[llvm-commits] Speeding up instruction selection

[Evan Cheng]

+  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>