Date: Wed, 27 May 1998 04:04:17 +0800 From: Peter Wemm <peter@netplex.com.au> To: sos@FreeBSD.ORG Cc: eivind@yes.no (Eivind Eklund), nate@mt.sri.com, current@FreeBSD.ORG Subject: Re: Switching default compiler (was Re: Fix for undefined "__error" and discussion of shared object versioning) Message-ID: <199805262004.EAA28582@spinner.netplex.com.au> In-Reply-To: Your message of "Tue, 26 May 1998 21:11:48 %2B0200." <199805261911.VAA23526@sos.freebsd.dk>
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S ren Schmidt wrote:
> In reply to Eivind Eklund who wrote:
> > On Tue, May 26, 1998 at 12:40:15PM -0600, Nate Williams wrote:
> > > Eivind Eklund writes:
> > > > On Tue, May 26, 1998 at 11:50:53AM -0600, Nate Williams wrote:
> > > > > > Personally I'd prefer to use TenDRA if at all possible. It seems t
o
> > > > > > be much better than GCC when you look at error control etc.
> > > > >
> > > > > Can it do shlibs?
> > > >
> > > > I don't know - is there much special it would have to do?
> > >
> > > Generating PIC code is a big prerequisite, so the assembly it generates
> > > must be capable of being relocated. I'm not 100% sure if this is a
> > > function of the compiler, but given that GCC1 couldn't do it and GCC2
> > > could, I suspect it's a function of the compiler.
> >
> > It can do PIC for ELF on Linux. I suspect this means that we can make
> > it do PIC for ELF on FreeBSD, too. I don't know if making it do PIC
> > for a.out would be significantly different.
>
> No, its the same thing....
Almost the same thing, but there are differences.. ELF supports (and
requires) PIC jumps, our a.out doesn't. (jumps and calls have an absolute
address, branches do not. Both require relocation for PIC to work). Have
a look at the cerror stuff in libc. I don't think any of the compilers
generate code that will run into this though. So yes, at compiler->
assembler level, a.out and ELF have identical PIC output (this was the easy
part in dual-format gcc :-).
Cheers,
-Peter
--
Peter Wemm <peter@netplex.com.au> Netplex Consulting
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