[Bug tree-optimization/68823] [6/7 Regression][graphite] tramp3d-v4 compiled with -floop-nest-optimize crashes

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68823

--- Comment #5 from Martin Liška <marxin at gcc dot gnu.org> ---
Created attachment 40662
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=40662&action=edit
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?

Thanks