[llvm] r179060 - Update the docs about the fact that the loop vectorizer is enabled by default for -O3.

[Hal Finkel]

----- Original Message -----
> From: "Nadav Rotem" <nrotem at apple.com>
> To: llvm-commits at cs.uiuc.edu
> Sent: Monday, April 8, 2013 4:34:50 PM
> Subject: [llvm] r179060 - Update the docs about the fact that the loop	vectorizer is enabled by default for -O3.
> 
> Author: nadav
> Date: Mon Apr  8 16:34:49 2013
> New Revision: 179060
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=179060&view=rev
> Log:
> Update the docs about the fact that the loop vectorizer is enabled by
> default for -O3.
> 
> 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=179060&r1=179059&r2=179060&view=diff
> ==============================================================================
> --- llvm/trunk/docs/Vectorizers.rst (original)
> +++ llvm/trunk/docs/Vectorizers.rst Mon Apr  8 16:34:49 2013
> @@ -21,19 +21,14 @@ The Loop Vectorizer
>  Usage
>  -----
>  
> -LLVM's Loop Vectorizer is now available and will be useful for many
> people.
> -It is not enabled by default, but can be enabled through clang using
> the
> -command line flag:
> +LLVM's Loop Vectorizer is now enabled by default for -O3.
> +The vectorizer can be disabled using the command line:
>  
>  .. code-block:: console
>  
> -   $ clang -fvectorize -O3 file.c
> +   $ clang ... -fno-vectorize  file.c
>  
> -If the ``-fvectorize`` flag is used then the loop vectorizer will be
> enabled
> -when running with ``-O3``, ``-O2``. When ``-Os`` is used, the loop
> vectorizer
> -will only vectorize loops that do not require a major increase in
> code size.
> -
> -We plan to enable the Loop Vectorizer by default as part of the LLVM
> 3.3 release.
> +At this point the loop vectorizer is only enabled for -O3, and will
> not work for -O2 or -Os.

This makes it sound like -O2 -fvectorize will not vectorize at all. Is that right?

 -Hal

>  
>  Command line flags
>  ^^^^^^^^^^^^^^^^^^
> 
> 
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