[LLVMdev] Differences and Relationship between VLIW scheduler and VLIW packetizer?

[Triple Yang]

Thank you, Ivan.

In my opinion, it seems more natual for a vliw scheduler working on
machine instruction lists, since information like structure hazards
can be preserved for packetizing and need not to re-compute it.

Happy to see new implementation of instruction scheduling coming true.

Best regards.

2012/7/23 Ivan Llopard <ivanllopard at gmail.com>:
> Hi Yang,
>
> They have different implementations because they don't do the same thing and
> don't rely on the same structures. VLIW scheduling works on the
> SelectionDAG, right after the instruction selection, and it will schedule
> the DAG but it will not build any packet. The VLIW packetizer has been
> designed to work with machine instructions, using the ScheduleDAGInstr, and
> it does build packets (not scheduling). Both implementations have something
> in common, the DFAPacketizer which provides information about valid
> instruction packets. The former use it as a parameter for the computation of
> scheduling priorities and the latter use it to actually build the packets.
> I've read in this list that scheduling on the selectionDAG is likely to be
> replaced by the machine scheduling in the near future.
>
> Ivan
>
>
> On 23/07/2012 09:02, Triple Yang wrote:
>
> Hi,
>
> I notice that there exist some classes for VLIW packetizing and other
> classes for VLIW scheduling.
> Apparently these classes share something in common. Can someone
> explain why they
> should have separate implementation (i.e., in different function passes)?
>
> Best regards.
>
>
>
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-- 
杨勇勇 (Yang Yongyong)