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

[Martin Jambor <mjambor@suse.cz>]

Hi,

On Wed, Jun 25, 2014 at 03:14:31PM -0600, Jeff Law wrote:
> On 06/24/14 14:19, Martin Jambor wrote:
> >On Mon, Jun 23, 2014 at 03:35:01PM +0200, Bernd Edlinger wrote:
> >>Hi Martin,
> >>
> >>>>
> >>>>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?
> >>>
> >>>It's trivially to write one. The only pass that checks the param is
> >>>tree loop invariant motion and it does that when it applies store-motion.
> >>>Register pressure increase is increased by a factor of two.
> >>>
> >>>So I'd agree that we might want to disable this again for -Ofast.
> >>>
> >>>As nothing tests for the PACKED variants nor for the LOAD variant
> >>>I'd rather remove those. Claiming we don't create races for those
> >>>when you disable it via the param is simply not true.
> >>>
> >>>Thanks,
> >>>Richard.
> >>>
> >>
> >>OK, please go ahead with your patch.
> >
> >Perhaps not unsurprisingly, the patch is very similar.  Bootstrapped
> >and tested on x86_64-linux.  OK for trunk?
> >
> >Thanks,
> >
> >Martin
> >
> >
> >2014-06-24  Martin Jambor  <mjambor@suse.cz>
> >
> >	* params.def (PARAM_ALLOW_LOAD_DATA_RACES)
> >	(PARAM_ALLOW_PACKED_LOAD_DATA_RACES)
> >	(PARAM_ALLOW_PACKED_STORE_DATA_RACES): Removed.
> >	(PARAM_ALLOW_STORE_DATA_RACES): Set default to zero.
> >	* opts.c (default_options_optimization): Set
> >	PARAM_ALLOW_STORE_DATA_RACES to one at -Ofast.
> >	* doc/invoke.texi (allow-load-data-races)
> >	(allow-packed-load-data-races, allow-packed-store-data-races):
> >	Removed.
> >	(allow-store-data-races): Document the new default.
> >
> >testsuite/
> >	* g++.dg/simulate-thread/bitfields-2.C: Remove allow-load-data-races
> >	parameter.
> >	* g++.dg/simulate-thread/bitfields.C: Likewise.
> >	* gcc.dg/simulate-thread/strict-align-global.c: Remove
> >	allow-packed-store-data-races parameter.
> >	* gcc.dg/simulate-thread/subfields.c: Likewise.
> >	* gcc.dg/tree-ssa/20050314-1.c: Set parameter allow-store-data-races
> >	to one.
> Don't we want to deprecate, not remove the dead options?
> 

Is there a mechanism for deprecating parameters (I could not quickly
find any) or do you mean to leave them there and only document them as
deprecated?

I am not really concerned how we deal with the unused parameters,
removing or any form of deprecating is fine with me.

Thanks,

Martin