GNU bug report logs - #61660
[feature request] optimization of case-lambda

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: lloda <lloda <at> sarc.name>
To: "bug-guile <at> gnu.org" <bug-guile <at> gnu.org>
Subject: [feature request] optimization of case-lambda
Date: Mon, 20 Feb 2023 18:56:25 +0100

On 3.0.9


> ,optimize ((case-lambda (() 0)))
= 0

but 

> ,optimize ((case-lambda (() 0) ((a) 1)))
= ((case-lambda (() 0) ((a) 1)))


The problem with this is that when the output of a macro contains case-lambda, recursive application results in geometrical increase of code size. It seems that it should be possible to resolve the application on the spot; at last to reduce the case-lambda to a simple lambda when the arity is available (which now only happens when the case-lambda contains a single clause).

Thanks

  Daniel

Message #8 received at 61660 <at> debbugs.gnu.org (full text, mbox):

From: lloda <lloda <at> sarc.name>
To: 61660 <at> debbugs.gnu.org
Subject: Re: [feature request] optimization of case-lambda
Date: Thu, 23 Feb 2023 20:00:04 +0100

[Message part 1 (text/plain, inline)]

Patch attached, tests tbd. Thoughts?

[0001-peval-reduces-some-inlined-case-lambda-calls.patch (application/octet-stream, attachment)]

Message #11 received at 61660 <at> debbugs.gnu.org (full text, mbox):

From: lloda <lloda <at> sarc.name>
To: 61660 <at> debbugs.gnu.org
Subject: Re: bug#61660: [feature request] optimization of case-lambda
Date: Fri, 24 Feb 2023 18:26:29 +0100

[Message part 1 (text/plain, inline)]

Fixed patch handling rest & #:optional, with test cases.

[0001-peval-reduces-some-inlined-case-lambda-calls.patch (application/octet-stream, attachment)]

Message #16 received at 61660 <at> debbugs.gnu.org (full text, mbox):

From: Ludovic Courtès <ludo <at> gnu.org>
To: lloda <lloda <at> sarc.name>
Cc: 61660 <at> debbugs.gnu.org
Subject: Re: bug#61660: [feature request] optimization of case-lambda
Date: Mon, 27 Feb 2023 11:11:29 +0100

Hi Daniel,

lloda <lloda <at> sarc.name> skribis:

> From 61ed612fb36108e395bdee4b1bbb46b49ef017b3 Mon Sep 17 00:00:00 2001
> From: Daniel Llorens <lloda <at> sarc.name>
> Date: Thu, 23 Feb 2023 17:38:10 +0100
> Subject: [PATCH] peval reduces some inlined case-lambda calls
>
> * module/language/tree-il/peval.scm (peval): Reduce multiple case lambda
>   in <call> trees according to the number of arguments. Do not try to
>   reduce case-lambda using keyword arguments.
> * test-suite/tests/peval.test: Tests.

[...]

> +++ b/module/language/tree-il/peval.scm
> @@ -1668,6 +1668,29 @@ top-level bindings from ENV and return the resulting expression."
>  
>                    (log 'inline-end result exp)
>                    result)))))
> +           (($ <lambda> src-proc meta orig-body)
> +            ;; If there are multiple cases and one matches nargs, omit all the others.
> +            (or (and
> +                 (lambda-case-alternate orig-body)
> +                 (let ((nargs (length orig-args)))
> +                   (let loop ((body orig-body))
> +                     (match body
> +                       (#f #f) ;; No matching case; an error.
> +                       (($ <lambda-case> src-case req opt rest kw inits gensyms case-body alt)
> +                        (cond (kw
> +                               ;; FIXME: Not handling keyword cases.
> +                               #f)

Maybe s/FIXME/XXX/ since it’s at most a limitation, certainly not a bug.

It LGTM and Andy already approved it on IRC, so go ahead!

Ludo’.

Message #21 received at 61660-done <at> debbugs.gnu.org (full text, mbox):

From: lloda <lloda <at> sarc.name>
To: Ludovic Courtès <ludo <at> gnu.org>
Cc: 61660-done <at> debbugs.gnu.org
Subject: Re: bug#61660: [feature request] optimization of case-lambda
Date: Mon, 27 Feb 2023 18:19:42 +0100

> On 27 Feb 2023, at 11:11, Ludovic Courtès <ludo <at> gnu.org> wrote:
> 
> Hi Daniel,
> 
> lloda <lloda <at> sarc.name> skribis:
> 
>> From 61ed612fb36108e395bdee4b1bbb46b49ef017b3 Mon Sep 17 00:00:00 2001
>> From: Daniel Llorens <lloda <at> sarc.name>
>> Date: Thu, 23 Feb 2023 17:38:10 +0100
>> Subject: [PATCH] peval reduces some inlined case-lambda calls
>> 
>> * module/language/tree-il/peval.scm (peval): Reduce multiple case lambda
>>  in <call> trees according to the number of arguments. Do not try to
>>  reduce case-lambda using keyword arguments.
>> * test-suite/tests/peval.test: Tests.
> 
> [...]
> 
>> +++ b/module/language/tree-il/peval.scm
>> @@ -1668,6 +1668,29 @@ top-level bindings from ENV and return the resulting expression."
>> 
>>                   (log 'inline-end result exp)
>>                   result)))))
>> +           (($ <lambda> src-proc meta orig-body)
>> +            ;; If there are multiple cases and one matches nargs, omit all the others.
>> +            (or (and
>> +                 (lambda-case-alternate orig-body)
>> +                 (let ((nargs (length orig-args)))
>> +                   (let loop ((body orig-body))
>> +                     (match body
>> +                       (#f #f) ;; No matching case; an error.
>> +                       (($ <lambda-case> src-case req opt rest kw inits gensyms case-body alt)
>> +                        (cond (kw
>> +                               ;; FIXME: Not handling keyword cases.
>> +                               #f)
> 
> Maybe s/FIXME/XXX/ since it’s at most a limitation, certainly not a bug.
> 
> It LGTM and Andy already approved it on IRC, so go ahead!
> 
> Ludo’.

Apologies for not seeing this earlier. Pushed to 3b47f87618047ebb8812788c64a44877a4f2e0dd. Thanks!

  - Daniel

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