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-bugzi...@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.