Re: [PATCH] doc: discourage use of __attribute__((optimize())) in production code

["Manuel López-Ibáñez" <lopezibanez@gmail.com>]

On 14/12/15 16:40, Markus Trippelsdorf wrote:
> On 2015.12.14@11:20 -0500, Trevor Saunders wrote:
>> On Mon, Dec 14, 2015@10:01:27AM +0100, Richard Biener wrote:
>>> On Sun, Dec 13, 2015@9:03 PM, Andi Kleen <andi@firstfloor.org> wrote:
>>>> Markus Trippelsdorf <markus@trippelsdorf.de> writes:
>>>>
>>>>> Many developers are still using __attribute__((optimize())) in
>>>>> production code, although it quite broken.
>>>>
>>>> Wo reads documentation? @) If you want to discourage it better warn once
>>>> @runtime.
>>>
>>> We're also quite heavily using it in LTO internally now.
>>
>> besides that does this really make sense?  I suspect very few people are
>> using this for the fun of it.  I'd guess most usage is to disable
>> optimizations to work around bugs, or maybe trying to get a very hot
>> function optimized more.  Either way I suspect its only used by people
>> with good reason and this would just really iritate them.
>
> Well, if you look@bugzilla you'll find several wrong code bugs caused
> by this attribute, e.g.: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59262
>
> Also Richi stated in the past (I quote):
> »I consider the optimize attribute code seriously broken and
> unmaintained (but sometimes useful for debugging - and only that).«
>
> https://gcc.gnu.org/ml/gcc/2012-07/msg00201.html

It is even a FAQ: https://gcc.gnu.org/wiki/FAQ#optimize_attribute_broken

Cheers,

Manuel.