* Re: [Emacs-diffs] feature/byte-switch a75d080: * src/bytecode.c: Refactor to follow GNU coding standards
[not found] ` <20170211125134.80F4325FCF@vcs0.savannah.gnu.org>
@ 2017-02-11 15:46 ` Stefan Monnier
2017-02-11 18:13 ` Vibhav Pant
0 siblings, 1 reply; 2+ messages in thread
From: Stefan Monnier @ 2017-02-11 15:46 UTC (permalink / raw)
To: emacs-devel; +Cc: Vibhav Pant
> + if (BYTE_CODE_SAFE)
> + eassert (!NILP (HASH_HASH (h, i)));
Declaring that non-full hashtables are "dangerous" is rather annoying.
In this case, I think we can do better:
Lisp_Object hash_code
= make_number (h->test.hashfn (&h->test, v1));
this then lets us use EQ (hash_code, ...) instead of hash_code == XUINT
(...) which not only correctly skips nil hashes but might even be ever
so slightly faster (both use == on the same size of integers, but the
former avoids the cost of XUINT).
Stefan
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [Emacs-diffs] feature/byte-switch a75d080: * src/bytecode.c: Refactor to follow GNU coding standards
2017-02-11 15:46 ` [Emacs-diffs] feature/byte-switch a75d080: * src/bytecode.c: Refactor to follow GNU coding standards Stefan Monnier
@ 2017-02-11 18:13 ` Vibhav Pant
0 siblings, 0 replies; 2+ messages in thread
From: Vibhav Pant @ 2017-02-11 18:13 UTC (permalink / raw)
To: Stefan Monnier; +Cc: emacs-devel@gnu.org
On Sat, Feb 11, 2017 at 9:16 PM, Stefan Monnier
<monnier@iro.umontreal.ca> wrote:
>> + if (BYTE_CODE_SAFE)
>> + eassert (!NILP (HASH_HASH (h, i)));
>
> Declaring that non-full hashtables are "dangerous" is rather annoying.
> In this case, I think we can do better:
>
> Lisp_Object hash_code
> = make_number (h->test.hashfn (&h->test, v1));
>
> this then lets us use EQ (hash_code, ...) instead of hash_code == XUINT
> (...) which not only correctly skips nil hashes but might even be ever
> so slightly faster (both use == on the same size of integers, but the
> former avoids the cost of XUINT).
Indeed. Since we only use hash_code when h->test.cmpfn is not NULL,
calculating it only then would also make sense (at the cost of an
extra NULL check).
--
Vibhav Pant
vibhavp@gmail.com
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[not found] ` <20170211125134.80F4325FCF@vcs0.savannah.gnu.org>
2017-02-11 15:46 ` [Emacs-diffs] feature/byte-switch a75d080: * src/bytecode.c: Refactor to follow GNU coding standards Stefan Monnier
2017-02-11 18:13 ` Vibhav Pant
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