FDO and LTO on ARM

[Mike Hommey]

On Mon, Aug 08, 2011 at 11:25:56AM +0200, Mike Hommey wrote:
> On Fri, Aug 05, 2011 at 09:32:05AM +0200, Richard Guenther wrote:
> > Well, but unless your training coverage is 100% all parts with no coverage
> > get optimized with -O3 instead of -Os.  And I bet coverage for mozilla
> > isn't even close to 100%.  Thus I think recommending -O3 for FDO is
> > usually a bad idea.
> 
> Experience shows that this isn't true.
> 
> > So - did you try FDO with -O2? ;)
> 
> Leads to roughly the same as -O3+FDO. The apk is also the same size, as
> well as individual libraries.

Actually, I have to revise my result, I had forgottent to change the
optimization level for the javascript engine. The apk and library sizes
are still similar, but the performance is actually slower than both
-O3+PGO and -Os.

Mike