[LLVMdev] Supporting Complex Register Allocation Constraints (PBQP Allocator Status Update)

[Lang Hames]

 Hi Jakob,


> PBQP should be able to do well with -disable-physical-join, if it can model
> all the hinting properly.


That's a good point. I'll run some tests and see what it does to allocation
quality.


> SplitKit is currently pretty broken, but I am working on fixing it. It
> turns out you need a good deal of logic to correctly update LiveIntervals
> after a split. The intention is that you can cut out any connected region of
> the CFG and use a new register there. Examples of split regions are:
>
> - A loop.
> - A well connected cluster of basic blocks.
> - A single basic block.
> - A sequence of instructions inside a basic block.


That sounds fantastic. I'll start playing around with it.

LoopSplitter is currently broken too. I'd agree with your observation on
updating LiveIntervals - I had similar trouble.


Cheers,
Lang.

Regards,
Lang.
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