[PATCH] D89518: [windows-itanium] Add Windows Itanium How-To Guide

Tue Nov 17 03:59:59 PST 2020

bd1976llvm marked an inline comment as done.
bd1976llvm added inline comments.

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Comment at: llvm/docs/HowToBuildWindowsItaniumPrograms.rst:57
+there is no declaration available to the compiler so this can't be done. To allow
+programs to link we currently rely on the -lldmingw switch in LLD to auto-import
+references to __cxxabiv1::__class_type_info pointers (see: https://reviews.llvm.org/D43184
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mstorsjo wrote:
> bd1976llvm wrote:
> > mstorsjo wrote:
> > > Fwiw, since release 11, you can enable autoimporting alone without enabling the rest of the mingw specific quirks, with the `-autoimport` flag. Also see D89006 for a recent related fixup.
> > Thanks. This is a nice improvement!
> It seems nicer, yes, but it also gives the false impression that you can enable and use it without the corresponding mingw runtime, so that's not ideal either. I'm pondering if I should spend more effort on making it harder to fall into that trap.
Interestingly, If I try to use -auto-import in LLD it does diagnose the problem. I see errors like:

"lld-link: error: automatic dllimport of _ZTVN10__cxxabiv117__class_type_infoE in plugin-f2d5e0.o requires pseudo relocations"

This doesn't seem to happen with -lldmingw.

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https://reviews.llvm.org/D89518