[Bug lto/54231] LTO generates code for the wrong CPU if different options used

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54231

--- Comment #12 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-08-13 11:58:33 UTC ---
(In reply to comment #9)
> (In reply to comment #8)
> > If you do something like
> > 
> >  gcc -c t1.c -mavx -flto
> >  gcc -c t2.c -msse2 -flto
> >  gcc t1.o t2.o -flto
> > 
> > then the link step will use -mavx -msse2, that is, target options are
> > concatenated.
> 
> Indeed.
> 
> What I'm asking for is that each source file be compiled with its own target
> options. I realise this is a request for enhancement, though.

Yes, there are similar option-related bugs for this.  Note somebody needs
to sit down and document the desired semantics of combining translation
units T1 and T2, compiled with different options OP1 and OP2, at link-time with
options OP3.  Desired semantics including which cross-file optimizations
(inlining?) are possible.