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From: "law at redhat dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/35545] virtual call specialization not happening with FDO
Date: Tue, 17 Dec 2013 20:53:00 -0000 [thread overview]
Message-ID: <bug-35545-4-ShTwnNmsVl@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-35545-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=35545
--- Comment #8 from Jeffrey A. Law <law at redhat dot com> ---
It's not a matter of cost model, but if propagating the values to their uses.
I haven't looked closely at the tracer, but wouldn't it benefit by having
constants in particular propagated to their uses?
Yes, DOM's duplication/isolation of paths exposes the degenerate PHIs. So we
might have had:
One of the nice side effects of jump threading is that it isolates paths. So
we might have had
BBn
x = phi (a, b, c, constant, d, e, f)
duplication for threading might turn that into
BBn:
x = phi (a, b, c, d, e, f) // The original
elsewhere
BBm:
x' = phi (constant) // the duplicate
Propagating the constant for x' in BBm and eliminating the degenerate is what
the phi-only cprop pass does. If the tracer generates similar things, then
running phi-only cprop after it might be useful as well. It *should* be very
fast.
next prev parent reply other threads:[~2013-12-17 20:53 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <bug-35545-4@http.gcc.gnu.org/bugzilla/>
2013-12-17 16:34 ` hubicka at gcc dot gnu.org
2013-12-17 17:29 ` hubicka at gcc dot gnu.org
2013-12-17 18:06 ` rguenther at suse dot de
2013-12-17 18:09 ` hubicka at gcc dot gnu.org
2013-12-17 20:33 ` law at redhat dot com
2013-12-17 20:39 ` hubicka at ucw dot cz
2013-12-17 20:53 ` law at redhat dot com [this message]
2013-12-17 21:15 ` hubicka at ucw dot cz
2014-09-25 21:29 ` hubicka at gcc dot gnu.org
2014-09-26 7:44 ` [Bug middle-end/35545] tracer pass is run too late rguenth at gcc dot gnu.org
2014-09-26 15:52 ` law at redhat dot com
2014-09-27 0:04 ` hubicka at gcc dot gnu.org
2014-09-27 0:14 ` hubicka at gcc dot gnu.org
2014-09-27 0:23 ` xinliangli at gmail dot com
2014-09-27 1:04 ` hubicka at ucw dot cz
2014-09-28 18:22 ` xinliangli at gmail dot com
2014-09-29 8:17 ` rguenther at suse dot de
2014-09-29 10:22 ` rguenther at suse dot de
2014-09-29 16:48 ` hubicka at ucw dot cz
2014-09-29 19:30 ` xinliangli at gmail dot com
2014-10-01 11:30 ` mliska at suse dot cz
2008-03-12 5:56 [Bug middle-end/35545] New: virtual call specialization not happening with FDO xinliangli at gmail dot com
2008-03-12 6:08 ` [Bug middle-end/35545] " pinskia at gcc dot gnu dot org
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