Re: [PATCH 1/4] compiler.h: introduce unused_expression() macro

[Andrew Morton]

On Fri, 27 Apr 2012 13:55:06 +0400
Konstantin Khlebnikov <khlebnikov@xxxxxxxxxx> wrote:

> Andrew Morton wrote:
> > On Wed, 25 Apr 2012 15:26:23 +0400
> > Konstantin Khlebnikov<khlebnikov@xxxxxxxxxx>  wrote:
> 
> for example  VM_BUG_ON(!PageCompound(page) || !PageHead(page)); in
> do_huge_pmd_wp_page() generates 114 bytes.
> 
> But they mostly disappears if I replace it with
> -VM_BUG_ON(!PageCompound(page) || !PageHead(page));
> +VM_BUG_ON(!PageCompound(page));
> +VM_BUG_ON(!PageHead(page));
> weird...
> 
> add/remove: 0/0 grow/shrink: 7/97 up/down: 135/-1784 (-1649)

OK, thanks.  I'm inclined to apply the patchset as-is.  If the
apparently mythical use of side-effects in VM_BUG_ON() really exist
then we deserve everything which happens to us as a result ;)

Please update the changelogs so they cover all the points which have been
discussed, add my little code comment then send out a v2, being sure to
cc everyone who has been involved in the discussion?

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