From: "Basil L. Contovounesios" <basil@contovou.net>
To: Philip Kaludercic <philipk@posteo.net>
Cc: Felician Nemeth <felician.nemeth@gmail.com>, emacs-devel@gnu.org
Subject: Re: (byte-compile '(append '(1 2) '(3 4)))
Date: Sat, 16 Mar 2024 14:23:08 +0100 [thread overview]
Message-ID: <87wmq2nweb.fsf@epfl.ch> (raw)
In-Reply-To: <87cyrubazs.fsf@posteo.net> (Philip Kaludercic's message of "Sat, 16 Mar 2024 12:46:15 +0000")
Philip Kaludercic [2024-03-16 12:46 +0000] wrote:
> I am not sure what the danger is in the case of constant, quoted lists,
> but I am not familiar with the byte compiler either. It seems like this
>
> diff --git a/lisp/emacs-lisp/byte-opt.el b/lisp/emacs-lisp/byte-opt.el
> index f75be3f71ad..e6f18590705 100644
> --- a/lisp/emacs-lisp/byte-opt.el
> +++ b/lisp/emacs-lisp/byte-opt.el
> @@ -1599,6 +1599,12 @@ byte-optimize-append
> (cdr args))
> (cdr newargs)))
>
> + ;; (append '(C1...) ... '(C2...)) -> (append C1... ... C2...)
> + ((cl-loop for arg in args
> + always (and (eq (car arg) 'quote)
> + (proper-list-p (cdr arg))))
> + `',(mapcan #'cadr args))
> +
> ;; non-terminal arg
> ((cdr args)
> (cond
>
>
> would do the trick, and the byte-code is even better:
>
> byte code:
> args: nil
> 0 constant (1 2 3 4)
> 1 return
Is this correct? According to its docstring, append's last argument
must be eq to the tail of its return value.
--
Basil
next prev parent reply other threads:[~2024-03-16 13:23 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <87v8j28c2x.fsf@betli.tmit.bme.hu>
[not found] ` <874jdipfp5.fsf@posteo.net>
[not found] ` <87cys6t734.fsf@betli.tmit.bme.hu>
[not found] ` <87r0gmnjq4.fsf@posteo.net>
[not found] ` <87o7bprr04.fsf@betli.tmit.bme.hu>
[not found] ` <87bk7p57yz.fsf@posteo.net>
2024-03-16 12:16 ` (byte-compile '(append '(1 2) '(3 4))) Felician Nemeth
2024-03-16 12:46 ` Philip Kaludercic
2024-03-16 13:23 ` Basil L. Contovounesios [this message]
2024-03-16 13:45 ` Felician Nemeth
2024-03-16 13:55 ` Philip Kaludercic
2024-03-16 23:42 ` Basil L. Contovounesios
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