>>>If the pattern is not allowed to fail, then what code enforces the bias
>>>argument's restrictions? I don't see it in the generic expander code.
>
> I have no ideal since this is just copied from len_load/len_store which is
> s390 target dependent stuff.
>
> I have sent V7 patch with fixing doc by following your suggestion.
>
We have:
signed char
internal_len_load_store_bias (internal_fn ifn, machine_mode mode)
{
optab optab = direct_internal_fn_optab (ifn);
insn_code icode = direct_optab_handler (optab, mode);
if (icode != CODE_FOR_nothing)
{
/* For now we only support biases of 0 or -1. Try both of them. */
if (insn_operand_matches (icode, 3, GEN_INT (0)))
return 0;
if (insn_operand_matches (icode, 3, GEN_INT (-1)))
return -1;
}
return VECT_PARTIAL_BIAS_UNSUPPORTED;
}
This is used here:
static bool
vect_verify_loop_lens (loop_vec_info loop_vinfo)
{
[..]
signed char partial_load_bias = internal_len_load_store_bias
(IFN_LEN_LOAD, len_load_mode);
signed char partial_store_bias = internal_len_load_store_bias
(IFN_LEN_STORE, len_store_mode);
gcc_assert (partial_load_bias == partial_store_bias);
if (partial_load_bias == VECT_PARTIAL_BIAS_UNSUPPORTED)
return false;
/* If the backend requires a bias of -1 for LEN_LOAD, we must not emit
len_loads with a length of zero. In order to avoid that we prohibit
more than one loop length here. */
if (partial_load_bias == -1
&& LOOP_VINFO_LENS (loop_vinfo).length () > 1)
return false;
Regards
Robin
