[LLVMdev] rol/ror llvm instruction set

[Bill Wendling]

On Tue, Feb 3, 2009 at 2:45 PM, Dale Johannesen <dalej at apple.com> wrote:
>
> On Feb 3, 2009, at 2:35 PMPST, Mike Stump wrote:
>
>> On Feb 3, 2009, at 2:28 PM, Kasra wrote:
>>> I was looking around the LLVM instruction set and I failed to find
>>> ROL and ROR instructions. Is there any plans on adding these
>>> instructions to LLVM?
>>
>> Not sure what you mean:
>
> He's referring to the LLVM IR, I think, and it's true that doesn't
> have rotates.  The LLVM back ends do know about rotate instructions on
> targets that have them, though, and the llvm optimizers are pretty
> smart about recognizing the usual ways to express rotate with shift/
> and/or, as below.
>
Look in the DAGCombiner.cpp file to see which patterns it translates
into ROTL and ROTR instructions.

-bw