[wwwdocs] Mention ipa-ICF and auto-FDO

[Kyrill Tkachov]

Hi Honza,

On 21/01/15 21:58, Jan Hubicka wrote:
> Hi,
> these two rather noticeable features are not mentioned.
>
> Honza
>
> Index: changes.html
> ===================================================================
> RCS file: /cvs/gcc/wwwdocs/htdocs/gcc-5/changes.html,v
> retrieving revision 1.69
> diff -u -r1.69 changes.html
> --- changes.html	20 Jan 2015 16:37:54 -0000	1.69
> +++ changes.html	21 Jan 2015 21:57:30 -0000
> @@ -35,7 +35,15 @@
>     <ul>
>       <li>Inter-procedural optimization improvements:
>       <ul>
> -     <li>The devirtualization pass was significantly improved by adding
> +     <li>New identical code folding pass (controled via <code>-fipa-icf</code>).
> +	 Compared to the identical code folding performed by Gold linker this
> +	 pass does not require function sections.  It also performs merging
> +	 pre-inline so inter-procedural optimizations are aware of the
> +	 code re-use. On the other hand not all unifications performed
> +	 by linker are doable by GCC pass; the GCC pass must honnor
s/honnor/honor/

> +	 aliasing information. During link-time optimization of Firefox,
> +	 the pass unify about 29000 functions that is 10% overall</li>
I think it should be "unifies about 29000..."

> +     <li>Devirtualization pass was significantly improved by adding
>   	 better support for speculative devirtualization and dynamic type
>   	 detection. About 50% of virtual calls in Firefox are speculatively
>   	 devirtualized during link-time optimization.</li>
> @@ -72,6 +80,11 @@
>       </ul></li>
>       <li>Feedback directed optimization improvements:
>       <ul>
> +      <li>New auto-FDO mode that use profiles collected by low overhead
s/use/uses/

Cheers,
Kyrill

> +	  profiling tools (perf) instead of more expensive program
> +	  instrumentation (via <code>-fprofile-generate</code>). SPEC2006
> +	  benchmarks improve by 4.7% with auto-FDO and by 7.3% with
> +	  traditional feedback directed optimization.
>         <li>Profile precision was improved in presence of C++ inline and extern
>   	  inline functions.</li>
>         <li>New <code>gcov-tool</code> to manipulate profiles.</li>
>