shared libraries and exceptions, templates and the export keyword

shared libraries and exceptions, templates and the export keyword

[Smithers, Kit]

I note from the web pages for gcc2.95 that there is a caveat about the use
of shared libraries and exceptions on some platforms (including powerpc
which I assume includes RS6000's).

In addition the "export" keyword for templates isn't (I believe) implemented
yet. 

Can anyone provide some more information about either of these and if they
are likely to be fixed/supported. Bearing in mind that there's a (small)
possibility of getting cash out of my employer to assist in their
development. I'm not so much interested about work-arounds for which there's
plenty of info already but in the actual status of gcc with regards to these
two items.

Thanks

-- 
Kit Smithers

Re: shared libraries and exceptions, templates and the export keyword

[David Edelsohn]

>>>>> "Smithers, Kit" writes:

Kit> I note from the web pages for gcc2.95 that there is a caveat about the use
Kit> of shared libraries and exceptions on some platforms (including powerpc
Kit> which I assume includes RS6000's).

	Exception handling using the gcc exception handling mechanisms (as
opposed to setjmp/longjmp) are not implemented for RS/6000 AIX.
Exceptions may not be able to propagate through shared libraries at
present.  AIX already has some generic functionality for walking the stack
and the TOC calling convention needs unique support to maintain
addressibility when walking through frames that cross modules.  There does
not seem to be a lot of understanding or interest among those working on
exception handling to leverage AIX's builtin facilities to make an
implementation of this functionality efficient.

David

Re: shared libraries and exceptions, templates and the export keyword

[Richard Henderson]

On Thu, Jul 08, 1999 at 05:43:32PM -0400, David Edelsohn wrote:
> There does
> not seem to be a lot of understanding or interest among those working on
> exception handling to leverage AIX's builtin facilities to make an
> implementation of this functionality efficient.

Most of the other non-free systems are in the same boat.

It would perhaps be nice to use the vendor mechanisms, but
that leads to N completely different implementations, which
makes things a lot harder inside gcc.

I guess there's nothing to say but "we're taking patches".


r~

Re: shared libraries and exceptions, templates and the export keyword

[Martin v. Loewis]

Kit,

I cannot comment on the exception problem on RS 6000; I don't have
access to such a computer.

> In addition the "export" keyword for templates isn't (I believe) implemented
> yet. 

Right. And it is unlikely that it is implemented anytime soon, as this
is a major undertaking. Most likely, an implementation will be
restricted to a subset of the targets first; namely those that use ELF
as an object file, or one with similar capabilities.

Regards,
Martin

shared libraries and exceptions, templates and the export keyword

[Smithers, Kit]

I note from the web pages for gcc2.95 that there is a caveat about the use
of shared libraries and exceptions on some platforms (including powerpc
which I assume includes RS6000's).

In addition the "export" keyword for templates isn't (I believe) implemented
yet. 

Can anyone provide some more information about either of these and if they
are likely to be fixed/supported. Bearing in mind that there's a (small)
possibility of getting cash out of my employer to assist in their
development. I'm not so much interested about work-arounds for which there's
plenty of info already but in the actual status of gcc with regards to these
two items.

Thanks

-- 
Kit Smithers

Re: shared libraries and exceptions, templates and the export keyword

[Martin v. Loewis]

Kit,

I cannot comment on the exception problem on RS 6000; I don't have
access to such a computer.

> In addition the "export" keyword for templates isn't (I believe) implemented
> yet. 

Right. And it is unlikely that it is implemented anytime soon, as this
is a major undertaking. Most likely, an implementation will be
restricted to a subset of the targets first; namely those that use ELF
as an object file, or one with similar capabilities.

Regards,
Martin

Re: shared libraries and exceptions, templates and the export keyword

[David Edelsohn]

>>>>> "Smithers, Kit" writes:

Kit> I note from the web pages for gcc2.95 that there is a caveat about the use
Kit> of shared libraries and exceptions on some platforms (including powerpc
Kit> which I assume includes RS6000's).

	Exception handling using the gcc exception handling mechanisms (as
opposed to setjmp/longjmp) are not implemented for RS/6000 AIX.
Exceptions may not be able to propagate through shared libraries at
present.  AIX already has some generic functionality for walking the stack
and the TOC calling convention needs unique support to maintain
addressibility when walking through frames that cross modules.  There does
not seem to be a lot of understanding or interest among those working on
exception handling to leverage AIX's builtin facilities to make an
implementation of this functionality efficient.

David

Re: shared libraries and exceptions, templates and the export keyword

[Richard Henderson]

On Thu, Jul 08, 1999 at 05:43:32PM -0400, David Edelsohn wrote:
> There does
> not seem to be a lot of understanding or interest among those working on
> exception handling to leverage AIX's builtin facilities to make an
> implementation of this functionality efficient.

Most of the other non-free systems are in the same boat.

It would perhaps be nice to use the vendor mechanisms, but
that leads to N completely different implementations, which
makes things a lot harder inside gcc.

I guess there's nothing to say but "we're taking patches".


r~