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Re: [PATCH] add statistics counting to postreload, copy-rename, and math-opts
On Tue, Apr 12, 2011 at 04:37:42PM +0200, Richard Guenther wrote:
> On Tue, Apr 12, 2011 at 4:32 PM, Nathan Froyd <froydnj@codesourcery.com> wrote:
> > Thanks. ?I may go twiddle that patch to do something similar to mine and
> > submit that. ?Do you use your patch for checking that the same set of
> > optimizations get performed, then? ?I'm interested in using the
> > statistics for identifying passes that don't buy us much across a wide
> > variety of codebases. ?(Suggestions for suitable ones welcome!)
>
> Yes, I used it exactly for that. And also to verify that passes don't
> do anything if replicated (well, for those that shouldn't at least).
>
> Don't expect any low-hanging fruit though ;) I catched all of it already.
>
> Candidates are obviously SPEC and GCC itself. I also use tramp3d
> of course. That said, even if a pass does nearly nothing we often
> have testcases that need it ...
True, but maybe those testcases should be adjusted--per-pass flags,
rather than blindly assuming -O2 includes them. And it's not clear to
me that the statistics_counter_event infrastructure really helps
catching do-nothing passes, since it doesn't record stats that increment
by zero...
-Nathan