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

[Qing Zhao]

Hi,


Attached is the patch for new -flive-patching=[inline-only-static | inline-clone] master option.

'-flive-patching=LEVEL'
     Control GCC's optimizations to provide a safe compilation for
     live-patching.  Provides multiple-level control on how many of the
     optimizations are enabled by users' request.  The LEVEL argument
     should be one of the following:

     'inline-only-static'

          Only enable inlining of static functions, disable all other
          ipa optimizations/analyses.  As a result, when patching a
          static routine, all its callers need to be patches as well.

     'inline-clone'

          Only enable inlining and all optimizations that internally
          create clone, for example, cloning, ipa-sra, partial inlining,
          etc.; disable all other ipa optimizations/analyses.  As a
          result, when patching a routine, all its callers and its
          clones' callers need to be patched as well.

     When -flive-patching specified without any value, the default value
     is "inline-clone".

     This flag is disabled by default.

let me know your comments and suggestions on the implementation.

thanks a lot.

Qing

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> On Nov 12, 2018, at 4:29 PM, Qing Zhao <qing.zhao@oracle.com> wrote:
> 
> 
>> On Nov 12, 2018, at 2:53 AM, Martin Li?ka <mliska@suse.cz> wrote:
>> 
>>> 
>>> Okay, I see.
>>> 
>>> I am also working on a similar option as yours, but make the -flive-patching as two level control:
>>> 
>>> +flive-patching
>>> +Common RejectNegative Alias(flive-patching=,inline-clone)
>>> +
>>> +flive-patching=
>>> +Common Report Joined RejectNegative Enum(live_patching_level) Var(flag_live_patching) Init(LIVE_NONE)
>>> +-flive-patching=[inline-only-static|inline-clone]      Control optimizations to provide a safe comp for live-patching purpose.
>>> 
>>> the implementation for -flive-patching=inline-clone (the default) is exactly as yours,  the new level -flive-patching=inline-only-static
>>> is to only enable inlining of static function for live patching, which is important for multiple-processes live patching to control memory
>>> consumption. 
>>> 
>>> (please see my 2nd version of the -flive-patching proposal).
>>> 
>>> I will send out my complete patch in another email.
>> 
>> Hi, sure, works for me. Let's make 2 level option.
> 
> thank you.
> 
> I will send the patch tomorrow.
> 
> Qing
>> 
>> Martin
>