[llvm-dev] [SelectionDAG] lowering shifts to parts

[Krzysztof Parzyszek via llvm-dev]

On 6/29/2018 8:18 AM, Davis, Alan via llvm-dev wrote:
> 
> Is there some other way? Do I need to make a custom action? If so, can I 
> just call ExpandIntRes_Shift(), which performs that transformation for 
> type legalization?

Yes, you need to implement custom lowering to the operations that are 
legal on your target. You cannot call ExpandResInt_Shift because that 
function is not available in target lowering (it's a function in the 
type legalizer). Your lowering to parts will need to combine the results 
into a value of type i64, so that the result type will match the 
original type of the shift.

-Krzysztof

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