Date: Tue, 29 Nov 2016 17:56:46 -0500 From: Ed Maste <emaste@freebsd.org> To: Mark Millard <markmi@dsl-only.net> Cc: FreeBSD Toolchain <freebsd-toolchain@freebsd.org>, FreeBSD PowerPC ML <freebsd-ppc@freebsd.org>, Dimitry Andric <dim@freebsd.org> Subject: Re: WITH_LLVM_LIBUNWIND vs. WITHOUT_LLVM_LIBUNWIND, clang vs. gcc (such as devel/powerpc64-xtoolchain-gcc ): What is intended to be required for C++ exceptions to work? Message-ID: <CAPyFy2ArXUYsyTC9LY_CqbU3FLVV0TeV%2BSandqd-SpPGMBL6Cg@mail.gmail.com> In-Reply-To: <750FCE4D-F25B-46E1-9383-B8A94AAA8792@dsl-only.net> References: <750FCE4D-F25B-46E1-9383-B8A94AAA8792@dsl-only.net>
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On 29 November 2016 at 16:46, Mark Millard <markmi@dsl-only.net> wrote: > > > Summary: Does using clang 3.9.0 as the system compiler imply one should or > must (eventually?) use WITH_LLVM_LIBUNWIND to have C++ exceptions work? > > Do WITH_LLVM_LIBUNWIND and WITHOUT_LLVM_LIBUNWIND have the same criteria > for what dwarfdump should show for the exception information (if the > information to be shown is to be correct/sufficient for libunwind)? It does not. It should be possible to build a functional system both WITH_ and WITHOUT_LLVM_LIBUNWIND. The compiler is unaware of the _LLVM_LIBUNWIND setting. Both unwind libraries use the same unwind data. Eventually new features may show up in Clang and LLVM's libunwind (and new versions of GNU's unwinder) that won't work with the old unwinder. > Your answer's detail might indicate that I've misdirected the llvm folks > in submittals like https://llvm.org/bugs/show_bug.cgi?id=26844 . > > There is also the question of if/when llvm's libunwind is ready to be used > for powerpc64 or powerpc (or . . .) if there are architecture specifics > involved. That answer might determine when C++ exceptions work (and so > when devel/kyua might have a chance to work) and is sort of separate from > the main question here but is still of interest overall. > > Should powerpc64 and powerpc clang 3.9.0 testing be using > WITH_LLVM_LIBUNWIND ? WITHOUT_LLVM_LIBUNWIND ? Both? For testing I think WITH_LLVM_LIBUNWIND is the interesting case. My eventual goal is to have a functioning Clang, LLD, LLDB, libunwind, and ELF Tool Chain on all of our supported architectures.
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