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Re: List of simplifications we should perform
- To: Daniel Berlin <dan at www dot cgsoftware dot com>
- Subject: Re: List of simplifications we should perform
- From: Richard Earnshaw <rearnsha at arm dot com>
- Date: Fri, 11 May 2001 13:13:18 +0100
- cc: Andi Kleen <ak at suse dot de>, gcc at gcc dot gnu dot org, Richard dot Earnshaw at arm dot com
- Organization: ARM Ltd.
- Reply-To: Richard dot Earnshaw at arm dot com
> On 11 May 2001, Andi Kleen wrote:
> > Daniel Berlin <firstname.lastname@example.org> writes:
> > If this is supposed to be C...
> > > Simplifications for ~ and !:
> > >
> > > ! ! j j
> > !!j is not j, it is j?1:0.
> That's what I thought, but SGI's compiler quite clearly disagrees.
> It just says:
> if (<it's of the form ! ! j>)
> delete the not's.
> It performs this at all optimization levels, too.
Then it looks like a bug, since clearly
x + !!j != x + j
Just consider j = 2