[PATCH] D23378: Explicitly specify MSVC mangling of iostream globals

[Dave Lee via llvm-commits]

kastiglione created this revision.
kastiglione added reviewers: compnerd, EricWF, mclow.lists.
kastiglione added a subscriber: llvm-commits.

With MS ABI, the `char []` definition of iostream globals results in a mangled
symbols that don't match the mangled symbol of the declared stream type.

For example, `istream cin` mangles to:

    ?cin at __1@std@@3V?$basic_istream at DU?$char_traits at D@__1 at std@@@12 at A

but its definition in iostream.cpp is `char cin[sizeof(istream)]`, which
incorrectly mangles to:

    ?cin at __1@std@@3PADA

To work aound this issue, this change manually sets the symbol name using an
`__asm__` label, for win32 only.

https://reviews.llvm.org/D23378

Files:
  src/iostream.cpp

Index: src/iostream.cpp
===================================================================
--- src/iostream.cpp
+++ src/iostream.cpp
@@ -14,32 +14,64 @@
 _LIBCPP_BEGIN_NAMESPACE_STD
 
 #ifndef _LIBCPP_HAS_NO_STDIN
-_ALIGNAS_TYPE (istream)  _LIBCPP_FUNC_VIS char cin [sizeof(istream)];
-_ALIGNAS_TYPE (__stdinbuf<char> ) static char __cin [sizeof(__stdinbuf <char>)];
+_ALIGNAS_TYPE (istream) _LIBCPP_FUNC_VIS char cin[sizeof(istream)]
+#if defined(_WIN32)
+__asm__("?cin at __1@std@@3V?$basic_istream at DU?$char_traits at D@__1 at std@@@12 at A")
+#endif
+;
+_ALIGNAS_TYPE (__stdinbuf<char> ) static char __cin[sizeof(__stdinbuf <char>)];
 static mbstate_t mb_cin;
-_ALIGNAS_TYPE (wistream) _LIBCPP_FUNC_VIS char wcin [sizeof(wistream)];
-_ALIGNAS_TYPE (__stdinbuf<wchar_t> ) static char __wcin [sizeof(__stdinbuf <wchar_t>)];
+_ALIGNAS_TYPE (wistream) _LIBCPP_FUNC_VIS char wcin[sizeof(wistream)]
+#if defined(_WIN32)
+__asm__("?wcin at __1@std@@3V?$basic_istream at _WU?$char_traits at _W@__1 at std@@@12 at A")
+#endif
+;
+_ALIGNAS_TYPE (__stdinbuf<wchar_t> ) static char __wcin[sizeof(__stdinbuf <wchar_t>)];
 static mbstate_t mb_wcin;
 #endif
 
 #ifndef _LIBCPP_HAS_NO_STDOUT
-_ALIGNAS_TYPE (ostream)  _LIBCPP_FUNC_VIS char cout[sizeof(ostream)];
+_ALIGNAS_TYPE (ostream) _LIBCPP_FUNC_VIS char cout[sizeof(ostream)]
+#if defined(_WIN32)
+__asm__("?cout at __1@std@@3V?$basic_ostream at DU?$char_traits at D@__1 at std@@@12 at A")
+#endif
+;
 _ALIGNAS_TYPE (__stdoutbuf<char>) static char __cout[sizeof(__stdoutbuf<char>)];
 static mbstate_t mb_cout;
-_ALIGNAS_TYPE (wostream) _LIBCPP_FUNC_VIS char wcout[sizeof(wostream)];
+_ALIGNAS_TYPE (wostream) _LIBCPP_FUNC_VIS char wcout[sizeof(wostream)]
+#if defined(_WIN32)
+__asm__("?wcout at __1@std@@3V?$basic_ostream at _WU?$char_traits at _W@__1 at std@@@12 at A")
+#endif
+;
 _ALIGNAS_TYPE (__stdoutbuf<wchar_t>) static char __wcout[sizeof(__stdoutbuf<wchar_t>)];
 static mbstate_t mb_wcout;
 #endif
 
-_ALIGNAS_TYPE (ostream)  _LIBCPP_FUNC_VIS char cerr[sizeof(ostream)];
+_ALIGNAS_TYPE (ostream) _LIBCPP_FUNC_VIS char cerr[sizeof(ostream)]
+#if defined(_WIN32)
+__asm__("?cerr at __1@std@@3V?$basic_ostream at DU?$char_traits at D@__1 at std@@@12 at A")
+#endif
+;
 _ALIGNAS_TYPE (__stdoutbuf<char>) static char __cerr[sizeof(__stdoutbuf<char>)];
 static mbstate_t mb_cerr;
-_ALIGNAS_TYPE (wostream) _LIBCPP_FUNC_VIS char wcerr[sizeof(wostream)];
+_ALIGNAS_TYPE (wostream) _LIBCPP_FUNC_VIS char wcerr[sizeof(wostream)]
+#if defined(_WIN32)
+__asm__("?wcerr at __1@std@@3V?$basic_ostream at _WU?$char_traits at _W@__1 at std@@@12 at A")
+#endif
+;
 _ALIGNAS_TYPE (__stdoutbuf<wchar_t>) static char __wcerr[sizeof(__stdoutbuf<wchar_t>)];
 static mbstate_t mb_wcerr;
 
-_ALIGNAS_TYPE (ostream)  _LIBCPP_FUNC_VIS char clog[sizeof(ostream)];
-_ALIGNAS_TYPE (wostream) _LIBCPP_FUNC_VIS char wclog[sizeof(wostream)];
+_ALIGNAS_TYPE (ostream) _LIBCPP_FUNC_VIS char clog[sizeof(ostream)]
+#if defined(_WIN32)
+__asm__("?clog at __1@std@@3V?$basic_ostream at DU?$char_traits at D@__1 at std@@@12 at A")
+#endif
+;
+_ALIGNAS_TYPE (wostream) _LIBCPP_FUNC_VIS char wclog[sizeof(wostream)]
+#if defined(_WIN32)
+__asm__("?wclog at __1@std@@3V?$basic_ostream at _WU?$char_traits at _W@__1 at std@@@12 at A")
+#endif
+;
 
 ios_base::Init __start_std_streams;
 


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