[LLVMdev] Help regarding ad new functionality in Backend

[Tim Northover]

Hi Pratik,

> With respect to the example you mention, I will be having a CPU that can
> execute the sign extended addition as an instruction and its decomposition
> to add and sext won't be required. Since, I will be having a CPU with such
> capabilities, do i still need to such things?

If I understand you correctly, yes you need such things. LLVM's DAGs
are going to have separate "sext" and "add" nodes, so you're going to
have to map those to your single instruction somehow. Put another way,
the input has separate nodes so you can't ignore them completely.

Cheers.

Tim.