[PATCH][RFC] Fix PR39233, SCEV, IVOPTs and overflow

[H.J. Lu]

On Tue, Feb 24, 2009 at 3:02 AM, Richard Guenther <rguenther@suse.de> wrote:
> On Tue, 24 Feb 2009, Richard Guenther wrote:
>
>> On Mon, 23 Feb 2009, Zdenek Dvorak wrote:
>>
>> > Hi,
>> >
>> > > > > Can you have a look at the testcase in PR39233?
>> > > >
>> > > > here is a patch; I do not have time to test it just now.  It could be
>> > > > simplified by casting the values to unsigned type in
>> > > > add_iv_value_candidates unconditionally (most of the patch makes
>> > > > us push the value of the no_overflow flag there, so that we do not
>> > > > add these casts when not necessary).
>> > >
>> > > I am going to give the patch testing, most of it looks like useful
>> > > cleanup.  Note that using unsigned_type_for is probably not a good
>> > > idea, so I'll change it to use get_nonstandard_integer_type instead.
>> >
>> > actually, looking at the issue again, there already is a code dealing
>> > with this problem in add_candidate_1; unfortunately, there is a test
>> > excluding pointers from being casted to a safe type, which causes
>> > PR39233.  So, it should suffice to remove that test,
>>
>> Indeed, that works.  The previous patch bootstrapped and tested ok,
>> I'm going to test the simpler one now.
>
> Done as follows.  Bootstrapped and tested on x86_64-unknown-linux-gnu,
> applied to trunk.
>
> Thanks,
> Richard.
>
> 2009-02-24  Richard Guenther  <rguenther@suse.de>
>        Zdenek Dvorak  <ook@ucw.cz>
>
>        PR tree-optimization/39233
>        * tree-ssa-loop-ivopts.c (add_candidate_1): Do not except pointers
>        from converting them to a generic type.
>
>        * gcc.c-torture/execute/pr39233.c: New testcase.
>

This patch may be the cause for

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=39297


-- 
H.J.