Re: [jamboost] problem with -fPIC flag

From: Toon Knapen (toon.knapen_at_[hidden])
Date: 2005-01-20 08:28:44

Vladimir Prus wrote:

>>The solution I see is adding following to gcc.jam
>><quote>
>>if [ os.name ] != CYGWIN && [ os.name ] != NT
>>{
>> flags gcc.compile OPTIONS <link>shared/<main-target-type>LIB : -fPIC ;
>>+ flags gcc.compile OPTIONS <link>shared/<main-target-type>OBJ : -fPIC ;
>>}
>></quote>
>>
>>Can anybody tell me if this is indeed the way to go?
> 
> 
> Looks like a reasonable solution for me. The downside is that now all targets 
> defined with "obj" will be compiled with -fPIC, not only when they are part 
> of a shared library.

Indeed I see that happen although I did not suspect it. IIUC the 
'<link>shared' means that it should only be applied _if_ the OBJ is used 
for a shared library, right ?

> 
> This can be avoided by using some new <shared-linkable> property but target 
> paths will become even longer. When I introduce automatic computation if 
> properties relevant to a target, this might not be a problem, but until now, 
> the above code seems the most reasonable.
> 

Considering -fPIC can have a considereable influence on performance, I 
guess we don't want to use the flag for compiling objects for static 
libraries. Or do you think this is not an issue ?