[llvm-dev] how to type-legalize a dag

[Krzysztof Parzyszek via llvm-dev]

On 3/18/2016 2:20 PM, Rail Shafigulin wrote:
>
> Given that the action is "Expand" how does legalizer know which
> replacement to use for a given operation?

It's pretty much all hardcoded.  A more complex operation is rewritten 
in terms of simpler operations, which are more likely to be legal.
Look in SelectionDAGLegalize::ExpandNode to see what happens in each case.

-Krzysztof

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