Re: [Xen-devel] [PATCH] x86: fix variable_test_bit() asmconstraints

[Samuel Thibault <samuel.thibault@xxxxxxxxxxxxx>]

Jan Beulich, le Fri 14 Mar 2008 13:51:26 +0000, a écrit :
> >memory-clobber would be needed for the atomic ops, but a dummy memory
> >operand would suffice for non-atomic ops. I used memory clobber everywhere
> 
> Atomic ops imply a barrier (otherwise the compiler can defeat the
> purpose of the atomic operation). The non-atomic ones don't need a
> dummy operand, but one that precisely describes the place in memory
> that changes.

Mmm, won't that unnecessarily make the compiler put code to compute that
place?

Samuel

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