From mboxrd@z Thu Jan  1 00:00:00 1970
From: Keir Fraser <keir.fraser@eu.citrix.com>
Subject: Re: [PATCH] x86: fix variable_test_bit()
 asmconstraints
Date: Fri, 14 Mar 2008 14:04:14 +0000
Message-ID: <C400365E.1503B%keir.fraser@eu.citrix.com>
References: <20080314135938.GN4358@implementation.uk.xensource.com>
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On 14/3/08 13:59, "Samuel Thibault" <samuel.thibault@eu.citrix.com> wrote:

>> 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?

x86 has enough fancy addressing modes that usually the compiler can emit the
effective address without pre-computing any part of it. It's not guaranteed
to do this, though, it's true.

 -- Keir