If it's not all true or all false, then you'll have a csel with a vector
constant, and the backend failed to translate appropriately. Expand the
constant to fix it.
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/21476>
op = is_float ? (mixed ? midgard_alu_op_fcsel_v : midgard_alu_op_fcsel)
: (mixed ? midgard_alu_op_icsel_v : midgard_alu_op_icsel);
+ int index = nir_src_index(ctx, &instr->src[0].src);
+ emit_explicit_constant(ctx, index, index);
+
break;
}