[LLVMdev] [PATCH] Emit rbit, clz on ARM for __builtin_ctz

Jakob Stoklund Olesen
Tue, 19 Jan 2010 01:10:39 -0000

On Jan 15, 2010, at 10:03 AM, Chris Lattner wrote:
>
> When/if another target wants this, we could add a ISD::RBIT operation,
> it doesn't need to be added at the llvm ir level,

Blackfin can add with backwards carry, essentially doing

(rbit (add (rbit a), (rbit b)))

This is used for FFTs.

I wasn't hoping to be able to pattern-match something so complicated.