From: Andrew MacLeod <amacleod@redhat.com>
To: Diego Novillo <dnovillo@redhat.com>
Cc: gcc mailing list <gcc@gcc.gnu.org>
Subject: Re: [tree-ssa] Out of SSA status and issues
Date: Tue, 13 May 2003 12:49:00 -0000 [thread overview]
Message-ID: <1052830148.3299.80.camel@p4> (raw)
In-Reply-To: <1052829209.27232.210.camel@frodo.toronto.redhat.com>
On Tue, 2003-05-13 at 08:33, Diego Novillo wrote:
> On Mon, 2003-05-12 at 14:45, Andrew MacLeod wrote:
>
> > ie it would look something like this hacked up example:
> >
> > # (*T.6)_13 = VDEF <(*T.6)_7>;
> > T.6_12 = T.2_8 + T.5_11;
> >
> > # VUSE <T.6_12>;
> > i_14 = (*T.6)_13
> >
> > # (*T.6)_22 = VDEF <(*T.6)_13>
> > # VUSE <T.6_12>
> > *T.6 = 30;
> > };
> > # i_1 = PHI <i_6(0), (*T.6)_13(1)>;
> >
> > Or is there a reason that copyprop would never happen?
> >
> Correctness wise? No, there's no reason. We can safely do the
> propagation in this case.
>
> But I wouldn't think it's efficient. Pointer dereferences are bound to
> be slower than a straight scalar reference. The copy propagator in the
> SSA renamer blocks propagation of INDIRECT_REF nodes. The stand-alone
> copy propagator should probably do the same.
>
>
but this code is rewritten into:
T.6 = T.2 + T.5
i_14 = *T.6
*T.6 = 30
i_1 = *T.6
Thats not the same meaning at all....
Andrew
next prev parent reply other threads:[~2003-05-13 12:49 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-05-12 14:42 Andrew MacLeod
2003-05-12 15:38 ` Diego Novillo
2003-05-12 15:57 ` Andrew MacLeod
2003-05-12 16:05 ` Michael Matz
2003-05-12 16:10 ` Andrew MacLeod
2003-05-12 16:16 ` law
2003-05-12 17:08 ` law
2003-05-12 17:12 ` Andrew MacLeod
2003-05-12 17:26 ` law
2003-05-12 18:57 ` Andrew MacLeod
2003-05-13 9:07 ` Michael Matz
2003-05-13 12:42 ` Diego Novillo
2003-05-13 12:50 ` Andrew MacLeod
2003-05-13 13:05 ` Diego Novillo
2003-05-13 13:29 ` Andrew MacLeod
2003-05-13 13:57 ` Diego Novillo
2003-05-13 12:57 ` Michael Matz
2003-05-13 13:11 ` Diego Novillo
2003-05-13 13:18 ` Andrew MacLeod
2003-05-14 17:19 ` Jan Vroonhof
2003-05-14 18:05 ` Andrew MacLeod
2003-05-14 18:33 ` Diego Novillo
2003-05-14 19:11 ` Daniel Berlin
2003-05-13 15:01 ` Daniel Berlin
2003-05-13 12:33 ` Diego Novillo
2003-05-13 12:49 ` Andrew MacLeod [this message]
2003-05-13 12:58 ` Diego Novillo
2003-05-13 13:17 Richard Kenner
2003-05-13 13:27 ` Diego Novillo
2003-05-13 13:40 ` Michael Matz
2003-05-13 15:08 ` Michael S. Zick
2003-05-13 13:42 Richard Kenner
2003-05-13 15:23 Richard Kenner
2003-05-13 18:50 ` Geoff Keating
2003-05-13 23:28 ` Michael S. Zick
2003-05-17 17:19 ` Michael S. Zick
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