From: "Adam J. Richter" <adam@yggdrasil.com>
Date: Thu, 12 Apr 2001 12:29:33 -0700
Message-Id: <200104121929.MAA04049@adam.yggdrasil.com>
To: drepper@cygnus.com
Subject: Re: List of all-zero .data variables in linux-2.4.3 available
Cc: linux-kernel@vger.kernel.org
Sender: linux-kernel-owner@vger.kernel.org

>> = Adam Richter
>  = Ulrich Drepper

>> >Shouldn't a compiler be able to deal with this instead?
>> 
>> 	Yes.

>No.  gcc must not do this.  There are situations where you must place
>a zero-initialized variable in .data.  It is a programmer problem.

	I am aware of a couple of cases where code relied on static
variables being allocated contiguously, but, in both cases, those
variables were either all zeros or all non-zeros, so my proposed
change would not break such code.  Also, variables being allocated
contiguously is not an assumption supported by any standard that
I am aware of, and the very rare cases where code relies on this
should instead use an array (they've been of the same type in the
examples that I have come across).  At the very least, it seems
to me that this should be a compiler optimization flag, preferably
defaulted to "on".

	If you have some other scenario in mind, I'd appreciate an
example or a clear reference to some explanation, and I think others
on linux-kernel would probably appreciate that too.  It is a topic
that comes up repeatedly on linux-kernel.

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