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Re: [PATCH][RFC] Instrument alias oracle
- From: Diego Novillo <dnovillo at google dot com>
- To: Richard Guenther <rguenther at suse dot de>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Fri, 6 Feb 2009 10:00:00 -0500
- Subject: Re: [PATCH][RFC] Instrument alias oracle
- References: <alpine.LNX.2.00.0902061506110.11836@zhemvz.fhfr.qr>
On Fri, Feb 6, 2009 at 09:16, Richard Guenther <rguenther@suse.de> wrote:
> As a different but iteresting instrumentation kind the patch
> instruments all different disambiguations in refs_may_alias_p
> with statistic counters, only bailing out on must-aliases but
> continuing to count other disambiguators even if a previous
> one said no-alias. This allows telling apart the most effective
> disambiguators and may help sorting them. This instrumentation
> is costly as well, and somehow even makes the code more ugly.
Well, it's not pretty, but with adequate commentary in the macros it's
not too bad. I think it will provide useful information, so I'm
willing to put up with the macro hackery.
> So - do we just want to attribute all alias-oracle time to
> a single timevar? Which also uglifies code as you have to
> pop the timevar on every function exit, like for example if
> one would push at the entry of refs_may_alias_p.
I was thinking of having a set of timers for each of the most popular
external entry points. If the API is very wide, then simply have a
set of 5 timers (to pick a random smallish number) and put those
timers at the entry points of the 5 most popular entry points.
Diego.