSt11char_traitsIcEEE15_M_insert_floatIdEES4_S4_RSt8ios_baseccT_,
-		     _ZNKSt7num_putIcSt19ostreambuf_iteratorIcSt11char_traitsIcEEE15_M_insert_floatIdEES3_S3_RSt8ios_baseccT_);
-_GLIBCXX_LDBL_COMPAT(_ZNKSt7num_putIcSt19ostreambuf_iteratorIcSt11char_traitsIcEEE15_M_insert_floatIdEES3_S3_RSt8ios_baseccT_,
-		     _ZNKSt7num_putIcSt19ostreambuf_iteratorIcSt11char_traitsIcEEE15_M_insert_floatIeEES3_S3_RSt8ios_baseccT_);
-_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1289money_getIcSt19istreambuf_iteratorIcSt11char_traitsIcEEE10_M_extractILb0EEES4_S4_S4_RSt8ios_baseRSt12_Ios_IostateRSs,
-		     _ZNKSt9money_getIcSt19istreambuf_iteratorIcSt11char_traitsIcEEE10_M_extractILb0EEES3_S3_S3_RSt8ios_baseRSt12_Ios_IostateRSs);
-_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1289money_getIcSt19istreambuf_iteratorIcSt11char_traitsIcEEE10_M_extractILb1EEES4_S4_S4_RSt8ios_baseRSt12_Ios_IostateRSs,
-		     _ZNKSt9money_getIcSt19istreambuf_iteratorIcSt11char_traitsIcEEE10_M_extractILb1EEES3_S3_S3_RSt8ios_baseRSt12_Ios_IostateRSs);
-_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1289money_putIcSt19ostreambuf_iteratorIcSt11char_traitsIcEEE9_M_insertILb0EEES4_S4_RSt8ios_basecRKSs,
-		     _ZNKSt9money_putIcSt19ostreambuf_iteratorIcSt11char_traitsIcEEE9_M_insertILb0EEES3_S3_RSt8ios_basecRKSs);
-_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1289money_putIcSt19ostreambuf_iteratorIcSt11char_traitsIcEEE9_M_insertILb1EEES4_S4_RSt8ios_basecRKSs,
-		     _ZNKSt9money_putIcSt19ostreambuf_iteratorIcSt11char_traitsIcEEE9_M_insertILb1EEES3_S3_RSt8ios_basecRKSs);
-
+#if defined _GLIBCXX_LONG_DOUBLE_COMPAT && ! _GLIBCXX_USE_CXX11_ABI
+#include "compatibility-ldbl-facets-aliases.h"
 #endif // _GLIBCXX_LONG_DOUBLE_COMPAT
diff --git a/libstdc++-v3/src/c++11/wlocale-inst.cc b/libstdc++-v3/src/c++11/wlocale-inst.cc
index 3a54fb51aab..a9a246f8f97 100644
--- a/libstdc++-v3/src/c++11/wlocale-inst.cc
+++ b/libstdc++-v3/src/c++11/wlocale-inst.cc
@@ -33,47 +33,4 @@
 #ifdef _GLIBCXX_USE_WCHAR_T
 #define C wchar_t
 #include "locale-inst.cc"
-
-// XXX GLIBCXX_ABI Deprecated
-#if defined _GLIBCXX_LONG_DOUBLE_COMPAT
-
-#pragma GCC diagnostic ignored "-Wattribute-alias"
-
-#define _GLIBCXX_LDBL_COMPAT(dbl, ldbl) \
-  extern "C" void ldbl (void) __attribute__ ((alias (#dbl), weak))
-
-_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_getIwSt19istreambuf_iteratorIwSt11char_traitsIwEEE14_M_extract_intIjEES4_S4_S4_RSt8ios_baseRSt12_Ios_IostateRT_,
-		     _ZNKSt7num_getIwSt19istreambuf_iteratorIwSt11char_traitsIwEEE14_M_extract_intIjEES3_S3_S3_RSt8ios_baseRSt12_Ios_IostateRT_);
-_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_getIwSt19istreambuf_iteratorIwSt11char_traitsIwEEE14_M_extract_intIlEES4_S4_S4_RSt8ios_baseRSt12_Ios_IostateRT_,
-		     _ZNKSt7num_getIwSt19istreambuf_iteratorIwSt11char_traitsIwEEE14_M_extract_intIlEES3_S3_S3_RSt8ios_baseRSt12_Ios_IostateRT_);
-_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_getIwSt19istreambuf_iteratorIwSt11char_traitsIwEEE14_M_extract_intImEES4_S4_S4_RSt8ios_baseRSt12_Ios_IostateRT_,
-		     _ZNKSt7num_getIwSt19istreambuf_iteratorIwSt11char_traitsIwEEE14_M_extract_intImEES3_S3_S3_RSt8ios_baseRSt12_Ios_IostateRT_);
-_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_getIwSt19istreambuf_iteratorIwSt11char_traitsIwEEE14_M_extract_intItEES4_S4_S4_RSt8ios_baseRSt12_Ios_IostateRT_,
-		     _ZNKSt7num_getIwSt19istreambuf_iteratorIwSt11char_traitsIwEEE14_M_extract_intItEES3_S3_S3_RSt8ios_baseRSt12_Ios_IostateRT_);
-_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_getIwSt19istreambuf_iteratorIwSt11char_traitsIwEEE14_M_extract_intIxEES4_S4_S4_RSt8ios_baseRSt12_Ios_IostateRT_,
-		     _ZNKSt7num_getIwSt19istreambuf_iteratorIwSt11char_traitsIwEEE14_M_extract_intIxEES3_S3_S3_RSt8ios_baseRSt12_Ios_IostateRT_);
-_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_getIwSt19istreambuf_iteratorIwSt11char_traitsIwEEE14_M_extract_intIyEES4_S4_S4_RSt8ios_baseRSt12_Ios_IostateRT_,
-		     _ZNKSt7num_getIwSt19istreambuf_iteratorIwSt11char_traitsIwEEE14_M_extract_intIyEES3_S3_S3_RSt8ios_baseRSt12_Ios_IostateRT_);
-_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_putIwSt19ostreambuf_iteratorIwSt11char_traitsIwEEE13_M_insert_intIlEES4_S4_RSt8ios_basewT_,
-		     _ZNKSt7num_putIwSt19ostreambuf_iteratorIwSt11char_traitsIwEEE13_M_insert_intIlEES3_S3_RSt8ios_basewT_);
-_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_putIwSt19ostreambuf_iteratorIwSt11char_traitsIwEEE13_M_insert_intImEES4_S4_RSt8ios_basewT_,
-		     _ZNKSt7num_putIwSt19ostreambuf_iteratorIwSt11char_traitsIwEEE13_M_insert_intImEES3_S3_RSt8ios_basewT_);
-_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_putIwSt19ostreambuf_iteratorIwSt11char_traitsIwEEE13_M_insert_intIxEES4_S4_RSt8ios_basewT_,
-		     _ZNKSt7num_putIwSt19ostreambuf_iteratorIwSt11char_traitsIwEEE13_M_insert_intIxEES3_S3_RSt8ios_basewT_);
-_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_putIwSt19ostreambuf_iteratorIwSt11char_traitsIwEEE13_M_insert_intIyEES4_S4_RSt8ios_basewT_,
-		     _ZNKSt7num_putIwSt19ostreambuf_iteratorIwSt11char_traitsIwEEE13_M_insert_intIyEES3_S3_RSt8ios_basewT_);
-_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1287num_putIwSt19ostreambuf_iteratorIwSt11char_traitsIwEEE15_M_insert_floatIdEES4_S4_RSt8ios_basewcT_,
-		     _ZNKSt7num_putIwSt19ostreambuf_iteratorIwSt11char_traitsIwEEE15_M_insert_floatIdEES3_S3_RSt8ios_basewcT_);
-_GLIBCXX_LDBL_COMPAT(_ZNKSt7num_putIwSt19ostreambuf_iteratorIwSt11char_traitsIwEEE15_M_insert_floatIdEES3_S3_RSt8ios_basewcT_,
-		     _ZNKSt7num_putIwSt19ostreambuf_iteratorIwSt11char_traitsIwEEE15_M_insert_floatIeEES3_S3_RSt8ios_basewcT_);
-_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1289money_getIwSt19istreambuf_iteratorIwSt11char_traitsIwEEE10_M_extractILb0EEES4_S4_S4_RSt8ios_baseRSt12_Ios_IostateRSs,
-		     _ZNKSt9money_getIwSt19istreambuf_iteratorIwSt11char_traitsIwEEE10_M_extractILb0EEES3_S3_S3_RSt8ios_baseRSt12_Ios_IostateRSs);
-_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1289money_getIwSt19istreambuf_iteratorIwSt11char_traitsIwEEE10_M_extractILb1EEES4_S4_S4_RSt8ios_baseRSt12_Ios_IostateRSs,
-		     _ZNKSt9money_getIwSt19istreambuf_iteratorIwSt11char_traitsIwEEE10_M_extractILb1EEES3_S3_S3_RSt8ios_baseRSt12_Ios_IostateRSs);
-_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1289money_putIwSt19ostreambuf_iteratorIwSt11char_traitsIwEEE9_M_insertILb0EEES4_S4_RSt8ios_basewRKSbIwS3_SaIwEE,
-		     _ZNKSt9money_putIwSt19ostreambuf_iteratorIwSt11char_traitsIwEEE9_M_insertILb0EEES3_S3_RSt8ios_basewRKSbIwS2_SaIwEE);
-_GLIBCXX_LDBL_COMPAT(_ZNKSt17__gnu_cxx_ldbl1289money_putIwSt19ostreambuf_iteratorIwSt11char_traitsIwEEE9_M_insertILb1EEES4_S4_RSt8ios_basewRKSbIwS3_SaIwEE,
-		     _ZNKSt9money_putIwSt19ostreambuf_iteratorIwSt11char_traitsIwEEE9_M_insertILb1EEES3_S3_RSt8ios_basewRKSbIwS2_SaIwEE);
-
-#endif // _GLIBCXX_LONG_DOUBLE_COMPAT
-#endif
+#endif // _GLIBCXX_USE_WCHAR_T
diff --git a/libstdc++-v3/src/c++17/Makefile.am b/libstdc++-v3/src/c++17/Makefile.am
index 642efb976ac..37cdb53c076 100644
--- a/libstdc++-v3/src/c++17/Makefile.am
+++ b/libstdc++-v3/src/c++17/Makefile.am
@@ -61,6 +61,13 @@ vpath % $(top_srcdir)/src/c++17
 
 libc__17convenience_la_SOURCES = $(sources)  $(inst_sources)
 
+if GLIBCXX_LDBL_ALT128_COMPAT
+floating_from_chars.lo: floating_from_chars.cc
+	$(LTCXXCOMPILE) -mabi=ibmlongdouble $(LONG_DOUBLE_128_FLAGS) -c $<
+floating_from_chars.o: floating_from_chars.cc
+	$(CXXCOMPILE) -mabi=ibmlongdouble $(LONG_DOUBLE_128_FLAGS) -c $<
+endif
+
 # AM_CXXFLAGS needs to be in each subdirectory so that it can be
 # modified in a per-library or per-sub-library way.  Need to manually
 # set this option because CONFIG_CXXFLAGS has to be after
diff --git a/libstdc++-v3/src/c++17/Makefile.in b/libstdc++-v3/src/c++17/Makefile.in
index ce08eb3ff11..ccae721ab3f 100644
--- a/libstdc++-v3/src/c++17/Makefile.in
+++ b/libstdc++-v3/src/c++17/Makefile.in
@@ -262,6 +262,8 @@ LIBS = @LIBS@
 LIBTOOL = @LIBTOOL@
 LIPO = @LIPO@
 LN_S = @LN_S@
+LONG_DOUBLE_128_FLAGS = @LONG_DOUBLE_128_FLAGS@
+LONG_DOUBLE_ALT128_COMPAT_FLAGS = @LONG_DOUBLE_ALT128_COMPAT_FLAGS@
 LONG_DOUBLE_COMPAT_FLAGS = @LONG_DOUBLE_COMPAT_FLAGS@
 LTLIBICONV = @LTLIBICONV@
 LTLIBOBJS = @LTLIBOBJS@
@@ -401,11 +403,13 @@ toolexeclibdir = $(glibcxx_toolexeclibdir)
 @ENABLE_WERROR_TRUE@WERROR_FLAG = -Werror
 @ENABLE_EXTERN_TEMPLATE_FALSE@XTEMPLATE_FLAGS = 
 @ENABLE_EXTERN_TEMPLATE_TRUE@XTEMPLATE_FLAGS = -fno-implicit-templates
+@GLIBCXX_LDBL_ALT128_COMPAT_FALSE@LDBL_128_FLAGS = 
+@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@LDBL_128_FLAGS = $(LONG_DOUBLE_128_FLAGS)
 
 # These bits are all figured out from configure.  Look in acinclude.m4
 # or configure.ac to see how they are set.  See GLIBCXX_EXPORT_FLAGS.
 CONFIG_CXXFLAGS = \
-	$(SECTION_FLAGS) $(HWCAP_CFLAGS) -frandom-seed=$@
+	$(SECTION_FLAGS) $(HWCAP_CFLAGS) -frandom-seed=$@ $(LDBL_128_FLAGS)
 
 WARN_CXXFLAGS = \
 	$(WARN_FLAGS) $(WERROR_FLAG) -fdiagnostics-show-location=once 
@@ -752,6 +756,11 @@ uninstall-am:
 
 vpath % $(top_srcdir)/src/c++17
 
+@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@floating_from_chars.lo: floating_from_chars.cc
+@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@	$(LTCXXCOMPILE) -mabi=ibmlongdouble $(LONG_DOUBLE_128_FLAGS) -c $<
+@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@floating_from_chars.o: floating_from_chars.cc
+@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@	$(CXXCOMPILE) -mabi=ibmlongdouble $(LONG_DOUBLE_128_FLAGS) -c $<
+
 # Tell versions [3.59,3.63) of GNU make to not export all variables.
 # Otherwise a system limit (for SysV at least) may be exceeded.
 .NOEXPORT:
diff --git a/libstdc++-v3/src/c++17/floating_from_chars.cc b/libstdc++-v3/src/c++17/floating_from_chars.cc
index c279809cf35..a1943351493 100644
--- a/libstdc++-v3/src/c++17/floating_from_chars.cc
+++ b/libstdc++-v3/src/c++17/floating_from_chars.cc
@@ -44,6 +44,14 @@
 # include <xlocale.h>
 #endif
 
+#ifdef _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT
+#ifndef __LONG_DOUBLE_IBM128__
+#error "floating_from_chars.cc must be compiled with -mabi=ibmlongdouble"
+#endif
+// strtold for __ieee128
+extern "C" __ieee128 __strtoieee128(const char*, char**);
+#endif
+
 #if _GLIBCXX_HAVE_USELOCALE
 namespace std _GLIBCXX_VISIBILITY(default)
 {
@@ -316,6 +324,10 @@ namespace
 	  tmpval = std::strtod(str, &endptr);
 	else if constexpr (is_same_v<T, long double>)
 	  tmpval = std::strtold(str, &endptr);
+# ifdef _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT
+	else if constexpr (is_same_v<T, __ieee128>)
+	  tmpval = __strtoieee128(str, &endptr);
+# endif
 #else
 	tmpval = std::strtod(str, &endptr);
 #endif
@@ -332,7 +344,7 @@ namespace
 	const ptrdiff_t n = endptr - str;
 	if (conv_errno == ERANGE) [[unlikely]]
 	  {
-	    if (isinf(tmpval)) // overflow
+	    if (__builtin_isinf(tmpval)) // overflow
 	      ec = errc::result_out_of_range;
 	    else // underflow (LWG 3081 wants to set value = tmpval here)
 	      ec = errc::result_out_of_range;
@@ -469,6 +481,8 @@ from_chars(const char* first, const char* last, long double& value,
 }
 
 #ifdef _GLIBCXX_LONG_DOUBLE_COMPAT
+// Make std::from_chars for 64-bit long double an alias for the overload
+// for double.
 extern "C" from_chars_result
 _ZSt10from_charsPKcS0_ReSt12chars_format(const char* first, const char* last,
 					 long double& value,
@@ -476,6 +490,28 @@ _ZSt10from_charsPKcS0_ReSt12chars_format(const char* first, const char* last,
 __attribute__((alias ("_ZSt10from_charsPKcS0_RdSt12chars_format")));
 #endif
 
+#ifdef _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT
+from_chars_result
+from_chars(const char* first, const char* last, __ieee128& value,
+	   chars_format fmt) noexcept
+{
+  buffer_resource mr;
+  pmr::string buf(&mr);
+  size_t len = 0;
+  errc ec = errc::invalid_argument;
+  __try
+    {
+      if (const char* pat = pattern(first, last, fmt, buf)) [[likely]]
+	len = from_chars_impl(pat, value, ec);
+    }
+  __catch (const std::bad_alloc&)
+    {
+      fmt = chars_format{};
+    }
+  return make_result(first, len, fmt, ec);
+}
+#endif
+
 _GLIBCXX_END_NAMESPACE_VERSION
 } // namespace std
 #endif // _GLIBCXX_HAVE_USELOCALE
diff --git a/libstdc++-v3/src/c++20/Makefile.in b/libstdc++-v3/src/c++20/Makefile.in
index 0e2de19ae59..e6892d370fb 100644
--- a/libstdc++-v3/src/c++20/Makefile.in
+++ b/libstdc++-v3/src/c++20/Makefile.in
@@ -257,6 +257,8 @@ LIBS = @LIBS@
 LIBTOOL = @LIBTOOL@
 LIPO = @LIPO@
 LN_S = @LN_S@
+LONG_DOUBLE_128_FLAGS = @LONG_DOUBLE_128_FLAGS@
+LONG_DOUBLE_ALT128_COMPAT_FLAGS = @LONG_DOUBLE_ALT128_COMPAT_FLAGS@
 LONG_DOUBLE_COMPAT_FLAGS = @LONG_DOUBLE_COMPAT_FLAGS@
 LTLIBICONV = @LTLIBICONV@
 LTLIBOBJS = @LTLIBOBJS@
@@ -396,11 +398,13 @@ toolexeclibdir = $(glibcxx_toolexeclibdir)
 @ENABLE_WERROR_TRUE@WERROR_FLAG = -Werror
 @ENABLE_EXTERN_TEMPLATE_FALSE@XTEMPLATE_FLAGS = 
 @ENABLE_EXTERN_TEMPLATE_TRUE@XTEMPLATE_FLAGS = -fno-implicit-templates
+@GLIBCXX_LDBL_ALT128_COMPAT_FALSE@LDBL_128_FLAGS = 
+@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@LDBL_128_FLAGS = $(LONG_DOUBLE_128_FLAGS)
 
 # These bits are all figured out from configure.  Look in acinclude.m4
 # or configure.ac to see how they are set.  See GLIBCXX_EXPORT_FLAGS.
 CONFIG_CXXFLAGS = \
-	$(SECTION_FLAGS) $(HWCAP_CFLAGS) -frandom-seed=$@
+	$(SECTION_FLAGS) $(HWCAP_CFLAGS) -frandom-seed=$@ $(LDBL_128_FLAGS)
 
 WARN_CXXFLAGS = \
 	$(WARN_FLAGS) $(WERROR_FLAG) -fdiagnostics-show-location=once 
diff --git a/libstdc++-v3/src/c++98/Makefile.in b/libstdc++-v3/src/c++98/Makefile.in
index 5e9f2216203..ae75fbf4dd6 100644
--- a/libstdc++-v3/src/c++98/Makefile.in
+++ b/libstdc++-v3/src/c++98/Makefile.in
@@ -278,6 +278,8 @@ LIBS = @LIBS@
 LIBTOOL = @LIBTOOL@
 LIPO = @LIPO@
 LN_S = @LN_S@
+LONG_DOUBLE_128_FLAGS = @LONG_DOUBLE_128_FLAGS@
+LONG_DOUBLE_ALT128_COMPAT_FLAGS = @LONG_DOUBLE_ALT128_COMPAT_FLAGS@
 LONG_DOUBLE_COMPAT_FLAGS = @LONG_DOUBLE_COMPAT_FLAGS@
 LTLIBICONV = @LTLIBICONV@
 LTLIBOBJS = @LTLIBOBJS@
@@ -417,11 +419,13 @@ toolexeclibdir = $(glibcxx_toolexeclibdir)
 @ENABLE_WERROR_TRUE@WERROR_FLAG = -Werror
 @ENABLE_EXTERN_TEMPLATE_FALSE@XTEMPLATE_FLAGS = 
 @ENABLE_EXTERN_TEMPLATE_TRUE@XTEMPLATE_FLAGS = -fno-implicit-templates
+@GLIBCXX_LDBL_ALT128_COMPAT_FALSE@LDBL_128_FLAGS = 
+@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@LDBL_128_FLAGS = $(LONG_DOUBLE_128_FLAGS)
 
 # These bits are all figured out from configure.  Look in acinclude.m4
 # or configure.ac to see how they are set.  See GLIBCXX_EXPORT_FLAGS.
 CONFIG_CXXFLAGS = \
-	$(SECTION_FLAGS) $(HWCAP_CFLAGS) -frandom-seed=$@
+	$(SECTION_FLAGS) $(HWCAP_CFLAGS) -frandom-seed=$@ $(LDBL_128_FLAGS)
 
 WARN_CXXFLAGS = \
 	$(WARN_FLAGS) $(WERROR_FLAG) -fdiagnostics-show-location=once 
diff --git a/libstdc++-v3/src/c++98/locale_init.cc b/libstdc++-v3/src/c++98/locale_init.cc
index c3841ccbd3c..77c6eecc1a3 100644
--- a/libstdc++-v3/src/c++98/locale_init.cc
+++ b/libstdc++-v3/src/c++98/locale_init.cc
@@ -57,8 +57,16 @@ _GLIBCXX_LOC_ID(_ZNSt8messagesIwE2idE);
 
 namespace
 {
-  const int num_facets = _GLIBCXX_NUM_FACETS + _GLIBCXX_NUM_UNICODE_FACETS
-    + (_GLIBCXX_USE_DUAL_ABI ? _GLIBCXX_NUM_CXX11_FACETS : 0);
+  const int num_facets = (
+      _GLIBCXX_NUM_FACETS + _GLIBCXX_NUM_CXX11_FACETS
+#ifdef _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT
+      + _GLIBCXX_NUM_LBDL_ALT128_FACETS
+#endif
+      )
+#ifdef _GLIBCXX_USE_WCHAR_T
+    * 2
+#endif
+    + _GLIBCXX_NUM_UNICODE_FACETS;
 
   __gnu_cxx::__mutex&
   get_locale_mutex()
@@ -559,6 +567,10 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 
 #endif
 
+#ifdef _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT
+    _M_init_extra_ldbl128(true);
+#endif
+
 #if _GLIBCXX_USE_DUAL_ABI
     facet* extra[] = { __npc, __mpcf, __mpct
 # ifdef  _GLIBCXX_USE_WCHAR_T
@@ -566,6 +578,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
 # endif
     };
 
+    // This call must be after creating all facets, as it sets caches.
     _M_init_extra(extra);
 #endif
 
diff --git a/libstdc++-v3/src/c++98/localename.cc b/libstdc++-v3/src/c++98/localename.cc
index 243acce164c..29f439ffa9a 100644
--- a/libstdc++-v3/src/c++98/localename.cc
+++ b/libstdc++-v3/src/c++98/localename.cc
@@ -171,8 +171,16 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
       }
   }
 
-const int num_facets = _GLIBCXX_NUM_FACETS + _GLIBCXX_NUM_UNICODE_FACETS
-  + (_GLIBCXX_USE_DUAL_ABI ? _GLIBCXX_NUM_CXX11_FACETS : 0);
+const int num_facets = (
+    _GLIBCXX_NUM_FACETS + _GLIBCXX_NUM_CXX11_FACETS
+#ifdef _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT
+    + _GLIBCXX_NUM_LBDL_ALT128_FACETS
+#endif
+    )
+#ifdef _GLIBCXX_USE_WCHAR_T
+  * 2
+#endif
+  + _GLIBCXX_NUM_UNICODE_FACETS;
 
   // Construct named _Impl.
   locale::_Impl::
@@ -284,6 +292,10 @@ const int num_facets = _GLIBCXX_NUM_FACETS + _GLIBCXX_NUM_UNICODE_FACETS
         _M_init_extra(&__cloc, &__clocm, __s, __smon);
 #endif
 
+#ifdef _GLIBCXX_LONG_DOUBLE_ALT128_COMPAT
+	_M_init_extra_ldbl128(false);
+#endif
+
 	locale::facet::_S_destroy_c_locale(__cloc);
 	if (__clocm != __cloc)
 	  locale::facet::_S_destroy_c_locale(__clocm);
diff --git a/libstdc++-v3/src/filesystem/Makefile.in b/libstdc++-v3/src/filesystem/Makefile.in
index 95657ca3343..74a6d2765fc 100644
--- a/libstdc++-v3/src/filesystem/Makefile.in
+++ b/libstdc++-v3/src/filesystem/Makefile.in
@@ -286,6 +286,8 @@ LIBS = @LIBS@
 LIBTOOL = @LIBTOOL@
 LIPO = @LIPO@
 LN_S = @LN_S@
+LONG_DOUBLE_128_FLAGS = @LONG_DOUBLE_128_FLAGS@
+LONG_DOUBLE_ALT128_COMPAT_FLAGS = @LONG_DOUBLE_ALT128_COMPAT_FLAGS@
 LONG_DOUBLE_COMPAT_FLAGS = @LONG_DOUBLE_COMPAT_FLAGS@
 LTLIBICONV = @LTLIBICONV@
 LTLIBOBJS = @LTLIBOBJS@
@@ -425,11 +427,13 @@ toolexeclibdir = $(glibcxx_toolexeclibdir)
 @ENABLE_WERROR_TRUE@WERROR_FLAG = -Werror
 @ENABLE_EXTERN_TEMPLATE_FALSE@XTEMPLATE_FLAGS = 
 @ENABLE_EXTERN_TEMPLATE_TRUE@XTEMPLATE_FLAGS = -fno-implicit-templates
+@GLIBCXX_LDBL_ALT128_COMPAT_FALSE@LDBL_128_FLAGS = 
+@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@LDBL_128_FLAGS = $(LONG_DOUBLE_128_FLAGS)
 
 # These bits are all figured out from configure.  Look in acinclude.m4
 # or configure.ac to see how they are set.  See GLIBCXX_EXPORT_FLAGS.
 CONFIG_CXXFLAGS = \
-	$(SECTION_FLAGS) $(HWCAP_CFLAGS) -frandom-seed=$@
+	$(SECTION_FLAGS) $(HWCAP_CFLAGS) -frandom-seed=$@ $(LDBL_128_FLAGS)
 
 WARN_CXXFLAGS = \
 	$(WARN_FLAGS) $(WERROR_FLAG) -fdiagnostics-show-location=once 
diff --git a/libstdc++-v3/testsuite/26_numerics/complex/abi_tag.cc b/libstdc++-v3/testsuite/26_numerics/complex/abi_tag.cc
index 2f8569eb8b9..bf2441320c6 100644
--- a/libstdc++-v3/testsuite/26_numerics/complex/abi_tag.cc
+++ b/libstdc++-v3/testsuite/26_numerics/complex/abi_tag.cc
@@ -8,7 +8,7 @@
 float (std::complex<float>::*p1)() const = &std::complex<float>::real;
 // { dg-final { scan-assembler "_ZNKSt7complexIdE4realB5cxx11Ev" } }
 double (std::complex<double>::*p2)() const = &std::complex<double>::real;
-// { dg-final { scan-assembler "_ZNKSt7complexI\[eg\]E4realB5cxx11Ev" } }
+// { dg-final { scan-assembler "_ZNKSt7complexI\(e\|g\|u9__ieee128\)E4realB5cxx11Ev" } }
 long double (std::complex<long double>::*p3)() const
   = &std::complex<long double>::real;
 // { dg-final { scan-assembler "_ZNKSt7complexIiE4realB5cxx11Ev" } }
@@ -18,7 +18,7 @@ int (std::complex<int>::*p4)() const = &std::complex<int>::real;
 float (std::complex<float>::*p5)() const = &std::complex<float>::imag;
 // { dg-final { scan-assembler "_ZNKSt7complexIdE4imagB5cxx11Ev" } }
 double (std::complex<double>::*p6)() const = &std::complex<double>::imag;
-// { dg-final { scan-assembler "_ZNKSt7complexI\[eg\]E4imagB5cxx11Ev" } }
+// { dg-final { scan-assembler "_ZNKSt7complexI\(e\|g\|u9__ieee128\)E4imagB5cxx11Ev" } }
 long double (std::complex<long double>::*p7)() const
   = &std::complex<long double>::imag;
 // { dg-final { scan-assembler "_ZNKSt7complexIiE4imagB5cxx11Ev" } }
diff --git a/libstdc++-v3/testsuite/Makefile.in b/libstdc++-v3/testsuite/Makefile.in
index 7418680e935..1aac7edff7f 100644
--- a/libstdc++-v3/testsuite/Makefile.in
+++ b/libstdc++-v3/testsuite/Makefile.in
@@ -216,6 +216,8 @@ LIBS = @LIBS@
 LIBTOOL = @LIBTOOL@
 LIPO = @LIPO@
 LN_S = @LN_S@
+LONG_DOUBLE_128_FLAGS = @LONG_DOUBLE_128_FLAGS@
+LONG_DOUBLE_ALT128_COMPAT_FLAGS = @LONG_DOUBLE_ALT128_COMPAT_FLAGS@
 LONG_DOUBLE_COMPAT_FLAGS = @LONG_DOUBLE_COMPAT_FLAGS@
 LTLIBICONV = @LTLIBICONV@
 LTLIBOBJS = @LTLIBOBJS@
@@ -358,11 +360,13 @@ toolexeclibdir = $(glibcxx_toolexeclibdir)
 @ENABLE_WERROR_TRUE@WERROR_FLAG = -Werror
 @ENABLE_EXTERN_TEMPLATE_FALSE@XTEMPLATE_FLAGS = 
 @ENABLE_EXTERN_TEMPLATE_TRUE@XTEMPLATE_FLAGS = -fno-implicit-templates
+@GLIBCXX_LDBL_ALT128_COMPAT_FALSE@LDBL_128_FLAGS = 
+@GLIBCXX_LDBL_ALT128_COMPAT_TRUE@LDBL_128_FLAGS = $(LONG_DOUBLE_128_FLAGS)
 
 # These bits are all figured out from configure.  Look in acinclude.m4
 # or configure.ac to see how they are set.  See GLIBCXX_EXPORT_FLAGS.
 CONFIG_CXXFLAGS = \
-	$(SECTION_FLAGS) $(HWCAP_CFLAGS) -frandom-seed=$@
+	$(SECTION_FLAGS) $(HWCAP_CFLAGS) -frandom-seed=$@ $(LDBL_128_FLAGS)
 
 WARN_CXXFLAGS = \
 	$(WARN_FLAGS) $(WERROR_FLAG) -fdiagnostics-show-location=once 
diff --git a/libstdc++-v3/testsuite/util/testsuite_abi.cc b/libstdc++-v3/testsuite/util/testsuite_abi.cc
index 33b9ec15935..75029549c0d 100644
--- a/libstdc++-v3/testsuite/util/testsuite_abi.cc
+++ b/libstdc++-v3/testsuite/util/testsuite_abi.cc
@@ -211,6 +211,7 @@ check_version(symbol& test, bool added)
       known_versions.push_back("GLIBCXX_3.4.28");
       known_versions.push_back("GLIBCXX_3.4.29");
       known_versions.push_back("GLIBCXX_LDBL_3.4.29");
+      known_versions.push_back("GLIBCXX_IEEE128_3.4.29");
       known_versions.push_back("CXXABI_1.3");
       known_versions.push_back("CXXABI_LDBL_1.3");
       known_versions.push_back("CXXABI_1.3.1");
@@ -226,6 +227,7 @@ check_version(symbol& test, bool added)
       known_versions.push_back("CXXABI_1.3.11");
       known_versions.push_back("CXXABI_1.3.12");
       known_versions.push_back("CXXABI_1.3.13");
+      known_versions.push_back("CXXABI_IEEE128_1.3.13");
       known_versions.push_back("CXXABI_TM_1");
       known_versions.push_back("CXXABI_FLOAT128");
     }
@@ -244,9 +246,11 @@ check_version(symbol& test, bool added)
 
       // Check that added symbols are added in the latest pre-release version.
       bool latestp = (test.version_name == "GLIBCXX_3.4.29"
-	  // XXX remove next line when GLIBCXX_3.4.30 is added and baselines
-	  // have been regenerated to include GLIBCXX_LDBL_3.4.29 symbols:
+	  // 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"
 		     || test.version_name == "CXXABI_1.3.13"
 		     || test.version_name == "CXXABI_FLOAT128"
 		     || test.version_name == "CXXABI_TM_1");
@@ -260,7 +264,17 @@ check_version(symbol& test, bool added)
 	  && test.demangled_name.find("std::__cxx11::") != 0)
 	{
 	  if (test.version_name.find("_LDBL_") == std::string::npos
-	      && test.version_name.find("_FLOAT128") == std::string::npos)
+	      && test.version_name.find("_FLOAT128") == std::string::npos
+	      && test.version_name.find("_IEEE128") == std::string::npos)
+	    test.version_status = symbol::incompatible;
+	}
+
+      // Check that IEEE128 long double compatibility symbols demangled as
+      // __ieee128 are put into some _LDBL_IEEE version name.
+      // XXX is this right? might not want *everything* for __ieee128 in here.
+      if (added && test.demangled_name.find("__ieee128") != std::string::npos)
+	{
+	  if (test.version_name.find("_IEEE128") == std::string::npos)
 	    test.version_status = symbol::incompatible;
 	}