R600: Add BFE DAG combines

Tue May 13 15:47:46 PDT 2014

On Mon, May 12, 2014 at 11:46:39AM -0700, Matt Arsenault wrote:
> 
> On Apr 25, 2014, at 1:57 PM, Matt Arsenault <arsenm2 at gmail.com> wrote:
> 
> > These patches allow some simplifications of BFE nodes. I just noticed the instruction patterns aren’t actually trying to match the BFE pattern, but that can be fixed later
> > 
> > 
> > <0001-R600-Implement-computeMaskedBitsForTargetNode-for-BF.patch><0002-R600-Implement-ComputeNumSignBitsForTargetNode-for-B.patch><0003-R600-Add-dag-combine-for-BFE.patch><0004-R600-Try-to-convert-BFE-back-to-standard-bit-ops-whe.patch>
> 
> Ping

Can you explain the purpose of patch #4?  I don't understand why we are
converting BFE back to bit ops.

-Tom