Re: [Tinycc-devel] -fPIC anyone?

[Michael Matz]

Hi,

On Tue, 27 Sep 2016, Jean-Claude Beaudoin wrote:

> Hello TCC devs,
> 
> I am starting an effort to implement -fPIC support for real in TCC.
> The target is to have TCC generate full fledged shared libraries
> on ELF platforms.

For which architectures?  For x86_64 that's already implemented.  On i386 
you can produce shared libraries but they contain .text relocations (i.e. 
are unshared at runtime).  Dunno about arm64.

> Any objection?  Any advice?
> 
> I noticed also that "constructors" have been at the top of the TODO list
> for ages now. If we are talking here of "__attribute__ ((constructor))"
> then I am definitely interested in knowing what is up with that too?

I'm guessing as well it's about the ctor and dtor attributes.  That's 
relatively easy to add: for all functions so marked you need to put 
addresses of them into a .init_array (.fini_array) section. (Or rather 
into ELF sections of type SHT_INIT_ARRAY or SHT_FINI_ARRAY, the name isn't 
relevant, but this one is customary).

The linker part of tcc also needs two additions: when the input objects 
contain sections of type SHT_INIT_ARRAY or SHT_FINI_ARRAY it needs to add 
{INIT,FINI}_ARRAY{,SZ} dynamic tags covering those.


Ciao,
Michael.