ira-loop-pressure not marked as optimization?

[Vladimir Makarov]

On 03/06/2014 03:14 PM, Paulo J. Matos wrote:
> On 06/03/14 15:15, Vladimir Makarov wrote:
>> On 03/06/2014 08:55 AM, Paulo Matos wrote:
>>> Hi,
>>>
>>> Upon noticing ira-hoist-pressure in `gcc --help=optimizers` and not
>>> ira-loop-pressure,
>>> I am wondering why the latter is not marked as an Optimization in
>>> common.opt:
>>>
>>> fira-loop-pressure
>>> Common Report Var(flag_ira_loop_pressure)
>>> Use IRA based register pressure calculation
>>> in RTL loop optimizations.
>>>
>>> Should we mark it as such?
>>>
>>>
>> It is not an optimization strictly speaking.  It is a better register
>> pressure calculation used for invariant loop motion decisions.
>>
>> On the other hand, using this option can improve generated code
>> performance (e.g. as I remember it improved SPECFP2000 by 1% for
>> ppc64).  So I guess, it should mark as such in order to see this
>> possibility to improve the code by a programmer.
>>
>>
>
> I have just run a few long benchmarks and even though I had high
> expectations for improving performance the flag in our port causes a
> ~3% degradation in performance. Haven't had time to investigate why.
>


Strange.  What port is this?  Can I see the benchmarks.  I know Pat
Haugen from IBM found a bug which can generated worse code in some cases
and has a fix.  I hope Pat submits it on stage 1.
 
> Still, would you accept a patch to mark this flag as an optimization?
>
I think we should.