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[Bug middle-end/47383] ivopts miscompiles Pmode != ptr_mode
- From: "rguenth at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Fri, 21 Jan 2011 12:38:24 +0000
- Subject: [Bug middle-end/47383] ivopts miscompiles Pmode != ptr_mode
- Auto-submitted: auto-generated
- References: <bug-47383-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47383
--- Comment #7 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-01-21 12:38:22 UTC ---
(In reply to comment #6)
> Sent from my Palm Pre on AT&T
> On Jan 20, 2011 21:34, hjl.tools at gmail dot com
> <gcc-bugzilla@gcc.gnu.org> wrote:
>
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47383
>
>
>
> --- Comment #4 from H.J. Lu <hjl.tools at gmail dot com> 2011-01-21
> 05:33:53 UTC ---
>
> (In reply to comment #3)
>
> > The ivopts pass transforms
>
> >
>
> >
>
> > unsigned int D.2715;
>
> > unsigned int D.2716;
>
> > ...
>
> > D.2715_43 = (unsigned int) elems_3(D);
>
> > D.2716_42 = D.2715_43 + 4294967295;
>
> > n_49 = (int) D.2716_42;
>
> >
>
> > leads o the wrong result when Pmode != unsigned int. Adding
>
> > -fno-ivopts fixes the bug.
>
> >
>
>
>
> This is OK due to cast to int. But
>
>
>
> long unsigned int D.2757;
>
> long unsigned int D.2749;
>
> long unsigned int D.2750;
>
> unsigned int ivtmp.20;
>
> int D.2748;
>
> unsigned int ivtmp.17;
>
> ...
>
> D.2749_6 = (long unsigned int) prephitmp.8_18;
>
> D.2750_34 = ivtmp.17_28 - D.2749_6;
>
> MEM[symbol: heap, index: D.2750_34, step: 8, offset: 2296B] = n_11;
>
>
>
> Mem here should have been rejected.
>
>
> looks wrong since it assumes D.2750_34 can be negative. But
sizetype values are sign-extended.
> D.2750_34 is unsigned. It won't work when ptr_mode == unsigned
>
> and Pmode is unsigned long long.