Re: Linux doesn't follow x86/x86-64 ABI wrt direction flag

Joe Buck
2008-03-05T20:42:57Z

On Wed, Mar 05, 2008 at 09:38:13PM +0100, Michael Matz wrote:
> Hi,
>
> On Wed, 5 Mar 2008, Aurelien Jarno wrote:
>
> > > So I think gcc at least needs an *option* to revert to the old behavior,
> > > and there's a good argument to make it the default for now, at least for
> > > x86/x86-64 on Linux.
> >
> > And for other kernels. I tested OpenBSD 4.1, FreeBSD 6.3, NetBSD 4.0,
> > they have the same behaviour as Linux, that is they don't clear DF
> > before calling the signal handler.
>
> Sigh. We could perhaps insert a cld for all functions which can be
> recognized as possible signal handlers and call other unknown or string
> functions. But it's probably even faster to emit cld in front of the
> inline copies of mem functions again :-(

Yes, if there are four kernels that get it "wrong", that effectively means
that the ABI document doesn't describe reality and gcc has to adjust.