[PATCH][RFC] Come up with -flive-patching master option.

[Martin Liška]

On 11/10/18 6:03 PM, Jan Hubicka wrote:
>> On 11/9/18 6:43 PM, Qing Zhao wrote:
>>> Hi, Martin,
>>>
>>> thanks a lot for the previous two new options for live-patching. 
>>>
>>>
>>> I have two more questions below:
>>
>> Hello.
>>
>>>
>>> 1. do we still need new options to disable the following:
>>>    A. unreachable code/variable removal? 
>>
>> I hope it's guarded with newly added option -fipa-reference-addressable. Correct me
>> if I'm wrong.
> 
> No, unreachable code removal is still independent (we track all
> references and can remove variable with address taken)
> If you really want to keep all the symbols, you probably can mark
> everything as force_output like flag_keep_inline functions is
> implemented.  I am not sure how practical it would be though.

I see, that's probably not practical to start using a function/variable that
wasn't used before a live patch.

Martin

> 
> Honza
>>
>>>    B. Visibility changes with -flto and/or -fwhole-program?
>>
>> The options are not used in linux kernel, thus I didn't consider.
>>
>>>
>>> 2. for this new patch, could you please explain a little bit more on the problem?
>>
>> We want to enable a single option that will disable all possible (and future) optimizations
>> that influence live patching.
>>
>> Martin
>>
>>>
>>> Thanks.
>>>
>>> Qing
>>>
>>>> On Nov 9, 2018, at 9:33 AM, Martin Liška <mliska@suse.cz> wrote:
>>>>
>>>> Hi.
>>>>
>>>> After I added 2 new options, I would like to include a new master option.
>>>> It's minimal version which only disables optimizations that we are aware of
>>>> and can potentially cause problems for live-patching.
>>>>
>>>> Martin
>>>> <0001-Come-up-with-fvectorized-functions.patch>
>>>
>>