[PATCH][DAG] PR16726: extend rol/ror matching

[Owen Anderson]

LGTM.

—Owen

On Sep 19, 2013, at 12:39 PM, Kai Nacke <kai.nacke at redstar.de> wrote:

> Ping^2.
> 
> Regards
> Kai
> 
> On 15.09.2013 20:00, Kai Nacke wrote:
>> Ping.
>> 
>> On 10.09.2013 01:26, Kai Nacke wrote:
>>> Hi!
>>> 
>>> C-like languages promote types like unsigned short to unsigned int
>>> before performing an arithmetic operation. The rotate matcher in the
>>> DAGCombiner does not consider this situation.
>>> The attached patch extends the DAGCombiner in the way that the pattern
>>> 
>>> (or (shl ([az]ext x), (*ext y)), (srl ([az]ext x), (*ext (sub 32, y))))
>>> 
>>> is folded into
>>> 
>>> ([az]ext (rotl x, y))
>>> 
>>> The matching is restricted to aext and zext because in this cases the
>>> upper bits are either undefined or known. Test case is included.
>>> 
>>> This fixes PR16726.
>>> 
>>> Please review.
>>> 
>>> Regards
>>> Kai
>>> 
>>> 
>>> _______________________________________________
>>> llvm-commits mailing list
>>> llvm-commits at cs.uiuc.edu
>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
>>> 
>> 
>> 
>> 
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