https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94727
--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #2)
> test() is basic-block vectorized on the c-loop body which has the d- and
> e-loops
> completely unrolled. We create some weird
>
> mask__84.17_18 = vect_cst__94 < vect_cst__20;
> vect_patt_266.18_6 = VEC_COND_EXPR <mask__84.17_18, vect_cst__16,
> vect_cst__15>;
>
> where vect_cst__94 and vect_cst__20 look like
>
> { var_3.1_42 ? -1 : 0, var_3.1_42 ? -1 : 0, ...
>
> or even
>
> { _272 ? -1 : 0, ...
>
> with
>
> _272 = _271 < var_11.0_40
>
> so the vectorization is quite imperfect, mainly due to
>
> t1.C:9:32: note: ==> examining statement: _85 = var_11.0_40 > _86;
> t1.C:12:69: missed: not vectorized: relevant stmt not supported: _85 =
> var_11.0_40 > _86;
> t1.C:9:32: note: Building vector operands from scalars instead
>
> that doesn't yet explain what goes wrong here.
If you change the e loop iteration to stop at e < 16 the testcase is not
miscompiled, so somehow the
t1.C:9:20: missed: Build SLP failed: incompatible vector types for:
arr_42[a_26][0][c_11][0][16] = _44;
t1.C:9:20: note: old vector type: vector(2) long long int
t1.C:9:20: note: new vector type: vector(1) long long int
might be a relevant factor. Leaving to Richard.
