[Mesa-dev] [PATCH] configure: Trust LLVM >= 4.0 llvm-config --libs for shared libraries

Michel Dänzer michel at daenzer.net
Mon Aug 14 08:11:19 UTC 2017

On 11/08/17 02:13 AM, Jan Vesely wrote:
> On Thu, 2017-08-10 at 17:45 +0100, Emil Velikov wrote:
>> Topic for another thread:
>> There's been a handful of issues reported with BUILD_SHARED_LIBS=ON.
>> Should we consider that unsupported setup and error out?

I don't really see the point / gain in that.

> please no.
> BUILD_SHARED_LIBS=ON is a must for development setup
> debug build of clang + llvm takes 1.4GB, each. Having a ~2.8GB library,
> is a really bad idea for testing,

Not sure what testing you're referring to exactly, but IME application
startup takes on the order of hundreds of ms longer when linking against
the individual shared libraries than when linking against the single
one. It's one reason why distros building with BUILD_SHARED_LIBS=ON is
just silly.

> not to mention linking time that goes well into minutes for even a
> minor change in LLVM.

It can certainly take a long time, but I don't remember it taking
minutes. Are you counting the time for linking other libraries / tools
against libLLVM-*.0*.so as well? You can avoid that by explicitly
building only the library, e.g.:

 ninja [...] lib/libLLVM-6.0svn.so

Also, using the gold or lld linker might help.

Earthling Michel Dänzer               |               http://www.amd.com
Libre software enthusiast             |             Mesa and X developer

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