Re: please drop whatever you're doing and add -fPIC to all your rockspecs.

[Stefan <stefan@...>]

Jeff Pohlmeyer wrote:
> On Sat, Feb 27, 2010 at 1:58 PM, Hisham wrote:
>
> > Does anyone have anything against LuaRocks adding -fPIC to CFLAGS on
> > every architecture?
>
>
> I have no idea about any of this stuff, but I did find this page:
>
>   http://lua-users.org/wiki/BuildingModules
>
> It says:
>
> "Avoid -fPIC since it comes with a big performance penalty on some
> RISC architectures (Sparc in particular)."
>
> So if -fPIC  should be used everywhere, maybe that sentence could use
> some clarification.
>
> - Jeff

This recent discussion prompted me to do some research about the 
subject. Found a very in-depth explanation of modern linkers and 
position dependent/independent code, along with relocators.

http://www.airs.com/blog/archives/41

I would call into question the claim: "Unfortunately -fpic comes with a 
*significant* performance loss on x86." (emphasis is mine) -> can anyone 
verify this on modern CPUs with some benchmarks?

Also, even if -fPIC is bad on only a small minority of systems, would 
not one want it for the default, and have it taken off only in those 
rare circumstances?

To me this whole premise (trying to avoid -fPIC like the flu in a build 
system) just seems like a very effective way to hit oneself on the head 
with a hammer. Sure, it might help keep you focused sometimes, but most 
of the time it is simply not a good idea...