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Re: -fno-tree-cselim not working?
- From: Ian Lance Taylor <iant at google dot com>
- To: Andi Kleen <andi at firstfloor dot org>
- Cc: gcc at gcc dot gnu dot org
- Date: 26 Oct 2007 13:23:15 -0700
- Subject: Re: -fno-tree-cselim not working?
- References: <20071026070903.GS2896@sunsite.mff.cuni.cz.suse.lists.egcs> <20071026.002701.193707917.davem@davemloft.net.suse.lists.egcs> <20071026074825.GT2896@sunsite.mff.cuni.cz.suse.lists.egcs> <20071026.005802.107688735.davem@davemloft.net.suse.lists.egcs> <m3bqamj5x7.fsf@localhost.localdomain.suse.lists.egcs> <p73k5p9prwx.fsf@bingen.suse.de>
Andi Kleen <andi@firstfloor.org> writes:
> Ian Lance Taylor <iant@google.com> writes:
> >
> > This code isn't going to be a problem, because spin_unlock presumably
> > includes a memory barrier.
>
> At least in the Linux kernel and also in glibc for mutexes locks are just plain
> function calls, which are not necessarily full memory barriers.
True, and problematic in some cases--but a function call which gcc
can't see is a memory barrier for all addressable memory.
Ian