[llvm-dev] [GlobalISel] [X86] unable to legalize instruction

Friedman, Eli via llvm-dev llvm-dev at lists.llvm.org
Fri Nov 10 12:16:31 PST 2017

On 11/10/2017 12:00 PM, S. Bharadwaj Yadavalli via llvm-dev wrote:
> Thank you very much for your reply. That helped.
> I spent a little bit of time debugging the failure. It appears that 
> X86LegalizerInfo does not (yet?) set up the required actions and 
> tables for the opcode G_SDIV. I have not looked at GlobalISel phase 
> earlier, but am curious to learn of the reasons for G_SDIV not being 
> supported, yet. Are there any pointers that give some background? Of 
> course, I hope to continue to dig irrespectively (albeit slowly :-)).

The x86 IDIV instruction is a bit unusual; it actually has three 
register inputs.  DAG ISel custom-lowers it; GlobalISel probably needs 
to do the same.


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