[TODO] config/auto/alignptrs.pm: inform user to use --64compat for parrot

[jkeenan]

This TODO statement is found within config/auto/alignptrs.pm:

inform the user to use --64compat for parrot. Milestone v2.6

Perl::Critic flagged it and so we must create a ticket for it.

[doughera]

I don't understand this ticket at all. What is this hypothetical "--64compat" ?

I do see this puzzling note in auto/alignptrs.pm:

# On 8-byte ptr_alignment we cannot read 4-byte pbc's. Warn the user about it.

But surely this is just a limitation of the current pbc reader code. I don't see why the appropriate fix would be to ask 32-bit systems to pay a penalty here instead of changing the reader code. It is certainly possible to read 4-byte integers on an 8-byte system. You may have to read and copy the data, but it can be done. If there's a penalty to be paid, I think it's fair to have the foreign reader pay it.

[jkeenan]

Will CC the original poster of that comment. (My role was just to convert it into Trac ticket.)

[jkeenan]

Replying to doughera:

I don't understand this ticket at all. What is this hypothetical "--64compat" ?

Andy,

At some point since I filed this ticket, the original TODO comment vanished. So the original rationale for this ticket is largely gone.

Grepping the repository, the only reference to --64compat I could find was in ./docs/pdds/pdd13_bytecode.pod in a section on Packfiles:

       So we relax pointer alignment strictness on Sparc64, but may add a
       "--64compat" option to parrot in the future to produce 8-byte aligned
       data.  Operations on aligned pointers are much faster than on un-
       aligned pointers.

I do see this puzzling note in auto/alignptrs.pm: # On 8-byte ptr_alignment we cannot read 4-byte pbc's. Warn the user about it.

This comment has also disappeared.

So I propose we close this ticket and open a new one to discuss any related issues.

If there is no objection, I'll do so in 2-3 days.

Thank you very much.
kid51

[doughera]

On Fri, 18 Dec 2009, Parrot wrote:
>  Replying to [comment:2 doughera]:
>  > I don't understand this ticket at all.  What is this hypothetical "--
>  64compat" ?
> 
>  Andy,
> 
>  At some point since I filed this ticket, the original ''TODO'' comment
>  vanished.  So the original rationale for this ticket is largely gone.

Agreed.  If parrot ever wants to implement reading and writing .pbc files 
across different architectures, the alignment issues that originally 
inspired this ticket will probably re-surface, but appropriate tickets can 
be opened then, when there's a well-understood plan.  Close this one.

-- 
    Andy Dougherty		doughera@lafayette.edu

[jkeenan]

No objection and -- better yet -- a ++ from Andy D! Closing ticket.

Thank you very much.
kid51