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RE: [PATCH] Change default for --param allow-...-data-races to off
- From: Bernd Edlinger <bernd dot edlinger at hotmail dot de>
- To: Richard Biener <richard dot guenther at gmail dot com>
- Cc: Martin Jambor <mjambor at suse dot cz>, "gcc-patches at gcc dot gnu dot org" <gcc-patches at gcc dot gnu dot org>
- Date: Mon, 23 Jun 2014 15:35:01 +0200
- Subject: RE: [PATCH] Change default for --param allow-...-data-races to off
- Authentication-results: sourceware.org; auth=none
- References: <DUB118-W318F2CAA5BBAC891FBC6D6E4130 at phx dot gbl>,<20140620114418 dot GB24436 at virgil dot suse>,<DUB118-W4683B0ED69FBB39F01AB5DE41F0 at phx dot gbl>,<CAFiYyc10wiXtqtaZd7taOBYAuG5a7o6iKR_0gWdwLUDkZqNHow at mail dot gmail dot com>
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.
Thanks
Bernd.