On 16 Dec 2014, at 17:15, David Chisnall <[email protected]> wrote:
> 
> On 16 Dec 2014, at 16:04, Dimitry Andric <[email protected]> wrote:
>> This is precisely why the libs should go into /usr/lib/private, so as to
>> avoid collisions with any upstream libraries installed by e.g. ports (or
>> when you manually run "make install" after building).
> 
> That's still potentially an issue if we add local tools that use libclang 
> APIs (which we may well do).
> 
>> I'm not sure we want to go the 'libbsdfoo.so' route again, as Baptiste
>> tried this before, and seems to have reversed it again. :)
> 
> Upstream doesn't call it libclang (that's the name of the library with a 
> stable C ABI, which is why I'd like us not to confuse it with something with 
> a library with an unstable C++ API).  They do produce a libLLVM.so from the 
> LLVM builds and work is underway to have shared library builds for clang.
> 
> libLLVM.so could potentially be in /usr/lib in 11 if we have a packaged base 
> system, as it would allow us to have different .so versions installed if 
> things demanded them.  The point releases guarantee backwards ABI 
> compatibility, so we can still upgrade to them if required.

Unfortunately we already imported quite a lot of ABI-breaking bug fixes.
I would prefer only our own tools to be linked against the "FreeBSD"
version of libllvm.so/libwhatever.so.


> That said, I agree with the general idea, but one of the first things
>> we should decide is whether this will be optional or not.  Having to
>> maintain yet another WITH_CLANG_FOO option is burdensome...
> 
> I agree.  I'd quite like to see performance numbers for the compiler.  I 
> think I saw about a 10% overhead for buildworld last time I tried, but that 
> was a couple of years ago.

There is already a WITH_SHARED_TOOLCHAIN option, that defaults to off,
but I have had it on since approximately the time Kostik added it.  I
might just have gotten used to the overhead, if any...

I would like to do a bit of testing with that, but my TODO list is
rather full at this point, working on the 3.5.0 import. :)

-Dimitry

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