http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48702
--- Comment #8 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-04-21 12:39:10 UTC --- (In reply to comment #7) > IVOPTs generates > > ivtmp.25_24 = (long unsigned int) &array; > array.26_26 = (long unsigned int) &array; > D.2769_27 = array.26_26 + 0x0fffffffffffffff0; > > <bb 3>: > # ans_21 = PHI <ans_16(4), 0(2)> > # ivtmp.25_20 = PHI <ivtmp.25_19(4), ivtmp.25_24(2)> > D.2741_10 = ans_21 * 2; > D.2767_25 = (void *) ivtmp.25_20; Actually D.2767_25 is already the problem as it can point before &array. > D.2737_15 = MEM[(int *)D.2767_25 + 12B]; Here we assume that the memory reference happens only to array[3] or beyond, as D.2767_25 is assumed to at least point to &array[0] but never to &array[-1]. Other passes could derive similar info for D.2767_25 given that points-to analysis computes it points somewhere into array.
