2016-04-26 18:12 GMT+03:00 H.J. Lu <hjl.to...@gmail.com>:
> On Tue, Apr 26, 2016 at 8:05 AM, Ilya Enkovich <enkovich....@gmail.com> wrote:
>> 2016-04-26 17:55 GMT+03:00 H.J. Lu <hjl.to...@gmail.com>:
>>> On Tue, Apr 26, 2016 at 7:15 AM, Ilya Enkovich <enkovich....@gmail.com>
>>> wrote:
>>>> 2016-04-26 17:07 GMT+03:00 H.J. Lu <hjl.to...@gmail.com>:
>>>>> On Mon, Apr 25, 2016 at 9:13 AM, Ilya Enkovich <enkovich....@gmail.com>
>>>>> wrote:
>>>>>> 2016-04-25 18:27 GMT+03:00 H.J. Lu <hjl.to...@gmail.com>:
>>>>>>>
>>>>>>> Ilya, can you take a look?
>>>>>>>
>>>>>>> Thanks.
>>>>>>>
>>>>>>> --
>>>>>>> H.J.
>>>>>>
>>>>>> Hi,
>>>>>>
>>>>>> Algorithmic part of the patch looks OK to me except the following piece
>>>>>> of code.
>>>>>>
>>>>>> +/* Check REF's chain to add new insns into a queue
>>>>>> + and find registers requiring conversion. */
>>>>>>
>>>>>> Comment is wrong because you don't have any conversions required for
>>>>>> your candidates.
>>>>>
>>>>> I will fix it.
>>>>>
>>>>>> +
>>>>>> +void
>>>>>> +scalar_chain_64::analyze_register_chain (bitmap candidates, df_ref ref)
>>>>>> +{
>>>>>> + df_link *chain;
>>>>>> +
>>>>>> + gcc_assert (bitmap_bit_p (insns, DF_REF_INSN_UID (ref))
>>>>>> + || bitmap_bit_p (candidates, DF_REF_INSN_UID (ref)));
>>>>>> + add_to_queue (DF_REF_INSN_UID (ref));
>>>>>> +
>>>>>> + for (chain = DF_REF_CHAIN (ref); chain; chain = chain->next)
>>>>>> + {
>>>>>> + unsigned uid = DF_REF_INSN_UID (chain->ref);
>>>>>> +
>>>>>> + if (!NONDEBUG_INSN_P (DF_REF_INSN (chain->ref)))
>>>>>> + continue;
>>>>>> +
>>>>>> + if (!DF_REF_REG_MEM_P (chain->ref))
>>>>>> + continue;
>>>>>>
>>>>>> I believe here you wrongly jump to the next ref intead of actually
>>>>>> adding it
>>>>>> to a queue. You may just use
>>>>>>
>>>>>> gcc_assert (!DF_REF_REG_MEM_P (chain->ref));
>>>>>>
>>>>>> because you should'n have a candidate used in address operand.
>>>>>
>>>>> I will update.
>>>>>
>>>>>> +
>>>>>> + if (bitmap_bit_p (insns, uid))
>>>>>> + continue;
>>>>>> +
>>>>>> + if (bitmap_bit_p (candidates, uid))
>>>>>> + add_to_queue (uid);
>>>>>>
>>>>>> Probably gcc_assert (bitmap_bit_p (candidates, uid)) since no uses and
>>>>>> defs
>>>>>> out of candidates list are allowed?
>>>>>
>>>>> That would be wrong since there are
>>>>>
>>>>> while (!bitmap_empty_p (queue))
>>>>> {
>>>>> insn_uid = bitmap_first_set_bit (queue);
>>>>> bitmap_clear_bit (queue, insn_uid);
>>>>> bitmap_clear_bit (candidates, insn_uid);
>>>>> add_insn (candidates, insn_uid);
>>>>> }
>>>>>
>>>>> An instruction is a candidate and the bit is cleared when
>>>>> analyze_register_chain is called.
>>>>
>>>> You clear candidates bit but the first thing you do in add_insn is set
>>>> insns bit.
>>>> Thus you should hit:
>>>>
>>>> if (bitmap_bit_p (insns, uid))
>>>> continue;
>>>>
>>>> For handled candidates.
>>>>
>>>> Probably it would be more clear if we keep this clear/set pair
>>>> together? E.g. move
>>>> bitmap_clear_bit (candidates, insn_uid) to scalar_chain::add_insn.
>>>>
>>>
>>> After we started processing candidates, we only use candidates
>>> to check if an instruction is a candidate, not to check if an
>>> instruction is NOT a candidate.
>>
>> I don't see how it's related to what I said. My point is that
>> when you analyze added insn you shouldn't reach insns which are both
>> not in candidates and not in current scalar_chain_64. That's why I
>> think you miss an assert in scalar_chain_64::analyze_register_chain.
>
> Since all candidates will be processed by
>
> while (!bitmap_empty_p (queue))
> {
> insn_uid = bitmap_first_set_bit (queue);
> bitmap_clear_bit (queue, insn_uid);
> bitmap_clear_bit (candidates, insn_uid);
> add_insn (candidates, insn_uid);
> }
This process only queue, not all candidates. analyze_register_chain
fills queue bitmap to build a chain.
>
> I will change to
>
> /* Check REF's chain to add new insns into a queue. */
>
> void
> timode_scalar_chain::analyze_register_chain (bitmap candidates,
> df_ref ref)
> {
> gcc_assert (bitmap_bit_p (insns, DF_REF_INSN_UID (ref))
> || bitmap_bit_p (candidates, DF_REF_INSN_UID (ref)));
> add_to_queue (DF_REF_INSN_UID (ref));
> }
>
The purpose of analyze_register_chain is to collect all register defs
or uses into chain's queue. You can't just remove a loop over ref's
chain then.
Thanks,
Ilya
>
>
> --
> H.J.
