RE: [PATCH] Change default for --param allow-...-data-races to off

[Bernd Edlinger <bernd.edlinger@hotmail.de>]

Hi,


On Fri, 20 Jun 2014 13:44:18, Martin Jambor wrote:
>
> Hi,
>
> On Thu, Jun 19, 2014 at 06:18:47PM +0200, Bernd Edlinger wrote:
>> Hi,
>>
>> from a recent discussion on gcc@gcc.gnu.org I have learned that the default of
>> --param allow-store-data-races is still 1, and it is causing problems.
>> Therefore I would like to suggest to change the default of this option to 0.
>
> I was about to propose a similar patch but I intended to leave the
> parameter set to one when -Ofast is specified so that benchmarks are
> not hurt by this and as a nice pointer for people exploring our
> options to really squeeze out 100% performance (which would of course
> mean documenting it too).
>

Well actually, I am not sure if we ever wanted to have a race condition here.
Have you seen any impact of --param allow-store-data-races on any benchmark?


Thanks
Bernd.

> Thanks,
>
> Martin
>
>>
>> Boot-strapped and regression tested on x86_64-linux-gnu.
>> Ok for trunk?
>>
>>
>> Thanks
>> Bernd.
>>
>
>> gcc/ChangeLog:
>> 2014-06-19 Bernd Edlinger <bernd.edlinger@hotmail.de>
>>
>> Set default for --param allow-...-data-races to off.
>> * params.def (PARAM_ALLOW_LOAD_DATA_RACES,
>> PARAM_ALLOW_STORE_DATA_RACES, PARAM_ALLOW_PACKED_LOAD_DATA_RACES,
>> PARAM_ALLOW_PACKED_STORE_DATA_RACES): Set default to off.
>>
>> testsuite/ChangeLog:
>> 2014-06-19 Bernd Edlinger <bernd.edlinger@hotmail.de>
>>
>> Adjust to new default for --param allow-...-data-races.
>> * c-c++-common/cxxbitfields-3.c: Adjust.
>> * c-c++-common/cxxbitfields-6.c: Adjust.
>> * c-c++-common/simulate-thread/bitfields-1.c: Adjust.
>> * c-c++-common/simulate-thread/bitfields-2.c: Adjust.
>> * c-c++-common/simulate-thread/bitfields-3.c: Adjust.
>> * c-c++-common/simulate-thread/bitfields-4.c: Adjust.
>> * g++.dg/simulate-thread/bitfields.C: Adjust.
>> * g++.dg/simulate-thread/bitfields-2.C: Adjust.
>> * gcc.dg/lto/pr52097_0.c: Adjust.
>> * gcc.dg/simulate-thread/speculative-store.c: Adjust.
>> * gcc.dg/simulate-thread/speculative-store-2.c: Adjust.
>> * gcc.dg/simulate-thread/speculative-store-3.c: Adjust.
>> * gcc.dg/simulate-thread/speculative-store-4.c: Adjust.
>> * gcc.dg/simulate-thread/strict-align-global.c: Adjust.
>> * gcc.dg/simulate-thread/subfields.c: Adjust.
>> * gcc.dg/tree-ssa/20050314-1.c: Adjust.
>>
>
>