From: Richard Biener <richard.guenther@gmail.com>
To: abenson@carnegiescience.edu
Cc: "fortran@gcc.gnu.org" <fortran@gcc.gnu.org>
Subject: Re: Optimization of add_dt_to_dt_list() in resolve.c
Date: Fri, 25 May 2018 07:06:00 -0000 [thread overview]
Message-ID: <CAFiYyc0Y_tSM-hD51iNJqHdf5QULKNX_aEDHUeeiv+EcTna17g@mail.gmail.com> (raw)
In-Reply-To: <6944935.KTWIneVxun@andrew-precision-3520>
On Fri, May 25, 2018 at 12:53 AM Andrew Benson <abenson@carnegiescience.edu>
wrote:
> I've been attempting to track down some of the causes of very long compile
> times for files which use modules that contain a large number of symbols.
The
> worst case offender in my code takes around 12 minutes to compile.
> After profiling f951 for this source file it turns out that the majority
of the
> time is spent in add_dt_to_dt_list() in resolve.c. In cases where the
number
> of symbols imported becomes very large (~10,000 in some cases in this
code),
> the O(N) search in this function becomes inefficient.
> A simple optimization for this problem seems to be to just have the
gfc_symbol
> struct include a pointer back to the corresponding entry in the
> gfc_derived_types list. It's then fast to check if a symbol is already on
that
> list by checking if this pointer is non-null. (It could just as easily be
an
> int in gfc_symbol which indicates if the symbol is already added to the
list -
> I don't know if having a pointer to the list entry is useful for any other
> reason.)
> With this change in place compile times are much faster - my worst case
> offender now takes just under 1 minute to compile.
> My patch is attached. I freely admit that I have only a very shallow
> understanding of the inner workings of the compiler, so I would not be
> surprised if there are good reasons not to do this. I did "make
check-fortran"
> and did not see any failures. If any one wants to try this out and/or
provide
> any feedback I'd be happy to hear it.
It looks like it would be cheaper to simply embed gtc_dt_list *next in
gfc_symbol?
(in case a gfc_symbol can be only on one gfc_dt_list which your patch
assumes as well)
Richard.
> Thanks,
> Andrew
> --
> * Andrew Benson: http://users.obs.carnegiescience.edu/abenson/contact.html
> * Galacticus: https://bitbucket.org/abensonca/galacticus
next prev parent reply other threads:[~2018-05-25 7:06 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-24 22:53 Andrew Benson
2018-05-25 7:06 ` Richard Biener [this message]
2018-05-25 7:13 ` Richard Biener
2018-05-25 21:54 ` Andrew Benson
2018-05-28 9:54 ` Richard Biener
2018-05-29 20:25 ` Andrew Benson
2018-05-30 9:44 ` Richard Biener
2018-05-30 17:01 ` Andrew Benson
2018-05-30 18:25 ` Steve Kargl
2018-05-30 18:37 ` Andrew Benson
2018-05-30 20:43 ` Janus Weil
2018-05-30 22:22 ` Andrew Benson
2018-05-31 8:56 ` Janus Weil
2018-05-31 18:04 ` Andrew Benson
2018-06-01 6:14 ` Janus Weil
2018-06-11 18:45 ` Steve Kargl
2018-06-11 19:22 ` Andrew Benson
2018-06-14 5:15 ` Andrew Benson
2018-06-15 0:12 ` Steve Kargl
2018-06-15 7:59 ` Andrew Benson
2018-07-11 2:33 ` Andrew Benson
2018-07-20 16:29 ` Andrew Benson
2018-07-20 18:59 ` Janus Weil
2018-07-20 19:02 ` Andrew Benson
2018-07-20 19:10 ` Janus Weil
2018-07-20 20:04 ` Janus Weil
2018-07-20 20:22 ` Andrew Benson
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