Re: [PATCH] gimple-match: Do not try UNCOND optimization with COND_LEN.

[Richard Sandiford <richard.sandiford@arm.com>]

Richard Sandiford <richard.sandiford@arm.com> writes:
> Robin Dapp via Gcc-patches <gcc-patches@gcc.gnu.org> writes:
>> [...]
>> @@ -386,9 +390,29 @@ try_conditional_simplification (internal_fn ifn, gimple_match_op *res_op,
>>      default:
>>        gcc_unreachable ();
>>      }
>> -  *res_op = cond_op;
>> -  maybe_resimplify_conditional_op (seq, res_op, valueize);
>> -  return true;
>> +
>> +  if (len)
>> +    {
>> +      /* If we had a COND_LEN before we need to ensure that it stays that
>> +	 way.  */
>> +      gimple_match_op old_op = *res_op;
>> +      *res_op = cond_op;
>> +      maybe_resimplify_conditional_op (seq, res_op, valueize);
>> +
>> +      auto cfn = combined_fn (res_op->code);
>> +      if (internal_fn_p (cfn)
>> +	  && internal_fn_len_index (as_internal_fn (cfn)) != -1)
>> +	return true;
>
> Why isn't it enough to check the result of maybe_resimplify_conditional_op?

Sorry, ignore that part.  I get it now.

But isn't the test whether res_op->code itself is an internal_function?
In other words, shouldn't it just be:

      if (internal_fn_p (res_op->code)
	  && internal_fn_len_index (as_internal_fn (res_op->code)) != -1)
	return true;

maybe_resimplify_conditional_op should already have converted to an
internal function where possible, and if combined_fn (res_op->code)
does any extra conversion on the fly, that conversion won't be reflected
in res_op.

Thanks,
Richard