I meant issues of emacs with Ofast. If some things are known to be broken on emacs with this. I'm not sure gcc man will give notes on emacs.

On Wed, Aug 14, 2019, 05:36 Eli Zaretskii <eliz@gnu.org> wrote:

> From: "otadmor ." <otadmor@gmail.com>
> Date: Wed, 14 Aug 2019 00:10:50 +0300
> Cc: oub@mat.ucm.es, emacs-devel@gnu.org
>
> Are there any known issues with Ofast?

Yes, they are described in the GCC manual.