https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68823
--- Comment #7 from Sebastian Pop <spop at gcc dot gnu.org> ---
(In reply to Martin Liška from comment #5)
> Created attachment 40662 [details]
> Isolated graphite dump for miscompiled function
>
> As shown in the dump file, there are dependencies for the problematic stmts:
>
> Adding must write to depedence graph: pdr_121 (write
> in gimple stmt: MEM[(Element_t[2] &)_7][0] = _9;
> data accesses: { S_3[i2] -> [2, o1, 0] : 8*floor((o1)/8) = o1 and
> 18446744073709551616*floor((8i2 - o1)/18446744073709551616) = 8i2 - o1 and 0
> <= o1 <= 18446744073709551608 }
>
> Adding read to depedence graph: pdr_124 (read
> in gimple stmt: _15 = MEM[(int *)_14];
> data accesses: { S_6[i1] -> [2, o1] : 18446744073709551616*floor((-8i1 +
> o1)/18446744073709551616) = -8i1 + o1 and 0 <= o1 <= 18446744073709551608 }
>
> If I understand the notation correctly, both have equal alias set (2). Do
> you see Sebastian why the dependence is not caught?
>
S_3[i2] -> [2, o1, 0]
S_6[i1] -> [2, o1]
we do not detect the dependence because the two arrays do not have the same
number of subscripts: also on the gimple representation we have
MEM[(Element_t[2] &)_7][0] = _9;
vs.
_15 = MEM[(int *)_14];
