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

["H.J. Lu" <hjl dot tools at gmail dot com>]

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.