Re: [Gcl-devel] New random tester failures

[Paul F. Dietz]

Camm Maguire wrote:
> Greetings, and thanks again as always, Paul!
>
> I have a fix for this, as yet uncommitted.  But I realize as I chase
> these down that I need very frequently to rebind arguments in a let*
> using gensymmed temporaries, and this has reminded me of a
> longstanding performance problem with this I'd like to fix.  In brief,
> doing this destroys any type information that may exist for the
> rebound variable via declaration or proclamation.
>
> I have plan A and plan B, and would like to solicit your opinion:
>
> A) When the compiler expands macros, or funcalls compiler macro
> functions, detect whether new bindings are introduced, and if so,
> recursively macroexpand the form, determine whether the binding is
> changed in the body of the new let, and if not, add a declaration read
> from a stack when appropriate at the head of the let.  Advantage --
> centralized -- disadvantage -- could be slightly tricky.


Isn't this just a special case of the more general procedure of adding
declarations for locals that are not later assigned?  There's no need for
those locals to have been introduced by a macro.


> B) Push declarations onto the environment passed to macroexpand, and
> rewrite each relevant macro (mostly setf expanders and compiler
> macros) to insert the declarations where appropriate.
>
> I'm leaning toward A, but am quite open minded.

Either one sounds ok, although the first could be made more general.

> Remember your aluding to an Allegro proposal by Duane Rettig (?) when
> we discussed this before, but never could find this.

It's in the ACL 7.0 release notes.

http://www.franz.com/support/documentation/7.0/doc/environments.htm

        Paul