From: Andy Moreton <andrewjmoreton@gmail.com>
To: emacs-devel@gnu.org
Subject: Re: Using __builtin_expect (likely/unlikely macros)
Date: Thu, 18 Apr 2019 18:56:22 +0100 [thread overview]
Message-ID: <vz1k1fr5ha1.fsf@gmail.com> (raw)
In-Reply-To: 313555ec-aef0-4892-f312-1a5d263a5df6@cs.ucla.edu
On Thu 18 Apr 2019, Paul Eggert wrote:
> On 4/18/19 6:47 AM, Andy Moreton wrote:
>> Please don't use this macro, as it makes the code much less readable.
>>
>> It is reasonable to have a macro that combines the '_Noreturn' and
>> 'ATTRIBUTE_COLD' decorations, but that should not be combined with the
>> return type.
>
> Actually I first tried it the way that you suggested, but found that
> having a single macro improved readability for me, partly because
> _Noreturn functions don't return anything so their return type doesn't
> matter except for static type checking. 'AVOID' lets a traditionalist
> reader easily see that the type 'void' is intended, while also connoting
> that the function is rarely used because calls to it are normally
> avoided. (I tried to shoehorn "cold" and "does not return" into the
> macro's name too, but couldn't come up with anything better than
> "AVOID_SKIJUMP". :-)
I had an entirely different impression: AVOID is a weird name for a
return type, so where is the return type, and does this even compile ?
In addition, using this macro makes it entirely non-obvious that the
function has a "_NoReturn" specifier, making it harder for the reader to
understand the intended semantics.
I have no objection to adding "noreturn" and "noreturn_cold" macros if
that helps, but the "AVOID" macro should be avoided as harmful to
readability.
AndyM
next prev parent reply other threads:[~2019-04-18 17:56 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-15 0:15 Using __builtin_expect (likely/unlikely macros) Alex Gramiak
2019-04-15 1:18 ` Paul Eggert
2019-04-15 3:11 ` Alex Gramiak
2019-04-15 4:41 ` Paul Eggert
2019-04-16 0:16 ` Alex Gramiak
2019-04-16 2:34 ` Eli Zaretskii
2019-04-16 5:33 ` Alex Gramiak
2019-04-16 15:23 ` Eli Zaretskii
2019-04-16 15:47 ` Alex Gramiak
2019-04-16 3:42 ` Paul Eggert
2019-04-16 13:05 ` Stefan Monnier
2019-04-16 15:22 ` Paul Eggert
2019-04-16 16:10 ` Alex Gramiak
2019-04-16 17:54 ` Paul Eggert
2019-04-16 20:50 ` Alex Gramiak
2019-04-16 21:11 ` Alex Gramiak
2019-04-16 21:27 ` Stefan Monnier
2019-04-16 21:27 ` Konstantin Kharlamov
2019-04-18 8:25 ` Paul Eggert
2019-04-18 8:43 ` Konstantin Kharlamov
2019-04-18 13:47 ` Andy Moreton
2019-04-18 17:27 ` Paul Eggert
2019-04-18 17:56 ` Andy Moreton [this message]
2019-04-18 19:32 ` Paul Eggert
2019-04-19 13:45 ` Alex Gramiak
2019-04-19 13:58 ` Konstantin Kharlamov
2019-04-19 14:45 ` Alex Gramiak
2019-04-19 17:33 ` Paul Eggert
2019-04-19 20:53 ` Alex Gramiak
2019-04-20 0:05 ` Alan Mackenzie
2019-04-20 0:42 ` Paul Eggert
2019-04-20 19:46 ` Alan Mackenzie
2019-04-20 15:29 ` Andy Moreton
2019-04-20 15:57 ` Paul Eggert
2019-04-20 16:03 ` Eli Zaretskii
2019-04-20 16:11 ` Paul Eggert
2019-04-20 16:18 ` Eli Zaretskii
2019-04-20 16:57 ` Paul Eggert
2019-04-20 17:22 ` Eli Zaretskii
2019-04-20 19:13 ` Paul Eggert
2019-04-20 16:28 ` Óscar Fuentes
2019-04-20 18:58 ` Paul Eggert
2019-04-20 19:35 ` Óscar Fuentes
2019-04-20 22:54 ` Paul Eggert
2020-04-15 3:14 ` John Carter
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