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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)
In-reply-to: Your message of "Tue, 26 May 1998 21:11:48 +0200."
<199805261911.VAA23526@sos.freebsd.dk>
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Date: Wed, 27 May 1998 04:04:17 +0800
From: Peter Wemm <peter@netplex.com.au>
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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 s=
eems 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 gener=
ates
> > > 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 GC=
C2
> > > 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 mak=
e
> > 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 absolut=
e
address, branches do not. Both require relocation for PIC to work). Hav=
e
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 ea=
sy
part in dual-format gcc :-).
Cheers,
-Peter
--
Peter Wemm <peter@netplex.com.au> Netplex Consulting
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