[llvm-dev] Prioritizing an SDNode for scheduling

[Ehsan Amiri via llvm-dev]

You can do this by changing instruction scheduling heuristics. I think the
more important question is if this correct always for all platforms.

I don't know which scheduler you use. We use GenericScheduler and
PostGenericScheduler before and after RA. These classes have a
::tryCandidate method which compares two instructions that can be legally
scheduled and decide which of the two should be scheduled. Currently these
method are target independent.

The correctness question still remains open for me.


On Thu, Oct 20, 2016 at 8:08 PM, Alex Susu via llvm-dev <
llvm-dev at lists.llvm.org> wrote:

>   Hello.
>     Is there a way to specify in the back end an (ISD::INLINEASM) SDNode
> to be scheduled first under all circumstances? I need to specify something
> like node priority to schedule the node before all other nodes in the
> SelectionDAG of the basic block.
>     (Using chain or glue edges in order to make a node first is not a good
> idea, since I am doing this at instruction selection time, on individual
> nodes.)
>
>   Thank you,
>     Alex
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