-O3 and -ftree-vectorize

Xinliang David Li davidxl@google.com
Thu Feb 6 19:01:00 GMT 2014


It is a bug in the help message dump. You can see that
ftree-loop-vectorize ftree-slp-vectorize are indeed enabled.

David

On Thu, Feb 6, 2014 at 10:51 AM, Uros Bizjak <ubizjak@gmail.com> wrote:
> Hello!
>
> 4.9 does not enable -ftree-vectorize for -O3 (and Ofast) anymore. Is
> this intentional?
>
> $/ssd/uros/gcc-build/gcc/xgcc -B /ssd/uros/gcc-build/gcc -O3 -Q
> --help=optimizers
>
> ...
> -ftree-vectorize                      [disabled]
> ...
>
> This is the reason for low scores on SciMark v2.0 as conducted by
> Phoronix. Please see comment #18 in [1].
>
> [1] http://phoronix.com/forums/showthread.php?95147-Clang-s-Competition-For-GCC-On-Intel-Haswell/page2
>
> Uros.



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