[llvm-commits] Fwd: Speeding up instruction selection

[Evan Cheng]

Hi Roman,

Please do more testing on this patch. I am seeing failures:

/Users/echeng/LLVM/llvm/Release/bin/llc  -f Output/burg.llvm.bc -o  
Output/burg.llc.s
Assertion failed: (RemovedNum == 1 && "Not in queue!"), function  
remove, file ScheduleDAGRRList.cpp, line 1321.

/Users/echeng/LLVM/llvm/Release/bin/llc  -f Output/sqlite3.llvm.bc -o  
Output/sqlite3.llc.s
Assertion failed: (RemovedNum == 1 && "Not in queue!"), function  
remove, file ScheduleDAGRRList.cpp, line 1321.

Thanks,

Evan

On Apr 21, 2008, at 12:44 PM, Evan Cheng wrote:

>
> On Apr 21, 2008, at 11:54 AM, Roman Levenstein wrote:
>
>> Hi Evan,
>>
>> Good point. This code is here due to the historical reasons ;-) I
>> introduced it when I was experimenting with different alternatives  
>> and
>> then forgot to remove it... The commit version will not contain it.
>>
>> Any further comments on this patch? Can I commit it or is it too
>> early?
>
> Please hold off committing for a few days until I have a chance to
> evaluate the performance impact. Thanks.
>
> Evan
>
>>
>>
>> - Roman
>>
>> 2008/4/21, Evan Cheng <evan.cheng at apple.com>:
>>
>>> +  if (left->NodeQueueId && right->NodeQueueId)
>>> +    return (left->NodeQueueId < right->NodeQueueId);
>>> +  return left->NodeNum < right->NodeNum;
>>>
>>> Why would NodeQueueId ever be zero? Nodes that are entered into the
>>> queue
>>> must have this field set, no?
>>>
>>> Evan
>>>
>>>
>>> On Apr 18, 2008, at 4:31 AM, Roman Levenstein wrote:
>>>
>>>
>>>>
>>>> Hi Evan,
>>>>
>>>> 2008/4/2, Evan Cheng <evan.cheng at apple.com>:
>>>>
>>>>>
>>>>> On Apr 2, 2008, at 1:57 AM, Roman Levenstein wrote:
>>>>>
>>>>>
>>>>>> 2008/4/2, Evan Cheng <evan.cheng at apple.com>:
>>>>>>
>>>>>>>
>>>>>>> On Apr 2, 2008, at 12:55 AM, Roman Levenstein wrote:
>>>>>>>
>>>>>>>
>>>>>>>> Hi Evan,
>>>>>>>>
>>>>>>>> 2008/4/1, Evan Cheng <evan.cheng at apple.com>:
>>>>>>>>
>>>>>>>>> Please hold off checking it in for a bit. llvm tot is having
>>> some
>>>>>>>>> problems and I'd like to get to the bottom of it first.
>>>>>>>>>
>>>>>>>>
>>>>>>>> OK.
>>>>>>>>
>>>>>>>>
>>>>>>>>> Also, the tie breaker is less than ideal. I think we need a
>>>>>>>>> tie-
>>>>>>>>> breaker that is "the SUnit that's added to the queue is
>>> preferred".
>>>>>>>>> That means it prefers nodes which are closer to the end of
>>> block.
>>>>>>>>> What
>>>>>>>>> do you think?
>>>>>>>>>
>>>>>>>>
>>>>>>>> Do you actually mean "the SUnit that's added to the queue LAST
>>>>>>>> (or
>>>>>>>> FIRST) is preferred"? I'll think about it.
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> Yep "first".  Basically, if all else being equal, let the node
>>> that's
>>>>>>> ready first be scheduled first. We can add a order id to SUnit
>>>>>>> which
>>>>>>> gets set when it's pushed into the ready queue. What do you
>>>>>>> think?
>>>>>>>
>>>>>>
>>>>>> Makes sense. The queue should have a global "current id"
>>>>>> counter. Its
>>>>>> current value is assigned to each node being inserted into the
>>>>>> ready
>>>>>> queue and then incremented. When the node is removed from the
>>>>>> queue
>>>>>> for any reason, its queue order id is reset. It should be rather
>>>>>> easy
>>>>>> to implement.
>>>>>>
>>>>>
>>>>
>>>>
>>>>>
>>>>>> BTW, do you really want this queue order id in the SUnit or in a
>>>>>> separate array indexed by SUnit unique ids?
>>>>>>
>>>>>
>>>>>
>>>>> It should be in SUnit since the sort functions don't have access  
>>>>> to
>>>>> ScheduleDAG members.
>>>>>
>>>>
>>>> Please find and review the attached patch implementing:
>>>> - a proper tie-breaker as discussed above.
>>>> - and unmodified part for replacing the slow std::priority_queue by
>>>> std::set, as it I already did before.
>>>>
>>>> What do you think?
>>>>
>>>> -Roman
>>>> <ScheduleDAGRRList.patch>
>>>>
>>>
>>>
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