[LLVMdev] [X86] DAG Combine - VSELECT

[Juergen Ributzka]

Hi @ll,

I am wondering about the use of !isBeforeLegalize in PerformSELECTCombine in the X86 backend. This defers all VSELECT related DAG combines until after the Legalizer has run. If the IR has already only legal types the second round of DAG combines is skipped and no VSELECT specified optimizations are performed at all.

Is there a reason we don’t run the X86 DAG combiner before Type Legalization?

Thanks

Cheers,
Juergen