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Re: Compiling Elisp to a native code with a GCC plugin
From: |
David Kastrup |
Subject: |
Re: Compiling Elisp to a native code with a GCC plugin |
Date: |
Fri, 17 Sep 2010 15:31:26 +0200 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/24.0.50 (gnu/linux) |
Lars Magne Ingebrigtsen <address@hidden> writes:
> "Stephen J. Turnbull" <address@hidden> writes:
>
>> > Does everything have to be slow? :-)
>>
>> Wrong polarity. The question here is "does everything have to be
>> fast?", and the answer is "no -- I mean, HELL NO!"
>>
>> Make your case that this function needs to be faster than a pure elisp
>> implementation.
>
> I think that's a rather ... stunning approach, but might explain many
> things about XEmacs.
>
> I've presented a use case, and I've demonstrated how all the alternative
> implementations are 50-150% slower than my suggested new implementation,
> and I've done the implementation, which turned out to be totally
> trivial.
Not really sure about that.
+ looking_at_literally (Lisp_Object string)
+ {
+ int start_byte = CHAR_TO_BYTE (PT);
+ int end_byte, end = PT + SCHARS (string);
PT + SCHARS (string) can overflow here. Better check first rather than
later whether ZV - PT < SCHARS (string).
Yes, I know that most-positive-fixnum <= MAX_INT/2, but just on
principle.
+ end_byte = CHAR_TO_BYTE (end);
+
+ if (! memcmp (SDATA (string), BYTE_POS_ADDR (start_byte),
+ end_byte - start_byte))
That is assuming that both string and buffer are identically encoded
(nowadays that likely means both have the same multibyteness).
--
David Kastrup
- Re: Compiling Elisp to a native code with a GCC plugin, (continued)
- Re: Compiling Elisp to a native code with a GCC plugin, Lars Magne Ingebrigtsen, 2010/09/16
- Re: Compiling Elisp to a native code with a GCC plugin, Stephen J. Turnbull, 2010/09/15
- Re: Compiling Elisp to a native code with a GCC plugin, David Kastrup, 2010/09/16
- Re: Compiling Elisp to a native code with a GCC plugin, Stephen J. Turnbull, 2010/09/16
- Re: Compiling Elisp to a native code with a GCC plugin, David Kastrup, 2010/09/16
- Re: Compiling Elisp to a native code with a GCC plugin, Lars Magne Ingebrigtsen, 2010/09/16
- Re: Compiling Elisp to a native code with a GCC plugin, Stephen J. Turnbull, 2010/09/17
- Re: Compiling Elisp to a native code with a GCC plugin, Lars Magne Ingebrigtsen, 2010/09/17
- Re: Compiling Elisp to a native code with a GCC plugin,
David Kastrup <=
- Re: Compiling Elisp to a native code with a GCC plugin, Lars Magne Ingebrigtsen, 2010/09/17
- Re: Compiling Elisp to a native code with a GCC plugin, David Kastrup, 2010/09/17
- Re: Compiling Elisp to a native code with a GCC plugin, Lars Magne Ingebrigtsen, 2010/09/17
- Re: Compiling Elisp to a native code with a GCC plugin, David Kastrup, 2010/09/17
- Re: Compiling Elisp to a native code with a GCC plugin, Lars Magne Ingebrigtsen, 2010/09/17
- Re: Compiling Elisp to a native code with a GCC plugin, Lars Magne Ingebrigtsen, 2010/09/17
- Re: Compiling Elisp to a native code with a GCC plugin, Eli Zaretskii, 2010/09/17
- Re: Compiling Elisp to a native code with a GCC plugin, David Kastrup, 2010/09/17
- Re: Compiling Elisp to a native code with a GCC plugin, Andreas Schwab, 2010/09/17
- Re: Compiling Elisp to a native code with a GCC plugin, David Kastrup, 2010/09/17