svn commit: r316100 - head/sys/boot/i386/boot2

[Ngie Cooper (yaneurabeya)]

> On Mar 28, 2017, at 11:09, Warner Losh <imp at freebsd.org> wrote:
> 
> Author: imp
> Date: Tue Mar 28 18:09:01 2017
> New Revision: 316100
> URL: https://svnweb.freebsd.org/changeset/base/316100
> 
> Log:
>  Remove -fno-guess-branch-probability and -fno-unit-at-a-time.
> 
>  bde enabled -fno-guess-branch-probability in 2003, well before our
>  current compiler was imported. At the time it produced weirdly orded
>  code. It no longer does that. It also saves 0-4 bytes depending on
>  other options.
> 
>  kan disabled unit-at-a-time in 2004 because it badly mangled boot2 so
>  it wouldn't work. That too was before the 4.2.1 compiler, where it no
>  longer does that. This saves 44 bytes.
> 
>  I had planned to document why they were needed, but when I discovered
>  their antiquity, I removed them and boot2 still works and is
>  smaller. In qemu, the old and new boot2's behaved identically.
> 
>  These are gcc specific hacks, and won't affect clang-built boot2
>  at all.

Nice!!!
-Ngie
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