[PATCH] cmake: Export symbols in all tools that support plugins.

[Will Dietz]

Committed as r196447, thanks!

~Will

On Wed, Dec 4, 2013 at 5:06 PM, Reid Kleckner <rnk at google.com> wrote:
> Go for it.  Somebody could play around with protected ELF visibility if they
> want to win back the ~3%.
> http://www.airs.com/blog/archives/307
>
>
> On Wed, Dec 4, 2013 at 2:56 PM, Will Dietz <w at wdtz.org> wrote:
>>
>> Interesting.
>>
>> Before this change 'ninja check' takes 1:47 on my machine, after the
>> patch takes 1:50.
>> (Minimum of 5 runs, times were pleasantly consistent, "-j1" added to
>> LIT_ARGS)
>>
>> Note that in Make we presently export symbols in llc and lli, so we
>> already take this hit on
>> 'make check' when not using CMake.  llvm-stress doesn't currently
>> export, but it should
>> (since it supports plugins) but that shouldn't impact the testing use
>> case.
>>
>> Accordingly IMO a configuration option for managing test times isn't worth
>> it,
>> but it might be useful for making the installed (stripped) binaries
>> smaller.
>> If this route is taken, I'd suggest disabling plugin loading in a
>> friendlier
>> way than removing -export-dynamic and giving undefined reference errors
>> should a user attempt to load a plugin.
>>
>> Anyway, updated patch attached to address the inconsistencies.  Okay to
>> commit?
>>
>> ~Will
>>
>>
>> On Wed, Dec 4, 2013 at 12:58 PM, Rafael Espíndola
>> <rafael.espindola at gmail.com> wrote:
>> > On 4 December 2013 13:49, Reid Kleckner <rnk at google.com> wrote:
>> >> Can you make sure that this doesn't slow down 'make check' on Linux too
>> >> much?  I worry that we --export-dynamic for llc, lots of symbol uses
>> >> will
>> >> become dynamic PLT lookups and startup time will regress.
>> >>
>> >
>> > Good point. If it does, we should probably add a --enable-plugins (and
>> > cmake equivalent) and replace CLANG_IS_PRODUCTION with it.
>> >
>> > Cheers,
>> > Rafael
>
>