[libc++] Instantiate additional <iostream> members in the dylib
This commit adds new explicit instantiations for some classes in <iostream>
in the library. This is done after noticing that many programs that use
streams end up containing weak definitions of these classes, which has a
negative impact on both code size and load times (due to the need to
resolve weak symbols at load time). Note that we are just adding the
additional explicit instantiations for the `char` specializations, since
the `wchar_t` specializations are not used as often, and as a result there
wouldn't be a clear benefit.
This change is not an ABI break, since we are just adding additional
symbols.
Differential Revision: https://reviews.llvm.org/D90677
GitOrigin-RevId: 997d41cdec536a0b632505d9b0c4ab5dec5d7d12
diff --git a/include/__config b/include/__config
index 4a15730..a85c074 100644
--- a/include/__config
+++ b/include/__config
@@ -130,6 +130,13 @@
use _LIBCPP_DEPRECATED_ABI_DISABLE_PAIR_TRIVIAL_COPY_CTOR instead
#endif
+#if defined(_LIBCPP_BUILDING_LIBRARY) || defined(_LIBCPP_ABI_UNSTABLE) || _LIBCPP_ABI_VERSION >= 2
+// Enable additional explicit instantiations of iostreams components. This
+// reduces the number of weak definitions generated in programs that use
+// iostreams by providing a single strong definition in the shared library.
+# define _LIBCPP_ABI_ENABLE_ADDITIONAL_IOSTREAM_EXPLICIT_INSTANTIATIONS_1
+#endif
+
#define _LIBCPP_CONCAT1(_LIBCPP_X,_LIBCPP_Y) _LIBCPP_X##_LIBCPP_Y
#define _LIBCPP_CONCAT(_LIBCPP_X,_LIBCPP_Y) _LIBCPP_CONCAT1(_LIBCPP_X,_LIBCPP_Y)
diff --git a/include/fstream b/include/fstream
index 98897f4..1e2d607 100644
--- a/include/fstream
+++ b/include/fstream
@@ -241,7 +241,7 @@
return open(__p.c_str(), __mode);
}
#endif
- _LIBCPP_INLINE_VISIBILITY
+ inline _LIBCPP_INLINE_VISIBILITY
basic_filebuf* __open(int __fd, ios_base::openmode __mode);
#endif
basic_filebuf* close();
@@ -571,7 +571,8 @@
}
template <class _CharT, class _Traits>
-_LIBCPP_INLINE_VISIBILITY basic_filebuf<_CharT, _Traits>*
+inline _LIBCPP_INLINE_VISIBILITY
+basic_filebuf<_CharT, _Traits>*
basic_filebuf<_CharT, _Traits>::__open(int __fd, ios_base::openmode __mode) {
basic_filebuf<_CharT, _Traits>* __rt = 0;
if (__file_ == 0) {
@@ -1757,6 +1758,12 @@
this->setstate(ios_base::failbit);
}
+#if defined(_LIBCPP_ABI_ENABLE_ADDITIONAL_IOSTREAM_EXPLICIT_INSTANTIATIONS_1)
+_LIBCPP_EXTERN_TEMPLATE(class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS basic_ifstream<char>)
+_LIBCPP_EXTERN_TEMPLATE(class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS basic_ofstream<char>)
+_LIBCPP_EXTERN_TEMPLATE(class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS basic_filebuf<char>)
+#endif
+
_LIBCPP_END_NAMESPACE_STD
_LIBCPP_POP_MACROS
diff --git a/include/sstream b/include/sstream
index 042766c..1439d9c 100644
--- a/include/sstream
+++ b/include/sstream
@@ -836,6 +836,13 @@
__x.swap(__y);
}
+#if defined(_LIBCPP_ABI_ENABLE_ADDITIONAL_IOSTREAM_EXPLICIT_INSTANTIATIONS_1)
+_LIBCPP_EXTERN_TEMPLATE(class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS basic_stringbuf<char>)
+_LIBCPP_EXTERN_TEMPLATE(class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS basic_stringstream<char>)
+_LIBCPP_EXTERN_TEMPLATE(class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS basic_ostringstream<char>)
+_LIBCPP_EXTERN_TEMPLATE(class _LIBCPP_EXTERN_TEMPLATE_TYPE_VIS basic_istringstream<char>)
+#endif
+
_LIBCPP_END_NAMESPACE_STD
_LIBCPP_POP_MACROS