[llvm-commits] [PATCH] LoopVectorizer

[Hal Finkel]

----- Original Message -----
> From: "Nadav Rotem" <nrotem at apple.com>
> To: "Hal Finkel" <hfinkel at anl.gov>
> Cc: "llvm-commits at cs.uiuc.edu LLVM" <llvm-commits at cs.uiuc.edu>, "Ralf Karrenberg" <karrenberg at cdl.uni-saarland.de>
> Sent: Wednesday, October 17, 2012 10:32:20 PM
> Subject: Re: [llvm-commits] [PATCH] LoopVectorizer
> 
> 
> 
> 
> On Oct 17, 2012, at 6:24 PM, Hal Finkel < hfinkel at anl.gov > wrote:
> 
> 
> he current pass handles only fixed trip-count (single-exit) loops
> without inter-iteration dependencies, correct? For this class of
> loops, I believe that what I proposed is correct. Maybe I'm thinking
> about this incorrectly, can you please provide a counterexample?
> 
> 
> Yes. If there are no cross-iteration dependencies then x equals to
> the last SIMD lane. I missed the part which said that there are no
> cross-iteration deps.

Right; my point was that this is exactly the class of loops currently handled by the loop vectorizer. If that is correct, then it would be simple to handle these use-of-last-iteration cases as well.

Thanks again,
Hal

> 

-- 
Hal Finkel
Postdoctoral Appointee
Leadership Computing Facility
Argonne National Laboratory