[llvm] r179511 - Document our desire to enable the loop vectorizer on -Os in future releases.

[Nadav Rotem]

On Apr 15, 2013, at 1:33 AM, Chandler Carruth <chandlerc at google.com> wrote:

> On Sun, Apr 14, 2013 at 10:56 PM, Nadav Rotem <nrotem at apple.com> wrote:
> Author: nadav
> Date: Mon Apr 15 00:56:55 2013
> New Revision: 179511
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=179511&view=rev
> Log:
> Document our desire to enable the loop vectorizer on -Os in future releases.
> 
> Perhaps I've missed it, but is there somewhere a discussion of this?
> For example, why, what the requirements are, what is being measured? 

We talked about it in the Vectorization BOF at the last developers meeting. For -Os, the idea is to enable vectorization for two scenarios. First, we want to vectorize a very small number of hot loops because its worth the increase in code size. And the second kind of loops is loops that can be vectorized without any code size increase. We already check for the 'optsize' attribute and don't vectorize loops that require a scalar tail loop. 
 
> 
> Modified:
>     llvm/trunk/docs/Vectorizers.rst
> 
> Modified: llvm/trunk/docs/Vectorizers.rst
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/docs/Vectorizers.rst?rev=179511&r1=179510&r2=179511&view=diff
> ==============================================================================
> --- llvm/trunk/docs/Vectorizers.rst (original)
> +++ llvm/trunk/docs/Vectorizers.rst Mon Apr 15 00:56:55 2013
> @@ -22,6 +22,7 @@ Usage
>  -----
> 
>  LLVM's Loop Vectorizer is now enabled by default for -O3.
> +We plan to enable parts of the Loop Vectorizer on -O2 and -Os in future releases.
>  The vectorizer can be disabled using the command line:
> 
>  .. code-block:: console
> 
> 
> _______________________________________________
> llvm-commits mailing list
> llvm-commits at cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
> 
> 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20130415/490eb5c2/attachment.html>