linux-kernel - Re: [PATCH] work around gcc4 issue with -Os in Dwarf2 stack unwind code

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Date:	Tue, 28 Nov 2006 09:59:13 -0500
From:	Jakub Jelinek <jakub@...hat.com>
To:	Jan Beulich <jbeulich@...ell.com>
Cc:	Andi Kleen <ak@...e.de>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] work around gcc4 issue with -Os in Dwarf2 stack unwind code

On Tue, Nov 28, 2006 at 02:48:15PM +0000, Jan Beulich wrote:
> I disagree - the standard says there's a sequence point at a function
> call after evaluating all function arguments. To me this means that any

That's true, that sequence point makes sure e.g. all side effects such as
pre-{dec,inc}rement on the arguments happen before the call.
But as I said, no sequence point demands any particular ordering of
evaluation of the LHS and RHS of +=.

> (parts of an) expression the function call is contained in must be
> evaluated after the function call. Otherwise it would be illegal to e.g.
> modify a variable in both operands of && or ||.

That's different, there is a sequence point at the end of the first operand
of &&, ||, ?: and , operators (second bullet in ISO C99 Annex C).

	Jakub
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