[llvm-dev] Supporting libunwind on Windows 10 (32bit; 64bit) for MSVC and Clang
Ivan Serdyuk via llvm-dev
llvm-dev at lists.llvm.org
Sun Aug 16 16:17:18 PDT 2020
good to hear from you.
Thanks for the effort - I will test on 32bit and 64bit Windows 10.
I will report ASAP.
On Sun, Aug 16, 2020 at 8:42 PM Martin Storsjö <martin at martin.st> wrote:
> On Sat, 15 Aug 2020, Ivan Serdyuk wrote:
> > On Sat, Aug 15, 2020 at 8:39 PM Martin Storsjö <martin at martin.st> wrote:
> > Hi,
> > On Sat, 15 Aug 2020, Ivan Serdyuk wrote:
> > > Just as Shoaib said, libunwind only is useful in
> > environments
> > > that use
> > > the Itanium C++ ABI - there's really no use for it in an
> > MSVC
> > > context
> > > (either using MSVC or clang-cl to compile it).
> > >
> > > The particular linker error comes from the fact that
> > there's
> > > functions
> > > implemented in assembly, that expect the function name
> > to be
> > > mangled the
> > > itanium way, while the object files built by the
> > compiler expect
> > > the
> > > symbols to use the MSVC C++ name mangling, so there's an
> > > undefined
> > > reference.
> > >
> > >
> > > I see, thanks.
> > >
> > > Which options exist for MSVC, in sense an alternative to
> > libunwind and
> > > libbacktrace ?
> > Well for libunwind, there's really no use for it in an MSVC
> > setting. All
> > the unwinding functionality is already built into the operating
> > system,
> > available via the Rtl*Unwind* functions.
> > Martin,
> > you mean these functions
> > 2
> > ex
> > lunwind
> > ?
> Yes, those are the functions used for unwinding on windows.
> > For libbacktrace, I guess the _Unwind_Backtrace function in
> > libunwind
> > might work and be useful, even if the rest of libunwind doesn't
> > make sense
> > in such a context.
> Just FWIW, I made a RFC patch that fixes building libunwind in MSVC mode
> (still requiring clang-cl though), at https://reviews.llvm.org/D86041 -
> mostly just to show what it takes - not convinced that it necessarily is
> something that should be done.
> It does seem like _Unwind_Backtrace in libunwind doesn't work properly on
> x86_64 windows at the moment though, but on aarch64 it seems to do what
> one would expect.
> // Martin
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