[cfe-dev] unraveling libcxxabi/libcxx

David Fang fang at csl.cornell.edu
Wed Apr 3 15:30:40 PDT 2013

Hi Howard and all,

I was able to build libcxxabi and libcxx on powerpc-darwin8.
I've documented my experiences here. 

I might need some explanation for how the test suite is expected to be 
run.  The 'testit' script in libcxxabi doesn't even refer to the 
libc++abi.dylib that was built, so there must be some implicit 
assumptions in this script?

I'm hoping there's a way to test the dylib before having to install it.
Likewise with libc++.


> On Apr 2, 2013, at 8:35 PM, David Fang <fang at csl.cornell.edu> wrote:
>> Hi,
>> 	I'm currently looking into porting libcxx to an ancient system (powerpc-darwin8), and I noticed that libcxx depends on libcxxabi. However, libcxxabi's sources include headers like <exception> which are expected to be in some C++ library.  Does it (mutually) depend on libcxx? Maybe this was obvious, but I take it libcxxabi needs a c++11 compiler to build, correct?  (This would be fine, as I have stage-1 clang built from gcc-4.0/libstdc++.)  Does one {libcxx,libcxxabi} need to be installed before the other, or should they be built cross-referencing each others include dirs?  In terms of shared-library dependencies, libcxx should link to libcxxabi, right?
>> Is there better documentation somewhere that I don't know about?
>> All I see are html pages at http://libcxxabi.llvm.org and http://libcxx.llvm.org/.
> Contributions to better documentation (and your experiences in doing this) are welcome. :-)
> Yes, libcxxabi is the lower-level library.  libcxx should link to libcxxabi.
> Yes, currently libcxxabi is using -std=c++0x and probably needs it, though I can't think offhand of a specific need.  If you need to, try changing that to -std=c++03.  If there's any breakage it will almost certainly be compile-time breakage.  So that is a safe experiment.
> libcxxabi is designed to be ABI compatible with a gcc-4.2 era libstdc++.  And therefore could almost certainly use a libstdc++-4.2 set of headers if need be to build against (another untested theory).
> As libcxxabi is the lower-level library, I would go with installing that first.  But understand you're traversing territory where few have gone before.
> Keep us posted, and blogs of your experience which might help future porters are welcome.
> Howard

David Fang

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