Re: Possible wrong-way example in gcc4-4-2 documentation of __builtin_expect

[Jonathan Wakely <jwakely dot gcc at gmail dot com>]

On 21 December 2011 18:03, Jonathan Wakely wrote:
> On 21 December 2011 02:00, Jim Avera wrote:
>> Ok, here is a patch which improves the example:
>>
>> --- gcc/doc/extend.texi.ORIG??? 2011-12-20 17:35:32.236578828 -0800
>> +++ gcc/doc/extend.texi??? 2011-12-20 17:37:10.460583316 -0800
>> @@ -7932,7 +7932,7 @@
>>
>> ?@smallexample
>> ?if (__builtin_expect (ptr != NULL, 1))
>> -? error ();
>> +? ptr->do_something();
>> ?@end smallexample
>>
>> ?@noindent
>
> In order to follow the GCC coding style (a space between the function
> name and opening parenthesis) and to match the first example for
> __builtin_expect, I propose this patch instead:
>
> Index: extend.texi
> ===================================================================
> --- extend.texi (revision 182452)
> +++ extend.texi (working copy)
> @@ -7932,7 +7932,7 @@ expressions for @var{exp}, you should us
>
> ?@smallexample
> ?if (__builtin_expect (ptr != NULL, 1))
> - ?error ();
> + ?ptr->foo ();
> ?@end smallexample
>
> ?@noindent

Then again, maybe foo (*ptr) would be even better, so it looks more
like C not C++ code.

> I've CC'd the gcc-patches list, which is where patches should be sent
> for review, and included a ChangeLog entry:
>
> 2011-12-21 ?Jonathan Wakely ?<jwakely.gcc@gmail.com>
> ? ? ? ? ? ?Jim Avera ?<james_avera@yahoo.com>
>
> ? ? ? ?* doc/extend.texi (__builtin_expect): Improve example.
>
>
> Can I get approval to check this in to trunk?
>
>
>
>>
>>
>> ________________________________
>> From: Jonathan Wakely <jwakely.gcc@gmail.com>
>> To: Segher Boessenkool <segher@kernel.crashing.org>
>> Cc: james_avera@yahoo.com; gcc@gcc.gnu.org
>> Sent: Tuesday, December 20, 2011 5:22 AM
>> Subject: Re: Possible wrong-way example in gcc4-4-2 documentation of __builtin_expect
>>
>> On 20 December 2011 12:49, Segher Boessenkool wrote:
>>>
>>> The point of the example is that you cannot write
>>>
>>> ? ? ? ? ?if (__builtin_expect (ptr, 1))
>>> ? ? ? ? ? ?error ();
>>>
>>> so the "!= NULL" is important here. ?But you are right that
>>> "error ()" is a bit unexpected; care to send a patch that changes
>>> it to e.g. "do_something ()"?
>>
>> or even ptr->do_something() since that would depend on the value of ptr