Re: [PATCH] trivial: the memset operation on a automatic array variable should be optimized out by data initialization

Adrian Bunk
2007-06-23T13:57:26Z

On Sat, Jun 23, 2007 at 03:41:26PM +0200, Oleg Verych wrote:
> On Sat, Jun 23, 2007 at 03:13:55PM +0200, Adrian Bunk wrote:
> > On Sat, Jun 23, 2007 at 09:59:33AM +0200, Oleg Verych wrote:
> []
> > > > From: Denis Cheng <crquan@gmail.com>
> > > >
> > > > the explicit memset call could be optimized out by data initialization,
> > > > thus all the fill working can be done by the compiler implicitly.
> > >
> > > Can be optimized and can be done by compiler are just words;
> > >
> > > > and C standard guaranteed all the unspecified data field initialized to zero.
> > >
> > > standards and implementation are on opposite poles of magnet
> >
> > Bullshit.
> >
> > We expect a C compiler, and if a C compiler violates the C standard
> > that's a bug in the compiler that has to be fixed.
>
> If you are serious, please consider last kernel headers vs ANSI C
> discussion,

If only Joerg would tell us where the problem exactly is...

There might be a bug in the kernel header, but this simply has to be
fixed.

> then GNU extensions of the GCC C compiler and relevant "if
> ICC doesn't support GCC extensions it's ICC's bug".

gcc is a C compiler and claims to follow the C standard.
The kernel does not claim to be compilable by a plain C compiler.

Spot the difference?

> That was about
> implementation. About standards you are not serious, aren't you?
> (Please don't see this as for this particular case, but as general
> viewpoint)

And as with many generalizations, that's often wrong...

> > And gcc is usually quite good in following the C standard.
>
> > > > Signed-off-by: Denis Cheng <crquan@gmail.com>
> > > >
> > > > ---
> > > > After comments in the former threads:
> > > > http://lkml.org/lkml/2007/6/18/119
> > >
> > > i see a patch
> > >
> > > > http://lkml.org/lkml/2007/6/18/48
> > >
> > > same patch.
> > >...
> >
> > Open your eyes and you'll find thread overviews at the left side of
> > the URLs he gave...
>
> Two threads with *different* URLs but with *same* patch...
>...

The comments are in the _threads_.
The patches are only the roots of the threads.

cu
Adrian

--

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of the darkness. There had been need of rain for many days.
"Only a promise," Lao Er said.
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