Re: [patch] for PR 23361

["Richard Guenther" <richard dot guenther at gmail dot com>]

On 2/8/07, Zdenek Dvorak <rakdver@atrey.karlin.mff.cuni.cz> wrote:
> Hello,
>
> > >one of the reasons for this PR is that we fail to fold expressions like
> > >a + 10 > MIN_INT + 2, that are always true (assuming that the
> > >arithmetics in the considered type does not overflow).  Such expressions
> > >are fairly often produced by number of iterations analysis.
> > >This patch implements such simplifications.
> > >
> > >Bootstrapped & regtested on i686 and x86_64.
> >
> > Hmm, this looks overly complicated.  But maybe I'm missing something
> > obvious - the
> > attached also works for your testcase, but I dind't yet bootstrap & test it.
>
> well, it seems to work (*).  I think you should also extend the comment
> explaining how the code works -- it took me about half an hour before I
> understood it.  Also please include the compare-3 testcase (it took me
> longer time to write than the fold-const code :-)

Yeah - you are right ;)

I'm now bootstrapping and testing the following.

Thanks!
Richard.


2007-02-08  Zdenek Dvorak  <dvorakz@suse.cz>
       Richard Guenther  <rguenther@suse.de>

       PR middle-end/23361
       * fold-const.c (fold_comparison): Handle obfuscated comparisons
       against INT_MIN/INT_MAX.
       * tree-ssa-loop-ivcanon.c (remove_empty_loop): Print to dump
       file if a loop is removed.

       * gcc.dg/fold-compare-3.c: New testcase.
       * gcc.dg/tree-ssa/loop-24.c: Likewise.

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