[lto] Reader-writer compatibility?

[lto] Reader-writer compatibility?

[Ryan Mansfield]

Is it required that the same compiler that generated lto objects be used 
to read them? I've come across a couple ICEs with the current revision 
reading lto objects created by a slightly older version  but same 
configuration. Is this simply invalid usage of my part?

Regards,

Ryan Mansfield

Re: [lto] Reader-writer compatibility?

[Diego Novillo]

On Tue, Sep 1, 2009 at 11:42, Ryan Mansfield<rmansfield@qnx.com> wrote:
> Is it required that the same compiler that generated lto objects be used to
> read them? I've come across a couple ICEs with the current revision reading
> lto objects created by a slightly older version  but same configuration. Is
> this simply invalid usage of my part?

It's likely.  How much drift between the two revisions?  Can you
recreate the ICE if you write and read with the exact same revision?
If so, please file a bug.


Diego.

Re: [lto] Reader-writer compatibility?

[Ryan Mansfield]

Diego Novillo wrote:
> On Tue, Sep 1, 2009 at 11:42, Ryan Mansfield<rmansfield@qnx.com> wrote:
>> Is it required that the same compiler that generated lto objects be used to
>> read them? I've come across a couple ICEs with the current revision reading
>> lto objects created by a slightly older version  but same configuration. Is
>> this simply invalid usage of my part?
> 
> It's likely.  How much drift between the two revisions?  Can you
> recreate the ICE if you write and read with the exact same revision?
> If so, please file a bug.

The objects were created with rev 151111 and being read using 151271.
No, I can't reproduce the ICE using the same version.

Thanks for confirming this is not expected to work.

Regards,

Ryan Mansfield

Re: [lto] Reader-writer compatibility?

[Frank Ch. Eigler]

Ryan Mansfield <rmansfield@qnx.com> writes:

> The objects were created with rev 151111 and being read using 151271.
> No, I can't reproduce the ICE using the same version.
> Thanks for confirming this is not expected to work.

Is it the intent that this work properly in the future?  It is not
absurd to imagine that someone with a treeful of .o files might suffer
an unexpected compiler upgrade before a later reuse/relink attempt.

- FChE

Re: [lto] Reader-writer compatibility?

[Diego Novillo]

On Tue, Sep 1, 2009 at 14:32, Frank Ch. Eigler<fche@redhat.com> wrote:
> Ryan Mansfield <rmansfield@qnx.com> writes:
>
>> The objects were created with rev 151111 and being read using 151271.
>> No, I can't reproduce the ICE using the same version.
>> Thanks for confirming this is not expected to work.
>
> Is it the intent that this work properly in the future?

Yes.  We likely want to maintain streamer compatibility within the
same major release.  I actually don't think we'll change the bytecode
format too much.  It will mostly depend on how much gimple changes in
a single release.

Clearly, we need better version drift detection.

Diego.

Re: [lto] Reader-writer compatibility?

[Toon Moene]

Diego Novillo wrote:

> On Tue, Sep 1, 2009 at 11:42, Ryan Mansfield<rmansfield@qnx.com> wrote:

>> Is it required that the same compiler that generated lto objects be used to
>> read them? I've come across a couple ICEs with the current revision reading
>> lto objects created by a slightly older version  but same configuration. Is
>> this simply invalid usage of my part?
> 
> It's likely.  How much drift between the two revisions?  Can you
> recreate the ICE if you write and read with the exact same revision?
> If so, please file a bug.

Please add version checking.  gfortran's module files (extension .mod) 
that are generated from source files that contain MODULE ... END MODULE 
constructs *now* contain version information.

I still get occasionally beaten by picking up modules from 4.3 that 
don't have this - you'll get all sorts of unintelligible error messages 
that just distract from what's really wrong.

-- 
Toon Moene - e-mail: toon@moene.org - phone: +31 346 214290
Saturnushof 14, 3738 XG  Maartensdijk, The Netherlands
At home: http://moene.org/~toon/
Progress of GNU Fortran: http://gcc.gnu.org/gcc-4.5/changes.html

Re: [lto] Reader-writer compatibility?

[Richard Guenther]

On Tue, Sep 1, 2009 at 10:55 PM, Toon Moene<toon@moene.org> wrote:
> Diego Novillo wrote:
>
>> On Tue, Sep 1, 2009 at 11:42, Ryan Mansfield<rmansfield@qnx.com> wrote:
>
>>> Is it required that the same compiler that generated lto objects be used
>>> to
>>> read them? I've come across a couple ICEs with the current revision
>>> reading
>>> lto objects created by a slightly older version  but same configuration.
>>> Is
>>> this simply invalid usage of my part?
>>
>> It's likely.  How much drift between the two revisions?  Can you
>> recreate the ICE if you write and read with the exact same revision?
>> If so, please file a bug.
>
> Please add version checking.  gfortran's module files (extension .mod) that
> are generated from source files that contain MODULE ... END MODULE
> constructs *now* contain version information.
>
> I still get occasionally beaten by picking up modules from 4.3 that don't
> have this - you'll get all sorts of unintelligible error messages that just
> distract from what's really wrong.

There is bytecode version information - we just didn't bother to bump
it on the branch.

Richard.