[LLVMdev] TableGen: NumResults <= 1 restriction

Chris Lattner clattner at apple.com
Wed May 13 10:14:26 PDT 2009


On May 13, 2009, at 7:22 AM, Stripf, Timo wrote:

> Hi all,
>
> i’m working atm on a backend for a processor architecture that is  
> capable of storing the carry flag of ADDC in an 1-bit register  
> class. So I tried to lower the ADDC instruction to generate two  
> register values as result. On the tablegen description of the  
> instruction i came across the tablegen restriction that only one  
> output result of one instruction is possible:
>
>   assert(NumResults <= 1 &&
>          "We only work with nodes with zero or one result so far!");
>
> So my question is now how much work it would be to remove this  
> restriction in tablegen. What do I have to take into consideration?
>

I don't know offhand, but this would be a very welcome improvement!

-Chris

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