[llvm-dev] Supporting libunwind on Windows 10 (32bit; 64bit) for MSVC and Clang
Ivan Serdyuk via llvm-dev
llvm-dev at lists.llvm.org
Sat Aug 15 14:14:25 PDT 2020
On Sat, Aug 15, 2020 at 8:39 PM Martin Storsjö <martin at martin.st> wrote:
> 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.
you mean these functions
> 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.
please share your vision/propose some plan.
> I haven't tested this function on windows though, and
> it'd require you to fix the linker error one way or another.
> Another alternative, requiring much less code, would be to just extract
> the SEH version of _Unwind_Backtrace function from libgcc . I think
> that function is fairly independent from the rest of libgcc and from the
> rest of the surrounding file, and only calls Windows system APIs.
Well, adding committers to the discussion.
Richard, Tristan, Bernd, Jon - please verify/elaborate.
Thanks in advance.
> // Martin
>  https://github.com/gcc-mirror/gcc/blob/master/libgcc/unwind-seh.c#L434
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