https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105591
--- Comment #4 from Zdenek Sojka <zsojka at seznam dot cz> ---
(In reply to Richard Biener from comment #1)
> Confirmed. The offset is very large negative, built by simplify_bitfield_ref
> here:
>
> 2416 tem = build3 (BIT_FIELD_REF, TREE_TYPE (op),
> 2417 p, op1, bitsize_int (idx * elem_size));
> (gdb) p idx
> $11 = 13704120150654661628
>
> because we have a non-sensical permute:
>
> x_4 = VEC_PERM_EXPR <u_3(D), u_3(D), { 13704120150654661630, 0 }>;
>
> some sanity checking in simplify_bitfield_ref might be in order. Rejecting
> the __builtin_shuffle might be another option, it's surely going to cause
> issues elsewhere.
Indeed I am triggering probably related failures elsewhere:
testcase-min0.i:54:5: error: invalid position or size operand to
'bit_field_ref'
54 | int main(void)
| ^~~~
_66 = BIT_FIELD_REF <{ 2305807824841605120, 18446462598732840960, 65535,
268431360, 65535, 68718428160, 18446181123756130304, 72056494526300160 }, 64,
0xfffffffffffffffff0a1a0c0f3732940>;
testcase-min0.i:54:5: error: position plus size exceeds size of referenced
object in 'bit_field_ref'
_89 = BIT_FIELD_REF <{ 2305807824841605120, 18446462598732840960, 65535,
268431360, 65535, 68718428160, 18446181123756130304, 72056494526300160 }, 64,
5392423424>;
...
