linux-kernel - Re: [PATCH] ubi: kill homegrown endian macros

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Date:	Sun, 20 May 2007 12:29:38 +0100
From:	David Woodhouse <dwmw2@...radead.org>
To:	Segher Boessenkool <segher@...nel.crashing.org>
Cc:	Matthieu CASTET <castet.matthieu@...e.fr>,
	"John Anthony Kazos Jr." <jakj@...-k-j.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] ubi: kill homegrown endian macros

On Sat, 2007-05-19 at 14:24 +0200, Segher Boessenkool wrote:
> >> It's not the compiler who decides -- struct layout is
> >> dictated by the ABI you're compiling for.
> >
> > This is true in the case of externally-visible stuff. I think the
> > compiler is permitted to violate the ABI for purely unit-internal 
> > things
> > if it makes sense though, isn't it?
> 
> Sure.  It isn't "violating the ABI" in that case though,
> to be perfectly clear.

Of course. It's not conforming to the ABI because there's no need to.

> > The rule stands -- empirical testing of what the compiler will do isn't
> > usually the right answer.
> 
> It is *never* the right answer.  You should always write
> your code so that it will do the right thing no matter
> what the compiler decides to do to it.

Well, there's sometimes some benefit in _also_ checking that the output
of the compiler matches your expectations. :)

-- 
dwmw2

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