From: Richard Guenther <richard.guenther@gmail.com>
To: Mikael Pettersson <mikpe@it.uu.se>
Cc: Hans-Peter Nilsson <hp@bitrange.com>,
Richard Henderson <rth@redhat.com>,
Michael Walle <michael@walle.cc>,
gcc@gcc.gnu.org
Subject: Re: libgcc: strange optimization
Date: Tue, 02 Aug 2011 09:47:00 -0000 [thread overview]
Message-ID: <CAFiYyc0uPz9SXg68VLzSna7RwucZjc6B9paOzvO0XCBTdJTiWw@mail.gmail.com> (raw)
In-Reply-To: <20023.47611.116809.875356@pilspetsen.it.uu.se>
On Tue, Aug 2, 2011 at 10:48 AM, Mikael Pettersson <mikpe@it.uu.se> wrote:
> Hans-Peter Nilsson writes:
> > On Mon, 1 Aug 2011, Richard Henderson wrote:
> >
> > > On 08/01/2011 01:30 PM, Michael Walle wrote:
> > > > 1) function inlining
> > > > 2) deferred argument evaluation
> > > > 3) because our target has no barrel shifter, (arg >> 10) is emitted as a
> > > > function call to libgcc's __ashrsi3 (_in place_!)
> > > > 4) BAM! dead code elimination optimizes r8 assignment away because calli
> > > > may clobber r1-r10 (callee saved registers on lm32).
> > >
> > > I'm afraid the only solution I can think of is to force F1 out-of-line.
> >
> > Or another temporary - but the parameter should already have
> > that effect.
>
> It should, but doesn't. See PR48863 for similar breakage on ARM.
On GIMPLE we don't see either the libcall nor those "dependencies".
Don't use register vars.
Richard.
> /Mikael
>
next prev parent reply other threads:[~2011-08-02 9:47 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-08-01 20:30 Michael Walle
2011-08-01 20:51 ` Georg-Johann Lay
2011-08-01 21:14 ` Michael Walle
2011-08-02 6:47 ` Georg-Johann Lay
2011-08-02 6:29 ` Hans-Peter Nilsson
2011-08-01 21:30 ` Richard Henderson
2011-08-02 6:37 ` Hans-Peter Nilsson
2011-08-02 8:49 ` Mikael Pettersson
2011-08-02 9:47 ` Richard Guenther [this message]
2011-08-02 10:02 ` Georg-Johann Lay
2011-08-02 10:11 ` Richard Guenther
2011-08-02 10:55 ` Michael Walle
2011-08-02 12:06 ` Mikael Pettersson
2011-08-02 12:23 ` Richard Guenther
2011-08-02 12:36 ` Georg-Johann Lay
2011-08-02 12:54 ` Hans-Peter Nilsson
2011-08-02 13:09 ` Richard Guenther
2011-08-02 13:16 ` Hans-Peter Nilsson
2011-08-03 4:59 ` Miles Bader
2011-08-02 13:23 ` Ian Lance Taylor
2011-08-02 13:42 ` Richard Guenther
2011-08-02 14:35 ` Ian Lance Taylor
2011-08-03 9:12 ` Ulrich Weigand
2011-08-03 9:51 ` Georg-Johann Lay
2011-08-03 10:04 ` Richard Guenther
2011-08-03 13:27 ` Michael Matz
2011-08-03 14:02 ` Richard Guenther
2011-08-03 14:55 ` Georg-Johann Lay
2011-08-03 15:05 ` Richard Henderson
2011-08-04 0:20 ` Hans-Peter Nilsson
2011-08-04 7:29 ` Andreas Schwab
2011-08-04 13:04 ` Hans-Peter Nilsson
2011-08-04 9:51 ` Andrew Haley
2011-08-04 9:52 ` Richard Guenther
2011-08-04 11:11 ` Andrew Haley
2011-08-04 11:20 ` Richard Guenther
2011-08-04 14:46 ` Andrew Haley
2011-08-06 15:00 ` Paolo Bonzini
2011-08-08 8:06 ` Richard Guenther
2011-08-08 10:59 ` Paolo Bonzini
2011-08-02 16:03 ` Richard Henderson
2011-08-02 20:10 ` Richard Guenther
2011-08-02 17:21 ` Georg-Johann Lay
2011-08-09 16:55 ` Richard Earnshaw
2011-08-09 17:24 ` Ulrich Weigand
2011-08-09 19:48 ` Hans-Peter Nilsson
2011-08-10 0:40 ` Hans-Peter Nilsson
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